Sustainable Environmental Technologies

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.5	5.3	2011	17.8 Days	CHF 2400
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600
Environments environments	3.5	5.7	2014	25.7 Days	CHF 1800
Toxics toxics	3.9	4.5	2013	15.6 Days	CHF 2600
Water water	3.0	5.8	2009	16.5 Days	CHF 2600

24 pages, 1526 KiB

Open AccessArticle

Life Cycle Assessment of Four Floating Wind Farms around Scotland Using a Site-Specific Operation and Maintenance Model with SOVs

by Iain A. Struthers, Nadezda Avanessova, Anthony Gray, Miriam Noonan, R. Camilla Thomson and Gareth P. Harrison

Energies 2023, 16(23), 7739; https://doi.org/10.3390/en16237739 - 23 Nov 2023

Viewed by 1977

Abstract

This paper presents a life cycle assessment (LCA) of the International Energy Agency (IEA) 15 MW Reference Wind Turbine (RWT), on floating platforms, deployed in commercial-scale arrays at multiple locations around Scotland in the ScotWind leasing round. Site-specific energy production and vessel operations [...] Read more.

This paper presents a life cycle assessment (LCA) of the International Energy Agency (IEA) 15 MW Reference Wind Turbine (RWT), on floating platforms, deployed in commercial-scale arrays at multiple locations around Scotland in the ScotWind leasing round. Site-specific energy production and vessel operations are provided by a dedicated offshore wind farm operations and maintenance (O&M) model, COMPASS, allowing service operation vessel (SOV) O&M impacts to be assessed with increased confidence. For climate change, the median global warming impact varied from 17.4 to 26.3 gCO₂eq/kWh across the four sites within a 95% confidence interval using an uncertainty assessment of both foreground and background data. As is common with other offshore renewable energy systems, materials and manufacture account for 71% to 79% of global warming impact, while O&M comprise between 9% and 16% of the global warming impacts. High-voltage direct current (HVDC) export cables, floating platforms, and composite blades are significant contributors to the environmental impacts of these arrays (by mass and material choice), while the contributions from ballast, vessel transportation emissions, and power-train components are lower. The results suggest that material efficiencies, circularity, and decarbonizing material supply inventories should be a priority for the Scottish floating wind sector, followed by minimizing vessel operations and the decarbonization of vessel propulsion, while avoiding burden shifting to other impact categories. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 23104 KiB

Open AccessArticle

Multi-Indicator Weighted Robustness Analysis of Planktonic Community Systems under Different Destructive Factors

by Danfeng Zhao, Tao Zhang, Tianwen Chen, Qi He and Dongmei Huang

Appl. Sci. 2023, 13(15), 8742; https://doi.org/10.3390/app13158742 - 28 Jul 2023

Viewed by 927

Abstract

Marine plankton communities play a vital role in global carbon and nutrient cycles. Ensuring the robustness of these intricate ecosystems is critical for sustainable environmental management. In this paper, we apply complex network analysis to assess plankton community resilience against disturbances. We construct [...] Read more.

Marine plankton communities play a vital role in global carbon and nutrient cycles. Ensuring the robustness of these intricate ecosystems is critical for sustainable environmental management. In this paper, we apply complex network analysis to assess plankton community resilience against disturbances. We construct ecological interaction networks and simulate disruptions using four attack strategies targeting vertices and edges. Our multi-indicator evaluation scheme provides a more nuanced measure of robustness compared to single metrics. Our experiments revealed varying vulnerabilities across networks. Targeted attacks caused abrupt collapse, while random failures led to gradual decline. Identifying critical species and linkages is key to guiding protection efforts. Overall, plankton networks proved fragile, especially against deliberate attacks on central hubs. In our simulations, betweenness-based attacks were the most destructive. The multi-indicator robustness coefficient achieved better performance than individual metrics, with under 3% variance. This network methodology reveals hidden topological vulnerabilities and complements traditional plankton research. The quantitative insights provided in this paper can support marine conservation and governance. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 6128 KiB

Open AccessArticle

Development and Evaluation of Cow Dung Composting Equipment with Ventilation and Heating

by Kailin Ren, Lide Su, Yong Zhang, Xiang He and Hao Wu

Appl. Sci. 2023, 13(15), 8649; https://doi.org/10.3390/app13158649 - 27 Jul 2023

Cited by 3 | Viewed by 2435

Abstract

Traditional cow manure composting equipment often lacks ventilation, heating, and real-time monitoring and adjustment capabilities, hindering manure maturation and proper utilization of compost, moisture reduction, and optimal environmental conditions for microbial activity. To address these limitations, we optimized and redesigned the structure and [...] Read more.

Traditional cow manure composting equipment often lacks ventilation, heating, and real-time monitoring and adjustment capabilities, hindering manure maturation and proper utilization of compost, moisture reduction, and optimal environmental conditions for microbial activity. To address these limitations, we optimized and redesigned the structure and control elements of conventional composting equipment. In doing so, we developed a novel cow manure composting apparatus based on the target composting quantity method. The new design features a refined ventilation and heating structure, as well as an enhanced control system using PLC and MCGS. This equipment provides improved composting effects while offering real-time monitoring of composting data, effectively promoting the composting process. Further evaluation of the modified equipment was conducted using fermented cow dung, demonstrating its feasibility. The experiment yielded positive results, indicating that the composted cow manure satisfied all necessary standards across all evaluation parameters. These parameters included the moisture content of the compost, the duration of high temperature, the pH, and the seed germination index. The seed germination rate reaches 85%, and the water content of manure is 9.3%, which is much higher than the industry standard. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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18 pages, 5177 KiB

Open AccessArticle

Stabilization of Road Embankments on Peat Soils Using Oil Shale Ash and Pozzolanic Additives

by Vello Pallav, Tõnis Teppand, Andrus Leinpuu, Merrit Shanskiy, Mait Mets, Hugo Mändar, Ergo Rikmann and Jüri Liiv

Appl. Sci. 2023, 13(14), 8366; https://doi.org/10.3390/app13148366 - 19 Jul 2023

Cited by 4 | Viewed by 1275

Abstract

Using kukersite oil shale ash for the stabilization of organic-rich soils has been extensively studied but without much success. The main reason for this is the retarding effect of humic acids present in organic-rich soils on the formation of the C–S–H (calcium–silicate–hydrate) phase, [...] Read more.

Using kukersite oil shale ash for the stabilization of organic-rich soils has been extensively studied but without much success. The main reason for this is the retarding effect of humic acids present in organic-rich soils on the formation of the C–S–H (calcium–silicate–hydrate) phase, which effectively prevents the solidification of cementitious materials in peat soils. Based on the studies performed at the University of Tartu, we have developed a novel method for the in situ mass stabilization of peat soils using waste materials (calcareous fly ash and silica fume). In this manner, the perfect hardening of peat–ash mixtures (to each 1 m³ of soil, 150–400 kg ash, 25–50 L pozzolanic additives, and 2.5–5 kaNaOH were added) can be achieved. A test road embankment was constructed under extremely hard conditions in a peat quarry that is currently in use. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 4657 KiB

Open AccessArticle

Effects of Wind Barrier Porosity and Inclination on Wind Speed Reduction

by Sang-Hyun Lee, Hyun Kim, Hyunshik Moon, Hyun-Soo Kim, Sang-Sub Han and Seonghun Jeong

Appl. Sci. 2023, 13(14), 8310; https://doi.org/10.3390/app13148310 - 18 Jul 2023

Cited by 1 | Viewed by 1368

Abstract

Wind barriers play a vital role in protecting saplings until maturity when planted as vegetative windbreak forests. Most previous studies have focused on the porosity of wind barriers, but no studies have simultaneously examined the effects of the porosity and inclination, despite the [...] Read more.

Wind barriers play a vital role in protecting saplings until maturity when planted as vegetative windbreak forests. Most previous studies have focused on the porosity of wind barriers, but no studies have simultaneously examined the effects of the porosity and inclination, despite the potential of the inclination to decrease wind speed. We tested three wind barrier cases in wind tunnel experiments: (1) Case A (porosity of 0% with inclinations (90°, 80°, and 70°)), (2) Case B (porosity of 25% with inclinations (90°, 80°, and 70°)), and (3) Case C (porosity of 50% with inclinations (90°, 80°, and 70°)). The vertical and horizontal wind velocities were measured at three vertical and seven horizontal points behind the barriers. The results demonstrated a statistically significant decrease in the correlation between the distance and mean wind velocity for all cases, with up to a six-fold wind protection effect. The wind barrier with 0% porosity and a 90° inclination provided the highest degree of wind protection. However, the wind protection range was limited downwind, and recirculation of wind flow could occur in the leeward direction, potentially damaging saplings. A wind barrier with 50% porosity and 70° inclination sufficiently decreased the wind velocity and prevented recirculation of wind flow, demonstrating that both porosity and inclination considerably impacted the wind protection effect by reducing wind velocity. Our findings offer novel insights into the influence of wind barriers with varying porosities and inclinations and can provide valuable guidance for constructing efficient windbreak forests. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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20 pages, 2760 KiB

Open AccessReview

Artificial Reefs around the World: A Review of the State of the Art and a Meta-Analysis of Its Effectiveness for the Restoration of Marine Ecosystems

by Carolina Bracho-Villavicencio, Helena Matthews-Cascon and Sergio Rossi

Environments 2023, 10(7), 121; https://doi.org/10.3390/environments10070121 - 14 Jul 2023

Cited by 6 | Viewed by 5252

Abstract

Over the past decade, there has been increasing interest in marine restoration, requiring a consideration of various approaches for optimal success. Artificial reefs (ARs) have been employed for marine restoration and fisheries management, but their effectiveness in restoring ecosystems lacks well-defined ecological criteria [...] Read more.

Over the past decade, there has been increasing interest in marine restoration, requiring a consideration of various approaches for optimal success. Artificial reefs (ARs) have been employed for marine restoration and fisheries management, but their effectiveness in restoring ecosystems lacks well-defined ecological criteria and empirical evidence. A systematic review of the literature on ARs articles between 1990–2020, a meta-analysis of their effectiveness based on the similarity of species composition with reference natural reefs (NRs), as well as bias risk analyses were carried out. Research on ARs primarily focused production of marine communities (n = 168). There are important information gaps regarding socioeconomic aspects; design, materials, and disposal in the selected habitats; legal, management, and planning aspects considering long-term monitoring. Regarding effectiveness, few articles (n = 13) allowed comparisons between ARs and NRs, highlighting the need to apply proper reference sites in AR implementations. Meta-analysis showed that ARs are not similar to reference NRs (p = 0.03, common effect and p = 0.05 random effect models). However, a high index of heterogeneity (88%) suggests that this relation may be influenced by factors other than the reef type. Thus, further analysis can disguise variables conditioning this AR–NR similarity as a measure of restoration for degraded marine ecosystems. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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22 pages, 10255 KiB

Open AccessArticle

Definition and Validation of Vineyard Management Zones Based on Soil Apparent Electrical Conductivity and Altimetric Survey

by João Serrano, Vasco Mau, Rodrigo Rodrigues, Luís Paixão, Shakib Shahidian, José Marques da Silva, Luís L. Paniagua and Francisco J. Moral

Environments 2023, 10(7), 117; https://doi.org/10.3390/environments10070117 - 6 Jul 2023

Cited by 3 | Viewed by 2081

Abstract

In the current context of increasing costs of production factors, it is essential to optimize the management of available resources, seeking to incorporate technologies that improve knowledge of the variables involved in the agronomic production process. The aim of this study is to [...] Read more.

In the current context of increasing costs of production factors, it is essential to optimize the management of available resources, seeking to incorporate technologies that improve knowledge of the variables involved in the agronomic production process. The aim of this study is to define and validate management zones (MZ) in a 3.3 ha vineyard located near Évora, in the South of Portugal. A contact sensor (“Veris 2000 XA”) was used to map soil apparent electrical conductivity (EC_a) and a precision altimetric survey of the field was carried out with a global navigation satellite system receiver (GNSS). The results of these surveys were submitted to geostatistical treatments that allowed the definition of three MZ (less, intermediate, and more productive potential). The validation of such MZ was carried out by laboratory analysis of soil samples (texture, pH, organic matter—OM, moisture content, phosphorous, potassium, exchange bases, and cation exchange capacity—CEC), measurements of soil compaction (cone index—CI) with an electronic cone penetrometer, and through indices (Normalized Difference Vegetation Index—NDVI, and Normalized Difference Water Index—NDWI) obtained by remote sensing (RS) using Sentinel-2 satellite images. All these parameters (soil parameters and RS indices) proved the validity of the MZ (of less, intermediate, and more productive potential) defined from the EC_a and altimetric survey. This validation attests to the interest of expeditious technological tools for monitoring EC_a as a fundamental step in implementing smart agronomic decision-making processes. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 1823 KiB

Open AccessArticle

Assessment of the Impact of a New Industrial Discharge on an Urban Wastewater Treatment Plant: Proposal for an Experimental Protocol

by Maria Cristina Collivignarelli, Francesca Maria Caccamo, Stefano Bellazzi, Alessandro Abbà and Giorgio Bertanza

Environments 2023, 10(7), 108; https://doi.org/10.3390/environments10070108 - 22 Jun 2023

Cited by 3 | Viewed by 2042

Abstract

Assessing the compatibility of industrial discharges with the biological process of a municipal wastewater treatment plant (WWTP) may represent a critical task. Indeed, either focusing only on chemical characterization or ecotoxicity tests designed to assess the impact on surface waters may lead to [...] Read more.

Assessing the compatibility of industrial discharges with the biological process of a municipal wastewater treatment plant (WWTP) may represent a critical task. Indeed, either focusing only on chemical characterization or ecotoxicity tests designed to assess the impact on surface waters may lead to questionable or misleading conclusions. The feasibility of an industrial connection to the sewer should better take into account the features of the downstream WWTP, in particular by studying the potential effects on the biomass of that specific plant. With this aim, a multi-step experimental protocol applicable by water utilities has been proposed: (step 1) calculation of the flow rate/load ratio between industrial discharge (ID) and urban wastewater (WW); (step 2) analysis of the modified operating conditions of the biological stage; (step 3) experimental assessment of the impact of the ID on the WWTP biomass by means of respirometric tests. An application of this protocol is presented in this work as a case study, namely a new ID (average flowrate 200 m³ d⁻¹) coming from an aqueous waste treatment plant (AWTP) to be connected to the public sewer. The integrated evaluation of results showed that no negative impacts could be expected on the downstream urban activated sludge WWTP (treating a flow rate of around 45,000 m³ d⁻¹). Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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24 pages, 2333 KiB

Open AccessReview

Practices for Eutrophic Shallow Lake Water Remediation and Restoration: A Critical Literature Review

by Antônio Cavalcante Pereira and Catherine N. Mulligan

Water 2023, 15(12), 2270; https://doi.org/10.3390/w15122270 - 17 Jun 2023

Cited by 10 | Viewed by 6252

Abstract

Lake water has been impaired with nutrients due to the synergic action of human-made activities and climate change. This situation is increasing eutrophication around the globe faster than before, causing water degradation, loss of its uses, and water-associated economic and health effects. Following [...] Read more.

Lake water has been impaired with nutrients due to the synergic action of human-made activities and climate change. This situation is increasing eutrophication around the globe faster than before, causing water degradation, loss of its uses, and water-associated economic and health effects. Following the Sustainable Development Goal 6, more precisely its target 6.6, nations are already behind schedule in protecting and restoring water-related ecosystems (i.e., rivers and lakes). As concerns with eutrophication are escalating, eutrophic water remediation practices are the keys for restoring those lake waters. Diverse methodologies have been investigated focusing on the nutrient that limit primary productivity (i.e., phosphorus), but few have been applied to in-lake eutrophic water remediation. Thus, the objective of this paper is to provide an overview and critical comments on approaches and practices for facing eutrophic lake water remediation. Information on the successful cases and possible challenges/difficulties in the peer-reviewed literature are presented. This should be useful for supporting further remediation project selection by the stakeholders involved. In summary, for a successful and durable restoration project, external nutrient inputs need to be managed, followed by holistic and region-specific methods to attenuate internal legacy nutrients that are continually released into the water column from the sediment. When aligned well with stakeholder participation and continuous monitoring, these tools are the keys to long-lasting water restoration. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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20 pages, 746 KiB

Open AccessEditor’s ChoiceReview

Review on Separation Processes of End-of-Life Silicon Photovoltaic Modules

by Jongwon Ko, Kyunghwan Kim, Ji Woo Sohn, Hongjun Jang, Hae-Seok Lee, Donghwan Kim and Yoonmook Kang

Energies 2023, 16(11), 4327; https://doi.org/10.3390/en16114327 - 25 May 2023

Cited by 6 | Viewed by 3964

Abstract

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, [...] Read more.

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, in addition to silicon-based solar cells. The latter is the most widely commercialized type of solar cell because of its exceptional durability, long-term stability, and high photoconversion efficiency; consequently, the demand for Si solar cells has been consistently increasing. PV modules are designed for an operation lifespan of 25–30 years, which has led to a gradual increase in the number of end-of-life PV modules. The appropriate management of both end-of-life and prematurely failed PV modules is critical for the recovery and separation of valuable and hazardous materials. Effective methods for end-of-life PV waste management are necessary to minimize their environmental impact and facilitate transition to a more sustainable and circular economy. This paper offers a comprehensive overview of the separation processes for silicon PV modules and summarizes the attempts to design easily recyclable modules for sustainable solar module development. Based on the studies summarized in this paper, suggestions are provided for future research. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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21 pages, 625 KiB

Open AccessArticle

Can Green-Technology Innovation Reduce Atmospheric Environmental Pollution?

by Jingkun Zhou, Yunkai Zhou and Xu Bai

Toxics 2023, 11(5), 403; https://doi.org/10.3390/toxics11050403 - 24 Apr 2023

Cited by 5 | Viewed by 2336

Abstract

Rapid economic growth leads to such problems as resource scarcity and environmental degradation. Local governments successively take measures such as technological innovation to solve atmospheric environmental pollution; however, technological innovation fails to fundamentally alleviate atmospheric environmental pollution. Therefore, local governments come to realize [...] Read more.

Rapid economic growth leads to such problems as resource scarcity and environmental degradation. Local governments successively take measures such as technological innovation to solve atmospheric environmental pollution; however, technological innovation fails to fundamentally alleviate atmospheric environmental pollution. Therefore, local governments come to realize the importance of green-technology innovation, which means an inevitable choice for various countries in the world to seek long-term development and win competitive advantage. Under such circumstances, this paper chooses the panel data of 30 provinces and regions in China from 2005 to 2018, takes environmental regulation as the threshold variable, and empirically analyzes the relationship between green-technology innovation and atmospheric environmental pollution by constructing a Spatial Measurement Model and Panel Regression Model. As evinced, green-technology innovation has a significant inhibitory effect and a spatial spillover effect on atmospheric environmental pollution. When environmental regulation reaches a level of intensity, green-technology innovation can effectively curb atmospheric environmental pollution. Accordingly, relevant parties should strengthen green-technology innovation, coordinate the development of the governance system of green-technology innovation, establish a joint prevention and control mechanism, increase the investment in green technology research and development, and augment the role of green-technology innovation. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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14 pages, 6004 KiB

Open AccessEssay

Study on Atomization and Dust Reduction Mechanisms of AEO-9-Charged Solution

by Liying Sun, Shaocheng Ge, Xi Chen and Shuo Liu

Energies 2023, 16(6), 2800; https://doi.org/10.3390/en16062800 - 17 Mar 2023

Cited by 2 | Viewed by 1391

Abstract

To effectively improve the dust reduction rate of fine dust and prevent the occurrence of secondary dust, surfactant-charged water mist dust reduction technology is proposed. First, the water mist induction-charged atomization mechanism was perfected by an induction-charged spray experiment and the optimal atomization-charged [...] Read more.

To effectively improve the dust reduction rate of fine dust and prevent the occurrence of secondary dust, surfactant-charged water mist dust reduction technology is proposed. First, the water mist induction-charged atomization mechanism was perfected by an induction-charged spray experiment and the optimal atomization-charged voltage was determined to be 10 kV. Second, by surface tension and spray experiments on AEO-9-charged solutions, the lower the surface tension and viscosity of the solution, the better the atomization effect; the best atomization solution was 10 kV and 0.02% AEO-9. Finally, according to an electrostatic adsorption experiment, it was identified that there was an electrostatic interaction between coal dust and charged droplets. The contact angle experiment showed that the contact angle of the AEO-9 droplets decreased by 68.44% compared with water after 3 s of contact with coal dust. The wetting effect of bituminous coal was significantly improved by adding AEO-9 to water. A molecular simulation was used to study the molecular interaction mechanism among the H₂O, AEO-9, and bituminous coal molecules. The simulation results showed that AEO-9 was more active than water, it easily interacted with bituminous coal, and the hydrophilic group covered the surface of the bituminous coal molecules, which increased the electrostatic interaction between the water molecules and bituminous coal surface molecules. After adding AEO-9 to H₂O, the intermolecular interaction energy of the H₂O/AEO-9/bituminous coal system was enhanced more than that of the H₂O/bituminous coal system. This study provides the basis for the application of surfactant-charged water mist dust reduction technology. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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43 pages, 1448 KiB

Open AccessReview

A Comprehensive Review of the Current Progress of Chromium Removal Methods from Aqueous Solution

by Md. Monjurul Islam, Anika Amir Mohana, Md. Aminur Rahman, Mahbubur Rahman, Ravi Naidu and Mohammad Mahmudur Rahman

Toxics 2023, 11(3), 252; https://doi.org/10.3390/toxics11030252 - 8 Mar 2023

Cited by 29 | Viewed by 5888

Abstract

Chromium (Cr) exists in aqueous solution as trivalent (Cr³⁺) and hexavalent (Cr⁶⁺) forms. Cr³⁺ is an essential trace element while Cr⁶⁺ is a dangerous and carcinogenic element, which is of great concern globally due to its extensive [...] Read more.

Chromium (Cr) exists in aqueous solution as trivalent (Cr³⁺) and hexavalent (Cr⁶⁺) forms. Cr³⁺ is an essential trace element while Cr⁶⁺ is a dangerous and carcinogenic element, which is of great concern globally due to its extensive applications in various industrial processes such as textiles, manufacturing of inks, dyes, paints, and pigments, electroplating, stainless steel, leather, tanning, and wood preservation, among others. Cr³⁺ in wastewater can be transformed into Cr⁶⁺ when it enters the environment. Therefore, research on Cr remediation from water has attracted much attention recently. A number of methods such as adsorption, electrochemical treatment, physico-chemical methods, biological removal, and membrane filtration have been devised for efficient Cr removal from water. This review comprehensively demonstrated the Cr removal technologies in the literature to date. The advantages and disadvantages of Cr removal methods were also described. Future research directions are suggested and provide the application of adsorbents for Cr removal from waters. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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38 pages, 7113 KiB

Open AccessReview

Pathways for the Valorization of Animal and Human Waste to Biofuels, Sustainable Materials, and Value-Added Chemicals

by Jude A. Okolie, Toheeb Jimoh, Olugbenga Akande, Patrick U. Okoye, Chukwuma C. Ogbaga, Adekunle A. Adeleke, Peter P. Ikubanni, Fatih Güleç and Andrew Nosakhare Amenaghawon

Environments 2023, 10(3), 46; https://doi.org/10.3390/environments10030046 - 6 Mar 2023

Cited by 5 | Viewed by 6256

Abstract

Human and animal waste, including waste products originating from human or animal digestive systems, such as urine, feces, and animal manure, have constituted a nuisance to the environment. Inappropriate disposal and poor sanitation of human and animal waste often cause negative impacts on [...] Read more.

Human and animal waste, including waste products originating from human or animal digestive systems, such as urine, feces, and animal manure, have constituted a nuisance to the environment. Inappropriate disposal and poor sanitation of human and animal waste often cause negative impacts on human health through contamination of the terrestrial environment, soil, and water bodies. Therefore, it is necessary to convert these wastes into useful resources to mitigate their adverse environmental effect. The present study provides an overview and research progress of different thermochemical and biological conversion pathways for the transformation of human- and animal-derived waste into valuable resources. The physicochemical properties of human and animal waste are meticulously discussed, as well as nutrient recovery strategies. In addition, a bibliometric analysis is provided to identify the trends in research and knowledge gaps. The results reveal that the USA, China, and England are the dominant countries in the research areas related to resource recovery from human or animal waste. In addition, researchers from the University of Illinois, the University of California Davis, the Chinese Academy of Sciences, and Zhejiang University are front runners in research related to these areas. Future research could be extended to the development of technologies for on-site recovery of resources, exploring integrated resource recovery pathways, and exploring different safe waste processing methods. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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24 pages, 950 KiB

Open AccessReview

A Review on the Stability, Sustainability, Storage and Rejuvenation of Aerobic Granular Sludge for Wastewater Treatment

by K. S. Shameem and P. C. Sabumon

Water 2023, 15(5), 950; https://doi.org/10.3390/w15050950 - 1 Mar 2023

Cited by 9 | Viewed by 4003

Abstract

Aerobic granular sludge (AGS) is a recent innovative technology and is considered a forthcoming biological process for sustainable wastewater treatment. AGS is composed of the dense microbial consortium of aerobic, anaerobic, and facultative types of bacteria. The mechanism of AGS formation and its [...] Read more.

Aerobic granular sludge (AGS) is a recent innovative technology and is considered a forthcoming biological process for sustainable wastewater treatment. AGS is composed of the dense microbial consortium of aerobic, anaerobic, and facultative types of bacteria. The mechanism of AGS formation and its stability for long-term operation is still a subject of current research. On the other hand, AGS makes the treatment process sustainable in a cost-effective way. However, in order for AGS to be applied in a broader range of applications, there are several challenges to overcome, such as slow-speed granulation and the disintegration of AGS after granulation. Many factors play a role in the stability of granules. The storage of granules and the later use of them for granulation startup is a feasible method for reducing the time for granulation and maintaining stability. This review focuses on the granulation process and characteristics of AGS, granulation time and the stability of AGS under different conditions, the comparison of different storage methods of granules, and their recovery and rejuvenation. From this review, it is evident that additional research is required to assess the effectiveness of regenerated AGS after prolonged storage to promote AGS technology for commercial applications. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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15 pages, 4392 KiB

Open AccessArticle

Comparative Study of Two Organic Wastes as Adsorbents in the Treatment of Water Rich in Nitrogen Compounds

by Thais Fernandes Neulls, Paulo Leonardo Santos Gouveia, Carlos Drielson da Silva Pereira, Camilla Stephane Dias Souza, Fernanda Nayr Sena Chaves, Isabela Nascimento Souza, Rudys Rodolfo de Jesus Tavarez, Amanda Silva dos Santos Aliança, Maria Cláudia Gonçalves, Wolia Costa Gomes, Darlan Ferreira da Silva, Maria Raimunda Chagas Silva, Fabrício Brito Silva, Álvaro Silva Lima, Edelvio de Barros Gomes and Rita de Cássia M. de Miranda

Water 2023, 15(5), 876; https://doi.org/10.3390/w15050876 - 24 Feb 2023

Viewed by 2255

Abstract

Background: The objective of this work was to propose the treatment of the wastewater from Laguna da Jansen using adsorptive processes of residues of pineapple crown and shrimp chitosan. Methods: Residual substrates were distributed in 11 Erlenmeyers, and 250 mL of residual pond [...] Read more.

Background: The objective of this work was to propose the treatment of the wastewater from Laguna da Jansen using adsorptive processes of residues of pineapple crown and shrimp chitosan. Methods: Residual substrates were distributed in 11 Erlenmeyers, and 250 mL of residual pond water were added; the solution was incubated under agitation at the times and amounts established by the Experimental Design (DCCR). After this period, analyses of pH, electrical conductivity, turbidity, nitrate, and nitrite, morphological analyses by SEM, and structural analyses by FTIR and XRD were performed. Results: The FTIR and SEM results showed that the biomass presented active chemical groups and a morphology rich in pores. The experimental design showed that the substrate content was the variable that influenced the lagoon effluent treatments for both tested biomasses; however, when observing the specific values of the response variables, the vegetable adsorbent was more efficient with the conditions of 15g of substrate and 30 days of process. Conclusion: Plant biomass is more efficient in the treatment of effluents rich in organic materials. It can be used in treatment plants as an alternative for the removal of toxic compounds present in wastewater and effluents. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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31 pages, 3033 KiB

Open AccessArticle

Experimental Evaluation of Tubular Flocculator Implemented in the Field for Drinking Water Supply: Application in the Developing World

by Fernando García-Ávila, Angel Méndez-Heredia, Alex Trelles-Agurto, Esteban Sánchez-Cordero, Emigdio Antonio Alfaro-Paredes, Freddy Criollo-Illescas, María D. Tonon-Ordoñez and Gina Heredia-Cabrera

Water 2023, 15(5), 833; https://doi.org/10.3390/w15050833 - 21 Feb 2023

Cited by 3 | Viewed by 3460

Abstract

The purpose of this study was to evaluate the efficiency of a large-scale Horizontal Tubular Flocculator (HTF) as an easy-to-implement technology for potable water provision compared to the efficiency of a traditional baffle flocculator. The HTF was built with a 4-inch diameter PVC [...] Read more.

The purpose of this study was to evaluate the efficiency of a large-scale Horizontal Tubular Flocculator (HTF) as an easy-to-implement technology for potable water provision compared to the efficiency of a traditional baffle flocculator. The HTF was built with a 4-inch diameter PVC pipe and coupled to a sedimentation and filtration process. Experimental tests were performed using lengths of 68.4 m and 97.6 m for the HTF. These lengths were combined with raw water flow rates of 0.25, 0.5, 0.75, 1, and 2 L/s and five turbidity ranges <10 NTU, 10–20 NTU, 21–50 NTU, 51–100 NTU, >100 NTU, giving a total of 100 tests for one year. Jar tests were performed to determine the optimal dose of aluminum sulfate used as a coagulant. Hydraulic characteristics such as time of retention (TR) and velocity gradient (G) were evaluated; likewise, plug flow, dead volume, and short-circuit ratios were determined by tracer tests using the Wolf–Resnick model. The average results determined a removal of 98.8% of turbidity and 99.93% of color. The TR varied between 4.62 and 36.97 min and G varied between 6.15 and 109.62 s⁻¹. The results showed that HTF can be useful as a flocculation unit in a purification system. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 4529 KiB

Open AccessArticle

A Machine-Learning-Based Approach to Predict Deforestation Related to Oil Palm: Conceptual Framework and Experimental Evaluation

by Tarek Sboui, Salwa Saidi and Ahmed Lakti

Appl. Sci. 2023, 13(3), 1772; https://doi.org/10.3390/app13031772 - 30 Jan 2023

Cited by 5 | Viewed by 4860

Abstract

Deforestation is recognized as an issue that has negative effects on the ecosystem. Predicting deforestation and defining the causes of deforestation is an important process that could help monitor and prevent deforestation. Deforestation prediction has been boosted by recent advances in geospatial technologies [...] Read more.

Deforestation is recognized as an issue that has negative effects on the ecosystem. Predicting deforestation and defining the causes of deforestation is an important process that could help monitor and prevent deforestation. Deforestation prediction has been boosted by recent advances in geospatial technologies and applications, especially remote sensing technologies and machine learning techniques. This paper highlights the issue of predicting deforestation related to oil palm, which has not been focused on in existing research studies. The paper proposes an approach that aims to enhance the prediction of deforestation related to oil palm plantations and palm oil production. The proposed approach is based on a conceptual framework and an assessment of a set of criteria related to such deforestation. The criteria are assessed and validated based on a sensitivity analysis. The framework is based on machine learning and image processing techniques. It consists of three main steps, which are data preparation, model training, and validation. The framework is implemented in a case study in the Aceh province of Indonesia to show the feasibility of our proposed approach in predicting deforestation related to oil palm. The implementation of the proposed approach shows an acceptable accuracy for predicting deforestation. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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21 pages, 3341 KiB

Open AccessFeature PaperReview

Biomass and Cellulose Dissolution—The Important Issue in Renewable Materials Treatment

by Marta Przypis, Agata Wawoczny and Danuta Gillner

Appl. Sci. 2023, 13(2), 1055; https://doi.org/10.3390/app13021055 - 12 Jan 2023

Cited by 12 | Viewed by 3327

Abstract

Sustainable development strategies, as well as the shift toward a circular bioeconomy, has led to high interest in the development and implementation of technologies that efficiently utilize biomass as a raw material. Switching from fossil-based to bio-based resources requires the consideration of many [...] Read more.

Sustainable development strategies, as well as the shift toward a circular bioeconomy, has led to high interest in the development and implementation of technologies that efficiently utilize biomass as a raw material. Switching from fossil-based to bio-based resources requires the consideration of many new challenges and problems. One of the crucial issues is the solubility of lignocellulose or at least its ingredients. According to the trends and legislation, the selected chemicals and methods of dissolution/treatment should also be environmentally friendly. The pretreatment processes prepare biomass for further transformations (e.g., chemical, thermal including pyrolysis, or biological) to valuable products such as biofuels, bio-oils, Fine Chemicals, solvents, plastics, and many others. This review discusses the latest findings on the dissolution of biomass and its ingredients. The application of novel, green solvents such as ionic liquids or deep eutectic solvents is discussed in detail. The impact of the composition and structure of these solvents on the biomass/cellulose dissolution process, as well as the mechanism of cellulose–ionic liquid interaction, is presented. Some novel achievements in the usage of inorganic salts and specific metal complexes are also overviewed. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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29 pages, 1064 KiB

Open AccessReview

Process Evaluation of Scandium Production and Its Environmental Impact

by Aratrika Ghosh, Soniya Dhiman, Anirudh Gupta and Rohan Jain

Environments 2023, 10(1), 8; https://doi.org/10.3390/environments10010008 - 28 Dec 2022

Cited by 10 | Viewed by 6869

Abstract

With the advancement of technology and a global shift towards clean energy, the need for rare earth metals is increasing. Scandium, a rare earth metal, has been extensively used over the decades in solid oxide fuel cells and aluminum–scandium alloys that have a [...] Read more.

With the advancement of technology and a global shift towards clean energy, the need for rare earth metals is increasing. Scandium, a rare earth metal, has been extensively used over the decades in solid oxide fuel cells and aluminum–scandium alloys that have a vast, evolving market in aerospace, automobiles and 3D printing. However, the market struggles to maintain the supply chain due to expensive production processes and the absence of uniform global distribution of primary sources. Therefore, identification of alternative sources and technological advancements for scandium recovery are needed. To this end, an effort has been made to provide a review of the advances in different technologies applied in scandium recovery from diverse sources. Emphasis has been given to the improvements and upgrades to technologies in terms of environmental impact and recovery efficacy. An attempt has been made to discuss and deliver a clear representation of the challenges associated with every source for scandium recovery and the major developments in solving them. The environmental impact of scandium recovery and recycling has also been discussed. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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25 pages, 1764 KiB

Open AccessReview

Environment Friendly Pretreatment Approaches for the Bioconversion of Lignocellulosic Biomass into Biofuels and Value-Added Products

by Surbhi Sharma, Mei-Ling Tsai, Vishal Sharma, Pei-Pei Sun, Parushi Nargotra, Bijender Kumar Bajaj, Chiu-Wen Chen and Cheng-Di Dong

Environments 2023, 10(1), 6; https://doi.org/10.3390/environments10010006 - 23 Dec 2022

Cited by 49 | Viewed by 10325

Abstract

An upsurge in global population and rapid urbanization has accelerated huge dependence on petroleum-derived fuels and consequent environmental concerns owing to greenhouse gas emissions in the atmosphere. An integrated biorefinery uses lignocellulosic feedstock as raw material for the production of renewable biofuels, and [...] Read more.

An upsurge in global population and rapid urbanization has accelerated huge dependence on petroleum-derived fuels and consequent environmental concerns owing to greenhouse gas emissions in the atmosphere. An integrated biorefinery uses lignocellulosic feedstock as raw material for the production of renewable biofuels, and other fine chemicals. The sustainable bio-economy and the biorefinery industry would benefit greatly from the effective use of lignocellulosic biomass obtained from agricultural feedstocks to replace petrochemical products. Lignin, cellulose, hemicellulose, and other extractives, which are essential components of lignocellulosic biomass, must be separated or upgraded into useful forms in order to fully realize the potential of biorefinery. The development of low-cost and green pretreatment technologies with effective biomass deconstruction potential is imperative for an efficient bioprocess. The abundance of microorganisms along with their continuous production of various degradative enzymes makes them suited for the environmentally friendly bioconversion of agro-industrial wastes into viable bioproducts. The present review highlights the concept of biorefinery, lignocellulosic biomass, and its valorization by green pretreatment strategies into biofuels and other biochemicals. The major barriers and challenges in bioconversion technologies, environmental sustainability of the bioproducts, and promising solutions to alleviate those bottlenecks are also summarized. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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12 pages, 1208 KiB

Open AccessArticle

Optimized Production of Second-Generation Bioethanol from a Spent C4 Grass: Vetiver (Chrysopogon zizanioides)

by Sameer Neve, Dibyendu Sarkar, Zhiming Zhang and Rupali Datta

Energies 2022, 15(24), 9597; https://doi.org/10.3390/en15249597 - 17 Dec 2022

Cited by 5 | Viewed by 1893

Abstract

Vetiver grass (Chrysopogon zizanioides) is well-known for its contaminant phytoextraction potential and its capacity to reduce soil erosion, owing to its massive, dense root system. However, the shoots are not major contributors to either of these processes, and are either not [...] Read more.

Vetiver grass (Chrysopogon zizanioides) is well-known for its contaminant phytoextraction potential and its capacity to reduce soil erosion, owing to its massive, dense root system. However, the shoots are not major contributors to either of these processes, and are either not utilized at all or they become part of the waste stream. It is well-recognized that lignocellulosic biomass can serve as a source of raw material to produce second-generation bioethanol. This study investigated the simultaneous saccharification and fermentation (SSF) of acid–alkali pretreated vetiver (VG) shoots by Saccharomyces cerevisiae. Vetiver shoots were obtained from three sources: (1) shoots from VG grown in clean potting soil, (2) shoots from VG used for antibiotics phytoextraction from a constructed wetland setup, and (3) shoots from VG used for lead phytoextraction during soil remediation. Bioethanol yield from the shoots from clean soil was the highest (19.58 g/L), followed by the one used for lead phytoextraction (19.50 g/L) and the one used for antibiotics phytoextraction (19.17 g/L). Bioethanol yield and quality obtained from these three VG shoots was superior or similar to other C4 grasses used for bioethanol generation. This study successfully demonstrated that spent vetiver biomass after phytoextraction applications can be repurposed to generate high-quality bioethanol. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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34 pages, 2670 KiB

Open AccessReview

Uranium and Fluoride Removal from Aqueous Solution Using Biochar: A Critical Review for Understanding the Role of Feedstock Types, Mechanisms, and Modification Methods

by Anjali Thakur, Rakesh Kumar and Prafulla Kumar Sahoo

Water 2022, 14(24), 4063; https://doi.org/10.3390/w14244063 - 13 Dec 2022

Cited by 6 | Viewed by 3953

Abstract

Uranium (U) and fluoride (F⁻) are the major global geogenic contaminants in aquifers and pose serious health issues. Biochar, a potential adsorbent, has been widely applied to remediate geogenic and anthropogenic contaminants. However, there is a lack of research progress in [...] Read more.

Uranium (U) and fluoride (F⁻) are the major global geogenic contaminants in aquifers and pose serious health issues. Biochar, a potential adsorbent, has been widely applied to remediate geogenic and anthropogenic contaminants. However, there is a lack of research progress in understanding the role of different feedstock types, modifications, adsorption mechanisms on physico-chemical properties of biochar, and factors affecting the adsorption of U and F⁻ from aqueous solution. To fill this lacuna, the present review gives insight into the U and F⁻ removal from aqueous solution utilizing biochar from various feedstocks. Feedstock type, pyrolysis temperature, modifications, solution pH, surface area, and surface-charge-influenced biochar adsorption capacities have been discussed in detail. Major feedstock types that facilitated U and F⁻ adsorption were crop residues/agricultural waste, softwood, grasses, and animal manure. Low-to-medium pyrolyzing temperature yielded better biochar properties for U and F⁻ adsorption. Effective modification techniques were mainly acidic and magnetic for U adsorption, while metal oxides, hydroxides, alkali, and magnetic modification were favourable for F⁻ adsorption. The major mechanisms of U adsorption were an electrostatic attraction and surface complexation, while for F⁻ adsorption, the major mechanisms were ion exchange and electrostatic attraction. Lastly, the limitations and challenges of using biochar have also been discussed. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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13 pages, 3289 KiB

Open AccessArticle

Radioactivity in Soils of Kosovo and Radiological Implications

by Sehad Kadiri, Serdar Dizman, Cafer M. Yeşilkanat, Hamdi Aliu and Gezim Hodolli

Appl. Sci. 2022, 12(19), 9520; https://doi.org/10.3390/app12199520 - 22 Sep 2022

Cited by 8 | Viewed by 2904

Abstract

This study was carried out to determine the presence of the main radionuclides from natural and artificial radioactivity in the soil of Kosovo, using gamma-ray spectroscopy. The mean activity concentration for Ra-226, Th-232, K-40, and Cs-137 was 22.32 ± 1.41, 22.14 ± 1.31, [...] Read more.

This study was carried out to determine the presence of the main radionuclides from natural and artificial radioactivity in the soil of Kosovo, using gamma-ray spectroscopy. The mean activity concentration for Ra-226, Th-232, K-40, and Cs-137 was 22.32 ± 1.41, 22.14 ± 1.31, 358.16 ± 8.85, and 12.94 ± 0.44 Bq/kg, respectively. Radium equivalent activity ranged from 47 to 100 Bq/kg. The mean of calculated values for the gamma index (I_γ), external hazard index (H_ex), absorbed dose rate (ADR), annual gonadal dose rate (AGDE), annual effective dose rate (AEDE), and excess lifetime cancer risk (ELCR) were 0.61, 0.22, 40 nGy/h, 275 µSv/year, 49 µSv/year, and 170, respectively. In conclusion, the radiological parameters arising from the soil samples of Kosovo belong to the normal range of radionuclides, compared to those compiled by UNSCEAR from worldwide reports; therefore, health hazards are insignificant. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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14 pages, 3973 KiB

Open AccessArticle

Analysis of Water Quality Improvement Effect of Controlled River by Multi-Functional Weir Operation

by Jin-Kyoung Han, Woo-Suk Jung, Jung-Min Kim, In-Hwan Park and Young-Do Kim

Appl. Sci. 2022, 12(17), 8883; https://doi.org/10.3390/app12178883 - 4 Sep 2022

Cited by 1 | Viewed by 1550

Abstract

In this study, the water quality change in a stagnant controlled river containing hard management structures due to pulsed flow was simulated. The Environmental Fluid Dynamics Code (EFDC) model was used for the water quality change simulation, and the water quality improvement effect [...] Read more.

In this study, the water quality change in a stagnant controlled river containing hard management structures due to pulsed flow was simulated. The Environmental Fluid Dynamics Code (EFDC) model was used for the water quality change simulation, and the water quality improvement effect caused by pulsed flow was simulated for multiple scenarios. Based on Case 1, in which 274.2–291.8 CMS was discharged for five hours, other scenarios, in which the gate was opened by 0.5 m and 1.0 m while the discharge time was doubled, were simulated. On comparing the water level results with the observed data, a relatively positive result of R2 = 0.82 was obtained. The water quality simulation results showed that the concentrations of Chl-a, COD, and T-P were, respectively, approximately 7.7%, 4.5%, and 4.0% higher in Case 2 than in Case 1, 24 h after the start of discharge. Cases 3 and 4, on the other hand, exhibited decreased concentrations of Chl-a, COD, and T-P 24 h after the start of discharge. These results confirm that pulsed flow leads to different water quality improvement effects depending on the discharge amount and duration. Furthermore, the water quality improvement effect was recorded at close to 0% after 72 h in all scenarios. As the water quality improvement effect due to pulsed flow appears within 24 h and almost disappears after 72 h depending on the scenario, a physical solution to this problem is required. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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15 pages, 5565 KiB

Open AccessReview

A Systematic Bibliometric Review of Low Impact Development Research Articles

by Jin You, Xiang Chen, Liang Chen, Jianghai Chen, Beibei Chai, Aiqing Kang, Xiaohui Lei and Shuqian Wang

Water 2022, 14(17), 2675; https://doi.org/10.3390/w14172675 - 29 Aug 2022

Cited by 6 | Viewed by 2566

Abstract

The concept of low impact development (LID) plays a crucial role in rainstorm management and non-point source pollution prevention and control. Sorting and summarizing related research through the knowledge map can objectively present the disciplinary structure, research focus, and research hotspots of the [...] Read more.

The concept of low impact development (LID) plays a crucial role in rainstorm management and non-point source pollution prevention and control. Sorting and summarizing related research through the knowledge map can objectively present the disciplinary structure, research focus, and research hotspots of the LID research. Based on 2103 LID pieces of literature in Chinese and English included in the web of science (WOS) database and China’s integrated knowledge resources system (CNKI) database from 2004 to 2021, this paper aims to perform statistical analysis from three aspects: bibliometrics, keyword hotspot co-occurrence and clustering, and literature co-citation clustering. The obtained results reveal that research on LID-based issues maintains a high degree of enthusiasm in China and abroad, but their corresponding focuses are dissimilar. Foreign research essentially focuses on the environmental field with frequent interdisciplinary phenomena, combining the triple goals of water quality improvement, runoff reduction, and multi-functional expansion, and is committed to solving the impact of uncertain factors on urban stormwater management in extreme climates. Chinese research is mostly aimed at unlocking practical engineering problems, which also leads to the majority of research works in the field of building science and engineering. This is mainly due to a series of water-related problems caused by the change in land use types in China. The researchers have determined the type, quantity, location, and combination of the optimal LID measures by establishing appropriate models, using optimization algorithms, and developing multi-level analysis methods. Although the multi-dimensional results of LID in recent years have greatly expanded the framework paradigm, most of the conducted research works are still biased towards the micro-scale. The present hotspot research considers how to make a macroscopic overall layout and efficiently cooperate with the pipelines network, rivers, and lakes systems to unlock the problems pertinent to urban rainwater and non-point source pollution. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 633 KiB

Open AccessArticle

Rural Households’ Perceptions of the Adoption of Rooftop Solar Photovoltaics in Vhembe District, South Africa

by Ranganai Chidembo, Joseph Francis and Simbarashe Kativhu

Energies 2022, 15(17), 6157; https://doi.org/10.3390/en15176157 - 24 Aug 2022

Cited by 3 | Viewed by 2573

Abstract

Rooftop solar photovoltaics have the potential to successfully electrify rural and scattered communities worldwide. However, access to clean, high-quality, reliable and affordable energy remains elusive for several households in rural areas of the developing world. To fully comprehend, unpack and proffer meaningful solutions [...] Read more.

Rooftop solar photovoltaics have the potential to successfully electrify rural and scattered communities worldwide. However, access to clean, high-quality, reliable and affordable energy remains elusive for several households in rural areas of the developing world. To fully comprehend, unpack and proffer meaningful solutions to this mismatch, energy sources in use and types in areas where rural electrification through solar home systems are profiled. Furthermore, grassroot communities’ perceptions of rooftop solar photovoltaics (PVs) was explored. A case study design was adopted. Thirty (30) households were purposively sampled from three selected villages. Their perceptions on the adoption of solar photovoltaic home systems were analysed qualitatively using Atlas ti 8 software. Thematic network analysis was pursued. Households in the chosen villages use grid connections, paraffin, solar PV, firewood and candles to meet their energy needs. The chosen villages used energy for water heating, refrigeration, cooking, illumination, space heating, entertainment and ironing at the household level. In general, the participating households perceived solar PVs as a relatively cheap, easy-to-use, environmentally friendly alternative energy, and did not demand regular payments once installed. However, there was a discerning perception that solar was a weak technology that could not be relied on because it produces an inferior quality of energy, could be easily stolen and needed high capital investment beyond the reach of many consumers. The results obtained in this study highlight that the solar home system (SHS) rollout should be sensitive to rural communities’ financial situations and be innovative in that low-income households are included. In addition, there is a need for a robust awareness programme that highlights the energy availability, reliability, quality, cost effectiveness and legal, health and safety benefits of the SHS to the rural families in the district. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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14 pages, 2781 KiB

Open AccessArticle

Acoustic Stimulation of Anaerobic Digestion: Effects on Biogas Production and Wastewater Malodors

by John Loughrin, Philip Silva, Nanh Lovanh and Karamat Sistani

Environments 2022, 9(8), 102; https://doi.org/10.3390/environments9080102 - 15 Aug 2022

Cited by 2 | Viewed by 3252

Abstract

Wastewater created from various solid wastes and agricultural residues was treated by anaerobic digestion, and the biogas and wastewater odors were quantified. One digester was exposed to low-frequency sound (<5 kHz) from underwater loudspeakers, while the other received no sonic treatment. It was [...] Read more.

Wastewater created from various solid wastes and agricultural residues was treated by anaerobic digestion, and the biogas and wastewater odors were quantified. One digester was exposed to low-frequency sound (<5 kHz) from underwater loudspeakers, while the other received no sonic treatment. It was hypothesized that low-frequency sound, by accelerating the breakdown of sludge via mechanisms such as cavitation induction and mechanical vibration, and enhancing biogas production, could also affect the concentrations of wastewater odors. During warm seasons, biogas production from the sound-treated digester was 29% higher than that from the control digester, and 184% higher during the cool season. Malodors—Mainly consisting of typical aromatic malodorants such as p-cresol and skatole, aliphatic secondary ketones, and dimethyl disulfide—were quantified. In contrast to the findings for biogas production, little difference was found in the concentrations of volatile compounds in the control and sound-treated digestates. Concentrations of dimethyl polysulfides increased over time in both the control and sound-treated digestates, likely due to the use of recycled system effluent that contained precipitated elemental sulfur. The digestate contained considerable concentrations of volatile fatty acids and ammonium, but due to the near neutral pH of the digestate it was surmised that neither made appreciable contributions to the wastewater’s malodor. However, the volatile fatty acid concentrations were reduced by sonic treatment, which was not unexpected, since volatile fatty acids are precursors to methane. Therefore, although sonic treatment of the anaerobic digestate boosted biogas production, it did not markedly affect the wastewater malodors. The biosynthetic origins of wastewater malodors are discussed in this paper. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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19 pages, 4039 KiB

Open AccessArticle

Hydrophobicity/Oleophilicity of Autoclaved Aerated Concrete (AAC) Grains Coated with Oleic and Stearic Acids for Application as Oil/Water Separating Filtration and Adsorbent Materials in Vietnam

by Akihiro Matsuno and Ken Kawamoto

Environments 2022, 9(8), 101; https://doi.org/10.3390/environments9080101 - 10 Aug 2022

Cited by 2 | Viewed by 4418

Abstract

Separation of oil and water is an effective technique to treat oily wastewater. For examining the applicability of porous grains coated with hydrophobic agents (HA) as low-cost and easily available filtration and adsorbent materials in the separation of oil and water, this study [...] Read more.

Separation of oil and water is an effective technique to treat oily wastewater. For examining the applicability of porous grains coated with hydrophobic agents (HA) as low-cost and easily available filtration and adsorbent materials in the separation of oil and water, this study assessed the hydrophobicity/oleophilicity of porous grains made from autoclaved aerated concrete scrap coated with low-cost and harmless hydrophobic agents such as oleic and stearic acids. Tests using a sessile droplet method showed unique relationships between the contact angles (CA) of water droplets in air (CA_wa), oil droplets in water (CA_ow) and coated HA concentrations. The CA_wa increased linearly with increasing HA concentration and then became almost constant and/or gently increased after a specific point, indicating that a minimum coating amount gives the maximum hydrophobicity to HA-coated porous grains exists. The CA_ow gradually decreased exponentially with increasing HA concentration. In particular, the CA_ow of porous grains coated with stearic acid decreased with increasing of HA concentration in a two-step process. Furthermore, analyses of the Pearson correlation showed that both CA_wa and CA_ow correlated well with the specific surface area (SSA), implying that the SSA is a good indicator as a quick assessment of hydrophobicity/oleophilicity of HA-coated porous grains. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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15 pages, 894 KiB

Open AccessArticle

Biochar Is Not Durable for Remediation of Heavy Metal-Contaminated Soils Affected by Acid-Mine Drainage

by Junhao Qin, Xi Wang, Jidong Ying and Chuxia Lin

Toxics 2022, 10(8), 462; https://doi.org/10.3390/toxics10080462 - 9 Aug 2022

Cited by 4 | Viewed by 2219

Abstract

Biochar is a soil conditioner for enhancing plant growth and reducing plants’ uptake of heavy metals. However, the protonation of biochar surfaces in acid soils can weaken the capacity of biochar to reduce the phytoavailability of soil-borne heavy metals over time. The aim [...] Read more.

Biochar is a soil conditioner for enhancing plant growth and reducing plants’ uptake of heavy metals. However, the protonation of biochar surfaces in acid soils can weaken the capacity of biochar to reduce the phytoavailability of soil-borne heavy metals over time. The aim of this study was to test this hypothesis by performing a plant-growth experiment with five harvest cycles to examine the durability of rice-straw biochar for the remediation of an acidic-mine-water-contaminated soil. The application of the biochar significantly reduced the phytoavailability of the heavy metals and inhibited the plant uptake of cationic heavy metals but not anionic Cr. The beneficial effects of the biochar were weakened with the increasing number of harvest cycles caused by the gradual protonation of the biochar surfaces, which resulted in the desorption of the adsorbed heavy metals. The weakening capacity of the biochar to reduce the heavy-metal uptake by the vegetable plants was more evident for Cu, Zn, and Pb compared to Ni and Cd. The experimental results generally confirmed the hypothesis. It was also observed that the bioaccessible amount of various metals in the edible portion of the vegetable was also reduced as a result of the biochar application. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 1464 KiB

Open AccessArticle

Comprehensive Meta-Analysis of Pathways to Increase Biogas Production in the Textile Industry

by Thuane Mendes Anacleto, Betina Kozlowsky-Suzuki, Alan E. Wilson and Alex Enrich-Prast

Energies 2022, 15(15), 5574; https://doi.org/10.3390/en15155574 - 1 Aug 2022

Cited by 3 | Viewed by 2190

Abstract

The textile industry is one of the largest environmental polluters in the world. Although waste management via anaerobic digestion (AD) is a sustainable strategy to transform waste into clean energy and water recovery, the efficiency of the AD process is reduced by the [...] Read more.

The textile industry is one of the largest environmental polluters in the world. Although waste management via anaerobic digestion (AD) is a sustainable strategy to transform waste into clean energy and water recovery, the efficiency of the AD process is reduced by the presence of recalcitrant materials, chemicals, and toxic contents. This study aims to investigate the performance of several chemical, physical, and biological pretreatments applied to improve the biodegradability of textile waste. We performed a meta-analysis with 117 data extracted from 13 published articles that evaluated the efficiency of pretreatments applied to textile waste prior to AD to increase biogas production measured as methane (CH₄) yield. Even though the majority of the studies have focused on the effect of chemical and physical pretreatments, our results showed that the application of biological pretreatments are more efficient and eco-friendlier. Biological pretreatments can increase CH₄ yield by up to 360% with lower environmental risk and lower operating costs, while producing clean energy and a cleaner waste stream. Biological pretreatments also avoid the addition of chemicals and favor the reuse of textile wastewater, decreasing the current demand for clean water and increasing resource circularity in the textile industry. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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10 pages, 998 KiB

Open AccessArticle

Study on the Method of Household Waste Collection: Case Study

by Mirela Panainte-Lehadus, Mihai Vulpe, Valentin Nedeff, Emilian Mosnegutu, Grzegorz Przydatek, Claudia Tomozei and Dana Chitimus

Appl. Sci. 2022, 12(15), 7490; https://doi.org/10.3390/app12157490 - 26 Jul 2022

Cited by 2 | Viewed by 3166

Abstract

This article presents research on how household waste is collected. An online survey, with 348 participants, from the Romanian region of Bacau, was conducted from October 2018 to May 2019. The online questionnaire included a set of over 40 questions, some with the [...] Read more.

This article presents research on how household waste is collected. An online survey, with 348 participants, from the Romanian region of Bacau, was conducted from October 2018 to May 2019. The online questionnaire included a set of over 40 questions, some with the aim of identifying the nature of the people participating, but most of the questions being designed to determine the collection methods for household waste. The major goal of the current study, as previously stated, was to determine the primary way of collecting household garbage from the public, while also learning various details about the participants, including their residence location, gender, age, and level of education. Referring to the means used for collecting household waste, the following items were noted: trash cans, cardboard boxes, dumpsters, and raffia bags. As a result of the study carried out, the following conclusions were drawn: it was noticed that 70 percent of those who participated in the survey came from urban areas; a larger percentage of female respondents took part in the survey (128 from 348); the majority of respondents were aged 18–29 (182); 178 respondents had a higher education level; collection of household waste in garbage bags represented 62.9 percent of the total collection methods. Following statistical processing of the data, and an overview of the main ways in which household waste was collected, a number of connections were found between the characteristics of the respondents and their household waste collection. What is noteworthy is that the characteristics of the respondents could be grouped into cumulative factors that played an important role in household waste collection: the first group formed by level of education and location of the respondents, and the second group formed by age and gender of the respondents. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 4928 KiB

Open AccessCommunication

Fabrication of Carbon Aerogels Derived from Metal-Organic Frameworks/Carbon Nanotubes/Cotton Composites as an Efficient Sorbent for Sustainable Oil–Water Separation

by Yinyu Sun, Zhongcheng Ke, Caiyun Shen, Ruikang Sun, Qing Wei, Zihan Yin and Wei Yang

Appl. Sci. 2022, 12(14), 7285; https://doi.org/10.3390/app12147285 - 20 Jul 2022

Cited by 6 | Viewed by 1751

Abstract

Due to the continuous occurrence of water pollution problems, practical separation methods for oil–water mixtures have attracted more and more attention. To date, different kinds of materials have been developed with good hydrophobic properties and strong separation ability. Carbon aerogels, as a promising [...] Read more.

Due to the continuous occurrence of water pollution problems, practical separation methods for oil–water mixtures have attracted more and more attention. To date, different kinds of materials have been developed with good hydrophobic properties and strong separation ability. Carbon aerogels, as a promising ideal adsorbent for dealing with oil-spill accidents, have received extensive attention. In this work, zeolitic imidazolate frameworks (ZIFs), nanoparticles, and carbon nanotubes (CNTs) in the three-dimensional (3D) interconnected network structure of cotton balls (CBs) were successfully prepared by a simple and scalable process. The as-prepared carbonized CBs with carbonized ZIF-8 and CNTs (CZIF-8/CNTs/CCBs) were characterized. The oil–water separation performance of the composite was also measured. The results show that the ZIF-8 clusters intercalated with abundant CNTs are fully loaded into the porous structure of the CBs after the in situ synthesis process. Additionally, ZIF-8/CNTs/CBs was carbonized in nitrogen, leading to the formation of CZIF-8/CNTs/CCBs. The prepared material possesses excellent hydrophobicity with a water contact angle of 152.7°, showing good absorption capacities Q₁ in the range of 48 to 84 times its original weight for oil and organic liquids. In addition, CZIF-8/CNTs/CCBs exhibits good recyclability in the absorption–distillation test. In summary, this study proposes a novel and simple method for the preparation of a superhydrophobic material that could have wide application in the separation of oil–water mixtures. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 4248 KiB

Open AccessArticle

Performance Assessment of Concrete Using Discarded Membrane Filter Materials

by Sehwan Park and Junkyeong Kim

Water 2022, 14(14), 2167; https://doi.org/10.3390/w14142167 - 8 Jul 2022

Viewed by 1779

Abstract

Currently, membrane filters, which need to be replaced regularly as they get worn, are used in filtration facilities globally. The old membrane filters and housings become continuous industrial waste and are currently 100% incinerated. To solve this environmental problem, this study proposes the [...] Read more.

Currently, membrane filters, which need to be replaced regularly as they get worn, are used in filtration facilities globally. The old membrane filters and housings become continuous industrial waste and are currently 100% incinerated. To solve this environmental problem, this study proposes the development of an eco-friendly concrete by mixing waste membrane resources with concrete. Through this, the environmental pollution and wastage of resources due to incineration, and the enormous amount of carbon dioxide generated during cement production, can be decreased by reducing the cement required when mixing concrete. To this end, the membrane module outer surface (acrylic butadiene styrene, ABS) and inner membrane (poly vinylidene fluoride, PVDF) were extracted from the waste membrane system and pulverized. Different mix ratios of 1%, 3%, and 5% for replacing cement were used when mixing concrete. The test specimens were then tested and compared with the reference concrete (ordinary Portland cement) specimen. It was confirmed that the compressive strength was high after 28 days in all the specimens to which ABS was added at 1%, 3%, and 5% mix ratios. Therefore, the possibility of technological development of eco-friendly concrete using waste resources from membrane filtration facilities was verified. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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10 pages, 1306 KiB

Open AccessArticle

Effects of Bioliquid Recirculation on Hydrothermal Carbonization of Lignocellulosic Biomass

by Sun-Ju Lee, Min-Ah Oh, Seung-Jin Oh, Na-Hyeon Cho, Young-Yeul Kang and Jai-Young Lee

Energies 2022, 15(13), 4903; https://doi.org/10.3390/en15134903 - 4 Jul 2022

Cited by 2 | Viewed by 1802

Abstract

The characteristics of bioliquid produced through the hydrothermal carbonization (HTC) of wood wastes and the effects of recirculation on hydrochar production were analyzed. The organic acids and total organic carbon of bioliquid increased with progressive recirculation, whereas intermediate byproducts decreased. Hydrochar production by [...] Read more.

The characteristics of bioliquid produced through the hydrothermal carbonization (HTC) of wood wastes and the effects of recirculation on hydrochar production were analyzed. The organic acids and total organic carbon of bioliquid increased with progressive recirculation, whereas intermediate byproducts decreased. Hydrochar production by bioliquid recirculation increased mass yield, carbon content, caloric value, and energy yield of the former, while improving its quality as a solid refuse fuel. We concluded that bioliquid recirculation promoted HTC, as demonstrated by Fourier-transform infrared spectroscopy. Furthermore, contrary to predictions, a relatively constant quantity of bioliquid was generated in each step, indicating that its continuous reuse is feasible. Therefore, bioliquid recirculation can improve hydrochar production while simultaneously mitigating the environmental impact of wastewater generation. This method should be considered an important strategy toward the implementation of carbon-neutrality goals. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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23 pages, 6178 KiB

Open AccessArticle

Parametric Study of Methyl Orange Removal Using Metal–Organic Frameworks Based on Factorial Experimental Design Analysis

by Abdollah Karami, Reem Shomal, Rana Sabouni, Mohammad H. Al-Sayah and Ahmed Aidan

Energies 2022, 15(13), 4642; https://doi.org/10.3390/en15134642 - 24 Jun 2022

Cited by 8 | Viewed by 2653

Abstract

Wastewater treatment plants (WWTPs) are one of the most energy-intensive industries. Every stage of wastewater treatment consumes energy, which is the primary contributor to WWTP costs. Adsorbents and process optimization are critical for energy savings. The removal of dyes from industrial wastewater by [...] Read more.

Wastewater treatment plants (WWTPs) are one of the most energy-intensive industries. Every stage of wastewater treatment consumes energy, which is the primary contributor to WWTP costs. Adsorbents and process optimization are critical for energy savings. The removal of dyes from industrial wastewater by adsorption using commercially available adsorbents is inefficient. Metal–organic frameworks (MOFs) have outstanding properties that can improve separation performance over current commercial adsorbents, and thus, these materials represent a milestone in improving dye removal in water treatment methods. In this work, three types of metal–organic frameworks (Fe-BTC, Cu-BTC, and ZIF-8) have been investigated as prospective adsorbents for methyl orange removal from water in batch setups. The results showed that at 15 mg/L MO initial concentration and 100 mg dosage, Fe-BTC had the highest removal efficiency of 91%, followed by ZIF-8 (63%), and finally Cu-BTC (35%), which exhibited structural damage due to its instability in water. Fe-BTC maintained consistent adsorption capacity over a wide range of pH values. Furthermore, a 2³ full factorial design analysis was implemented to evaluate the conditions for maximum MO-removal efficiency. The main effects, interaction effects, analysis of variance (ANOVA), and the Pareto chart were reported. The statistical analysis demonstrated that the MOF type was the most significant factor, followed by dosage and initial concentration. The analysis indicated that the type of MOF and dosage had a positive effect on the removal efficiency, while the initial concentration had a negative effect. The two-way and three-way interactions were also found to be significant. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 5798 KiB

Open AccessArticle

Predicting Mining Areas Deformations under the Condition of High Strength and Depth of Cover

by Piotr Strzałkowski

Energies 2022, 15(13), 4627; https://doi.org/10.3390/en15134627 - 24 Jun 2022

Cited by 3 | Viewed by 1424

Abstract

This paper presents an analysis of mining area deformations in the rock mass consisting of high depth and strength strata deposited in the cover. The analysis of land surveying results enabled the identification of the parameters required to predict subsidence, which differed from [...] Read more.

This paper presents an analysis of mining area deformations in the rock mass consisting of high depth and strength strata deposited in the cover. The analysis of land surveying results enabled the identification of the parameters required to predict subsidence, which differed from the typical parameters for the Upper Silesian Coal Basin. The parameters of the Budryk–Knothe theory were determined based on the results of geodetic measurements. The calculations of the final state of deformations for planned mining were made using the average and characteristics for the study area parameter values. Based on experience, it is known that the range of subsidence trough depends on the mechanical properties of the rock mass. This study shows that the presence of high-strength rocks also reduces the value of the coefficient of roof control. Subsequently, calculations were made by a computer simulation of longwall mining to determine the course of indices of deformation over time. The calculations were conducted twice: on the assumption that the impact was immediate and on the assumption of the parameter values typical for the basin, and formula expressing the course of subsidence over time with the parameter values based on the measurement results. The obtained distributions of deformation indicators were diametrically opposed to each other. The results of the calculations with the parameter values appropriate for the region indicate that it is possible to carry out a planned mining operation without creating a risk to objects on the surface. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 2212 KiB

Open AccessArticle

Effects of Calcium on the Removal of Ammonium from Aged Landfill Leachate by Struvite Precipitation

by Hussein Rayshouni and Mahmoud Wazne

Water 2022, 14(12), 1933; https://doi.org/10.3390/w14121933 - 16 Jun 2022

Cited by 6 | Viewed by 2458

Abstract

Ammonium in landfill leachates is a major contributor to environmental degradation if not effectively treated. However, it could be converted to a valuable fertilizer when it is co-precipitated with phosphate and magnesium as struvite. Low-cost magnesium and phosphate sources are sought to offset [...] Read more.

Ammonium in landfill leachates is a major contributor to environmental degradation if not effectively treated. However, it could be converted to a valuable fertilizer when it is co-precipitated with phosphate and magnesium as struvite. Low-cost magnesium and phosphate sources are sought to offset the co-precipitation treatment costs, but most of the identified alternative magnesium sources have significant amounts of calcium, which may negatively impact the ammonium removal rates. In this study, the effects of calcium on ammonium removal from high-strength aged field landfill leachate as struvite were investigated. Laboratory-scale batch tests were conducted to assess the effects of the pH, Mg²⁺:NH₄⁺:PO₄³⁻, and Ca²⁺:Mg²⁺ molar ratios on ammonium removal. Magnesium chloride salt was used as a model dissolved magnesium source, whereas different compounds derived from dolomite (CaMg(CO₃)₂) were used as model solid-phase magnesium sources. X-ray powder diffraction and activity ratio diagrams were used to delineate the ammonium removal mechanisms and struvite stability. The ammonium removal rate of the magnesium salt decreased from approximately 97% to 70%, upon increasing the Ca²⁺:Mg²⁺ molar ratio from 0 to 1.0, for the Mg²⁺:NH₄⁺:PO₄³⁻ molar ratio of 1.25:1:1.25 and pH = 9.5. For similar pH values, as well as the Mg²⁺:NH₄⁺:PO₄³⁻ and Ca²⁺:Mg²⁺ molar ratios, the ammonium removal rates by the dolomite-derived compounds reached up to 55%, which highlighted the limited availability of magnesium in solid phases, in addition to the negative impacts of calcium. The diffractometric analysis and thermodynamic calculations revealed the stable regions of struvite in the presence of competing solid phases. The new findings in this study could aid in the design of ammonium and phosphate removal and recovery systems by struvite precipitation. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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12 pages, 3876 KiB

Open AccessArticle

Simulation on the Electric and Thermal Fields of a Microwave Reactor for Ex Situ Biomass Tar Elimination

by Cheng Yang, Kanfeng Ying, Fan Yang, Huanghu Peng and Zezhou Chen

Energies 2022, 15(11), 4143; https://doi.org/10.3390/en15114143 - 4 Jun 2022

Cited by 1 | Viewed by 1654

Abstract

Microwave treatment is an emerging technique for biomass tar elimination. The electric and thermal fields of the microwave reactor are the key to high elimination efficiency and energy utilization. In this work, we simulated the electric and thermal fields of a microwave reactor [...] Read more.

Microwave treatment is an emerging technique for biomass tar elimination. The electric and thermal fields of the microwave reactor are the key to high elimination efficiency and energy utilization. In this work, we simulated the electric and thermal fields of a microwave reactor with various parameters including irradiation feed position, microwave power, silicon carbide length and flow velocity. Results show that the irradiation feed position that locates 5 mm vertically to the central plane can obtain the highest electric intensity and silicon carbide temperature (ca. 1100 K) after wave absorbing. Both the electric and thermal fields are strengthened when microwave power is increased. Extending the silicon carbide bed length will decrease the bed temperature and heating rate. A high flow velocity leads to non-uniform temperature distribution of the silicon carbide. For the purpose of achieving a high microwave energy utilization and uniform bed temperature, suitable irradiation feed position (z_i = 5 mm), high microwave power (P = 1000 W), short silicon carbide bed length (l_SiC = 100 mm) and low flow velocity (v = 0.02 m/s) are preferred, but the chemical kinetics of biomass tar elimination should also be considered in the practical application. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 5274 KiB

Open AccessArticle

Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning

by Xiaoling Yang, Zhefeng Wang, Ze Zhang, Shuangtao Chen, Yu Hou and Liang Chen

Appl. Sci. 2022, 12(10), 5287; https://doi.org/10.3390/app12105287 - 23 May 2022

Cited by 5 | Viewed by 3999

Abstract

As a requirement for sustainable development, air-cycle refrigeration has received wide attention as a candidate for environmentally friendly air conditioning technology. In this study, the thermodynamic performance of air refrigeration cycles is investigated in compartment air conditioning. The effects of compressor efficiency, expander [...] Read more.

As a requirement for sustainable development, air-cycle refrigeration has received wide attention as a candidate for environmentally friendly air conditioning technology. In this study, the thermodynamic performance of air refrigeration cycles is investigated in compartment air conditioning. The effects of compressor efficiency, expander efficiency, ambient humidity, all-fresh-air supply and ambient pressure on the cycle performance are presented. The effects of compressor arrangement in the high-pressure cycle and the low-pressure cycle are compared. An open-loop high-pressure cycle has a larger COP than that of an open-loop low-pressure cycle but requires larger heat exchange. The performance of air refrigeration cycles with full fresh air is studied, and the influence of fresh air is discussed. Schemes for condensed water recirculation with wet compression are proposed, which can improve the COPs of open-loop low-pressure cycles by 44.7%, 48.8% and 48.4%. In the air conditioning of plateau trains, open-loop high-pressure cycles have slightly lower COPs, but they can supply air with elevated pressure and oxygen concentration. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 1195 KiB

Open AccessEditor’s ChoiceReview

Modified Biochars and Their Effects on Soil Quality: A Review

by Abdul Hafeez, Taowen Pan, Jihui Tian and Kunzheng Cai

Environments 2022, 9(5), 60; https://doi.org/10.3390/environments9050060 - 15 May 2022

Cited by 35 | Viewed by 7743

Abstract

Biochar (BC) has attracted attention due to its impacts on soil quality by enhancing soil fertility, carbon storage and contaminants immobilization. BC also induces changes in microbial community structure and enhances crop productivity in long term scenarios compared to many other organic amendments. [...] Read more.

Biochar (BC) has attracted attention due to its impacts on soil quality by enhancing soil fertility, carbon storage and contaminants immobilization. BC also induces changes in microbial community structure and enhances crop productivity in long term scenarios compared to many other organic amendments. However, information related to the role of modified BCs in altering the soil quality is still scarce. BC can be modified by using physical, chemical and microbial methods. Modified BC can change the functional groups, pore size, pore structure, surface area and chemical properties of soil, which plays a key role in changing the soil quality. The addition of modified BCs as soil amendment increased soil CEC (cation exchange capacity), EC (electron conductivity), pH, organic matter, hydraulic conductivity, soil porosity, infiltration rate, microbial activities (enzymes and community), nutrient profile and gas exchange properties, but it varies according to the soil structure and pervading environmental conditions. This study provides a basis for effective practical approaches to modifying BCs for improving soil quality. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 2522 KiB

Open AccessArticle

Fixed-Bed Adsorption of Phenol onto Microporous Activated Carbon Set from Rice Husk Using Chemical Activation

by Samah B. Daffalla, Hilmi Mukhtar, Maizatul S. Shaharun and Abdalhaleem A. Hassaballa

Appl. Sci. 2022, 12(9), 4354; https://doi.org/10.3390/app12094354 - 25 Apr 2022

Cited by 7 | Viewed by 2333

Abstract

In the course of this research, the potential of activated carbon from rice husk was examined as being a phenol removal medium from an aqueous solution in a fixed-bed adsorption column. The activated carbon was characterized through FESEM (Field-Emission Scanning Electron Microscopy) and [...] Read more.

In the course of this research, the potential of activated carbon from rice husk was examined as being a phenol removal medium from an aqueous solution in a fixed-bed adsorption column. The activated carbon was characterized through FESEM (Field-Emission Scanning Electron Microscopy) and BET (Brunauer–Emmett–Teller) surface area. According to the FESEM micrograph and BET surface area, RHAC (rice husk activated carbon) had a porous structure with a large surface area of 587 m²·g⁻¹ and mean diameter of pores of 2.06 nm. The concentration effects on the influent phenol (100–2000 mg·L⁻¹), rate of flow (5–10 mL·min⁻¹), and bed depth (8.5–15.3 cm) were examined. It was found that the capacity of bed adsorption increased according to the increase in the influent concentration and bed depth. However, the capacity of bed adsorption decreased according to the increase in the feed flow rate. The regeneration of activated carbon column using 0.1 M sodium hydroxide was found to be effective with a 75% regeneration efficiency after three regeneration cycles. Data on adsorption were observed to be in line with many well-established models (i.e., Yoon–Nelson and Adams–Bohart, as well as bed depth service time models). Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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13 pages, 1049 KiB

Open AccessArticle

Impact and Challenges of Reducing Petroleum Consumption for Decarbonization

by Ryoma Matsumoto and Tomohiro Tabata

Appl. Sci. 2022, 12(8), 3738; https://doi.org/10.3390/app12083738 - 7 Apr 2022

Cited by 3 | Viewed by 2616

Abstract

This study aimed to identify the impact of achieving the 1.5 °C target on the petroleum supply chain in Japan, and discuss the feasibility and challenges of decarbonization. First, a national material flow was established for the petroleum supply chain in Japan, including [...] Read more.

This study aimed to identify the impact of achieving the 1.5 °C target on the petroleum supply chain in Japan, and discuss the feasibility and challenges of decarbonization. First, a national material flow was established for the petroleum supply chain in Japan, including processes for crude petroleum refining, petroleum product manufacturing, plastic resin and product manufacturing, and by-product manufacturing. In particular, by-product manufacturing processes, such as hydrogen, gaseous carbon dioxide, and sulfur, were selected because they are utilized in other industries. Next, the outlook for the production of plastic resin, hydrogen, dry ice produced from carbon dioxide gas, and sulfur until 2050 was estimated for reducing petroleum consumption required to achieve the 1.5 °C target. As a result, national petroleum treatment is expected to reduce from 177,048.00 thousand kl in 2019 to 126,643.00 thousand kl in 2030 if the reduction in petroleum consumption is established. Along with this decrease, plastic resin production is expected to decrease from 10,500.00 thousand ton in 2019 to 7511.00 thousand ton by 2030. Conversely, the plastic market is expected to grow steadily, and the estimated plastic resin production in 2030 is expected to be 20,079.00 thousand ton. This result indicates that there is a large output gap between plastic supply and demand. To mitigate this gap, strongly promoting the recycling of waste plastics and making the price competitiveness of biomass plastics equal to that of petroleum-derived plastics are necessary. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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32 pages, 1063 KiB

Open AccessReview

Gas Hydrate-Based Heavy Metal Ion Removal from Industrial Wastewater: A Review

by Sirisha Nallakukkala, Adeel ur Rehman, Dzulkarnain B. Zaini and Bhajan Lal

Water 2022, 14(7), 1171; https://doi.org/10.3390/w14071171 - 6 Apr 2022

Cited by 22 | Viewed by 4886

Abstract

Innovating methods for treating industrial wastewater containing heavy metals frequently incorporate toxicity-reduction technologies to keep up with regulatory requirements. This article reviews the latest advances, benefits, opportunities and drawbacks of several heavy metal removal treatment systems for industrial wastewater in detail. The conventional [...] Read more.

Innovating methods for treating industrial wastewater containing heavy metals frequently incorporate toxicity-reduction technologies to keep up with regulatory requirements. This article reviews the latest advances, benefits, opportunities and drawbacks of several heavy metal removal treatment systems for industrial wastewater in detail. The conventional physicochemical techniques used in heavy metal removal processes with their advantages and limitations are evaluated. A particular focus is given to innovative gas hydrate-based separation of heavy metals from industrial effluent with their comparison, advantages and limitations in the direction of commercialization as well as prospective remedies. Clathrate hydrate-based removal is a potential technology for the treatment of metal-contaminated wastewater. In this work, a complete assessment of the literature is addressed based on removal efficiency, enrichment factor and water recovery, utilizing the gas hydrate approach. It is shown that gas hydrate-based treatment technology may be the way of the future for water management purposes, as the industrial treated water may be utilized for process industries, watering, irrigation and be safe to drink. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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9 pages, 1301 KiB

Open AccessArticle

Foliar Application of Wood Distillate Alleviates Ozone-Induced Damage in Lettuce (Lactuca sativa L.)

by Andrea Vannini, Riccardo Fedeli, Massimo Guarnieri and Stefano Loppi

Toxics 2022, 10(4), 178; https://doi.org/10.3390/toxics10040178 - 5 Apr 2022

Cited by 18 | Viewed by 2737

Abstract

This study examined whether foliar applications of wood distillate (WD) have a protective effect on photosynthesis and the antioxidant power of lettuce when exposed to an ecologically relevant O₃ concentration. Seedlings of lettuce (Lactuca sativa L.) were fumigated daily with 60 [...] Read more.

This study examined whether foliar applications of wood distillate (WD) have a protective effect on photosynthesis and the antioxidant power of lettuce when exposed to an ecologically relevant O₃ concentration. Seedlings of lettuce (Lactuca sativa L.) were fumigated daily with 60 ppb of O₃ for 30 days, five hours per day. Once per week, 50% of the fumigated plants were treated with foliar applications of 0.2% WD, while control plants were treated with water. The results clearly showed the ability of WD to protect lettuce plants from ozone-induced damage. Specifically, WD-treated plants exhibited lower damage to the photosynthetic machinery, assessed through a series of chlorophyll fluorescence parameters, a higher chlorophyll content, higher antioxidant power, as well as antioxidant molecules, i.e., caffeic acid and quercetin, and higher biomass. Counteracting the overproduction of ozone-generated reactive oxygen species (ROS) is speculated to be the main mechanism by which WD protects the plant from ozone-induced damage. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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15 pages, 3651 KiB

Open AccessArticle

Open-Loop Exhaust-Gas Cleaning System: Analysis of Effects Produced on Barcelona Port Water pH

by Nelson Gustavo Díaz Delgado and Francesc Xavier Martínez De Osés

Water 2022, 14(7), 1146; https://doi.org/10.3390/w14071146 - 2 Apr 2022

Cited by 2 | Viewed by 3112

Abstract

The implementation of a 0.5% mass/mass sulphur cap in fuels used by ships has become a reality. Furthermore, regulation 14 of the MARPOL Convention–Annex VI (amended) establishes that the limit on fuel used by ships operating in a Sulphur Emission Control Area (SECA) [...] Read more.

The implementation of a 0.5% mass/mass sulphur cap in fuels used by ships has become a reality. Furthermore, regulation 14 of the MARPOL Convention–Annex VI (amended) establishes that the limit on fuel used by ships operating in a Sulphur Emission Control Area (SECA) cannot exceed 0.1% of mass/mass. To deal with these requirements while considering nature of the shipping business, which is the continuous carriage of cargo around the world, shipowners or shipping companies have few options for following this regulation. Apart from the use of a low-sulphur-content fuel is the use of an exhaust-gas cleaning system, also known as “scrubbers”, as an alternative. The use of these systems, specifically the open-loop system, entails the discharge to the sea of residual water used during the cleaning process of exhaust gases from ship engines. The objective of this paper is to study the effect produced by discharging this residual water on the acidity level (pH) of Barcelona port water. This objective was achieved through the periodical sampling and analysis of Barcelona port water in collaboration with the IDAEA (CSIC) laboratory. We analysed the evolution of the pH results obtained so far and obtained an initial picture of the pH Barcelona port water situation in real time regarding the effect of wash-water discharges from open-loop scrubbers. Furthermore, this paper describes the implementation of a system which is going to improve the operation of open-loop exhaust-gas cleaning systems. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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19 pages, 6674 KiB

Open AccessEditor’s ChoiceArticle

Stabilisation of Ozone in Water for Microbial Disinfection

by Emmanuel I. Epelle, Andrew Macfarlane, Michael Cusack, Anthony Burns, Ngozi Amaeze, Kenny Richardson, William Mackay, Mostafa E. Rateb and Mohammed Yaseen

Environments 2022, 9(4), 45; https://doi.org/10.3390/environments9040045 - 1 Apr 2022

Cited by 17 | Viewed by 7932

Abstract

In current times of increasing global decontamination concerns, sustainable and environmentally-friendly technologies that possess rapid and effective disinfection capabilities are necessary for public health and safety. In this study, we evaluate the potential of ozone-based technology to reveal its immense potential in disinfection [...] Read more.

In current times of increasing global decontamination concerns, sustainable and environmentally-friendly technologies that possess rapid and effective disinfection capabilities are necessary for public health and safety. In this study, we evaluate the potential of ozone-based technology to reveal its immense potential in disinfection applications. Ozonated water generated by an electrolytic method was utilised to quantify ozone retention as a function of mineralogical composition for microbial decontamination. The impacts of temperature and detergent concentration on ozone concentration are critically analysed, as well as ozone’s decomposition and stain removal characteristics. In addition, fabric swatches inoculated with known concentrations of environmental microbes (Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus fumigatus) are washed with ozonated water to ascertain the impact of wash duration on bacterial removal efficiency. The results show significant improvement in the stability and retention potential of ozone in mineral water at low temperature and in the presence of a detergent. The experiments demonstrate first-order decomposition kinetics of ozone in aqueous formulations. The disinfection potency of ozone is also substantiated by a significant removal of microbiota on the fabric utilised (up to 7 log reduction for the bacteria analysed), thus making it effective for sterilisation applications. This also reduces the need for toxic chemicals or chemicals with toxic by-products (e.g., chlorine) for large-scale decontamination operations in various industries. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 15378 KiB

Open AccessArticle

Selective Chlorination and Extraction of Valuable Metals from Iron Precipitation Residues

by Lukas Höber, Kerrin Witt and Stefan Steinlechner

Appl. Sci. 2022, 12(7), 3590; https://doi.org/10.3390/app12073590 - 1 Apr 2022

Cited by 4 | Viewed by 2095

Abstract

Due to the aggravating situations regarding climate change, resource supply, and land consumption by the landfilling of residual materials, it is necessary to develop recycling processes that allow the recovery of valuable metals from industrial residues with significantly reduced CO₂ emissions. In [...] Read more.

Due to the aggravating situations regarding climate change, resource supply, and land consumption by the landfilling of residual materials, it is necessary to develop recycling processes that allow the recovery of valuable metals from industrial residues with significantly reduced CO₂ emissions. In this context, it is conceivable that processes using chlorination reactions will be of importance in the future. The simultaneous selective chlorination and evaporation of nine valuable metals was evaluated theoretically and experimentally in small-scale STA trials; then, it was tested practically on six different iron precipitation residues from the zinc and nickel industries. The metal chlorides FeCl₃∙6H₂O and MgCl₂∙6H₂O were identified as the most effective reactants, resulting in high extraction rates for the metals In, Ag, Zn, Pb, Au, and Bi, while lower yields are achievable for Sn, Cu, and Ni. Iron, which is predominant in volume in the residual materials, shows lower chlorination tendencies which allows the effective separation of the valuable elements of interest from the iron containing matrix. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 2489 KiB

Open AccessArticle

Seasonal Enhancement of Nitrogen Removal on Domestic Wastewater Treatment Performance by Partially Saturated and Saturated Hybrid Constructed Wetland

by José Contreras, Daniela López, Gloria Gómez and Gladys Vidal

Water 2022, 14(7), 1089; https://doi.org/10.3390/w14071089 - 30 Mar 2022

Cited by 2 | Viewed by 2972

Abstract

The aim of this study is to evaluate seasonal enhancement of nitrogen removal on domestic wastewater treatment performance by partially saturated and saturated HBCWs. To achieve this, two HBCWs consisting of a vertical subsurface flow constructed wetland, followed by a horizontal subsurface flow [...] Read more.

The aim of this study is to evaluate seasonal enhancement of nitrogen removal on domestic wastewater treatment performance by partially saturated and saturated HBCWs. To achieve this, two HBCWs consisting of a vertical subsurface flow constructed wetland, followed by a horizontal subsurface flow constructed wetland (VSSF-HSSF) were evaluated. Two saturation levels were used: (a) partially saturated HB1:VSSF1 (0.6 m)-HSSF1 (0.15 m), (b) saturated HB2: VSSF2 (0.8 m)-HSSF2 (0.25 m). Each unit was planted with Schoenoplectus californicus and was operated for 297 days. The removal efficiencies in HB1 and HB2 were above 70%, 86%, 77% and 55% for chemical oxygen demand (COD), total suspended solids (TSS), nitrogen as ammonium (NH₄⁺-N), and total nitrogen (TN), respectively. For VSSF, a higher level of saturation (from 0.6 to 0.8 m) meant a decrease of 17% in the TN removal efficiencies, and for HSSF, an increase from 0.15 to 0.25 m of saturation meant a decrease of 11 and 10% in the NH₄⁺-N and TN removal efficiencies, respectively. Thus, the increase of saturation level in HBCWs reduces the transformation and/or removal of components of the wastewaters to be treated, particularly nitrogen. Through this research, the possibility of optimizing the transformation of nitrogen with partially saturated hybrids can be examined. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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15 pages, 4321 KiB

Open AccessArticle

Influence of Five Additives on No Loading Swelling Potential of Red Clay

by Bing Yue, Ziye Zhao and Zengzhen Qian

Appl. Sci. 2022, 12(7), 3455; https://doi.org/10.3390/app12073455 - 29 Mar 2022

Cited by 6 | Viewed by 1886

Abstract

In this study, cement, zeolite powder and three industrial by-products (blast furnace slag, steel slag, and fly ash) were selected as additives to study their effects on the swelling potential of red clay with different curing ages and dosages. At the same time, [...] Read more.

In this study, cement, zeolite powder and three industrial by-products (blast furnace slag, steel slag, and fly ash) were selected as additives to study their effects on the swelling potential of red clay with different curing ages and dosages. At the same time, the mechanism of additives reducing the swelling potential of red clay was analyzed by scanning electron microscope (SEM) and X-ray fluorescence (XRF) tests. The X-ray diffraction (XRD) test was used to detect the clay mineral content of the red clay specimens before and after the modification to determine the change in the clay mineral content of the specimens. The direct shear test was used to explore the influence of additives on the strength of red clay. The results show that with 9% cement content, the no loading swelling potential of specimens can be reduced by 82.5% under 28 days of curing, and the cohesion of the specimens can be greatly increased by 82%. However, the specimens with cement have an increase in no loading swelling potential under the condition of no curing. In contrast, when steel slag is used as an additive to modify the swelling properties of red clay, the swelling potential can be reduced without curing, but the addition of steel slag will reduce the cohesive strength of specimens. XRD testing shows that the clay mineral composition in cement-modified specimens and steel slag-modified specimens experienced a relative change, the relative content of montmorillonite and illite decreased, and the relative content of kaolinite increased. Combined with SEM and XRF test results, it is concluded that cement’s reduction in the swelling potential of red clay depends on pozzolanic reaction products filling the pores in specimens and bonding clay particles, so as to reduce the permeability of red clay and increase the resistance during swelling. The addition of cement can also convert hydrophilic clay minerals into nonhydrophilic clay minerals. Compared with cement, the reduction in swelling potential caused by steel slag mainly depends on the adsorption of ions to reduce the adsorption of water molecules on the surface of clay slices. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 347 KiB

Open AccessArticle

Nexus between Technological Innovation, Renewable Energy, and Human Capital on the Environmental Sustainability in Emerging Asian Economies: A Panel Quantile Regression Approach

by Miguel Angel Esquivias, Lilik Sugiharti, Hilda Rohmawati, Omar Rojas and Narayan Sethi

Energies 2022, 15(7), 2451; https://doi.org/10.3390/en15072451 - 26 Mar 2022

Cited by 56 | Viewed by 4803

Abstract

The goal of this study was to examine the interlinkage of renewable energy, technology innovation, human capital, and governance on environment quality by using a panel quantile regression in Asian emerging economies over the period of 1990–2019. The results indicated that higher economic [...] Read more.

The goal of this study was to examine the interlinkage of renewable energy, technology innovation, human capital, and governance on environment quality by using a panel quantile regression in Asian emerging economies over the period of 1990–2019. The results indicated that higher economic growth, population density, technological innovation in renewable energy, and exploitation of natural resources have significantly raised CO₂ emissions in emerging Asia. Furthermore, larger capital, more use of renewable energy, green technology, and human capital development can improve environmental sustainability in Asia. As for governances, proxied by corruption rates, no evidence indicated that it has resulted in more damage, unlike earlier studies have suggested. The findings indicated that the three channels exposed in the Kuznets hypothesis can serve as a reference for proposals for environmental policies (scale of consumption, energy composition, and choice of technologies). There are opportunities to reduce CO₂ emissions through investments in human development, investing in new technologies to increase efficiency in energy (generation and consumption), increasing working capital (GCF), and migrating to more environmentally friendly energy. The negative link between carbon dioxide emissions and economic growth, increases in population density, and exploitation of natural resources can compromise the achievement of sustainable environmental goals. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

16 pages, 1125 KiB

Open AccessReview

Reuse of Water Contaminated by Microplastics, the Effectiveness of Filtration Processes: A Review

by Juan A. Conesa and Nuria Ortuño

Energies 2022, 15(7), 2432; https://doi.org/10.3390/en15072432 - 25 Mar 2022

Cited by 11 | Viewed by 3616

Abstract

Water treatment generally does not specifically address the removal of microplastics (MPs). Nevertheless, treatment plants process water effectively, and the number of synthetic microparticles in effluents is usually very low. Still, discharge volumes from water-treatment plants are often elevated (reaching around 10⁸ [...] Read more.

Water treatment generally does not specifically address the removal of microplastics (MPs). Nevertheless, treatment plants process water effectively, and the number of synthetic microparticles in effluents is usually very low. Still, discharge volumes from water-treatment plants are often elevated (reaching around 10⁸ L/day), leading to the daily discharge of a substantial number of MPs and microfibers. Furthermore, MPs accumulate in the primary and secondary sludge, which in the end results in another environmental problem as they are currently used to amend soils, both for cultivation and forestry, leading to their dispersion. Something similar occurs with the treatment of water intended for human consumption, which has a much lower but still significant number of MPs. The amount of these pollutants being released into the environment depends on the processes that the water undergoes. One of the most-used treatment processes is rapid sand filtration, which is reviewed in this article. During the filtration process, MPs can break into smaller pieces, resulting in a greater number of plastic particles which mainly accumulate in sewage sludge. Thermal processes, such as incineration, carried out in facilities with the best available techniques in practice, could guarantee the safe disposal of highly MP-contaminated sewage sludges. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 1777 KiB

Open AccessArticle

Temporal Variations of Heavy Metal Sources in Agricultural Soils in Malta

by Christine Costa and Frederick Lia

Appl. Sci. 2022, 12(6), 3120; https://doi.org/10.3390/app12063120 - 18 Mar 2022

Cited by 5 | Viewed by 2663

Abstract

In the opportunity to understand the benefits of Maltese soil and its importance to our climate, the content of heavy metals—including Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn—was studied in two fields in proximity in the south-east region of Malta. [...] Read more.

In the opportunity to understand the benefits of Maltese soil and its importance to our climate, the content of heavy metals—including Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn—was studied in two fields in proximity in the south-east region of Malta. Analytical determinations were carried out using atomic absorption spectroscopy following heated aqua regia digestion on 50 collected samples using triple repeatability. The decreasing pattern of the concentrations obtained is Fe > Zn > Mn > Sr > Pb > Cu > Ni > Cr > Co. Correlations between pre-harvesting and post-harvesting concentrations were examined to assess lithogenic and anthropogenic relationships. Multivariate analysis including principal component analysis and factor analysis clarified the origin of heavy metals content reviewed. Some of the heavy metals studied showed a dominant relationship between concentration variation and their possible sources. Potential ecological risk assessment demonstrated that the fields reviewed are not contaminated by any of the heavy metals assessed except for Zn which posed a moderate/strong contamination but presented an overall low potential for ecological risk. Concentrations of heavy metals demonstrated no risk to human health and no carcinogenic risk through ingestion and dermal contact with the soil. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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14 pages, 1753 KiB

Open AccessFeature PaperArticle

The Role of Aquifers in Sustaining the Sponge City Concept in Chinese High-Density Housing

by Mengxiao Jin, Michele Lancia, Yong Tian, Stefano Viaroli, Charles Andrews, Junguo Liu and Chunmiao Zheng

Water 2022, 14(6), 929; https://doi.org/10.3390/w14060929 - 16 Mar 2022

Cited by 5 | Viewed by 2928

Abstract

Chinese cities and megacities occupy large areas with high population densities. These urban sectors have extensive impervious surfaces and import large amounts of water from pristine sources, putting pressure on the urban drainage systems during storms. To reduce flood risk and tackle water [...] Read more.

Chinese cities and megacities occupy large areas with high population densities. These urban sectors have extensive impervious surfaces and import large amounts of water from pristine sources, putting pressure on the urban drainage systems during storms. To reduce flood risk and tackle water scarcity, the Chinese government promulgated the Sponge City concept: an ensemble of absorbing features, including permeable pavements and green roofs, to reduce urban runoff and increase water storage. We evaluate the benefits of merging the urban aquifer with conventional Sponge City features by simulating stormwater storage in aquifers with a groundwater model (MODFLOW) and a stormwater management model (SWMM). The urban aquifers of an ideal district, characterized by high-density housing and a flat morphology, collect and dissipate extreme rains (200 mm in 6 h) when the hydraulic conductivity of the subsoil is higher than 1·10⁻⁵ m/s, roughly corresponding to a medium productive aquifer. Economic and ecological benefits at the catchment scale are also discussed. Suitable shallow aquifers are individuated and discussed throughout China via a hydrogeological and geomorphological approach. The proposed method increases the percentage of water that can be controlled above that obtained through conventional Sponge City features. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 2350 KiB

Open AccessArticle

Investigation of Mechanochemically Treated Municipal Solid Waste Incineration Fly Ash as Replacement for Cement

by Shuping Pan, Jiamin Ding, Yaqi Peng, Shengyong Lu and Xiaodong Li

Energies 2022, 15(6), 2013; https://doi.org/10.3390/en15062013 - 10 Mar 2022

Cited by 10 | Viewed by 2555

Abstract

Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste in China because of the leachable toxic heavy metals and high concentrations of chlorides and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). Currently, the main treatment method is still landfilling after [...] Read more.

Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste in China because of the leachable toxic heavy metals and high concentrations of chlorides and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). Currently, the main treatment method is still landfilling after chemical treatment or cement solidification, and an effective approach to realize fly ash utilization is still lacking. In the present work, the fly ash was firstly water-washed to remove the soluble chlorine salts, which can improve the performance of the produced cement mortar in later work. Mechanochemical pre-treatment was adopted to destroy the PCDD/Fs and improve the heavy metals’ stabilization. The results show that 75% of PCDD/Fs can be degraded and that most of the heavy metals are stabilized. After the mechanochemical pre-treatment, the average particle size of the fly ash decreases to 2–5 μm, which is beneficial for promoting the activation energy and accelerating the hydration process in cement mortar production. The compressive and flexural strengths of the fly ash cement mortar improve to 6.2 MPa and 32.4 MPa, respectively, when 35% of the OPC is replaced by treated fly ash. The similarity in the 3-day and 28-day strength with or without the addition of the treated ash shows the light influence of the fly ash addition. Thus, the mechanochemical process can stabilize the heavy metals and activate the fly ash, allowing it to partly substitute ordinary Portland cement in building materials, such as cement raw materials and concrete. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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32 pages, 5294 KiB

Open AccessArticle

Influence of Wood Properties and Building Construction on Energy Demand, Thermal Comfort and Start-Up Lag Time of Radiant Floor Heating Systems

by Álvaro Ruiz-Pardo, Enrique Ángel Rodríguez Jara, Marta Conde García and José Antonio Tenorio Ríos

Appl. Sci. 2022, 12(5), 2335; https://doi.org/10.3390/app12052335 - 23 Feb 2022

Cited by 7 | Viewed by 5046

Abstract

Radiant floor heating is becoming increasingly popular in cold climates because it delivers higher comfort levels more efficiently than conventional systems. Wood is one of the surface coverings most frequently used in radiant flooring, despite the widely held belief that in terms of [...] Read more.

Radiant floor heating is becoming increasingly popular in cold climates because it delivers higher comfort levels more efficiently than conventional systems. Wood is one of the surface coverings most frequently used in radiant flooring, despite the widely held belief that in terms of thermal performance it is no match for higher conductivity materials if a high energy performance is intended. Given that the highest admissible thermal resistance for flooring finishes or coverings is generally accepted to be 0.15 m²K/W, wood would appear to be a scantly appropriate choice. Nonetheless, the evaluation of the thermal performance of wooden radiant floor heating systems in conjunction with the building in terms of energy demand, thermal comfort, and start-up period, has been insufficiently explored in research. This has led to the present knowledge gap around its potential to deliver lower energy consumption and higher thermal comfort than high-thermal-conductivity materials, depending on building characteristics. This article studies the thermal performance of wood radiant floors in terms of three parameters: energy demand, thermal comfort, and start-up lag time, analysing the effect of wood properties in conjunction with building construction on each. An experimentally validated radiant floor model was coupled to a simplified building thermal model to simulate the performance of 60 wood coverings and one reference granite covering in 216 urban dwellings differing in construction features. The average energy demand was observed to be lower in the wood than in the granite coverings in 25% of the dwellings simulated. Similarly, on average, wood lagged behind granite in thermal comfort by less than 1 h/day in 50% of the dwellings. The energy demand was minimised in a significant 18% and thermal comfort maximised in 14% of the simulations at the lowest thermal conductivity value. The vast majority of the wooden floors lengthened the start-up lag time relative to granite in only 30 min or less in all the dwellings. Wood flooring with the highest thermal resistance (even over the 0.15 m²K/W cited in standard EN 1264-2) did not significantly affect the energy demand or thermal comfort. On average, wood flooring lowered energy demand by 6.4% and daily hours of thermal comfort by a mere 1.6% relative to granite coverings. The findings showed that wood-finished flooring may deliver comparable or, in some cases, higher thermal performance than high-conductivity material coverings, even when their thermal resistance is over 0.15 m²K/W. The suggestion is that the aforementioned value, presently deemed the maximum admissible thermal resistance, may need to be revised. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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12 pages, 51164 KiB

Open AccessArticle

Laboratory Test Campaign Aimed at the Analysis of an Uncommon Wear Phenomenon in a Marble Quarry

by Alfio Di Giovanni, Carmine Todaro, Marilena Cardu, Stefano Bianchini and Brunello Forfori

Appl. Sci. 2022, 12(4), 2264; https://doi.org/10.3390/app12042264 - 21 Feb 2022

Cited by 4 | Viewed by 2657

Abstract

The use of ornamental stones has a historical value that makes them strategically precious in Italy; marble can offer high performance in architectural applications, even though the variability of the rock mass requires detailed studies to optimize the exploitation techniques and reduce waste. [...] Read more.

The use of ornamental stones has a historical value that makes them strategically precious in Italy; marble can offer high performance in architectural applications, even though the variability of the rock mass requires detailed studies to optimize the exploitation techniques and reduce waste. Italy is world famous for its marble, which is extracted mainly through chainsaw cutting machines, which are currently used intensively due to their high-safety working conditions compared to alternative techniques and for their great versatility, especially in underground applications. Although this cutting technique is well-rooted, an uncommon problem of tool wear was found in the quarry under study, which strongly affected productivity. A series of laboratory test were carried out to estimate the wear potential of the rock and the suitability of the tools. The Cerchar abrasivity test highlighted a mean wear potential for the marble of 2.77, while microhardness outcomes pointed out the presence of quartz veins in the tested material (values over 10,000 MPa). Finally, additives typically used in the conditioning process of EPB machines in tunneling were tested with the purpose of reducing the extent of wear. A reduction of about 50% in the wear (in terms of weight lost) was obtained for a moisture content of 9%. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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8 pages, 1126 KiB

Open AccessArticle

Application of Electrocoagulation in Street Food Wastewater

by Wilawan Khanitchaidecha, Khakhanang Ratananikom, Bunyaphon Yangklang, Shotita Intanoo, Kanokphol Sing-Aed and Auppatham Nakaruk

Water 2022, 14(4), 655; https://doi.org/10.3390/w14040655 - 20 Feb 2022

Cited by 3 | Viewed by 2980

Abstract

Street food is commonly known as ready-to-eat and go foods and beverages, which is very famous in Thailand and other Asian countries. The street food daily generates high organic content and oily wastewater from washing and rinsing plates. The discharge of street food [...] Read more.

Street food is commonly known as ready-to-eat and go foods and beverages, which is very famous in Thailand and other Asian countries. The street food daily generates high organic content and oily wastewater from washing and rinsing plates. The discharge of street food wastewater to public drains leads to a clogged drain line and unpleasant smell. In this work, an electrocoagulation (EC) system with monopolar aluminum (Al) electrodes was developed to treat two well-known street foods; Hainanese chicken rice (HC) and noodles and dumplings (ND). The results revealed that excellent chemical oxygen demand (COD) and fat, oil, and grease (FOG) removals were achieved under a specific operating condition (i.e., an electric current of 20 mA/cm² and electrolytic time of 10 min). The initial COD of HC wastewater decreased from 40.6 g/L to 1.9 g/L, approximately 95%, whereas the FOG decreased from 310 mg/L to 50 mg/L, approximately 84%. The lower initial COD and FOG concentrations of ND wastewater obtained approximately 98% for COD removal and 86% for FOG removal; the effluent contained 0.5 g/L of COD and 25 mg/L of FOG. In addition, a relatively low Al concentration of 0.02–0.08 mg/L was observed in the effluents. The appropriate design factors together with ease of use and fast pollutants removal were significant advantages of this study; the EC system has potential to apply to on-site street food treatment. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 1081 KiB

Open AccessFeature PaperArticle

Modeling the Life Cycle Inventory of a Centralized Composting Facility in Greece

by Panagiotis Chazirakis, Apostolos Giannis and Evangelos Gidarakos

Appl. Sci. 2022, 12(4), 2047; https://doi.org/10.3390/app12042047 - 16 Feb 2022

Cited by 5 | Viewed by 4318

Abstract

Mechanical composting is a popular treatment method for the mechanically separated organic fraction of municipal solid wastes to stabilize the waste material and reduce its environmental impacts. The model and life cycle inventory database are created based on the existing centralized mechanical composting [...] Read more.

Mechanical composting is a popular treatment method for the mechanically separated organic fraction of municipal solid wastes to stabilize the waste material and reduce its environmental impacts. The model and life cycle inventory database are created based on the existing centralized mechanical composting facility located in Chania (Crete, Greece). This study aims to assess all stages of the composting process, wherein input-output flows are comprehensively analyzed based on specific waste fragments. The transfer coefficients are calculated for each waste fragment throughout the processes. The degradation rate is measured as kg of C and N released per Mg of the treated material. The results show that process degradation rates are independent of the initial fragmental composition. This is the first study that accurately models the fate of distinctive waste fragments in a composting plant, while the developed life cycle inventory (with regard to mass and energy balances) can be applied to estimate the environmental impacts regarding mechanical composting the organic fraction of municipal solid wastes. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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10 pages, 1646 KiB

Open AccessArticle

Adsorption and Its Mechanism of Arsenate in Aqueous Solutions by Red Soil

by Min Guo, Lili Shi, Wen Gu and Wenzhu Wu

Water 2022, 14(4), 579; https://doi.org/10.3390/w14040579 - 14 Feb 2022

Cited by 1 | Viewed by 2175

Abstract

The removal, and its mechanism, of arsenate from aqueous solutions was investigated using Yunnan red soil. A series of adsorption experiments was designed to disclose the effect of key factors (soil types, soil/solution rates, initial arsenate concentrations, and shaking speeds) on the adsorption [...] Read more.

The removal, and its mechanism, of arsenate from aqueous solutions was investigated using Yunnan red soil. A series of adsorption experiments was designed to disclose the effect of key factors (soil types, soil/solution rates, initial arsenate concentrations, and shaking speeds) on the adsorption capacity of Yunnan red soil for arsenate. The soil/solution ratio was optimized as 0.05 g/100 mL to balance the adsorption capacity and removal efficiency. The optimal shaking speed (225 rpm) not only ensured enough contact frequency between the Yunnan red soil and the arsenate, but also reduced the mass transfer resistance. The results from applying an orthogonal array method showed that the most significant factor affecting arsenate removal efficiency was soil type, followed by the soil/solution ratio, contact time, and shaking speed. The IR spectra of the precipitates further confirmed that the metal arsenide was settled by the Yunnan red soil, indicating that the arsenate ion existed on the red soil surface in the form of protonated bidentate surface complexation of –FeO₂As(O)(OH)⁻ and FeO₂As(O)²⁻. These results indicate that Yunnan red soil is promising for the removal of arsenate from aqueous solutions; it may thus be suitable as a new adsorbent for arsenate removal during water treatment. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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17 pages, 8381 KiB

Open AccessFeature PaperArticle

Changes in Wastewater Treatment Performance and the Microbial Community during the Bioaugmentation of a Denitrifying Pseudomonas Strain in the Low Carbon–Nitrogen Ratio Sequencing Batch Reactor

by Tianyuan Chen, Xiaoyong Yang, Qian Sun, Anyi Hu, Dan Qin, Jiangwei Li, Yinhan Wang and Chang-Ping Yu

Water 2022, 14(4), 540; https://doi.org/10.3390/w14040540 - 11 Feb 2022

Cited by 5 | Viewed by 2853

Abstract

The low carbon–nitrogen ratio (C/N) of influent wastewater results in the insufficient carbon source for the process of denitrification in urban wastewater treatment plants (WWTPs). A denitrifying bacterial strain, Pseudomonas sp. JMSTP, was isolated and demonstrated effective denitrification ability under a low C/N [...] Read more.

The low carbon–nitrogen ratio (C/N) of influent wastewater results in the insufficient carbon source for the process of denitrification in urban wastewater treatment plants (WWTPs). A denitrifying bacterial strain, Pseudomonas sp. JMSTP, was isolated and demonstrated effective denitrification ability under a low C/N ratio of 1.5–4 (w/w) in anoxic conditions. Sequencing batch reactor (SBR) studies were conducted to test the bioaugmentation of JMSTP on total nitrogen (TN) removal under the influent COD/N ratio of 3/1. After the second bioaugmentation, the TN of effluent in the bioaugmented SBR was significantly lower than that in the control SBR. Redundancy analysis results showed that there was a positive correlation between Pseudomonas sp. abundance and TN removal in the bioaugmented SBR. Microbial community analysis showed that, especially after the second bioaugmentation, the abundance of Pseudomonas sp. decreased rapidly, but it was still much higher than that in the control SBR. Correlation network analysis showed that after the addition, Pseudomonas sp. had no significant co-occurrence relationship with other native bacteria, owing to the quick increase and decrease. Our results suggest that JMSTP shows the potential to enhance TN removal through bioaugmentation. Since the effect of bioaugmentation gradually diminishes, further research is still needed to investigate its long-lasting applications. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 5203 KiB

Open AccessArticle

Evaluating Attraction and Passage Efficiencies of Pool-Weir Type Fishways Based on Hydraulic Analysis

by Kyong-Oh Baek, Jeong-Min Lee, Eun-Jin Han and Young-Do Kim

Appl. Sci. 2022, 12(4), 1880; https://doi.org/10.3390/app12041880 - 11 Feb 2022

Cited by 4 | Viewed by 2137

Abstract

In this study, a hydraulic analysis technique is presented for evaluating the efficiency of a pool-weir type fishway. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area proposed as [...] Read more.

In this study, a hydraulic analysis technique is presented for evaluating the efficiency of a pool-weir type fishway. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area proposed as an index of the efficiency. For the analysis of passage efficiency, the three-dimensional model, FLOW-3D, was used as an evaluating tool to describe the fluid behavior on a hydraulic structure with a free surface. The ice-harbor type fishway at Dalseong weir in the Nakdong River of Korea was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. The results of River-2D analysis showed that the location of the fishway near the right bank now was not appropriate for attracting the target fish to the fishway due to the deep water depth. The 3D analysis results presented that the flow velocity field inside the fishway showed a similar plunging flow in each pool, but various flow patterns appeared locally. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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22 pages, 4754 KiB

Open AccessArticle

Experimental Analysis of a Fish Guidance System for a River Water Intake

by Gabriela Cîrciumaru, Rareș-Andrei Chihaia, Andreea Voina, Daniela-Elena Gogoașe Nistoran, Ștefan-Mugur Simionescu, Lucia-Andreea El-Leathey and Lucian Mândrea

Water 2022, 14(3), 370; https://doi.org/10.3390/w14030370 - 26 Jan 2022

Cited by 5 | Viewed by 3514

Abstract

This paper describes the experimental study of a behavioural barrier consisting of a bubble curtain placed near an ecological river water intake, aiming to assess the bubble curtain’s influence on the velocity field of water flowing in the water intake proximity. The scientific [...] Read more.

This paper describes the experimental study of a behavioural barrier consisting of a bubble curtain placed near an ecological river water intake, aiming to assess the bubble curtain’s influence on the velocity field of water flowing in the water intake proximity. The scientific novelty is given by the water intake solution operating in tandem with the dedicated bubble curtain generator used for avoiding fish entrapment. The water intake solution used in the present research is based on a run-of-river intake without a dam in the riverbed, maintaining the mountain rivers longitudinal connectivity. An experimental setup was designed and built to study the behavioural barrier for ecological water intakes in different operating conditions. Thus, tests were performed for two water velocities (0.33 m/s and 0.535 m/s) in the experimental setup, two water depths (92 mm and 119 mm) and two air flow rates (10.5 LPM and 15 LPM). The results were compared with the case when no air is injected through the bubble curtain generator. The assessment of the bubble curtain influence on the water flow inside the channel was made by measuring and analysing the velocity variation in vertical and horizontal direction. The results showed a significant velocity gradient in the bubble curtain proximity, which can contribute to influencing the behaviour of the fish by deterring them from the water intake area. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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16 pages, 2798 KiB

Open AccessArticle

Hydrogen Energy Demand Growth Prediction and Assessment (2021–2050) Using a System Thinking and System Dynamics Approach

by Talal Yusaf, Mohamd Laimon, Waleed Alrefae, Kumaran Kadirgama, Hayder A. Dhahad, Devarajan Ramasamy, Mohd Kamal Kamarulzaman and Belal Yousif

Appl. Sci. 2022, 12(2), 781; https://doi.org/10.3390/app12020781 - 13 Jan 2022

Cited by 72 | Viewed by 10834

Abstract

Adoption of hydrogen energy as an alternative to fossil fuels could be a major step towards decarbonising and fulfilling the needs of the energy sector. Hydrogen can be an ideal alternative for many fields compared with other alternatives. However, there are many potential [...] Read more.

Adoption of hydrogen energy as an alternative to fossil fuels could be a major step towards decarbonising and fulfilling the needs of the energy sector. Hydrogen can be an ideal alternative for many fields compared with other alternatives. However, there are many potential environmental challenges that are not limited to production and distribution systems, but they also focus on how hydrogen is used through fuel cells and combustion pathways. The use of hydrogen has received little attention in research and policy, which may explain the widely claimed belief that nothing but water is released as a by-product when hydrogen energy is used. We adopt systems thinking and system dynamics approaches to construct a conceptual model for hydrogen energy, with a special focus on the pathways of hydrogen use, to assess the potential unintended consequences, and possible interventions; to highlight the possible growth of hydrogen energy by 2050. The results indicate that the combustion pathway may increase the risk of the adoption of hydrogen as a combustion fuel, as it produces NO_x, which is a key air pollutant that causes environmental deterioration, which may limit the application of a combustion pathway if no intervention is made. The results indicate that the potential range of global hydrogen demand is rising, ranging from 73 to 158 Mt in 2030, 73 to 300 Mt in 2040, and 73 to 568 Mt in 2050, depending on the scenario presented. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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11 pages, 2497 KiB

Open AccessArticle

Phytotoxicity and Accumulation of Antibiotics in Water Lettuce (Pistia stratiotes) and Parrot Feather (Myriophyllum aquaticum) Plants under Hydroponic Culture Conditions

by Young-Jae Park and Jae-Gwon Son

Appl. Sci. 2022, 12(2), 630; https://doi.org/10.3390/app12020630 - 10 Jan 2022

Cited by 5 | Viewed by 2261

Abstract

The aim of this research was to investigate the accumulation of antibiotics in two kinds of plants. The hydroponic culture solution included a mixture of antibiotics, including three commonly used antibiotics in South Korea: norfloxacin (NOR), sulfamethazine (SMZ), and tetracyclines (TC). None of [...] Read more.

The aim of this research was to investigate the accumulation of antibiotics in two kinds of plants. The hydroponic culture solution included a mixture of antibiotics, including three commonly used antibiotics in South Korea: norfloxacin (NOR), sulfamethazine (SMZ), and tetracyclines (TC). None of these antibiotics were detected in the shoots of water lettuce plants, only in the roots. However, in parrot feather plants, antibiotics were detected in both the shoots and the roots, with higher amounts detected in the shoots than in the roots. SMZ and TC were most likely to be detected in the roots and shoots of water lettuce and parrot feather plants, and about one-third of the NOR administered was later detected in the plants. The BCF (bioconcentration factor) of antibiotics ranged from 0.24 to 0.78, while that of NOR was much lower, ranging from 0.24 to 0.38. The SMZ (0.59–0.64) and TET (0.72–0.78) exhibited higher uptake accumulation in the water lettuce tissues compared with the parrot feather plants. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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