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Advances in Remediation of Environmental Pollutants for Sustainable Development

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Pollution Prevention, Mitigation and Sustainability".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 56644

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Guest Editor
Division of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, George Town 11800, Penang, Malaysia
Interests: environmental water pollutants and their safe removal; preparation of various nano-materials to protect the environment; water and wastewater treatment; adsorption and ion exchange; microbial fuel cells; advanced oxidation process; activated carbons and their electrochemical properties; environmental catalysis
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Guest Editor
Advanced Materials Research Chair, Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
Interests: environmental pollutants, their determination and removal; instrumental analysis of environmental and food samples; preparation of low-cost adsorbents and their application in the preparation of solid-phase extraction columns; waste water treatment and adsorption studies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Environmental quality is crucial to our health, economy, lives, and for future generations. However, during the last few years we have been faced with several serious challenges which include but are not limited to climate change, unsustainable consumption and production, as well as various forms of pollution. These challenges are global concerns for the sustainable development of human beings.

This Special Issue is collecting research papers aimed at a wide range of environmental topics: water and wastewater treatment and management, soil degradation and conservation, pollution control, the environmental impact of technologies, air quality and the indoor environment, and advanced environmental materials. Analytical methods developed for the determination of environmental pollutants are also welcome. Papers dealing in the synthesis of adsorbents for the solid-phase extraction of environmental pollutants also fall within the scope of this Special Issue. Contributions describing novel and significant knowledge, scientific results, and advanced applications in the field of environmental sciences and technology are welcome. This Special Issue provides an integrated view of the trends in solving the problems associated with the achievement of sustainability in environmental technology.

The Special Issue will publish experimental and review papers, as well as short communications, discussing recent developments in the remediation of environmental pollutants through physical, chemical, and biological methods. The topics of the papers to be submitted to this Special Issue are defined by the keywords presented below.

Dr. Mohd Rafatullah
Dr. Masoom Raza Siddiqui
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • sustainability
  • dyes
  • heavy metals adsorption
  • hydrochar
  • environmental pollutants
  • composite materials
  • analytical methods
  • solid-phase extraction
  • organic pollutants
  • bioremediation
  • biomass
  • social-environmental system
  • phytoremediation
  • waste management
  • human behavior
  • river pollution
  • ecological sustainability
  • pollution prevention
  • air pollution
  • effluent treatment
  • cost–benefit analysis for sustainable development

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Published Papers (15 papers)

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Research

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16 pages, 3422 KiB  
Article
Improving Air Pollution Prediction Modelling Using Wrapper Feature Selection
by Ahmad Zia Ul-Saufie, Nurul Haziqah Hamzan, Zulaika Zahari, Wan Nur Shaziayani, Norazian Mohamad Noor, Mohd Remy Rozainy Mohd Arif Zainol, Andrei Victor Sandu, Gyorgy Deak and Petrica Vizureanu
Sustainability 2022, 14(18), 11403; https://doi.org/10.3390/su141811403 - 11 Sep 2022
Cited by 5 | Viewed by 2149
Abstract
Feature selection is considered as one of the essential steps in data pre-processing. However, all of the previous studies on predicting PM10 concentration in Malaysia have been limited to statistical method feature selection, and none of these studies used machine-learning approaches. Therefore, [...] Read more.
Feature selection is considered as one of the essential steps in data pre-processing. However, all of the previous studies on predicting PM10 concentration in Malaysia have been limited to statistical method feature selection, and none of these studies used machine-learning approaches. Therefore, the objective of this research is to investigate the influence variables of the PM10 prediction model by using wrapper feature selection to compare the prediction model performance of different wrapper feature selection and to predict the concentration of PM10 for the next day. This research uses 10 years of daily data on pollutant concentrations from two stations (Klang and Shah Alam) obtained from the Department of Environment Malaysia (DOE) from 2009 until 2018. Six wrapper methods (forward selection, backward elimination, stepwise, brute-force, weight-guided and genetic algorithm evolution and the predictive analytics multiple linear regression (MLR) and artificial neural network (ANN)) were implemented in this study. This study found that brute-force is the dominant wrapper method in most of the best models in selecting important features for MLR. Moreover, compared to MLR, ANN provides more advantages regarding model accuracy and permits feature selection in predicting PM10. The overall results revealed that the RMSE value for next day prediction in Klang is 20.728, while the AE value is 15.69. Furthermore, the RMSE value for next day prediction in Shah Alam is 10.004, while the AE value is 7.982. Finally, all of the predicted models in Klang and Shah Alam can be used to predict the PM10 concentrations. This proposed model can be used as a tool for an early warning system in giving air quality information to local authorities in order to formulate air-quality-improvement strategies. Full article
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15 pages, 2478 KiB  
Article
Suitability of Selected Plant Species for Phytoremediation: A Case Study of a Coal Combustion Ash Landfill
by Artur Szwalec, Paweł Mundała and Renata Kędzior
Sustainability 2022, 14(12), 7083; https://doi.org/10.3390/su14127083 - 9 Jun 2022
Cited by 1 | Viewed by 2023
Abstract
Coal bottom and fly ash waste continue to be generated as a result of energy production from coal in the amount of about 750 million tonnes a year globally. Coal is the main source of energy in Poland, and about 338 million tonnes [...] Read more.
Coal bottom and fly ash waste continue to be generated as a result of energy production from coal in the amount of about 750 million tonnes a year globally. Coal is the main source of energy in Poland, and about 338 million tonnes of combustion waste has already been landfilled. The aim of the research was to identify factors determining the Cd, Pb, Zn and Cu phytostabilisation by vegetation growing on a coal combustion waste landfill. Soil and shoots of the following plants were analysed: wood small-reed, European goldenrod, common reed; silver birch, black locust, European aspen and common oak. The influence of the location where the plants grew and the influence of the interaction between the two factors (species and location) were significant. The tree species were more effective at accumulating heavy metals than the herbaceous plants. European aspen had the highest Bioaccumulation Factor (BCF) for cadmium and zinc. A high capacity to accumulate these elements was also demonstrated by silver birch, and in the case of cadmium, by common oak. Accumulation of both lead and copper was low in all plants. The Translocation Factors (TF) indicated that the heavy metals were accumulated mainly in the roots. European aspen, silver birch and European goldenrod were shown to be most suitable for stabilization of the metals analysed in the research. Full article
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21 pages, 3197 KiB  
Article
Comprehensive Energy Consumption of Elevator Systems Based on Hybrid Approach of Measurement and Calculation in Low- and High-Rise Buildings of Tropical Climate towards Energy Efficiency
by Jia Hui Ang, Yusri Yusup, Sheikh Ahmad Zaki, Ali Salehabadi and Mardiana Idayu Ahmad
Sustainability 2022, 14(8), 4779; https://doi.org/10.3390/su14084779 - 15 Apr 2022
Cited by 13 | Viewed by 5121
Abstract
Rapid population growth and urbanization contribute to an ever-increasing global energy demand, of which the building sector accounts for one-third. The increasing average height and density of buildings escalate the need for vertical transportation, expanding elevator usage and energy needs. This phenomenon accounts [...] Read more.
Rapid population growth and urbanization contribute to an ever-increasing global energy demand, of which the building sector accounts for one-third. The increasing average height and density of buildings escalate the need for vertical transportation, expanding elevator usage and energy needs. This phenomenon accounts for a significant amount of the total building energy use, necessitating a study of elevator system energy consumption. This study aimed to analyze the energy consumption and carbon emissions of elevator systems in low- and high-rise buildings towards energy-efficient estimations. A comprehensive analysis was performed based on a hybrid approach of measurement and calculation using a formula and reference values derived from previous studies. Four buildings were selected and thoroughly studied, representing the low- and high-rise categories. Data were collected based on on-site sampling and observation, as well as information from the building management offices. The mechanical parameters of the elevator system in each building and operational factors in terms of speed, number of trips, load, travel distance, and time were studied. In this analysis, the energy consumption calculation was performed according to International Standard ISO 25745. Annual carbon emissions were calculated in accordance with the USA EPA and IPCC guidelines. The elevator energy efficiency class was determined based on daily energy consumption. It was found from this study that the annual energy consumption of an elevator system is positively correlated to an elevator’s daily energy consumption. The annual carbon emissions of the elevator systems are dependent on increasing annual energy consumption, which is also connected to building height indirectly. The low-rise buildings showed better energy efficiency compared to the high-rise buildings due to lower travel distance, less trips, and fewer floors. The annual number of trips, travel distances, and energy consumption had an effect on the energy efficiency of the elevator systems in this study. Full article
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18 pages, 3236 KiB  
Article
Removal of Reactive Black 5 Dye by Banana Peel Biochar and Evaluation of Its Phytotoxicity on Tomato
by Riti Thapar Kapoor, Mohd Rafatullah, Masoom Raza Siddiqui, Moonis Ali Khan and Mika Sillanpää
Sustainability 2022, 14(7), 4176; https://doi.org/10.3390/su14074176 - 31 Mar 2022
Cited by 44 | Viewed by 3384
Abstract
Removal of Reactive Black 5 (RB5) dye from an aqueous solution was studied by its adsorption on banana peel biochars (BPBs). The factors affecting RB5 dye adsorption such as pH, exposure time, RB5 dye concentration, adsorbent dose, particle size [...] Read more.
Removal of Reactive Black 5 (RB5) dye from an aqueous solution was studied by its adsorption on banana peel biochars (BPBs). The factors affecting RB5 dye adsorption such as pH, exposure time, RB5 dye concentration, adsorbent dose, particle size and temperature were investigated. Maximum 97% RB5 dye removal was obtained at pH 3 with 75 mg/L adsorbate concentration by banana peel biochars. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used to characterize the adsorbent material. The data of equilibrium were analyzed by Langmuir and Freundlich isotherm models. The experimental results were best reflected by Langmuir isotherm with maximum 7.58 mg/g adsorption capacity. Kinetic parameters were explored and pseudo-second order was found suitable which reflected that rate of adsorption was controlled by physisorption. Thermodynamic variables exhibited that the sorption process was feasible, spontaneous, and exothermic in nature. Banana peel biochar showed excellent regeneration efficiency up to five cycles of successive adsorption-desorption. Banana peel biochar maintained >38% sorption potential of RB5 dye even after five cycles of adsorption-desorption. The phytotoxic study exhibited the benign nature of BPB-treated RB5 dye on tomato seeds. Full article
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16 pages, 5354 KiB  
Article
Baseline Assessment of Heavy Metal Pollution during COVID-19 near River Mouth of Kerian River, Malaysia
by Mohammad Nishat Akhtar, Mohd Talha Anees, Emaad Ansari, Jazmina Binti Ja’afar, Mohammed Danish and Elmi Abu Bakar
Sustainability 2022, 14(7), 3976; https://doi.org/10.3390/su14073976 - 28 Mar 2022
Cited by 4 | Viewed by 2777
Abstract
River water quality is a serious concern among scientist and government agencies due to increasing anthropogenic activities and uncontrolled industrial discharge to rivers. The present study was conducted near the river mouth of the Kerian River to assess heavy metal pollution during COVID-19 [...] Read more.
River water quality is a serious concern among scientist and government agencies due to increasing anthropogenic activities and uncontrolled industrial discharge to rivers. The present study was conducted near the river mouth of the Kerian River to assess heavy metal pollution during COVID-19 pandemic-lockdown conditions and post-COVID-19 pandemic-unlock conditions. Twelve samples of shallow, middle, and bottom depths were collected at four locations along a 9.6 km reach. A concentration of eight heavy metals including Cadmium, Chromium, Copper, Iron, Manganese, Nickel, Lead, and Zinc were extracted through atomic absorption spectrometry. Total suspended solid was measured during laboratory experimentation. The results showed that, during the pandemic, concentrations of Nickel, Zinc, and Iron were high at shallow, middle, and bottom depths, respectively. Decreasing orders of heavy metal concentration are variable at different depths due to either their high sinking tendency with other existing components of water matrix or the anthropogenic source. However, almost all values of heavy metals are under the permissible limit of National Water Quality Standards of Malaysia and Food and Drug Administration. A possible reason for the lack of heavy metal pollution may be the restriction of anthropogenic activities during the COVID-19 pandemic. Additionally, no significant differences were observed in total suspended solid. Full article
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16 pages, 4178 KiB  
Article
Adsorption of Methylene Blue by Biosorption on Alkali-Treated Solanum incanum: Isotherms, Equilibrium and Mechanism
by Hamza S. AL-Shehri, Hamdah S. Alanazi, Areej Mohammed Shaykhayn, Lina Saad ALharbi, Wedyan Saud Alnafaei, Ali Q. Alorabi, Ali S. Alkorbi and Fahad A. Alharthi
Sustainability 2022, 14(5), 2644; https://doi.org/10.3390/su14052644 - 24 Feb 2022
Cited by 11 | Viewed by 2442
Abstract
In this study, a new bio-adsorbent (NASIF) was successfully prepared via chemical activation of Solanum incanum (SI) with hydrogen peroxide and sodium hydroxide reagents as an inexpensive and effective adsorbent for the removal of methylene blue (MB) from aqueous media. The morphology of [...] Read more.
In this study, a new bio-adsorbent (NASIF) was successfully prepared via chemical activation of Solanum incanum (SI) with hydrogen peroxide and sodium hydroxide reagents as an inexpensive and effective adsorbent for the removal of methylene blue (MB) from aqueous media. The morphology of the NASIF adsorbent surface and the nature of the potential MB interactions were examined by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) micrograph. FTIR results suggested that carboxyl, carbonyl, and hydroxyl groups were involved in MB adsorption on the NASIF surface. EDX analysis confirmed the successful increase of oxygen-containing functional groups during the chemical activation. The influence of important factors was studied using the batch method. The results revealed that the maximum removal efficiency was 98% at contact time: 120 min; pH: 6.5, adsorbent dose: 40 mg; and temperature-25 °C. Isothermal behavior was evaluated using three non-linear isotherm models, Langmuir, Freundlich, and D–R isotherm. MB adsorption onto NASIF adsorbent followed the Langmuir isotherm model with maximum monolayer capacity (mg/g) at 25 °C. Meanwhile, the PSO kinetics model was found to be better than PFO kinetic model for describing the adsorption process using kinetic models. Based on the D–R model, the free energy (E, kJ mol−1) values were in the range of 0.090–0.1812 kJ mol−1, which indicated that the MB adsorption onto NASIF may belong to physical adsorption. The adsorption mechanism of MB onto NASIF adsorbent mainly includes electrostatic attraction, π-π interaction, n-π interaction, and H-bonding. The thermodynamic parameters revealed that the adsorption process was a feasibility, spontaneous and exothermic process. Finally, the result of the present work could provide strong evidence of the potential of NASIF adsorbent for eliminating MB from aqueous media. Full article
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12 pages, 4423 KiB  
Article
Combination of Coagulation, Adsorption, and Ultrafiltration Processes for Organic Matter Removal from Peat Water
by Muthia Elma, Amalia Enggar Pratiwi, Aulia Rahma, Erdina Lulu Atika Rampun, Mahmud Mahmud, Chairul Abdi, Raissa Rosadi, Dede Heri Yuli Yanto and Muhammad Roil Bilad
Sustainability 2022, 14(1), 370; https://doi.org/10.3390/su14010370 - 30 Dec 2021
Cited by 27 | Viewed by 3278
Abstract
The high content of natural organic matter (NOM) is one of the challenging characteristics of peat water. It is also highly contaminated and contributes to some water-borne diseases. Before being used for potable purposes, peat water must undergo a series of treatments, particularly [...] Read more.
The high content of natural organic matter (NOM) is one of the challenging characteristics of peat water. It is also highly contaminated and contributes to some water-borne diseases. Before being used for potable purposes, peat water must undergo a series of treatments, particularly for NOM removal. This study investigated the effect of coagulation using aluminum sulfate coagulant and adsorption using powdered activated carbon (PAC) as a pretreatment of ultrafiltration (UF) for removal of NOM from actual peat water. After preparation and characterization of polysulfone (Psf)-based membrane, the system’s performance was evaluated using actual peat water, particularly on NOM removal and the UF performances. The coagulation and adsorption tests were done under variable dosings. Results show that pretreatment through coagulation–adsorption successfully removed most of the NOM. As such, the UF fouling propensity of the pretreated peat water was substantially lowered. The optimum aluminum sulfate dosing of 175 mg/L as the first pretreatment stage removed up to 75–78% NOM. Further treatment using the PAC-based adsorption process further increased 92–96% NOM removals at an optimum PAC dosing of 120 mg/L. The final UF-PSf treatment reached NOM removals of 95% with high filtration fluxes of up to 92.4 L/(m2.h). The combination of three treatment stages showed enhanced UF performance thanks to partial pre-removal of NOM that otherwise might cause severe membrane fouling. Full article
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18 pages, 26891 KiB  
Article
Post-Treatment of Palm Oil Mill Effluent Using Immobilised Green Microalgae Chlorococcum oleofaciens
by Kah Aik Tan, Japareng Lalung, Norhashimah Morad, Norli Ismail, Wan Maznah Wan Omar, Moonis Ali Khan, Mika Sillanpää and Mohd Rafatullah
Sustainability 2021, 13(21), 11562; https://doi.org/10.3390/su132111562 - 20 Oct 2021
Cited by 9 | Viewed by 2762
Abstract
Microalgae immobilisation can be a long-term solution for effective wastewater post-treatment. This study was conducted to evaluate the ability of immobilised Chlorococcum oleofaciens to remove contaminants from palm oil mill effluent (POME) until it complies with the POME discharge standard. First, the native [...] Read more.
Microalgae immobilisation can be a long-term solution for effective wastewater post-treatment. This study was conducted to evaluate the ability of immobilised Chlorococcum oleofaciens to remove contaminants from palm oil mill effluent (POME) until it complies with the POME discharge standard. First, the native dominating green microalga was isolated from a polishing POME treatment pond. Then, the microalgae cells were immobilised on sodium alginate beads and cultivated in a lab-scale-treated POME to treat it further. The immobilised microalgae cells demonstrated a high removal of total phosphorus, total nitrogen, ammonia nitrogen, and soluble chemical oxygen demand with 90.43%, 93.51%, 91.26%, and 50.72% of reduction, respectively. Furthermore, the growth rate of the microalgae fitted nicely with the Verhulst logistical model with r2 of more than 0.99, indicating the model’s suitability in modelling the growth. Thus, we concluded that the species can be used for post-treatment of effluents to remove TP, TN, and ammonia nitrogen from palm oil mills until it complies with the POME effluent discharge standard. However, during the process, degradation of the beads occurred and the COD value increased. Therefore, it is not suitable to be used for COD removal. Full article
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14 pages, 1284 KiB  
Article
Formulation of Organic Wastes as Growth Media for Cultivation of Earthworm Nutrient-Rich Eisenia foetida
by Mashur Mashur, Muhammad Roil Bilad, Hunaepi Hunaepi, Nurul Huda and Jumardi Roslan
Sustainability 2021, 13(18), 10322; https://doi.org/10.3390/su131810322 - 15 Sep 2021
Cited by 8 | Viewed by 3120
Abstract
Inadequate management of solid organic waste can lead to the spread of diseases and negatively affects the environment. Fermentation and vermicomposting of organic waste could have dual benefits by generating earthworm biomass for a source of animal feed protein, and, at the same [...] Read more.
Inadequate management of solid organic waste can lead to the spread of diseases and negatively affects the environment. Fermentation and vermicomposting of organic waste could have dual benefits by generating earthworm biomass for a source of animal feed protein, and, at the same time, turning the organic waste into readily used compost. This study investigated the effect of an organic waste source (as a sole source or blended with others) totaling 24 media for the cultivation of the earthworm Eisenia foetida. Eight media sources were applied, namely cow manure, horse manure, goat manure, broiler chicken manure, market organic waste, household organic waste, rice straw, and beef rumen content. E. foetida was cultivated for 40 days, then the number of cocoons, earthworms, and the total biomass weight were measured at the end of the cultivation. Results demonstrated that the media source affected E. foetida earthworm cultivation. The most effective media were those containing horse manure that led to the production of the highest earthworms and the highest biomass. The produced cocoons and earthworms were poorly correlated with an r-value of 0.26 and p-value of 0.21. Meanwhile, the number and weight of the earthworms correlated well with an r-value of 0.784 and p-value of <0.01. However, the average numbers and weights of the produced earthworms in the media containing horse manure, cow manure, goat manure, and non-blended organic waste were insignificant. Overall results suggest that blended organic wastes can undergo composting to produce nutrient-rich earthworm biomass while turning the solid organic waste into readily used compost. Full article
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14 pages, 4118 KiB  
Article
Image Processing of UAV Imagery for River Feature Recognition of Kerian River, Malaysia
by Emaad Ansari, Mohammad Nishat Akhtar, Mohamad Nazir Abdullah, Wan Amir Fuad Wajdi Othman, Elmi Abu Bakar, Ahmad Faizul Hawary and Syed Sahal Nazli Alhady
Sustainability 2021, 13(17), 9568; https://doi.org/10.3390/su13179568 - 25 Aug 2021
Cited by 9 | Viewed by 2822
Abstract
The impact of floods is the most severe among the natural calamities occurring in Malaysia. The knock of floods is consistent and annually forces thousands of Malaysians to relocate. The lack of information from the Ministry of Environment and Water, Malaysia is the [...] Read more.
The impact of floods is the most severe among the natural calamities occurring in Malaysia. The knock of floods is consistent and annually forces thousands of Malaysians to relocate. The lack of information from the Ministry of Environment and Water, Malaysia is the foremost obstacle in upgrading the flood mapping. With the expeditious evolution of computer techniques, processing of satellite and unmanned aerial vehicle (UAV) images for river hydromorphological feature detection and flood management have gathered pace in the last two decades. Different image processing algorithms—structure from motion (SfM), multi-view stereo (MVS), gradient vector flow (GVF) snake algorithm, etc.—and artificial neural networks are implemented for the monitoring and classification of river features. This paper presents the application of the k-means algorithm along with image thresholding to quantify variation in river surface flow areas and vegetation growth along Kerian River, Malaysia. The river characteristic recognition directly or indirectly assists in studying river behavior and flood monitoring. Dice similarity coefficient and Jaccard index are numerated between thresholded images that are clustered using the k-means algorithm and manually segmented images. Based on quantitative evaluation, a dice similarity coefficient and Jaccard index of up to 97.86% and 94.36% were yielded for flow area and vegetation calculation. Thus, the present technique is functional in evaluating river characteristics with reduced errors. With minimum errors, the present technique can be utilized for quantifying agricultural areas and urban areas around the river basin. Full article
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16 pages, 3489 KiB  
Article
Membrane Filtration as Post-Treatment of Rotating Biological Contactor for Wastewater Treatment
by Sharjeel Waqas, Muhammad Roil Bilad, Nurul Huda, Noorfidza Yub Harun, Nik Abdul Hadi Md Nordin, Norazanita Shamsuddin, Yusuf Wibisono, Asim Laeeq Khan and Jumardi Roslan
Sustainability 2021, 13(13), 7287; https://doi.org/10.3390/su13137287 - 29 Jun 2021
Cited by 8 | Viewed by 3663
Abstract
A rotating biological contactor (RBC) offers a low energy footprint but suffers from performance instability, making it less popular for domestic wastewater treatment. This paper presents a study on an RBC integrated with membrane technology in which membrane filtration was used as a [...] Read more.
A rotating biological contactor (RBC) offers a low energy footprint but suffers from performance instability, making it less popular for domestic wastewater treatment. This paper presents a study on an RBC integrated with membrane technology in which membrane filtration was used as a post-treatment step (RBC–ME) to achieve enhanced biological performance. The RBC and RBC–ME systems were operated under different hydraulic retention times (HRTs) of 12, 18, 24, and 48 h, and the effects of HRT on biological performance and effluent filterability were assessed. The results show that RBC–ME demonstrates superior biological performance than the standalone RBC. The RBC–ME bioreactor achieved 87.9 ± 3.2% of chemical oxygen demand (COD), 98.9 ± 1.1% ammonium, 45.2 ± 0.7% total nitrogen (TN), and 97.9 ± 0.1% turbidity removals. A comparison of the HRTs showed that COD and TN removal efficiency was the highest at 48 h, with 92.4 ± 2.4% and 48.6 ± 1.3% removal efficiencies, respectively. The longer HRTs also lead to better RBC effluent filterability. The steady-state permeability increased respectively by 2.4%, 9.5%, and 19.1% at HRTs of 18, 24, and 48 h, compared to 12 h. Our analysis of membrane fouling shows that fouling resistance decreased at higher HRTs. Overall, RBC–ME offered a promising alternative for traditional suspended growth processes with higher microbial activity and enhanced biological performance, which is in line with the requirements of sustainable development and environment-friendly treatment. Full article
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14 pages, 1736 KiB  
Article
Adsorption/Desorption Capability of Potassium-Type Zeolite Prepared from Coal Fly Ash for Removing of Hg2+
by Yuhei Kobayashi, Fumihiko Ogata, Chalermpong Saenjum, Takehiro Nakamura and Naohito Kawasaki
Sustainability 2021, 13(8), 4269; https://doi.org/10.3390/su13084269 - 12 Apr 2021
Cited by 17 | Viewed by 2274
Abstract
The feasibility of using potassium-type zeolite (K-type zeolite) prepared from coal fly ash (CFA) for the removal of Hg2+ from aqueous media and the adsorption/desorption capabilities of various potassium-type zeolites were assessed in this study. Potassium-type zeolite samples were synthesized by hydrothermal [...] Read more.
The feasibility of using potassium-type zeolite (K-type zeolite) prepared from coal fly ash (CFA) for the removal of Hg2+ from aqueous media and the adsorption/desorption capabilities of various potassium-type zeolites were assessed in this study. Potassium-type zeolite samples were synthesized by hydrothermal treatment of CFA at different intervals (designated CFA, FA1, FA3, FA6, FA12, FA24, and FA48, based on the hours of treatment) using potassium hydroxide solution, and their physicochemical characteristics were evaluated. Additionally, the quantity of Hg2+ adsorbed was in the order CFA, FA1 < FA3 < FA6 < FA12 < FA24 < FA48, in the current experimental design. Therefore, the hydrothermal treatment time is important to enhance the adsorption capability of K-type zeolite. Moreover, the effects of pH, temperature, contact time, and coexistence on the adsorption of Hg2+ were elucidated. In addition, Hg2+ adsorption mechanism using FA48 was demonstrated. Our results indicated that Hg2+ was exchanged with K+ in the interlayer of FA48 (correlation coefficient = 0.946). Finally, adsorbed Hg2+ onto FA48 could be desorbed using a sodium hydroxide solution (desorption percentage was approximately 70%). Our results revealed that FA48 could be a potential adsorbent for the removal of Hg2+ from aqueous media. Full article
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Review

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27 pages, 11365 KiB  
Review
Clean Water Production Enhancement through the Integration of Small-Scale Solar Stills with Solar Dish Concentrators (SDCs)—A Review
by Mohd Fazly Yusof, Mohd Remy Rozainy Mohd Arif Zainol, Andrei Victor Sandu, Ali Riahi, Nor Azazi Zakaria, Syafiq Shaharuddin, Mohd Sharizal Abdul Aziz, Norazian Mohamed Noor, Petrica Vizureanu, Mohd Hafiz Zawawi and Jazaul Ikhsan
Sustainability 2022, 14(9), 5442; https://doi.org/10.3390/su14095442 - 30 Apr 2022
Cited by 6 | Viewed by 2476
Abstract
The conventional solar still, as a water treatment technique, has been reported to produce water at a low working temperature where various thermal resistance pathogens could survive in their distillate. In this work, the reviews of previous research on the quality of water [...] Read more.
The conventional solar still, as a water treatment technique, has been reported to produce water at a low working temperature where various thermal resistance pathogens could survive in their distillate. In this work, the reviews of previous research on the quality of water produced by passive solar stills and their productivities in initial basin water temperatures were first presented and discussed. The next review discussed some recent studies on the performances of small-scale solar stills integrated with SDCs (with and without sun-tracking systems (STSs)) to observe the operating temperatures from early hours until the end of operations, daily water yield, and cost per liter. Based on these findings, it was revealed that SDCs with STSs indicated an instant increase in the absorber water temperature up to 70 °C at the starting point of the experiments in which this temperature range marked the unbearable survival of the pathogenic organisms and viruses, particularly the recent SARS-CoV-2. Furthermore, disinfection was also observed when the absorbers’ water temperature reached beyond the boiling point until the end of operations. This indicates the effectiveness of SDCs with STS in reflecting a large amount of sun’s rays and heat to the small-scale absorbers and providing higher operating absorbers temperatures compared to immobile SDCs. Daily productivities and costs per liter of the SDCs with STSs were found to be higher and lower than those of the other previous passive and active solar stills. Therefore, it is recommended that small-scale absorbers integrated with SDCs and STS can be used as a cost-effective and reliable method to produce hygienic pathogen-free water for the communities in remote and rural areas which encounter water scarcity and abundant annual bright sunshine hours. Full article
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23 pages, 683 KiB  
Review
Degradation of Azo Dyes: Bacterial Potential for Bioremediation
by Lucas Rafael Santana Pinheiro, Diana Gomes Gradíssimo, Luciana Pereira Xavier and Agenor Valadares Santos
Sustainability 2022, 14(3), 1510; https://doi.org/10.3390/su14031510 - 28 Jan 2022
Cited by 84 | Viewed by 10926
Abstract
The use of dyes dates to ancient times and has increased due to population and industrial growth, leading to the rise of synthetic dyes. These pollutants are of great environmental impact and azo dyes deserve special attention due their widespread use and challenging [...] Read more.
The use of dyes dates to ancient times and has increased due to population and industrial growth, leading to the rise of synthetic dyes. These pollutants are of great environmental impact and azo dyes deserve special attention due their widespread use and challenging degradation. Among the biological solutions developed to mitigate this issue, bacteria are highlighted for being versatile organisms, which can be applied as single organism cultures, microbial consortia, in bioreactors, acting in the detoxification of azo dyes breakage by-products and have the potential to combine biodegradation with the production of products of economic interest. These characteristics go hand in hand with the ability of various strains to act under various chemical and physical parameters, such as a wide range of pH, salinity, and temperature, with good performance under industry, and environmental, relevant conditions. This review encompasses studies with promising results related to the use of bacteria in the bioremediation of environments contaminated with azo dyes in the most diverse techniques and parameters, both in environmental and laboratory samples, also addressing their mechanisms and the legislation involving these dyes around the world, showcasing the importance of bacterial bioremediation, specialty in a scenario in an ever-increasing pursuit for sustainable production. Full article
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21 pages, 1379 KiB  
Review
Insights into Solar Disinfection Enhancements for Drinking Water Treatment Applications
by Abdassalam A. Azamzam, Mohd Rafatullah, Esam Bashir Yahya, Mardiana Idayu Ahmad, Japareng Lalung, Sarah Alharthi, Abeer Mohammad Alosaimi and Mahmoud A. Hussein
Sustainability 2021, 13(19), 10570; https://doi.org/10.3390/su131910570 - 23 Sep 2021
Cited by 13 | Viewed by 4561
Abstract
Poor access to drinking water, sanitation, and hygiene has always been a major concern and a main challenge facing humanity even in the current century. A third of the global population lacks access to microbiologically safe drinking water, especially in rural and poor [...] Read more.
Poor access to drinking water, sanitation, and hygiene has always been a major concern and a main challenge facing humanity even in the current century. A third of the global population lacks access to microbiologically safe drinking water, especially in rural and poor areas that lack proper treatment facilities. Solar water disinfection (SODIS) is widely proven by the World Health Organization as an accepted method for inactivating waterborne pathogens. A significant number of studies have recently been conducted regarding its effectiveness and how to overcome its limitations, by using water pretreatment steps either by physical, chemical, and biological factors or the integration of photocatalysis in SODIS processes. This review covers the role of solar disinfection in water treatment applications, going through different water treatment approaches including physical, chemical, and biological, and discusses the inactivation mechanisms of water pathogens including bacteria, viruses, and even protozoa and fungi. The review also addresses the latest advances in different pre-treatment modifications to enhance the treatment performance of the SODIS process in addition to the main limitations and challenges. Full article
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