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25 pages, 12331 KiB

Open AccessArticle

Urban Wastewater Phytoremediation by Autochthonous Microalgae in Winter Season: Indoor and Outdoor Trials

by Pierluigi Giacò, Costanza Baldisserotto, Sara Demaria, Elisa Benà, Lorenzo Ferroni, Giulia Zanotti and Simonetta Pancaldi

Appl. Sci. 2025, 15(8), 4235; https://doi.org/10.3390/app15084235 - 11 Apr 2025

Viewed by 152

Abstract

Microalgae are gaining increasing attention for wastewater (WW) depuration thanks to their ability to remove pollutants from WW. As environmental conditions change widely geographically and throughout the year, also reaching growth-limiting temperatures during the cold season, sites and seasons specific tests are needed [...] Read more.

Microalgae are gaining increasing attention for wastewater (WW) depuration thanks to their ability to remove pollutants from WW. As environmental conditions change widely geographically and throughout the year, also reaching growth-limiting temperatures during the cold season, sites and seasons specific tests are needed to assess the actual implementation of microalgae phytoremediation. In this paper, two site-specific prototype-scale experiments were performed to test the ability of an autochthonous microalga to depurate urban WW efficiently during winter. Two setups were tested: one indoor and one outdoor. We evaluated dry biomass production, photosynthetic stress, and nitrogen (N) and phosphorus (P) removals from WW. In addition, Escherichia coli concentration was monitored on the effluent. Despite the limited growth in both conditions, N was largely removed from the medium, with the highest result recorded outdoors (almost 70%). No P removal was recorded, although P content in biomass increased both indoors and outdoors, meaning that multiple processes could occur at the same time. Moreover, a huge decrease in E. coli content was recorded in both conditions, suggesting potential for effluent disinfection. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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20 pages, 2995 KiB

Open AccessArticle

Environmental Life Cycle Assessment of Class A Biosolids Production Using Conventional and Low-Cost, Low-Tech Processes at Small Water Resource Recovery Facilities

by Janna L. Brown, Robert M. Handler, Jennifer G. Becker and Eric A. Seagren

Appl. Sci. 2025, 15(7), 3482; https://doi.org/10.3390/app15073482 - 22 Mar 2025

Viewed by 245

Abstract

Producing Class A biosolids that can be distributed or land-applied without restriction is a beneficial way to reuse wastewater treatment solids. For small water resource recovery facilities (WRRFs) in particular, low-cost, low-tech (LCLT) processes may be an appealing alternative to conventional technologies for [...] Read more.

Producing Class A biosolids that can be distributed or land-applied without restriction is a beneficial way to reuse wastewater treatment solids. For small water resource recovery facilities (WRRFs) in particular, low-cost, low-tech (LCLT) processes may be an appealing alternative to conventional technologies for producing Class A biosolids, such as processes to further reduce pathogens (PFRPs). Conventional Class A biosolids treatment processes tend to be energy-intensive and involve complex equipment and operations. However, a systematic comparison of the overall sustainability of conventional processes and LCLT alternatives for producing Class A biosolids to aid decision makers in selecting treatment processes is not readily available. Therefore, this study used life cycle assessments to compare five Class A biosolids treatment processes, including three conventional processes—Composting, Direct Heat Drying, and temperature-phased anaerobic digestion (TPAD)—and two LCLT processes—Air Drying, and long-term Lagoon Storage followed by Air Drying—on the basis of their environmental impacts. The environmental impacts were normalized to facilitate a comparison of the processes. The results indicate that Composting and Direct Heat Drying had the most significant environmental impacts, primarily from the biogenic emissions during Composting and the natural gas requirements for Direct Heat Drying. In comparison, TPAD and Air Drying had the lowest environmental impacts, and Lagoon Storage had intermediate impacts. Thus, LCLT processes may be more sustainable than some, but not all, conventional PFRPs. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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16 pages, 10442 KiB

Open AccessArticle

Exploring Convective Drying Behavior of Hydroxide Sludges Through Micro-Drying Systems

by Azeddine Fantasse, Sergio Luis Parra-Angarita, El Khadir Lakhal, Ali Idlimam, El Houssayne Bougayr and Angélique Léonard

Appl. Sci. 2025, 15(7), 3470; https://doi.org/10.3390/app15073470 - 21 Mar 2025

Viewed by 191

Abstract

The drying of hydroxide sludge is a critical step in its valorization process in drinking water treatment plants (WWTPs), due to the high energy requirements associated with this operation. This study investigates the convective drying behavior of hydroxide sludge using a convective micro-dryer, [...] Read more.

The drying of hydroxide sludge is a critical step in its valorization process in drinking water treatment plants (WWTPs), due to the high energy requirements associated with this operation. This study investigates the convective drying behavior of hydroxide sludge using a convective micro-dryer, with air heated to temperatures between 70 °C and 110 °C, velocities ranging from 1 m/s to 3 m/s, and constant absolute humidity of 0.005 kg of water per kg of dry air. The process was continuously monitored through X-ray microtomography, allowing the nondestructive observation of external surface texture evolution, shrinkage, and crack formation. A significant shrinkage, with a volume reduction ranging from 30% to 45%, was observed as the moisture content decreased. The experimental data were used to develop a characteristic drying curve specific to hydroxide sludge, which remained consistent across different operational conditions. The results showed that increasing air temperature and velocity enhanced the drying flux and reduced drying time, while higher air humidity produced the opposite effect. Additionally, the crack formation observed towards the end of the drying process was associated with internal moisture transfer limitations. Effective diffusivity increased with air temperature, highlighting the significant impact of temperature on the activation energy of the drying process. These findings provide valuable insights for optimizing the energy efficiency of sludge-drying operations. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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18 pages, 813 KiB

Open AccessArticle

Economies of Scale and Efficiency in the Wastewater Treatment Sector: A Decision Tree Approach

by Vicent Hernández-Chover, Águeda Bellver-Domingo, Lledó Castellet-Viciano and Francesc Hernández-Sancho

Appl. Sci. 2025, 15(7), 3423; https://doi.org/10.3390/app15073423 - 21 Mar 2025

Viewed by 295

Abstract

In this study, we use the efficiency analysis trees (EAT) model to evaluate the efficiency of wastewater treatment plants (WWTPs), focusing on identifying the key variables that enhance their performance. While traditional methods consider factors such as the plant size, age, and technology, [...] Read more.

In this study, we use the efficiency analysis trees (EAT) model to evaluate the efficiency of wastewater treatment plants (WWTPs), focusing on identifying the key variables that enhance their performance. While traditional methods consider factors such as the plant size, age, and technology, the EAT model improves the precision of and reduces errors in the efficiency estimation process. The results highlight the significance of facility size, particularly in areas with smaller populations, suggesting that economies of scale can play a crucial role in optimizing treatment processes. Centralizing the sector could lead to cost savings through ensuring better resource allocation and more effective management strategies. This study provides insights into how facility dimensions impact efficiency, aiding in strategic planning for wastewater treatment operations. The novelty of this study pertains to its implementation of the EAT model to assess efficiency from an economic point of view. Specifically, this makes it possible to identify which facility dimensions ensure better performance and, consequently, will help operators to establish criteria for intervention and geographical planning, both technically and economically. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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11 pages, 926 KiB

Open AccessArticle

Can Anaerobically Digested Food Effluent Support Arthrospira platensis Cultivation in Open Ponds?

by Mohammadjavad Raeisossadati, Odgerel Bumandalai and Navid Reza Moheimani

Appl. Sci. 2025, 15(6), 3115; https://doi.org/10.3390/app15063115 - 13 Mar 2025

Viewed by 448

Abstract

The cultivation of Arthrospira platensis (Spirulina) is well-established in applied phycology, but the high cost of conventional media limits large-scale production. Anaerobically digested food effluent (ADFE), rich in nitrogen and phosphorus, offers a cost-effective alternative while mitigating environmental impacts. This study evaluated ADFE [...] Read more.

The cultivation of Arthrospira platensis (Spirulina) is well-established in applied phycology, but the high cost of conventional media limits large-scale production. Anaerobically digested food effluent (ADFE), rich in nitrogen and phosphorus, offers a cost-effective alternative while mitigating environmental impacts. This study evaluated ADFE as a partial replacement for Zarrouk’s medium, with 37.5%, 50%, and 70% substitutions, the latter two added incrementally. Cultivation was conducted in paddlewheel-driven raceway ponds under outdoor conditions for 22 days during the Australian autumn. The highest biomass productivity (8.83 g m⁻² d⁻¹) was achieved with 70% ADFE, significantly outperforming Zarrouk’s medium (p < 0.05). Chlorophyll a content remained unaffected (p > 0.05), and ammonium (N-NH₄⁺) declined to near zero by day 9, indicating efficient nutrient uptake. These findings demonstrate that staged ADFE addition can successfully replace up to 70% of Zarrouk’s medium while maintaining robust A. platensis growth, highlighting its potential as a sustainable alternative for large-scale microalgal cultivation. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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16 pages, 1884 KiB

Open AccessArticle

Degradation and Ecotoxicity Mitigation of Perfluorooctane Sulfonate by Aeration-Assisted Cold Plasma

by Sengbin Oh, Joo-Youn Nam, Youngpyo Hong, Tae-Hun Lee, Jae-Cheol Lee and Hyun-Woo Kim

Appl. Sci. 2025, 15(6), 2936; https://doi.org/10.3390/app15062936 - 8 Mar 2025

Viewed by 1004

Abstract

Various advanced oxidation processes have been used to degrade perfluorooctane sulfonate (PFOS), one of the persistent organic pollutants that dissolves in aquatic ecosystems, but these processes suffer from inherent limitations. This study proposes aeration-assisted cold plasma (CP) technology as an alternative. PFOS removal [...] Read more.

Various advanced oxidation processes have been used to degrade perfluorooctane sulfonate (PFOS), one of the persistent organic pollutants that dissolves in aquatic ecosystems, but these processes suffer from inherent limitations. This study proposes aeration-assisted cold plasma (CP) technology as an alternative. PFOS removal via CP treatment reached 62.5% after 1 h of exposure, with a degradation rate constant of 3.1 h⁻¹. The detection of sulfate (SO₄²⁻) in the solution provides evidence of effective PFOS degradation. The close agreement between the measured and estimated fluoride concentrations further confirms mass balance after degradation. Acute toxicity tests indicate that PFOS degradation may initially increase the acute toxicity, possibly due to the formation of degradation by-products. However, this increased toxicity can be mitigated through additional exposure to the reactive species generated by CP. Furthermore, investigations into the energy per order of CP and the quantification of hydroxyl radicals support its operational effectiveness. This study confirms that aeration-assisted CP has the potential to serve as a viable treatment option for mitigating the environmental threats posed by PFOS. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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26 pages, 7119 KiB

Open AccessArticle

Simultaneous Electrochemical Removal of Selenium and Strontium from Aqueous Solution

by Katarina Licht, Ivan Halkijević, Hana Posavčić and Domagoj Nakić

Appl. Sci. 2025, 15(5), 2786; https://doi.org/10.3390/app15052786 - 5 Mar 2025

Viewed by 525

Abstract

This study investigated the removal of selenium (Se) and strontium (Sr) from water using a three-stage electrochemical reactor with integrated pH control. A total of 102 experiments were performed following a Box–Behnken design that varied the electrode material, applied current, number of electrodes, [...] Read more.

This study investigated the removal of selenium (Se) and strontium (Sr) from water using a three-stage electrochemical reactor with integrated pH control. A total of 102 experiments were performed following a Box–Behnken design that varied the electrode material, applied current, number of electrodes, operating time, and initial pH to evaluate their effects on the Se and Sr removal efficiencies. The complete removal of Se was achieved under multiple conditions, even without pH control, while effective Sr removal required a high current and initial pH adjustment. The top performance for both elements was achieved with a 25 A current, four Fe electrodes, 15 min of operational time per phase (cycle), and a middle range of pH values, which resulted in 97.92% and 99.96% removals of Sr and Se, respectively. This research highlighted the novel approach of using electrochemical pH control to achieve high removal efficiencies of Se and Sr from water in a short operating time, which surpassed the efficiencies reported in previous studies. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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15 pages, 2361 KiB

Open AccessArticle

From Waste to Value: Banana-Peel-Derived Adsorbents for Efficient Removal of Polar Compounds from Used Palm Oil

by Duangdao Channei, Panatda Jannoey, Punyanuch Thammaacheep, Wilawan Khanitchaidecha and Auppatham Nakaruk

Appl. Sci. 2025, 15(4), 2205; https://doi.org/10.3390/app15042205 - 19 Feb 2025

Viewed by 742

Abstract

The banana chip industry generates significant quantities of waste, including banana peels and used palm oil, which present both environmental and economic challenges. This study explored converting banana peel waste into porous adsorbents via chemical and thermal activation using sulfuric acid (S-BP) and [...] Read more.

The banana chip industry generates significant quantities of waste, including banana peels and used palm oil, which present both environmental and economic challenges. This study explored converting banana peel waste into porous adsorbents via chemical and thermal activation using sulfuric acid (S-BP) and 5% w/v acetic acid (A-BP) as activating agents. Characterization using field emission scanning electron microscopy (FESEM) and Brunauer–Emmett–Teller (BET) analysis revealed notable morphological distinctions and enhanced porosity. The BET surface areas of S-BP and A-BP were 338.959 m²/g and 201.722 m²/g, respectively, significantly higher than that of calcined banana peel (C-BP) at 3.202 m²/g. Despite the higher surface area of S-BP, A-BP, prepared under milder acetic acid conditions, was further investigated for adsorption studies. A-BP effectively reduced the free fatty acids (FFAs) in used palm oil from 3.108% to 1.69% within 30 min. Adsorption isotherms favored the Freundlich model (R² = 0.9115), indicating multilayer adsorption behavior. The adsorption energy derived from the Dubinin–Radushkevich (D–R) model was determined to be 2.61 J/mol, indicating that the adsorption process primarily occurs through physisorption. This study highlights a sustainable approach to waste management and resource recovery, promoting circular economy principles in the banana chip industry. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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13 pages, 2389 KiB

Open AccessArticle

Brown Coconut Husks as Media Within an Anaerobic Filter for Improving On-Site Wastewater Treatment

by Nicola Brown, John Edwards, Shogo Yarita and Sylvia Chia

Appl. Sci. 2025, 15(4), 1944; https://doi.org/10.3390/app15041944 - 13 Feb 2025

Viewed by 935

Abstract

Many small communities rely on on-site wastewater treatment systems such as septic tanks; however, there are concerns regarding the level of wastewater treatment being achieved. Appropriate solutions for these communities are needed to upgrade existing septic tanks. Anaerobic filters are a potential solution, [...] Read more.

Many small communities rely on on-site wastewater treatment systems such as septic tanks; however, there are concerns regarding the level of wastewater treatment being achieved. Appropriate solutions for these communities are needed to upgrade existing septic tanks. Anaerobic filters are a potential solution, which can be added downstream of the septic tank and operate by containing media which allow a biofilm to form. Ideally, this media would be easily accessible and affordable. In this work, the use of brown coconut husks is investigated, and it is found that 68% of the chemical oxygen demand (COD) can be removed by these systems. Nutrient levels were also monitored in the effluent to determine whether the leaching of nutrients from the coconut husks is a concern. It was found that initially some nitrogen and phosphorus had leached but these were washed out of the reactor very quickly and had a minimal impact on the effluent concentrations. Examination of the coconut husks after 10 months of operation showed no signs of the coconut husks beginning to break down, suggesting that the use of coconut husks as media in anaerobic filters should be investigated further. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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19 pages, 4625 KiB

Open AccessArticle

Removal of Zn(II), Cu(II) and Pb(II) from Rainwater by White Bean Peel: Optimization by Response Surface Methodology

by Gonçalo H. Cabral, Ana C. Estrada and Patrícia S. M. Santos

Appl. Sci. 2025, 15(2), 627; https://doi.org/10.3390/app15020627 - 10 Jan 2025

Cited by 1 | Viewed by 551

Abstract

Potentially toxic elements (PTEs) have been found in high levels in rainwater, highlighting the importance of removing them when the water is intended for domestic use. In this work, white bean peel was evaluated as sorbent for the removal of a mixture of [...] Read more.

Potentially toxic elements (PTEs) have been found in high levels in rainwater, highlighting the importance of removing them when the water is intended for domestic use. In this work, white bean peel was evaluated as sorbent for the removal of a mixture of PTEs from rainwater, namely Zn(II), Cu(II) and Pb(II). A uniform experimental design was used to evaluate the sorption and to optimize the removal process by response surface methodology. The biosorbent reduced the PTEs concentration in the solution, and their removal increased with the increase of the initial concentration and with time. The removal of Cu(II) and Pb(II) was affected by the pH of the solution since, at pH 7.0 for Cu(II), and at pH 5.6 and 7.0 for Pb(II), a decrease occurred in the removal. The optimal conditions for removal, 6 h of contact time between the sorbent and the solution, were applied to rainwater samples spiked with the mixture of PTEs and resulted in removals of 30–90% for Zn(II), 11–78% for Cu(II), and 11–97% for Pb(II), generally lower than those expected by the models, 91% for Zn(II) and 52% for Cu(II), highlighting that the rainwater matrix interferes with the removal of PTEs by peel. However, the white bean peel may be an alternative as sorbent to reduce Zn(II), Cu(II), and Pb(II) concentrations in rainwater, since it is a natural and sustainable material. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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14 pages, 5140 KiB

Open AccessArticle

Sulfonated Polyethersulfone Membranes for Brackish Water Desalination: Fabrication, Characterization, and Electrodialysis Performance Evaluation

by Li Chen, Eva M. Deemer, XiuJun Li and W. Shane Walker

Appl. Sci. 2025, 15(1), 216; https://doi.org/10.3390/app15010216 - 30 Dec 2024

Viewed by 763

Abstract

The widespread application of electrodialysis is constrained by the high cost of ion exchange membranes, necessitating the development of affordable alternatives. This study focuses on the fabrication and performance evaluation of cation exchange membranes made from polyethersulfone (PES) and sulfonated polyethersulfone (sPES). Membranes [...] Read more.

The widespread application of electrodialysis is constrained by the high cost of ion exchange membranes, necessitating the development of affordable alternatives. This study focuses on the fabrication and performance evaluation of cation exchange membranes made from polyethersulfone (PES) and sulfonated polyethersulfone (sPES). Membranes were synthesized through phase inversion with varying solvent evaporation times, using N-Methyl-2-Pyrrolidone (NMP) as the solvent. The structural and functional modifications were confirmed using FTIR, XPS, and AFM techniques. Performance tests identified optimal electrodialysis results for PES membranes with a 3 h solvent evaporation time and for sPES membranes with a 1 h evaporation time. Under varying operational conditions, including applied voltage, flow rates, and feed solutions, sPES membranes demonstrated superior performance, underscoring their potential for cost-effective brackish water desalination applications. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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19 pages, 5621 KiB

Open AccessArticle

Modified Kapok Fibers (Ceiba pentandra (L.) Gaerth) for Oil Spill Remediation

by Leonardo M. T. M. Oliveira, Eduardo J. S. Fonseca, Vanderson B. Bernardo, Carmem L. P. S. Zanta, Laís F. A. M. Oliveira, Jennifer N. S. R. de Oliveira, Samuel T. de Souza and José Leandro da Silva Duarte

Appl. Sci. 2024, 14(24), 11995; https://doi.org/10.3390/app142411995 - 21 Dec 2024

Viewed by 1451

Abstract

The search for efficient oil spill remediation techniques leads to the use of physical, chemical, and biological methods, featuring both natural and modified lipophilic materials. Kapok fibers (Ceiba pentandra (L.) Gaerth) have been studied as a result of their unusual natural oil [...] Read more.

The search for efficient oil spill remediation techniques leads to the use of physical, chemical, and biological methods, featuring both natural and modified lipophilic materials. Kapok fibers (Ceiba pentandra (L.) Gaerth) have been studied as a result of their unusual natural oil sorption capacity, which can be improved even further through physical or chemical treatments that augment their rugosity and alter their functional properties. Furthermore, the exact role of fiber morphology is not completely clear regarding the sorption process. Hence, this study investigated the efficacy of kapok fibers using different treatments, based on chemical and physical approaches, and characterized using advanced techniques (FTIR, SEM, AFM), aiming to improve the understanding of application possibilities in oil contamination scenarios. The results indicate that treatments using a low thermal intensity and low concentration do not lead to variation in sorption properties nor in surface structural features. Fiber rugosity varied from 4.40 to 12.35 nm, whereas an excessive increase in roughness was observed when the material was subject to more extreme conditions, such as a temperature of 120 °C and high concentrations (2.0 M) of both acid or alkali, accompanied by a loss in functionality and affecting the material sorption capacity. Thus, the study provides conditions to suggest that these treatments are not necessary for this type of material when inserted into sorption processes. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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14 pages, 2189 KiB

Open AccessArticle

Iron (Magnetite) Nanoparticle-Assisted Dark Fermentation Process for Continuous Hydrogen Production from Rice Straw Hydrolysate

by Jacobo Pérez-Barragán, Cristina Martínez-Fraile, Raúl Muñoz, Laura Vargas-Estrada, Rafael Maya-Yescas, Elizabeth León-Becerril, Roberto Castro-Muñoz and Octavio García-Depraect

Appl. Sci. 2024, 14(21), 9660; https://doi.org/10.3390/app14219660 - 23 Oct 2024

Cited by 3 | Viewed by 1353

Abstract

The use of metal nanoparticles (NPs) to enhance hydrogen production in dark fermentation (DF) has become a pioneering field of interest. In particular, iron-based nanoparticles (FeNPs) play a pivotal role in enhancing the activity of metalloenzymes and optimizing feedstock utilization, resulting in improved [...] Read more.

The use of metal nanoparticles (NPs) to enhance hydrogen production in dark fermentation (DF) has become a pioneering field of interest. In particular, iron-based nanoparticles (FeNPs) play a pivotal role in enhancing the activity of metalloenzymes and optimizing feedstock utilization, resulting in improved hydrogen production. This study investigated the effect of FeNPs (magnetite) supplementation at three different concentrations of 50, 100, and 200 ppm in a continuous dark fermenter for the production of hydrogen from rice straw acid hydrolysate. The highest hydrogen production rate of 2.6 ± 0.3 NL H₂/L-d was achieved with the addition of 100 ppm of nanoparticles, representing a 53% increase compared to the condition without FeNPs addition. This improvement was driven by a microbial community in which Clostridium was the major dominant genus. In addition, increasing the nanoparticle concentration to 100 ppm resulted in an increase in butyrate concentration to 2.0 ± 0.1 g/L, which is 43% higher than the butyrate concentration without FeNPs. However, when the NP concentration was increased to 200 ppm, the hydrogen production rate decreased to 1.6 ± 0.2 NL H₂/L-d. This study can serve as a guideline for future research aimed at evaluating the effects of FeNPs in continuous dark fermentation systems. This work highlights the potential benefits and challenges associated with the use of FeNPs, paving the way for future studies to optimize their application and improve the efficiency of dark fermentation processes. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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17 pages, 2970 KiB

Open AccessArticle

The Use of Beech Bark (Latin: Fagus sylvatica) and Birch Bark (Latin: Betula pendula Roth) for the Removal of Cationic Dyes from Aqueous Solutions

by Urszula Filipkowska, Tomasz Jóźwiak, Magdalena Filipkowska and Magdalena Deptuła

Appl. Sci. 2024, 14(14), 6128; https://doi.org/10.3390/app14146128 - 14 Jul 2024

Viewed by 1031

Abstract

The aim of this work was to determine the sorption capacity of the cationic dyes Basic Red 46 (BR46) and Basic Violet 10 (BV10) on the prepared sorbents: beech bark (BBe) and birch bark (BBi). Two fractions of bark were used in the [...] Read more.

The aim of this work was to determine the sorption capacity of the cationic dyes Basic Red 46 (BR46) and Basic Violet 10 (BV10) on the prepared sorbents: beech bark (BBe) and birch bark (BBi). Two fractions of bark were used in the research: fine (2–3 mm) and coarse (4–5 mm). The carried out tests made it possible to determine the influence of the pH value on the sorption efficiency, the sorption equilibrium time and the maximum sorption capacity of the two tested sorbents. The Langmuir model and the Freundlich model were used to describe the obtained experimental data. Beech and birch barks are effective sorbents for cationic dyes; however, the efficiency of dye sorption on both bark sorbents depends on the type of cationic dye. According to the obtained data, beech and birch bark sorbents showed higher sorption efficiency for Basic Red 46 than for Basic Violet 10. The pH correction was a necessary condition for sorption, and the sorption pH value for the cationic dyes Basic Red 46 and Basic Violet 10 was be determined individually for each dye. The most favourable pH value for the sorption of the BR46 dye on the beach and birch bark sorbents was pH = 6, while for the dye BV10, it was pH = 3. The sorption equilibrium time for Basic Red 46 was 300 min and for Basic Violet 10–240 min. The fine fraction of beech bark had the highest sorption capacity for both BR46 (128.45 mg/g dry matter) and BV10 (18.07 mg/g dry matter). Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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14 pages, 2083 KiB

Open AccessArticle

Feasibility of Using Reclaimed Water from the Alegria Wastewater Treatment Plant in Concrete Mixing Plants in Rio de Janeiro, Brazil

by Luis Carlos Soares da Silva Junior and Marcelo Obraczka

Appl. Sci. 2024, 14(12), 5293; https://doi.org/10.3390/app14125293 - 19 Jun 2024

Cited by 2 | Viewed by 1053

Abstract

Due to the rising costs of transportation and the more advanced treatment needed to meet the water demands of the urban population, the costs of potable water tend to increase as cities expand. For some water uses, potable water is not required, such [...] Read more.

Due to the rising costs of transportation and the more advanced treatment needed to meet the water demands of the urban population, the costs of potable water tend to increase as cities expand. For some water uses, potable water is not required, such as concrete mixing industries. Previous studies have proven the viability of using reused water in concrete production. In Caju, Rio de Janeiro, four large concrete mixing plants (CMPs) are located close to the Alegria Wastewater Treatment Plant. This study focused on assessing the technical and financial feasibility of reusing these effluents as an alternative source of water for the four CMPs. The alternatives were potable and reused water via two supply methods, water tank trucks and pipelines. All costs were analyzed and projected into the future with the market cost of capital. After comparing the costs, the use of reclaimed water proved to be highly feasible, especially when a using pipeline to supply the CMPs. The present costs for the reclaimed water supply were calculated to be USD 0.99 per m³ for the pipeline alternative and the other alternatives varied in being 5 to 7 times more costly. This water reuse project using pipelines to transport reclaimed water to concrete mixing plants provides a feasible, sustainable alternative water supply in water stressed regions such as Rio de Janeiro. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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14 pages, 1109 KiB

Open AccessArticle

Analytical Model for Predicting Induction Times in Reverse Osmosis Systems with and without Antiscalants

by Abraham Sagiv, Raphael Semiat and Hilla Shemer

Appl. Sci. 2024, 14(11), 4700; https://doi.org/10.3390/app14114700 - 30 May 2024

Viewed by 1005

Abstract

A simple predictive analytical model for induction times in reverse osmosis (RO), both with and without an antiscalant (AS), has been developed based on the fundamental principles of mass and momentum balance. The simplicity of the model arises from the very low Reynolds [...] Read more.

A simple predictive analytical model for induction times in reverse osmosis (RO), both with and without an antiscalant (AS), has been developed based on the fundamental principles of mass and momentum balance. The simplicity of the model arises from the very low Reynolds number in the vicinity of the cluster surface, enabling the use and derivation of exact equations. The main assumption of the induction time without AS, t_0A, is that the net growth of the cluster size results from the difference between adhesion and shear forces. With AS, the induction time, t_A, is extended due to the competition between the AS and the scaling molecules on the cluster’s surface ligands. The model was validated by fitting it to six independent datasets from experiments conducted with spiral-wound and tubular RO membranes under various operational conditions, resulting in an average difference of 8.0% (t_0A) and 8.7% (t_A) between predicted and experimental induction times. It was found that t_0A is governed by three dimensionless parameters: supersaturation ratio (S_a), shear (K_u), and scalant saturation (κ). t_A increases with t_0A and the AS concentration. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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Review

Jump to: Research

29 pages, 2161 KiB

Open AccessReview

Innovative Approaches for Minimizing Disinfection Byproducts (DBPs) in Water Treatment: Challenges and Trends

by Spyridon K. Golfinopoulos, Anastasia D. Nikolaou and Dimitrios E. Alexakis

Appl. Sci. 2024, 14(18), 8153; https://doi.org/10.3390/app14188153 - 11 Sep 2024

Cited by 1 | Viewed by 4586

Abstract

Growing concerns over public health and environmental safety have intensified the focus on minimizing harmful disinfection byproducts (DBPs) in water treatment. Traditional methods like chlorination, while effective against pathogens, often lead to the formation of DBPs, which pose significant risks. This paper explores [...] Read more.

Growing concerns over public health and environmental safety have intensified the focus on minimizing harmful disinfection byproducts (DBPs) in water treatment. Traditional methods like chlorination, while effective against pathogens, often lead to the formation of DBPs, which pose significant risks. This paper explores alternative strategies to reducing DBP formation while ensuring effective disinfection. The methodology involved a bibliographic study conducted through the Scopus platform, using appropriate keywords. The initial search yielded 9576 articles from the period 2020 to 2024. The key approaches identified include advanced oxidation processes (AOPs) such as UV/H₂O₂ and ozone, which mineralize natural organic matter (NOM) and minimize chemical use and sludge production; membrane-based filtration systems, like reverse osmosis, effectively removing contaminants without chemical disinfectants, reducing DBP risks. Furthermore, conventional processes, such as coagulation and filtration, serve as crucial pretreatment steps to lower NOM levels before disinfection. Additionally, optimizing chlorine dosing, using non-chlorine disinfectants, and employing post-disinfection methods like adsorption and biological filtration further mitigate DBP formation. Finally, the integration of artificial intelligence in process optimization is emerging as a promising tool for enhancing treatment efficiency and safety. This research contributes to the development of safer, more sustainable water treatment solutions, addressing regulatory demands and public health objectives. Full article

(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)

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