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Pollution and the rising energy demand are two major society issues, requiring urgent solutions. Here, we review the simultaneous production of hydrogen and removal of pollutants, with a focus on mechanisms, synthesis of photocatalysts, and applications. Remarkably, this method utilizes organic pollutants as sacrificial agents for photocatalytic hydrogen production, thus both reducing pollution and producing energy. Metal-doped, cocatalyst-loaded, organic and inorganic composite, heterostructure and heterojunction photocatalysts are described. We present applications to the removal of antibiotics and organic dyes. Pollutant degradation rates range from 5.3 to 100%, with hydrogen evolution of 13.7–2724.89 μmol·g–1h–1. [ABSTRACT FROM AUTHOR]

The growing presence of diverse pollutants, including heavy metals, organic compounds, pharmaceuticals, and emerging contaminants, poses significant environmental and health risks. Traditional methods for pollutant removal often face limitations in efficiency, selectivity, and sustainability. This review provides a comprehensive analysis of recent advancements in innovative adsorbents designed to address these challenges. It explores a wide array of non-conventional adsorbent materials, such as nanocellulose, metal–organic frameworks (MOFs), graphene-based composites, and biochar, emphasizing their sources, structural characteristics, and unique adsorption mechanisms. The review discusses adsorption processes, including the basic principles, kinetics, isotherms, and the factors influencing adsorption efficiency. It highlights the superior performance of these materials in removing specific pollutants across various environmental settings. The practical applications of these adsorbents are further explored through case studies in industrial settings, pilot studies, and field trials, showcasing their real-world effectiveness. Additionally, the review critically examines the economic considerations, technical challenges, and environmental impacts associated with these adsorbents, offering a balanced perspective on their viability and sustainability. The conclusion emphasizes future research directions, focusing on the development of scalable production methods, enhanced material stability, and sustainable regeneration techniques. This comprehensive assessment underscores the transformative potential of innovative adsorbents in pollutant remediation and their critical role in advancing environmental protection. [ABSTRACT FROM AUTHOR]

The attached microalgal–bacterial consortium (microalgae–bacteria biofilm, MBBF) has been increasingly recognized in wastewater treatment for its superior pollutant removal efficiency, resilience to toxic substances, and improved harvesting performance. This review initially discusses the advantages of MBBFs compared to activated sludge and suspended microalgal–bacterial consortia. These advantages stem from the coexistence of pollutant removal pathways for the bacteria and microalgae in MBBFs, as well as the synergistic interactions between the microalgae and bacteria that enhance pollutant removal and resilience capabilities. Subsequently, the establishment of the MBBF system is emphasized, covering the establishment process, influencing factors of MBBF formation, and the utilization of photobioreactors. Lastly, the challenges associated with implementing MBBFs in wastewater treatment are deliberated. This study aims to present a detailed and comprehensive overview of the application of MBBFs for wastewater treatment and biomass production. [ABSTRACT FROM AUTHOR]

The study investigates the feasibility and performance of an indigenously designed algal-bacterial biofilm reactor (ABR) for treating graywater in rural areas. Focusing on both treatment efficacy and sustainability, the research explored two key areas: optimizing the ABR for efficient graywater treatment and evaluating the use of readily available, low-cost materials for its construction. To achieve this, ABR was optimized to handle the specific characteristics of rural graywater, including potential seasonal variations in nutrient concentrations. The optimized ABR's adaptability was rigorously assessed across various operational modes--batch, fed-batch, and continuous--demonstrating consistent removal efficiencies for key pollutants (COD, nitrate-nitrogen, total dissolved phosphate, and total ammoniacal nitrogen) under changing conditions. The fiber supportbased ABR demonstrated significant pollutant removal from rural graywater: 81% COD reduction, 49.5% nitrate-nitrogen (NO3-N), 88.46% total dissolved phosphate (TDP), and 83.42% total ammoniacal nitrogen (TAN) in batch mode. Moreover, there was almost complete removal of total suspended solids (from 142 mg L-1 on Day 1 to 0 mg L-1 on Day 6) and total coliform (39,000 CFU mL-1 to 30 CFU mL-1). Notably, these removal efficiencies remained consistent across fed-batch (and continuous operation modes), showcasing the ABR's adaptability. This adaptability facilitated a significant increase in treatment capacity, scaling from 3 L treated in batch mode (6 days) to 40 L in fed-batch mode (12 days) and a continuous treatment rate of 20 L per day. Further enhancing the sustainability of this approach, the study successfully employed readily available natural materials like bamboo pipes and sheets for constructing the ABR. This innovative design resulted in a remarkable increase in biomass productivity (9.8 g m-2 day-1) compared to polypropylene fiber-based reactors (4.5 g m-2 day-1) with enhanced treatment potential for all the parameters in batch mode (77.7% COD removal, 86% NO3-N removal, 81% TDP removal, 92% TAN removal, and 100% removal of total coliforms). This is the first reported algae-bacterial biofilm system using bamboo for wastewater treatment, promoting local resource utilization and a bio-based sustainable approach for rural graywater treatment. [ABSTRACT FROM AUTHOR]

This study examined the treatment of surface water using a mixed natural (linseed) and chemical (alum)-based coagulant in terms of color, turbidity, and chemical oxygen demand (COD) (%) removal in a laboratory jar test. Experimental results showed that using a combined coagulant has shown higher removal of color (99.72%) and turbidity (97.76%) at pH values of 3.5 using a 1.5 g/L dosage and a stirring time of 38.58 min. Similarly, at the same pH value and 2.5 g/L dosage, the COD removal was 96%. To determine the optimum value with the highest percent removal efficiency of the coagulation–flocculation process, several experimental parameters including blended dosage, pH, COD concentration, and initial turbidity have been studied in terms of the percent of color, chemical oxygen demand, and turbidity removal. The optimum value was found for the highest removal of color-97.75%, turbidity-96.86%, and COD-90.33% with the pH values of 7.0, at a dosage of 2.5 g/L and a stirring time of 40 min, respectively. Statistical techniques of response surface methodology were used in experimental design and optimization, in order to calculate the confidence intervals to assess population parameter precision. An ANOVA-95% confidence interval ensures that the high reliability optimizes the result. The findings proved the excellent adsorption potential and high performance of the blended coagulant in the removal of contaminants from surface water. [ABSTRACT FROM AUTHOR]

In recent years, the phenomenon of black–odorous water has occurred frequently, and constructed wetlands have been widely used as an effective means of treating black–odorous water. In order to achieve the goal of low-carbon and high-efficiency long-term clean-up of black–odorous water, the modular constructed wetland system was optimized in this study. The optimized modular constructed wetland consisted of aeration, denitrification, and phosphorus removal, of which the denitrification module was a sulfur–iron autotrophic denitrification unit and the phosphorus removal module was a polyaluminum chloride composite filler phosphorus-removal unit. Experimental findings indicated that modular systems with layout ratios of 1:3:1 (A) and 1:2:2 (B) exhibit outstanding performance in remediating contaminants from black–odorous water. Notably, system B demonstrated superior treatment efficiency. Under conditions of high pollution loading, system B consistently achieved stable removal rates for COD (95.79%), TN (91.74%), NH4+-N (95.17%), and TP (82.21%). The combination of along-track changes and high-throughput sequencing results showed that the synergies among the units did not produce negative effects during the purification process, and each unit realized its predefined function. Changes in the substrate and internal environment of the wetland units caused changes in the microbial populations, and the unique microbial community structure of the units ensured that they were effective in removing different pollutants. [ABSTRACT FROM AUTHOR]

As a common necessity, masks have been used a lot in recent years, and the comprehensive utilization of waste masks has become a research priority in the post-COVID-19 pandemic era. However, traditional disposal methods suffer from a range of problems, including poor utilization and insecurity. To explore new solution ideas and efficiently utilize waste resources, waste masks and biomass wastes were used as raw materials to prepare mask-based biochar (WMB), bio-oil, and pyrolytic gas via oxygen-limited co-pyrolysis in this study. The obtained solid–liquid–gas product was systematically characterized to analyze the physicochemical properties, and the adsorption properties and mechanisms of WMB on the environmental endocrine bisphenol A (BPA) were investigated. The co-pyrolysis mechanisms were also studied in depth. Furthermore, the strengths and weaknesses of products prepared by co-pyrolysis and co-hydrothermal synthesis were discussed in comparison. The results indicated that the waste masks could shape the microsphere structure, leading to richer surface functional groups and stable mesoporous of WMB. Here, the risk of leaching of secondary pollutants was not detected. The theoretical maximum adsorption of BPA by WMB was 28.73 mg·g−1. The Langmuir and Pseudo-second-order models optimally simulated the isothermal and kinetic adsorption processes, which are a composite of physicochemical adsorption. Simultaneous pyrolysis of mask polymers with biomass polymers produces bio-oil and pyrolytic gas, which is rich in high-quality aliphatic and aromatic compounds. This could have potential as an energy source or chemical feedstock. The co-pyrolysis mechanisms may involve the depolymerization of waste masks to produce hydrocarbons and H radicals, which in turn undergo multi-step cleavage and oligomerization reactions with biomass derivatives. It is recommended to use the co-pyrolysis method to dispose of waste masks, as the products obtained are significantly better than those obtained by the co-hydrothermal method. This work provides a new contribution to the resourcing of waste masks into high-quality products. [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) is increasingly being applied to wastewater treatment to enhance efficiency, improve processes, and optimize resource utilization. This review focuses on objectives, advantages, outputs, and major findings of various AI models in the three key aspects: the prediction of removal efficiency for both organic and inorganic pollutants, real-time monitoring of essential water quality parameters (such as pH, COD, BOD, turbidity, TDS, and conductivity), and fault detection in the processes and equipment integral to wastewater treatment. The prediction accuracy (R2 value) of AI technologies for pollutant removal has been reported to vary between 0.64 and 1.00. A critical aspect explored in this review is the cost-effectiveness of implementing AI systems in wastewater treatment. Numerous countries and municipalities are actively engaging in pilot projects and demonstrations to assess the feasibility and effectiveness of AI applications in wastewater treatment. Notably, the review highlights successful outcomes from these initiatives across diverse geographical contexts, showcasing the adaptability and positive impact of AI in revolutionizing wastewater treatment on a global scale. Further, insights on the ethical considerations and potential future directions for the use of AI in wastewater treatment plants have also been provided. HIGHLIGHTS Artificial intelligence (AI) has immense potential to optimize the wastewater treatment processes.; Prediction, real-time monitoring, and fault detection using AI have been reviewed.; Cost-effectiveness of implementing AI in wastewater treatment has been discussed.; Adaptability and impact of AI in wastewater treatment globally has been highlighted.;

Abstract This study examined the treatment of surface water using a mixed natural (linseed) and chemical (alum)-based coagulant in terms of color, turbidity, and chemical oxygen demand (COD) (%) removal in a laboratory jar test. Experimental results showed that using a combined coagulant has shown higher removal of color (99.72%) and turbidity (97.76%) at pH values of 3.5 using a 1.5 g/L dosage and a stirring time of 38.58 min. Similarly, at the same pH value and 2.5 g/L dosage, the COD removal was 96%. To determine the optimum value with the highest percent removal efficiency of the coagulation–flocculation process, several experimental parameters including blended dosage, pH, COD concentration, and initial turbidity have been studied in terms of the percent of color, chemical oxygen demand, and turbidity removal. The optimum value was found for the highest removal of color-97.75%, turbidity-96.86%, and COD-90.33% with the pH values of 7.0, at a dosage of 2.5 g/L and a stirring time of 40 min, respectively. Statistical techniques of response surface methodology were used in experimental design and optimization, in order to calculate the confidence intervals to assess population parameter precision. An ANOVA-95% confidence interval ensures that the high reliability optimizes the result. The findings proved the excellent adsorption potential and high performance of the blended coagulant in the removal of contaminants from surface water.

Abstract Cyclodextrins are cyclic oligosaccharides characterized by a hydrophobic interior and a hydrophilic outside linked by α-1,4 glycosidic bonds. Cyclodextrins are biodegradable and generally considered environmentally friendly. These are utilized in diverse applications, encompassing environmental cleanup which is enhanced through the processes of cross-linking or surface modification. These molecules have a unique structure that enables them to form inclusion complexes with various guest molecules, including organic pollutants, pesticides, dyes, pharmaceuticals, and hydrocarbons. When used in water treatment, cyclodextrins can act as molecular sponges, trapping pollutants within their cavities through non-covalent interactions such as hydrogen bonding, van der Waals forces, and hydrophobic interactions. When cyclodextrins are introduced into water containing pollutants, the pollutants can enter the cavities of cyclodextrin molecules, forming inclusion complexes. This process effectively sequesters the pollutants from the surrounding water, reducing their concentration. It can often be regenerated and reused multiple times, making them cost-effective for water treatment applications. This review presents the primary applications of cyclodextrins for the adsorption of contaminants from various pollutants from diverse sources, based on recent publications.

Waste, often overlooked, stands out as a prime source of valuable products, meeting the demand for natural resources. In the face of environmental challenges, this study explores the crucial role of waste‐derived catalysts in sustainable practices, emphasizing the transformative potential of solid waste materials. Carbon‐based catalysts sourced from agricultural, municipal, and industrial waste streams can be transformed into activated carbon, biochar, and hydrochar which are extensively used adsorbents. Furthermore, the paper also highlights the potential of transition metal‐based catalysts derived from spent batteries, electronic waste, and industrial byproducts, showcasing their efficacy in environmental remediation processes. Calcium‐based catalysts originating from food waste, including seashells, eggshells, bones, as well as industrial and construction waste also find an extensive application in biodiesel production, providing a comprehensive overview of their promising role in sustainable and eco‐friendly practices. From mitigating pollutants to recovering valuable resources, waste‐derived catalysts exhibit a versatile role in addressing waste management challenges and promoting resource sustainability. By transforming waste into valuable catalysts, this study champions a paradigm shift towards a more sustainable and resource‐efficient future. [ABSTRACT FROM AUTHOR]

Currently, there is an increasing need to find new ways to purify water by eliminating bacterial biofilms, textile dyes, and toxic water pollutants. These contaminants pose significant risks to both human health and the environment. To address this issue, in this study, we have developed an eco-friendly approach that involves synthesizing a cobalt-doped cerium iron oxide (CCIO) nanocomposite (NC) using an aqueous extract of Gossypium arboreum L. stalks. The resulting nanoparticles can be used to effectively purify water and tackle the challenges associated with these harmful pollutants. Nanoparticles excel in water pollutant removal by providing a high surface area for efficient adsorption, versatile design for the simultaneous removal of multiple contaminants, catalytic properties for organic pollutant degradation, and magnetic features for easy separation, offering cost-effective and sustainable water treatment solutions. A CCIO nanocomposite was synthesized via a green co-precipitation method utilizing biomolecules and co-enzymes extracted from the aqueous solution of Gossypium arboreum L. stalk. This single-step synthesis process was accomplished within a 5-h reaction period. Furthermore, the synthesis of nanocomposites was confirmed by various characterization techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and energy dispersive X-ray (EDX) technology. CCIO NCs were discovered to have a spherical shape and an average size of 40 nm. Based on DLS zeta potential analysis, CCIO NCs were found to be anionic. CCIO NCs also showed significant antimicrobial and antioxidant activity. Overall, considering their physical and chemical properties, the application of CCIO NCs for the adsorption of various dyes (~91%) and water pollutants (chromium = ~60%) has been considered here since they exhibit great adsorption capacity owing to their microporous structure, and represent a step forward in water purification. [ABSTRACT FROM AUTHOR]

In this paper, the three inorganic flocculants polymeric chloride PAC, FeCl3, and Al2(SO4)3 and two organic flocculants anionic polyacrylamide APAM and cationic polyacrylamide CPAM were screened to determine the most efficient flocculants and the optimal dosage, optimizing the flocculation operating conditions through the orthogonal test and then proving the experimental effect according to a comparison study of the high-concentration method and the traditional activated sludge method. The results show that the addition of CPAM achieves the best flocculation for high-concentration activated sludge suspension, and that the sludge interface descent rate, sludge volume index, and sludge settling ratio are better than those of other flocculants. The orthogonal test was used on the sludge volume index to perform evaluations and analyses: mixing section mixing intensity > Flocculation Stage 1 section mixing intensity > Flocculation Stage 2 section mixing intensity > mixing section residence time > flocculation section hydraulic residence time. In the comparison test, the settling performance of the high-concentration method was higher than that of the traditional activated sludge method. In terms of pollutant removal, the removal rates of COD, ammonia nitrogen, and total nitrogen of the traditional activated sludge method were 90.85%, 95.74%, and 71.6%, respectively. The average removal rates of COD, ammonia nitrogen, and total nitrogen of high-concentration activated sludge method were 92.24%, 97.28%, and 80.97%—higher than that of the traditional activated sludge method. [ABSTRACT FROM AUTHOR]

• Facet-dependent OA activation on hematite for pollutants removal was studied. • {001} facet of hematite nanoplate has the optimal activity for OA activation. • {001} facet of hematite nanoplate has the stronger ability to adsorb OA. Naturally occurring hematite has been widely studied in the Fenton-like system for water pollutant remediation due to its abundance and non-toxicity. However, its inadequate catalytic activity results in difficulty in effectively degrading pollutants in the catalytic degradation system that it constitutes. Thus, we constructed a photochemical system composed of hematite with {001} facet of high activity facet and low-cost and non-toxic oxalic acid (OA) for the removal of various types of pollutants. The removal rate for the degradation of metronidazole, tetracycline hydrochloride, Rhodamine B, and hexavalent chromium by hematite nanoplate with the exposed {001} facet activating OA under visible light irradiation was 4.75, 2.25, 2.33, and 2.74 times than that by the exposed {110} facet, respectively. Density functional theory (DFT) calculation proved that the OA molecule was more easily adsorbed on the {001} facet of hematite than that on the {110} facet, which would favor the formation of the more Fe(III)-OA complex and reactive species. In addition, the reactive site of metronidazole for the attraction of radicals was identified on the basis of the DFT calculation on the molecular occupied orbitals, and the possible degradation pathway for metronidazole included carbon chain fracture, hydroxyethyl-cleavage, denitrogenation, and hydroxylation. Thus, this finding may offer a valuable direction in designing an efficient iron-based catalyst based on facet engineering for the improved activity of Fenton-like systems such as OA activation. [Display omitted] [ABSTRACT FROM AUTHOR]

Soil restoration by exploiting the principles and basics of electrokinetic (EK) has been extended to involve several categories, such as electrokinetic remediation in soil (SEKR), soil consolidation, the prevention of soil pollution, reclaiming salt-affected soil, the dewatering/dryness of wet soils, water reuse, seed germination, sedimentation, etc. As an extension of our recently published review articles on the soil electrokinetic (SEK) process intensification/optimization, the present review illustrates the effect of a reverse-polarity mode (RPM) on the efficiency of the SEK. Based on several searches of six database search engines, we did not find any relevant reviews focused on SEK improvements using the RPM. The influences of the RPM are described by various features, including (a) pollutant removal (organic, inorganic, and mixed pollutants) and (b) integration with other processes (phyto/bioremediation and Fenton oxidation), geosynthetics (consolidation, stabilization, and sedimentation), SEK operation conditions, and soil properties. Most of the RPM studies have focused on the remediation of organic pollutants. Several benefits can be gained from applying the RPM, such as (a) controlling the soil's temperature, pH, and moisture values at desirable levels, (b) reducing a large number of chemical additives, (c) high remediation efficiency, (d) maintaining the indigenous fungal community's appropriate diversity and abundance, (e) a stable and higher electric current, (f) enhancing microbial growth, etc. However, the hindrances to applying the RPM are (a) reducing the electroosmosis flow, (b) relatively high energy consumption, (c) reducing the diversity of soil microbes with a prolonged experiment period, (d) providing oxygen for a microbial community that may not be desirable for anaerobic bacteria, etc. Finally, the RPM is considered an important process for improving the performance of the SEK, according to experimental endeavors. [ABSTRACT FROM AUTHOR]

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4 +-N, 77.84% for NO3--N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives. [ABSTRACT FROM AUTHOR]

Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF research, encompassing their diverse sources (bacteria, fungi, and algae), major categories (polysaccharides, proteins, and glycoproteins), production processes, and flocculation performance and mechanisms. The wide-ranging applications of MBFs in removing suspended solids, heavy metals, dyes, and other pollutants from industrial and municipal wastewater are critically examined, highlighting their superior efficiency, selectivity, and environmental compatibility compared to traditional flocculants. Nonetheless, bioflocculants face significant challenges including high substrate costs, low production yields, and intricate purification methodologies, factors that impede their industrial scalability. Moreover, the risk of microbial contamination and the attendant health implications associated with the use of microbial flocculants (MBFs) necessitate thorough evaluation. To address the challenges of high production costs and variable product quality, strategies such as waste valorization, strain improvement, process optimization, and biosafety evaluation are discussed. Moreover, the development of multifunctional MBF-based flocculants and their synergistic use with other treatment technologies are identified as emerging trends for enhanced wastewater treatment and resource recovery. Future research directions are outlined, emphasizing the need for in-depth mechanistic studies, advanced characterization techniques, pilot-scale demonstrations to accelerate the industrial adoption of MBF, and moreover, integration with novel wastewater treatment processes, such as partial nitrification and the anammox process. This review is intended to inspire and guide further research and development efforts aimed at unlocking the full potential of MBFs as sustainable, high-performance, and cost-effective bioflocculants for addressing the escalating challenges in wastewater management and environmental conservation. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) represent a promising technology to generate bio-electricity and synchronously reduce wastewater pollutants. The presence of exoelectrogens in wastewater is critical for bio-electricity and pollutant reduction, but the performance of exoelectrogens at different pH levels remains unknown. This study aims to bridge this gap by offering an integrated approach to understanding the performance of exoelectrogens under varying substrate pH, particularly in bio-electricity generation and pollutant reduction in sugarbeet processing wastewater (SBWW). Three pH levels (ranging from acidic to alkaline) were studied and MFC’s electricity output was measured. Later, current density, power density, and coulombic efficiency (CE) were calculated. Both pre- and post-experiment substrate samples were analysed with inductively coupled plasma (ICP). Furthermore, 16S rRNA gene analysis, DNA amplification, sequencing library preparation, and bioinformatics workflows on post-experiment samples of the substrate and anode samples were conducted. A diverse community of microorganisms was identified, especially Alphaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria (Geobacter). Bacteroidetes and Desulfovibrio were the major exoelectrogens responsible for electricity generation. Among the three pH levels tested, the most alkaline pH level (9.5±0.1) outperformed the others, achieving a 54% higher power density, 21% greater current density, and a 40% higher CE compared to the acidic pH level (6.5±0.1). Around 50–99% of pollutants were removed from the SBWW. The study revealed that Gammaproteobacteria thrive and perform better in alkaline environment. [ABSTRACT FROM AUTHOR]

Cyclodextrins are cyclic oligosaccharides characterized by a hydrophobic interior and a hydrophilic outside linked by α-1,4 glycosidic bonds. Cyclodextrins are biodegradable and generally considered environmentally friendly. These are utilized in diverse applications, encompassing environmental cleanup which is enhanced through the processes of cross-linking or surface modification. These molecules have a unique structure that enables them to form inclusion complexes with various guest molecules, including organic pollutants, pesticides, dyes, pharmaceuticals, and hydrocarbons. When used in water treatment, cyclodextrins can act as molecular sponges, trapping pollutants within their cavities through non-covalent interactions such as hydrogen bonding, van der Waals forces, and hydrophobic interactions. When cyclodextrins are introduced into water containing pollutants, the pollutants can enter the cavities of cyclodextrin molecules, forming inclusion complexes. This process effectively sequesters the pollutants from the surrounding water, reducing their concentration. It can often be regenerated and reused multiple times, making them cost-effective for water treatment applications. This review presents the primary applications of cyclodextrins for the adsorption of contaminants from various pollutants from diverse sources, based on recent publications. [ABSTRACT FROM AUTHOR]

Efficient boron removal from irrigation waters is crucial for sustainable agriculture, as elevated levels of boron can be toxic to many plants, limiting growth and crop productivity. In this context, the present study investigated the sorption equilibrium of boron using zeolites in two types of aqueous matrices: a synthetic solution containing only boron and natural irrigation waters. Through the application of various isothermal sorption models (Langmuir, Freundlich, Sips, Toth, Jovanovic, Temkin, Dubinin–Radushkevich, and Redlich–Peterson), the efficacy of zeolite for boron removal under controlled and real conditions was evaluated. The results indicated a notable difference in sorption behavior between the two matrices, reflecting the complexity and heterogeneity of interactions in the boron–zeolite system. In the synthetic solution, the Freundlich model provided the best fit (R2 = 0.9917), suggesting heterogeneous and multilayer sorption, while the Sips model showed high efficacy in describing the sorption in both matrices, evidencing its capability to capture the complex nature of the interaction between boron and zeolite under different environmental conditions. However, in natural irrigation waters, the Jovanovic model demonstrated the most accurate fit (R2 = 0.999), highlighting the importance of physical interactions in boron sorption. These findings underscore the significant influence of the water matrix on the efficacy of zeolite as a boron removal agent, emphasizing the need to consider the specific composition of irrigation water in the design of removal treatments. Additionally, the results stress the importance of selecting the appropriate isothermal model to predict boron sorption behavior, which is crucial for developing effective and sustainable treatment strategies. This study provides a basis for optimizing boron removal in various agricultural and industrial applications, contributing to the design of more efficient and specific water treatment processes. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in drinking water is a growing concern due to its severe health effects on humans. Among the many metals, lead (Pb), which is a toxic and harmful element, has the most widespread global distribution. Pb pollution is a major problem of water pollution in developing countries and nations. The most common sources of lead in drinking water are lead pipes, faucets, and plumbing fixtures. Adsorption is the most efficient method for metal removal, and activated carbon has been used widely in many applications as an effective adsorbent, but its high production costs have created the necessity for a low-cost alternative adsorbent. Biochar can be a cost-effective substitute for activated carbon in lead adsorption because of its porous structure, irregular surface, high surface-to-volume ratio, and presence of oxygenated functional groups. Extensive research has explored the remarkable potential of biochar in adsorbing Pb from water and wastewater through batch and column studies. Despite its efficacy in Pb removal, several challenges hinder the real application of biochar as an adsorbent. These challenges include variability in the adsorption capacity due to the diverse range of biomass feedstocks, production processes, pH dependence, potential desorption, or a leaching of Pb from the biochar back into the solution; the regeneration and reutilization of spent biochar; and a lack of studies on scalability issues for its application as an adsorbent. This manuscript aims to review the last ten years of research, highlighting the opportunities and engineering challenges associated with using biochar for Pb removal from water. Biochar production and activation methods, kinetics, adsorption isotherms, mechanisms, regeneration, and adsorption capacities with process conditions are discussed. The objective is to provide a comprehensive resource that can guide future researchers and practitioners in addressing engineering challenges. [ABSTRACT FROM AUTHOR]

Exploring efficient adsorbents still remains an important challenge due to the poor efficiency of the reported adsorbents for the adsorption of antibiotics. Herein, we design and prepare a novel nanosheets-like hollow TiO 2 (NHT) adsorbent by using hollow TiO 2 as a precursor through alkaline hydrothermal treatment. Adsorption results show that NHT exhibits a high adsorption percentage (98.05%) within 20 min and a maximum adsorption uptake of 24.51 mg/g for Levofloxacin (LVOF) pollutant (10 mg/L, 50 mL), which is 17 times higher than that (1.4 mg/g) of pristine hollow TiO 2 (HT). Notably, NHT realizes >91% of the adsorption percentage for LVOF pollutant after the tenth run only through photo-regeneration without extra post-treatments, effectively overcoming the disadvantages of harsh regeneration procedures for most of the existed adsorbents. Adsorption data and the performance characterizations present deep insights into adsorption mechanism, which reveals that pore filling effect, hydrogen-bond interactions, and electrostatic attraction are the key parameters for the excellent adsorption of LVOF by NHT. Therefore, the present study can provide a promising direction for the fabrication of efficient adsorptive photocatalyst by using low-cost TiO 2 as a precursor. [Display omitted] • Novel nanosheets-like hollow TiO 2 (NHT) adsorbent was prepared via a facile alkaline hydrothermal treatment. • NHT adsorbent exhibited higher adsorption capacity of LVOF and faster adsorption kinetics than the present materials. • NHT manifested efficient adsorption of LVOF in ambient factors and real water matrices. • Exceptional levofloxacin adsorption/photo-regeneration cycles were realized by NHT adsorptive photocatalyst. • The efficient adsorption mechanism was ascribed to pore-filling effect, hydrogen bonding, and electrostatic interactions. [ABSTRACT FROM AUTHOR]

Biochar, a carbon‐rich material produced through the pyrolysis of biomass, has been shown to have the potential to remove contaminants from water and wastewater. However, due to the weak adsorption capacity and narrow adsorption range of pure biochar, it is modified, either chemically or physically, in order to optimize its applications in water and wastewater treatment. This study summarizes the recent advancements in the application of modified biochar for water and wastewater treatment. Modification of biochar increases its surface area and porous structure, which makes it an effective adsorbent to immobilize a range of contaminants, such as heavy metals, dyes, and organic contaminants. It can also be used as a catalyst in the biodegradation of organic pollutants as it can provide a substrate for microbial growth and metabolism, enhancing pollutant degradation. This study also summarizes various biochar modifications such as gas, acid, alkali, metal, organic compounds, and oxidizing agents. Among the metal‐modified biochar, Iron‐modified biochar has shown the highest tetracycline (TC) removal efficiency (90.7%) and nitrate adsorption capacity (32.33 mg g−1). N‐doped biochars were found to be the most effective biochars for removing heavy metals such as Cd2+ or Cu2+ and aromatic compounds as they can increase the adsorption of raw biochar by up to 70%. Increasing the number of functional groups on the surface of the biochar by using organic compounds like acrylonitrile and chitosan showed a two to three‐fold increase in the adsorption capacity of pollutants such as Cd2+ and Hg2+. According to this review, modified biochar technology is a cost‐effective and environmentally friendly wastewater treatment method. [ABSTRACT FROM AUTHOR]

In this paper, a novel CeO2/Co3[Co(CN)6]2 (CeO2/PBACo-Co) composite was prepared with co-precipitation and utilized to activate peroxymonosulfate (PMS) to eliminate tetracycline hydrochloride (TCH). Catalyst screening showed that the composite with a CeO2:PBACo-Co mass ratio of 1:5 (namely, 0.2-CeO2/PBACo-Co) had the best performance. The degradation efficiency of TCH in 0.2-CeO2/PBACo-Co/Oxone system was investigated. The experimental results illustrated that 98% of 50 mg/L TCH and 48.5% of TOC were degraded by 50 mg/L 0.2-CeO2/PBACo-Co and 400 mg/L Oxone within 120 min at 25 °C and initial pH 5.3. Recycling studies showed that the elimination rate of TCH can still achieve 85.8% after five cycles, suggesting that 0.2-CeO2/PBACo-Co composite processes good reusability. Trapping experiments and EPR tests revealed that the reaction system produced multiple active species (1O2, O2•–, SO4•–, and •OH). We proposed the catalytic mechanism of 0.2-CeO2/PBACo-Co for PMS activation, which mainly involves the promoted Co3+/Co2+ cycle by Ce3+ donated electrons. These results indicate that CeO2/PBACo-Co composite is an effective catalyst for wastewater remediation. [ABSTRACT FROM AUTHOR]

Discharging untreated wastewater into natural water systems poses significant risks to public health, economies, and ecological stability worldwide. This study addresses these effects by investigating the phytoremediation potential of Duranta Erecta in cascade hydroponics for treating domestic wastewater. It centers on the removal of dissolved and suspended solids as well as organic matter, representing a groundbreaking effort in this domain. It involved two experimental setups: one integrating Duranta Erecta with media (gravel (EXU-1) and polyester sponge (EXU-2)), and a control setup ((gravel (COU-1) and polyester sponge (COU-2))) using only media. Each configuration consisted of three bioreactors designed to treat wastewater from Kilinto prison camp. Four hydraulic retention times (HRTs) were tested, with the 7-day HRT emerging as the most effective compared to the 1, 3, and 5-day intervals. At the 7-day HRT, experimental units one and two demonstrated substantial reductions in pollutants: suspended solids (96.50 % & 89.3 %), turbidity (94.3 % & 87.2 %), dissolved solids (49.5 % & 45.15 %), biological oxygen demand (94.57 % & 89.78 %), and chemical oxygen demand (95.44 % & 90.65 %). Statistical analysis confirmed these reductions as statistically significant (P

Over the past two decades, interest in pollutant removal by yeasts has grown substantially. Yeasts can remove high amounts of pollutants at low production costs under non-sterile conditions. This work presents a compilation of the studies carried out regarding the potential application of yeasts in the treatment of wastewater. For example, a summary is presented on data about various yeast strains that are used to treat wastewater. The study will help the decision-making process for the selection of yeast for a type of wastewater and support research efforts by acquiring an overview of advancements in this area. Yeast treatment is versatile and has outstanding adaptability to varying treatment conditions. The effectiveness of yeast in treating wastewater is influenced by multiple factors. Yeast technology could potentially be retrofitted to existing activated sludge processes or be used instead of bacteria. Within its characteristics, we can observe tolerance to low pH (3.0–5.0), high salinity, high organic loads, antibiotics, and survive in up to 12% v/v alcohol mixtures. In fact, using low pH for yeast cultivation reduces bacterial contamination and supports yeast domination under non-sterile conditions. Laboratory-scale trials for yeast wastewater treatment have shown improvement over the past two decades; however, efficiencies differ according to the type of wastewater. In general, yeast offers several benefits compared to traditional microbial treatment methods, especially in its capacity to effectively process diverse organic carbon sources. However, it still must be proven to be an effective technology at an industrial scale.How to cite: Mohiuddin O, Harvey A, Orta Ledesma MT, et al. Bioremediation of waste by yeast strains. Electron J Biotechnol 2024;69. https://doi.org/10.1016/j.ejbt.2024.01.005.

Heavy metal contamination in drinking water is a growing concern due to its severe health effects on humans. Among the many metals, lead (Pb), which is a toxic and harmful element, has the most widespread global distribution. Pb pollution is a major problem of water pollution in developing countries and nations. The most common sources of lead in drinking water are lead pipes, faucets, and plumbing fixtures. Adsorption is the most efficient method for metal removal, and activated carbon has been used widely in many applications as an effective adsorbent, but its high production costs have created the necessity for a low-cost alternative adsorbent. Biochar can be a cost-effective substitute for activated carbon in lead adsorption because of its porous structure, irregular surface, high surface-to-volume ratio, and presence of oxygenated functional groups. Extensive research has explored the remarkable potential of biochar in adsorbing Pb from water and wastewater through batch and column studies. Despite its efficacy in Pb removal, several challenges hinder the real application of biochar as an adsorbent. These challenges include variability in the adsorption capacity due to the diverse range of biomass feedstocks, production processes, pH dependence, potential desorption, or a leaching of Pb from the biochar back into the solution; the regeneration and reutilization of spent biochar; and a lack of studies on scalability issues for its application as an adsorbent. This manuscript aims to review the last ten years of research, highlighting the opportunities and engineering challenges associated with using biochar for Pb removal from water. Biochar production and activation methods, kinetics, adsorption isotherms, mechanisms, regeneration, and adsorption capacities with process conditions are discussed. The objective is to provide a comprehensive resource that can guide future researchers and practitioners in addressing engineering challenges.

The bioretention system is one of the most widely used low impact development (LID) facilities with efficient purification capacity for stormwater, and its planting design has been a hot spot for research at home and abroad. In this paper, ryegrass (Lolium perenne L.), bermuda (Cynodon dactylon Linn.), bahiagrass (Paspalum notatum Flugge), and green grass (Cynodon dactylon × C .transadlensis ‘Tifdwarf’) were chosen as plant species to construct a shallow bioretention system. The growth traits and nutrient absorption ability of four gramineous plants were analyzed. Their tolerance, enrichment, and transportation capacity were also evaluated to compare plant species and their absorptive capacity of heavy metals (Cu, Pb, and Zn). Results showed that the maximum absorption rate (Imax) ranged from 22.1 to 42.4 μg/(g·h) for P and ranged from 65.4 to 104.8 μg/(g·h) for NH4+-N; ryegrass had the strongest absorption capacity for heavy metals and the maximum removal rates of Cu, Pb, and Zn by four grasses were 78.4, 59.4, and 51.3%, respectively; the bioretention cell with ryegrass (3#) was significantly more effective in purifying than the unplanted bioretention cell (1#) during the simulated rainfall test. Overall, the system parameters were optimized to improve the technical application of gramineous plants in the bioretention system. HIGHLIGHTS Four kinds of gramineous plants were selected as plant species to construct shallow bioretention systems.; Ryegrass showed the strongest absorptive capacity for phosphorus, ammonia nitrogen, and heavy metals.; The bioretention cell with ryegrass (3#) was significantly more effective in purifying than the unplanted bioretention cell (1#) during the simulated rainfall test.;

Abstract Recent textile industry expansion has a major environmental impact if not addressed. Being a water intensive industry, textile manufacturing is usually associated with wastewater management challenges. Electrocoagulation (EC) is recognized as one of the effective solutions to address these challenges. This study aims to investigate the potential of integrating seawater into the EC process for textile wastewater treatment, targeting optimal pollutant removal efficiencies. A simple electrolytic reactor was designed to investigate the removal efficiency of these treatments for chemical oxygen demand (COD), total suspended solids (TSS), turbidity, and color from textile wastewater at different seawater percentages and retention times. Notably, the addition of seawater not only improves the EC process efficiency but also significantly dilutes pollutants, reducing their concentrations. This dual effect enhances removal efficiency and dilution optimizes the treatment outcome. The highest removal efficiencies were achieved for COD (47.26%), TSS (99.52%), turbidity (99.30%), and color (98.19%). However, pH, dissolved oxygen (DO), and electrical conductivity increased with increasing retention times and seawater percentages in the EC process. Moreover, Seawater − EC integration reduces power usage to 15.769 Am−2 and costs approximately 0.20 USD/m3. To assess the effects of the retention times and seawater percentages on pollutant removal from textile wastewater, an analysis of variance (ANOVA) was conducted utilizing the Design-Expert 11 software. The best model obtained using Central Composite Design (CCD) was quadratic for COD (R 2 = 0.9121), color (R 2 = 0.9535), turbidity (R 2 = 0.9525), and TSS (R 2 = 0.9433). This study suggests that higher seawater percentages and longer retention times effectively eliminate contaminants but increase ion concentrations.

Over the past two decades, interest in pollutant removal by yeasts has grown substantially. Yeasts can remove high amounts of pollutants at low production costs under non-sterile conditions. This work presents a compilation of the studies carried out regarding the potential application of yeasts in the treatment of wastewater. For example, a summary is presented on data about various yeast strains that are used to treat wastewater. The study will help the decision-making process for the selection of yeast for a type of wastewater and support research efforts by acquiring an overview of advancements in this area. Yeast treatment is versatile and has outstanding adaptability to varying treatment conditions. The effectiveness of yeast in treating wastewater is influenced by multiple factors. Yeast technology could potentially be retrofitted to existing activated sludge processes or be used instead of bacteria. Within its characteristics, we can observe tolerance to low pH (3.0-5.0), high salinity, high organic loads, antibiotics, and survive in up to 12% v/v alcohol mixtures. In fact, using low pH for yeast cultivation reduces bacterial contamination and supports yeast domination under non-sterile conditions. Laboratory-scale trials for yeast wastewater treatment have shown improvement over the past two decades; however, efficiencies differ according to the type of wastewater. In general, yeast offers several benefits compared to traditional microbial treatment methods, especially in its capacity to effectively process diverse organic carbon sources. However, it still must be proven to be an effective technology at an industrial scale. [ABSTRACT FROM AUTHOR]

Algae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions. [ABSTRACT FROM AUTHOR]

Water pollutants harm ecosystems and degrade water quality. At the same time, many pollutants carry potentially valuable chemical energy, measured by chemical oxygen demand (COD). This study highlights the potential for energy harvesting during remediation using photocatalytic fuel cells (PCFCs), stressing the importance of economically viable and sustainable materials. To achieve this, this research explores alternatives to platinum cathodes in photocathodes and aims to develop durable, cost-effective photoanode materials. Here, zinc oxide nanorods of high density are fabricated on carbon fiber surfaces using a low-temperature aqueous chemical growth method that is simple, cost-efficient, and readily scalable. Alternatives to the Pt cathodes frequently used in PCFC research are explored in comparison with screen-printed PEDOT:PSS cathodes. The fabricated ZnO/carbon anode (1.5 × 2 cm2) is used to remove the model pollutant used here and salicylic acid from water (30 mL, 70 μM) is placed under simulated sunlight (0.225 Sun). It was observed that salicylic acid was degraded by 23 ±0.46% at open voltage (OV) and 43.2 ± 0.86% at 1 V with Pt as the counter electrode, degradation was 18.5 ± 0.37% at open voltage (OV) and 44.1 ± 0.88% at 1 V, while PEDOT:PSS was used as the counter electrode over 120 min. This shows that the PEDOT:PSS exhibits an excellent performance with the full potential to provide low-environmental-impact electrodes for PCFCs. [ABSTRACT FROM AUTHOR]

The effect of the simultaneous presence of fluoride (0.15–1.2 mg L−1), bicarbonates (83.6–596 mg L−1), and synthesized goethite (0.3 mg L−1) at typical concentrations often found in groundwater samples was evaluated on the degradation of 2,4‐dichlorophenoxyacetic acid (2,4‐D) at pH 6.9 under simulated sunlight irradiation (300 W m−2) and H2O2 concentrations of 10 mg L−1. The 2,4‐D removal was strongly enhanced by the presence of fluoride. F− could modify the surface of iron (hydr)oxide, leading to the formation of surface Fe–F bonds benefiting the formation of free •OH, producing upward band bending, reducing the electron‐hole recombination, and enhancing the electron transfer to H2O2. On the other hand, bicarbonate may react with •OH generating CO3−• species that could participate in pollutant oxidation, while solar light‐induced H2O2 photolysis also played an important role in removing 2,4‐D. These findings suggest that tuning of iron (hydr)oxides by fluoride could take place in real groundwater, generating photocatalysts with a high activity that could participate, by adding H2O2, in the enhancement of sunlight photoinduced natural abiotic processes for pollutant abatement. [ABSTRACT FROM AUTHOR]

Floating aquatic macrophytes have a high level of proficiency in the removal of various contaminants, particularly nutrients, from wastewater. Due to their rapid growth rates, it is imperative to ensure the safe removal of the final biomass from the system. The ultimate macrophyte biomass is composed of lignocellulose and has enhanced nutritional and energy properties. Consequently, it can serve as a viable source material for applications such as the production of bioenergy, fertilizer and animal feed. However, its use remains limited, and in-depth studies are scarce. Here, we provide a comprehensive analysis of floating aquatic macrophytes and their efficacy in the elimination of heavy metals, nutrients and organic pollutants from various types of wastewater. This study offers a wide-ranging scrutiny of the potential use of plant biomasses as feedstock for bioenergy generation, focusing on both biochemical and thermochemical conversion processes. In addition, we provide information regarding the conversion of biomass into animal feed, focusing on ruminants, fish and poultry, the manufacture of fertilizers and the use of treated water. Overall, we offer a clear idea of the technoeconomic benefits of using macrophytes for the treatment of wastewater and the challenges that need to be rectified to make this cradle-to-cradle concept more efficient. [ABSTRACT FROM AUTHOR]

Rapid scale-up and intensification of the livestock and poultry farming industry generates massive amount of wastewater that greatly contributes to the environmental pollution in the vicinity. The microbial fuel cell (MFC) is an electrochemical technology that enables removal of organic pollutants in the wastewater and power generation concomitantly with the aid of microorganisms. This technology has a great potential in treating high-concentration wastewater released from the livestock and poultry farming. The present study described the categories of MFCs and current research status of its application in wastewater treatment from two aspects: 1) removal of organic pollutants (e.g., chemical oxygen demand, ammonia nitrogen, total phosphorus, and antibiotics) and 2) electricity production performance. The potential of using multiple MFC technologies together in wastewater treatment was also elaborated. This study revealed the existing problems associated with current MFC technologies and provided directions for future research, including equipment scale-up, development of novel coupling MFC technologies, interpretation of interactions among controllable parameters, and in-depth exploitation of mechanisms underlying pollutant removal and electron transfer. [ABSTRACT FROM AUTHOR]

This comprehensive review explores recent advancements in immobilization strategies for graphitic carbon nitride (g-C3N4), a metal-free photocatalyst that has gained significant attention for its optical and physicochemical properties comparable to traditional photocatalysts like TiO2. However, a critical challenge regarding their application has emerged from the difficulty of its recovery due to its powdery nature. Therefore, several alternatives are being explored to immobilize this material, facilitating its recovery and reuse. This review systematically categorizes various physical and chemical immobilization techniques, providing an in-depth analysis of their advantages, drawbacks, and applications. Techniques such as encapsulation, electrospinning, casting, and coating, along with their adaptations for g-C3N4, are thoroughly examined. Additionally, the impact of these strategies on enhancing the photocatalytic efficiency and operational stability of g-C3N4, particularly in environmental applications, is also assessed. Thus, this review aims to provide valuable insights and guide future research in the realms of photocatalysis and environmental remediation. The review contributes to the understanding of how immobilization strategies can optimize the performance of g-C3N4, furthering its potential applications in sustainable and efficient environmental solutions. [ABSTRACT FROM AUTHOR]

The study investigates the feasibility and performance of an indigenously designed algal-bacterial biofilm reactor (ABR) for treating graywater in rural areas. Focusing on both treatment efficacy and sustainability, the research explored two key areas: optimizing the ABR for efficient graywater treatment and evaluating the use of readily available, low-cost materials for its construction. To achieve this, ABR was optimized to handle the specific characteristics of rural graywater, including potential seasonal variations in nutrient concentrations. The optimized ABR’s adaptability was rigorously assessed across various operational modes—batch, fed-batch, and continuous—demonstrating consistent removal efficiencies for key pollutants (COD, nitrate-nitrogen, total dissolved phosphate, and total ammoniacal nitrogen) under changing conditions. The fiber support-based ABR demonstrated significant pollutant removal from rural graywater: 81% COD reduction, 49.5% nitrate-nitrogen (NO3-N), 88.46% total dissolved phosphate (TDP), and 83.42% total ammoniacal nitrogen (TAN) in batch mode. Moreover, there was almost complete removal of total suspended solids (from 142 mg L−1 on Day 1 to 0 mg L−1 on Day 6) and total coliform (39,000 CFU mL−1 to 30 CFU mL−1). Notably, these removal efficiencies remained consistent across fed-batch (and continuous operation modes), showcasing the ABR’s adaptability. This adaptability facilitated a significant increase in treatment capacity, scaling from 3 L treated in batch mode (6 days) to 40 L in fed-batch mode (12 days) and a continuous treatment rate of 20 L per day. Further enhancing the sustainability of this approach, the study successfully employed readily available natural materials like bamboo pipes and sheets for constructing the ABR. This innovative design resulted in a remarkable increase in biomass productivity (9.8 g m−2 day−1) compared to polypropylene fiber-based reactors (4.5 g m−2 day−1) with enhanced treatment potential for all the parameters in batch mode (77.7% COD removal, 86% NO3-N removal, 81% TDP removal, 92% TAN removal, and 100% removal of total coliforms). This is the first reported algae-bacterial biofilm system using bamboo for wastewater treatment, promoting local resource utilization and a bio-based sustainable approach for rural graywater treatment.

Municipal wastewater treatment plays an indispensable role in enhancing water quality by eliminating contaminants. While the process is vital, its environmental footprint, especially in terms of greenhouse gas (GHG) emissions, remains underexplored. Here we offer a comprehensive assessment of GHG emissions from wastewater treatment plants (WWTPs) across China. Our analyses reveal an estimated 1.54 (0.92–2.65) × 104 Gg release of GHGs (CO2-eq) in 2020, with a dominant contribution from N2O emissions and electricity consumption. We can foresee a 60–65% reduction potential in GHG emissions with promising advancements in wastewater treatment, such as cutting-edge biological techniques, intelligent wastewater strategies, and a shift towards renewable energy sources.

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4+-N, 77.84% for NO3−-N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives.

The use of conventional direct current-electrocoagulation in wastewater treatment is limited by its drawbacks, which include electrode passivation, high energy consumption, and significant sludge generation. Therefore, to address these issues, pulsed-electrocoagulation (PECP) has been developed. The PECP is an advanced wastewater treatment technique that uses intermittent electrical pulses to target and break down organic compounds in wastewater. It offers several benefits, including enhanced removal of organic compounds, reduced chemical consumption, energy efficiency, treatment of complex wastewater composition, pathogen inactivation, environmental compliance, and potential for water reuse. In this research, removal efficiency of % Chemical Oxygen Demand (COD), % Color, % Turbidity, % phosphate, and %nitrate was investigated for the wet coffee processing wastewater by using PECP and the obtained results as the COD-98.75%, color-99.92%, turbidity-99.00%, phosphate-99.02%, and nitrate-98.83%, respectively. Independent variables were the major significant factors and the optimum value was investigated and obtained at pH of 7, electrolyte dosage of 0.75 g L−1, electrolysis time of 45 min, and current of 0.45 Amp. As a result, PECP with NaCl and CaCl2 as an electrolyte is an effective treatment technique for pollutant removal from wastewater. As a consequence, the specific benefits may vary depending on the system design, operational parameters, and wastewater characteristics. The pilot-scale studies and optimization are essential for assessing PECP feasibility and performance.

Abstract The electrode played an essential role in the operation of CW-MFC system due to its synergistic effect, and the development of electrode strategy has promoted the application of CW-MFC since 2012. In this paper, according to the material and the quantity, the electrode types in CW-MFC were distinctly divided into unified model, composited model, modified model, and multi-electrodes model combined with non-conductive or conductive particle. Different electrode strategies were provided to improve the performance of CW-MFC towards electricity generation, removal of pollutants, and control of greenhouse gas emission, and the coordination mechanism was further reviewed. Furthermore, the development process of the electrode strategy was summarized, and the low-cost, sustainable, and innovated electrode materials were emphatically recommended. For the scale-up application, multi-electrode model was systematically reviewed based on the optimizing of the material, shape, spacing distance, and connection type of electrode. This review may provide guidance to maximize the advantages of CW-MFC applications. Graphical Abstract

Despite numerous studies on fires, each simulation faces several limitations. Fire is a complex phenomenon, and some of its processes remain poorly understood. Furthermore, the progression of flames and smoke is influenced by turbulent flow phenomena. In this context, this article delves into the analysis of smoke flow behavior using numerical fluid dynamics simulations (CFD) with the assistance of ANSYS FLUENT. The primary focus lies in describing the longitudinal ventilation system, a critical element for fire management. The chosen study area is the Soumbédjioune tunnel located in Dakar, Senegal, characterized by a sinusoidal floor with an amplitude equivalent to one-third of the entrance height. The tunnel has dimensions of 300 m in length (L), 10.5 m in width (W), and 7.22 m in height (H). To simulate the source of heat and smoke, a 2-cubic meter fire was placed in the center of the tunnel, modeling the combustion of N2, H2O, and O2 gases at a high temperature of 926.85 °C. The simulations yielded a critical ventilation velocity of 5.8 m/s, a crucial piece of information for fire management in this specific context. Furthermore, this article extends its analysis by examining the evolution of temperature and velocity contours in both ventilated and non-ventilated conditions, providing a deeper understanding of the underlying mechanisms at play.

Treatment and reuse of greywater for non-potable applications especially in scarce countries is a feasible option. In this study, a simple greywater treatment system consisting of a low-cost simple multi-media filter with biological contact aeration system was developed and installed in a selected household in Muscat, the capital of Oman. Monitoring and measurements were made to investigate the productivity and efficiency of this system in treating the greywater from laundry and shower sources. The greywater from the collected laundry and shower contained 360 mg/L of COD and 28.5 mg/L of BOD. The experimental results showed that the greywater treatment unit achieved more than 99% of turbidity removal, more than 74% of BOD removal, and more than 50% of COD removal. BOD removal was primarily achieved through bacterial degradation whereas COD removal was attributed to the adsorption of organic compounds by activated carbon. The effluent quality of the treated greywater fell within the standard level and can be safely reused for various non-potable applications.

The growing presence of diverse pollutants, including heavy metals, organic compounds, pharmaceuticals, and emerging contaminants, poses significant environmental and health risks. Traditional methods for pollutant removal often face limitations in efficiency, selectivity, and sustainability. This review provides a comprehensive analysis of recent advancements in innovative adsorbents designed to address these challenges. It explores a wide array of non-conventional adsorbent materials, such as nanocellulose, metal–organic frameworks (MOFs), graphene-based composites, and biochar, emphasizing their sources, structural characteristics, and unique adsorption mechanisms. The review discusses adsorption processes, including the basic principles, kinetics, isotherms, and the factors influencing adsorption efficiency. It highlights the superior performance of these materials in removing specific pollutants across various environmental settings. The practical applications of these adsorbents are further explored through case studies in industrial settings, pilot studies, and field trials, showcasing their real-world effectiveness. Additionally, the review critically examines the economic considerations, technical challenges, and environmental impacts associated with these adsorbents, offering a balanced perspective on their viability and sustainability. The conclusion emphasizes future research directions, focusing on the development of scalable production methods, enhanced material stability, and sustainable regeneration techniques. This comprehensive assessment underscores the transformative potential of innovative adsorbents in pollutant remediation and their critical role in advancing environmental protection.

The attached microalgal–bacterial consortium (microalgae–bacteria biofilm, MBBF) has been increasingly recognized in wastewater treatment for its superior pollutant removal efficiency, resilience to toxic substances, and improved harvesting performance. This review initially discusses the advantages of MBBFs compared to activated sludge and suspended microalgal–bacterial consortia. These advantages stem from the coexistence of pollutant removal pathways for the bacteria and microalgae in MBBFs, as well as the synergistic interactions between the microalgae and bacteria that enhance pollutant removal and resilience capabilities. Subsequently, the establishment of the MBBF system is emphasized, covering the establishment process, influencing factors of MBBF formation, and the utilization of photobioreactors. Lastly, the challenges associated with implementing MBBFs in wastewater treatment are deliberated. This study aims to present a detailed and comprehensive overview of the application of MBBFs for wastewater treatment and biomass production.

In recent years, the phenomenon of black–odorous water has occurred frequently, and constructed wetlands have been widely used as an effective means of treating black–odorous water. In order to achieve the goal of low-carbon and high-efficiency long-term clean-up of black–odorous water, the modular constructed wetland system was optimized in this study. The optimized modular constructed wetland consisted of aeration, denitrification, and phosphorus removal, of which the denitrification module was a sulfur–iron autotrophic denitrification unit and the phosphorus removal module was a polyaluminum chloride composite filler phosphorus-removal unit. Experimental findings indicated that modular systems with layout ratios of 1:3:1 (A) and 1:2:2 (B) exhibit outstanding performance in remediating contaminants from black–odorous water. Notably, system B demonstrated superior treatment efficiency. Under conditions of high pollution loading, system B consistently achieved stable removal rates for COD (95.79%), TN (91.74%), NH4+-N (95.17%), and TP (82.21%). The combination of along-track changes and high-throughput sequencing results showed that the synergies among the units did not produce negative effects during the purification process, and each unit realized its predefined function. Changes in the substrate and internal environment of the wetland units caused changes in the microbial populations, and the unique microbial community structure of the units ensured that they were effective in removing different pollutants.