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The environmental burden of tannery wastewater, characterized by high levels of total dissolved solids (TDS) and other contaminants, presents a significant challenge for sustainable water management. This study addresses this issue by developing a novel polyvinyl alcohol (PVA) and polyvinyl chloride (PVC) composite membrane optimized for efficient TDS removal from tannery effluent. The membrane was fabricated using a solution casting technique, with glutaraldehyde employed as a crosslinking agent to enhance mechanical properties and stability. Characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential analysis, and contact angle measurements, were used to evaluate the membrane's surface chemistry, morphology, and hydrophilicity, which are crucial for pollutant separation. Performance testing demonstrated that the membrane achieved a TDS removal efficiency of 91.73% at an optimal pH of 8 and a transmembrane pressure of 3.5 bar, with a permeability of 194 Lm−2 h−1 bar−1. Additionally, substantial reductions in turbidity (94.51%), chemical oxygen demand (COD, 91.91%), biological oxygen demand (BOD, 89.70%), salinity (80.57%), and total suspended solids (TSS, 96.45%) were observed. The membrane exhibited impressive mechanical properties, with a tensile strength of 44 ± 0.43 MPa, 150 ± 0.67% elongation at break, Young's modulus of 750 ± 0.47 MPa, and flexibility of 23 ± 0.53%, indicating its flexibility and durability. Its partial biodegradability and potential for scalable production contribute to its environmental sustainability. This work establishes the PVA-PVC composite membrane as a promising and cost-effective solution for industrial wastewater treatment, offering a sustainable approach to mitigating water pollution in the leather industry. Fabrication of PVA-PVC Composite Membrane for TDS removal from tannery wastewater [ABSTRACT FROM AUTHOR]

The present study evaluates the efficiency of a coconut adsorbent (CSZAC and CSB) based filter system for textile dye effluent treatment. The coconut shell zinc chloride-activated carbon (CSZAC) is effectively used as a filter media in wastewater treatment due to its wider surface area (590.80 m2 g−1), good porosity and higher adsorption capacity. The TEM micrograph revealed that the activated carbon (CSZAC) appeared as black particles with pores in white areas and showed microsphere formation in their internal structure (60.4–91.25 nm). The fabricated coconut-based adsorbent filter system has a dimension of 90 × 60 × 30 cm with a holding tank of 50 litres capacity, a filtration tank and a storage tank with the optimised inlet and outlet flow rate of 5 × 10−4 m3 min−1. The Colour, pH, EC, TDS, TSS, BOD, COD, cations and anions of textile dyeing wastewater were significantly reduced, after the treatment through the CSZAC filtration system. The initial colour concentration of textile dye effluent was 7021 HU and after treatment, the colour was fully reduced within a few days of treatment and became colourless. CSZAC treatment reduced the BOD from 600 mg L−1 to 89.7 mg L−1 (80.6%) and COD from 2500 mg L−1 to 205 mg L−1 (90.5%). The cations and anions of raw textile water were reduced with CSZAC treatment which recorded a 50–80% reduction. Therefore, CSZAC can be used as an effective adsorbent material to remove different dye compounds and pollutants from textile wastewater compared to coconut shell biochar due to their activation process. [ABSTRACT FROM AUTHOR]

The management of municipal solid waste leachate has emerged as a pivotal challenge in sustainable urban development. Currently, there is limited information on the practical engineering applications of bioreactors and nanofiltration systems on the pilot scale. This work employs a bioreactor–nanofiltration pilot system for the treatment of leachate in municipal solid waste transfer stations. The results demonstrate that the bioreactor–nanofiltration system exhibits excellent and stable efficiency in removing organic pollutants and heavy metal ions. The effluent qualities of COD, TN, and TP are 50, 28, and 2 mg/L, and the removal rates are 99.4%, 99.3%, and 96.1%, respectively. All types of heavy metal ions also comply with the standard limits specified in the "Wastewater quality standards for discharge to municipal sewers" (GB/T 31962-2015). More importantly, using waste materials such as mineralized waste and animal aggregates as bioreactor fillers increases the diversity of the microbial community in the system, and provides an engineering basis for the resource utilization of waste materials. The bioreactor–nanofiltration process is expected to become an ideal solution for the treatment of leachate in transfer stations. [ABSTRACT FROM AUTHOR]

The sanitation resource recovery is a contemporary strategy fully in line with the concept of the circular economy. The by-products from constructed wetlands technology include treated water, nutrients, biomass and energy. The aim of the present study was to evaluate the sewage treatment and resources recovery in constructed wetlands operating in a tidal flow configuration, coupled with microbial fuel cells (MFC). The following factors were evaluated: two types of filling material (gravel #0 and #1) and two cultivated species, Pennisetum purpureum sp. (BRS capiaçu elephant grass) and Musa spp. (dwarf cavendish banana). The treatment cycle in each CW lasted a total of 8 h. An increase in the levels of dissolved oxygen was seen due to the tidal flow configuration, enabling the biochemical processes to remove contaminants and produce an electric current. Acceptable removal efficiency was seen for most monitored parameters. The mean values for the COD output concentration were 119, 109, 117 and 98 mg L−1; removal efficiency 80%, 83%, 80% and 82%; and for wetlands with banana in gravel #1 (BG1), banana in gravel #0 (BG0), capiaçu in gravel #1 (CG1) and capiaçu in gravel #0 (CG0), respectively. The plant and type of filling material affected the performance of the CW, with the CG0 system being the most efficient in COD removal, and standing out for productivity. The plant and filling material affected energy production in the MFC, where the CG0 CW was again the most efficient, with maximum values of up to 970 mV. The results show that tidal flow CW can function with reduced cycle times and, if coupled with MFC, are able to produce energy. This study integrates high-load tidal flow CW with MFC at a pilot scale, offering combined benefits of wastewater treatment and energy generation. By using locally adapted species, the research provides valuable insights into optimising system performance and understanding the impact of tidal flow cycles, enhancing the practical application of CW with MFC in tropical regions. [ABSTRACT FROM AUTHOR]

Constructed wetland coupled microbial fuel cells (CW-MFC) offer a dual benefit of wastewater treatment and bioelectricity generation. While existing research predominantly emphasizes cell configuration, there is a limited exploration of the impact that various wetland plants may have on bioelectricity production in CW-MFCs. This research examined three distinct native wetland plants: Canna indica, Typha latifolia, and Eichhornia crassipes. The study centered on addressing textile wastewater treatment and assessing bio-electricity production. Over the course of 4 weeks, regular assessments were conducted every 3rd day to monitor the alternations in the wastewater properties. The T. latifolia exhibited a chemical oxygen demand removal efficiency of 85.45%, surpassing that of E. crassipes (83.17%), C. indica (80.03%), mix culture (85.29%), and the control (unplanted) system (73.11%). Maximum removal efficacy of phosphate (96.84%) and nitrate (82.88%) was also achieved by the Typha plant in comparison to other plant species. An increase in both reactive biomass and chlorophyll content of Canna and Typha under single and mixed culture conditions was also observed. The highest current and voltage were obtained from T. latifolia plant species (1.04 mA; 0.178 V). Based on the findings of this study, T. latifolia emerged as the optimum wetland plant for bioelectricity generation and organic matter, phosphate, and ammonia removal among the examined plant species. Therefore, incorporating T. latifolia in the design of a CW-MFC is recommended for efficient textile wastewater and bioelectricity generation. [ABSTRACT FROM AUTHOR]

Electro-chlorination (E-Cl) is an emerging and promising electrochemical advanced oxidation technology for wastewater treatment with the advantages of high efficiency, deep mineralization, a green process, and easy operation. It was found that the mechanism of pollutant removal by electro-chlorination mainly involves an indirect oxidation process, in which pollutant removal is mainly driven by the intermediate active species, especially RCS and chlorine radicals, with a strong oxidization ability produced at the anodes. In this work, we summarized the principles and pathways of the removal/degradation of pollutants (organic pollutants and ammonia nitrogen) by E-Cl and the major affecting factors including the applied current density, voltage, electrolyte concentration, initial pH value, etc. In the E-Cl system, the DSA and BDD electrodes were the most widely used electrode materials. The flow-through electrode reactor was considered to be the most promising reactor since it had a high porosity and large pore size, which could effectively improve the mass transfer efficiency and electron transfer efficiency of the reaction. Of the many detection methods for chlorine radicals and RCS, electron paramagnetic resonance (EPR) and spectrophotometry with N, N-diethyl-1,4-phenylenediamine sulfate (DPD) as the chromogenic agent were the two most widely used methods. Overall, the E-Cl process had excellent performance and prospects in treating salt-containing wastewater. [ABSTRACT FROM AUTHOR]

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]

Dyes are organic compounds. Azo dyes, as the most important dyes, are usually synthesized and reduced after entering the human body, turning into mutagenic and carcinogenic amines. A new efficient composite containing calix [4] arene (Calix), metal‐organic framework (MIL‐101(Fe)), and copper(II) oxide (Calix/MIL‐101(Fe)/CuO) was synthesized and utilized for the degradation of Malachite Green (MG). The dye removal efficiency was 17% for Calix, 56% for CuO, 64% for MIL‐101(Fe), and 98.8% for the Calix/MIL‐101(Fe)/CuO composite using LED visible light. The degradation of MG by Calix/MIL‐101(Fe)/CuO using different doses, including 0, 1, 2, 3, and 4 mg, was 8%, 64%, 75%, 85%, and 98.8%, respectively. The degradation kinetic rate constants for 0, 1, 2, 3, and 4 mg of Calix/MIL‐101(Fe)/CuO were 0.0134, 0.1086, 0.1182, 0.1308, and 0.1727 (zero‐order rate), 5E‐04, 0.007, 0.008, 0.011, and 0.023 (first‐order rate), and 4E‐05, 0.0007, 0.001, 0.0017, and 0.0211 (second‐order rate), respectively. The MG degradation kinetics obeyed the zero‐order model. The Calix/MIL‐101(Fe)/CuO exhibited high reusability for MG degradation. The results suggest that Calix/MIL‐101(Fe)/CuO could serve as an alternative photocatalyst for the degradation of contaminants in aqueous media. [ABSTRACT FROM AUTHOR]

This study explores the development and performance of photocatalytic cementitious composites modified with nano-TiO2 to address urban air quality and sustainability challenges. Nine mortar series were prepared, incorporating binders with varying carbon footprints and mass contents across different series. The interplay between the fundamental (abrasion resistance) and functional (air purification efficiency) properties of the composites' surfaces and interfaces was investigated. The photocatalytic removal of airborne pollutants, specifically nitrogen oxides (NOx) and ozone (O3), was evaluated under simulated environmental conditions. The variations in binder composition influenced the composites' overall initial carbon footprint and air purification efficiency. The assessment revealed a possible net decrease in carbon emissions over the life cycle of the composite due to the removal of ozone (greenhouse gas) and its precursor—NOx, highlighting the potential of photocatalytic cementitious composites for dual environmental benefits in an urban environment, emphasizing the critical role of surface and interface engineering in achieving carbon-negative composites. [ABSTRACT FROM AUTHOR]

In a time characterized by the increasing interest in metal–organic frameworks (MOFs) as widely researched crystalline porous substances geared toward enhancing device and system capabilities across diverse environmental contexts, 2D MOFs emerge as a noteworthy class of nanomaterials that integrate the benefits of 2D structures with the unique characteristics inherent to MOFs. These 2D MOFs possess ultrathin nanosheet configuration, abundant accessible active sites, and remarkable mechanical flexibility. Such distinctive properties differentiate them from bulk MOFs and other 2D materials, offering the potential to instigate novel environmental phenomena and applications. This review focuses on the latest progress in the application of 2D MOFs within essential water‐related ecological fields, including contaminant adsorption, photocatalytic degradation, membrane separation, environmental sensing, and disinfection. A variety of synthesis approaches for 2D MOFs are analyzed, accompanied by a discussion on their effectiveness across different environmental settings. The unique structure and features of 2D MOFs that grant outstanding environmental functionalities are compared with those of bulk MOFs. The environmental ramifications of 2D MOFs are highlighted while outlining future research needs to explore the environmental applications of these innovative materials. [ABSTRACT FROM AUTHOR]