Search Results (286)

This work studies and analyzes the transition from a linear to a circular economy through wastewater treatment and resource recovery. As wastewater volumes grow, sustainable management becomes critical. This study highlights the reuse of treated effluent, beneficial sludge utilization, and energy generation via anaerobic digestion. Wastewater treatment plants should be envisioned as hubs for recovering water, materials, and energy, rather than disposal facilities. Emphasizing resource efficiency, the circular economy approach offers viable solutions to challenges related to resource scarcity, climate change, and ecological impact. Full article

Recycling washed mineral waste, generated as a byproduct of the mechanical wastewater treatment process, can be a beneficial alternative to widely used natural sand in construction. Studies on material from the Warsaw agglomeration, available in quantities sufficient for construction applications, demonstrated its high usability in specific hydrotechnical applications. Key laboratory tests for material characterization included physical, permeability, mechanical, and chemical property analyses. The tested waste corresponds to uniformly graded medium sands (uniformity coefficient: 2.20) and weakly calcareous (calcium carbonate content: 2.25–3.29%) mineral soils with organic content ranging from 0.24% to 1.49%. The minimum heavy metal immobilization level reached 91.45%. At maximum dry density of the soil skeleton (1.78/1.79 g/cm³) and optimal moisture content (11.34/11.95%), the hydraulic conductivity reached 4.38/7.71 m/d. The mechanical parameters of washed mineral waste included internal friction angle (34.4/37.8°) and apparent cohesion (9.37/14.98 kPa). The values of the determined parameters are comparable to those of natural sands used as construction aggregates. As a result, washed mineral waste has a high potential for use as an alternative material to natural sand in the analyzed hydrotechnical applications, particularly for flood embankment construction, by applicable technical standards and construction guidelines. Full article

Soil contamination with potentially toxic elements (PTEs) not only poses potential ecological risks (RI) but also leads to human health risks (HI) through the uptake of potentially toxic elements by crops. However, most studies primarily focus on potentially toxic element contamination in either soil or crops, often neglecting the intrinsic connections between soil and crop contamination risks. In reality, some regions may exhibit severe soil PTE exceedances, yet the PTE levels in crops may not necessarily exceed regulatory limits, resulting in human health risks that are not uniformly high. This study investigated a typical area with severe soil PTE pollution caused by wastewater from electroplating, smelting, and ore beneficiation industries, and conducted risk assessments on soil and crops. The research aims to elucidate the differences in soil and crop PTE contamination risks and the correlations between PTE concentrations in soil and crops. Results showed that Cd was the most severe PTE contaminant in the soil in the study area, with an average concentration of 1.11 mg/kg and a maximum concentration of 7.30 mg/kg. However, the average concentrations of eight PTEs in crops were all below the standard limits for cereal crops specified in the Food Safety National Standard for Pollutant Limits in Foods (GB 2726-2022). Cd was identified as the most severe PTE contaminant in the soil, resulting in the highest RI (836) in the MY sub-region of the study area. However, Cr in crops contributed the most to health risk (63.5%), leading to the highest HI (7.1) in sub-region MY. Despite Cd being the most severely polluting PTE in soil, its contribution to human health risk through crops was relatively low, ranging from 2.82% to 9.90%. This discrepancy in pollution risks indicates that a PTE causing severe soil contamination may not necessarily result in significant human health risks via crop uptake. Correlation and regression analyses revealed that soil PTEs had the greatest impact on Cd levels in crops. Soil Ni, Cd, Cu, As, and Zn exhibited different synergistic or antagonistic effects on crop PTE uptake. Notably, soil Cd content showed a highly significant positive regression relationship with Cd, Cr, and Ni concentrations in crops. Overall, the influence of soil PTEs on crop PTEs varied significantly, and the spatial differentiation characteristics of PTEs in soil and crops differed. For PTEs with high spatial differentiation, localized and precise management measures should be implemented. Conversely, for PTEs with low spatial differentiation, unified risk management and control measures can be adopted. Full article

Nanofiltration (NF) technology has extensive application in the treatment of wastewater generated in the dyeing industry. However, NF membranes often encounter fouling issues during the operation process. In this work, the superhydrophilic and self-cleaning multilayer nanofiltration membrane was prepared by self-assembling polyelectrolyte incorporating the anatase PSS-TiO₂ nanoparticles. The negatively charged PSS-TiO₂ nanoparticles were beneficial to the formation of the nanohybrid selective layers via electrostatic interforce. The prepared (PEI/PSS-TiO₂)_4.0 hybrid membrane showed favorable photoinduced superhydrophilicity. The water contact angle of the membrane decreased with the UV irradiation from 35.7° to 1.6°. The negatively charged (PEI/PSS-TiO₂)_4.0 membrane exhibited a 100% rejection rate to XO and EbT, with a permeance flux of 5.2 and 6.4 L/(m²·h·bar), respectively. After UV irradiation for 60 min, the permeance flux could be further increased to 13.4 and 14.0 L/(m²·h·bar), and the rejection remained at 97.8% and 96.7%. Owing to the low content of TiO₂ NPs photocatalytic effect under UV irradiation, the fabricated hybrid membrane exhibited a compromised permeance recovery of about 80.6%. Full article

This review aims to increase attention on present water quality issues on Central Asia, finding gaps in the literature on ways to address treatment needs, and help ensure future use of Central Asia surface waters and groundwater for all beneficial uses. Central Asia is a landlocked region known for its harsh climatic conditions and scarce water resources, despite being home to some of the world’s largest internal drainage basins. The available literature suggests that increasing salinity has rendered water unsuitable for irrigation and consumption; hazardous trace elements are found throughout Central Asia, most often associated with mining and industrial sources; and that legacy pesticides influence water quality, particularly in agriculturally influenced basins. This study also focuses on the effects of municipal and industrial wastewater discharge. Additionally, the impact of inadequately treated wastewater on water resources is analyzed through a review of available data and reports regarding surface and groundwater quantity and quality. Given the challenges of water scarcity and accessibility, the reuse of treated wastewater is becoming increasingly important, offering a valuable alternative that necessitates careful oversight to ensure public health, environmental sustainability, and water security. However, due to insufficient financial and technical resources, along with underdeveloped regulatory frameworks, many urban areas lack adequate wastewater treatment facilities, significantly constraining their safe and sustainable reuse. Proper management of wastewater effluent is critical, as it directly influences the quality of both surface and groundwater, which serve as key sources for drinking water and irrigation. Due to their persistent and biologically active nature even at trace levels, we discuss contaminants of emerging concern such as antibiotics, pharmaceuticals, and modern agrochemicals. This review thus highlights gaps in the literature reporting on impacts of wastewater inputs to water quality in Central Asia. It is recommended that future research and efforts should focus on exploring sustainable solutions for water quality management and pollution control to assure environmental sustainability and public health. Full article

The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene)—are byproducts of copper–porphyry gold-bearing ore beneficiation. The reduction of Ni powder in the wastewater induces the degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices. Full article

Hexavalent chromium (Cr(VI)) is of significant interest in the environmental field due to its high toxicity. Biochar is commonly used as an adsorbent for Cr(VI) removal from wastewater. However, its lower removal efficiency remains a persistent challenge. This study develops an iron-modified rice straw biochar through a simple precipitation and pyrolysis method and applies it for Cr(VI) removal in wastewater, which could convert waste into treasure and improve the adsorption performance of adsorbent. In the adsorption experiments, the results revealed that the adsorption efficiency of Cr(VI) reached 95.54% within 480 min (conditions: adsorbent dosage 2.67 g/L, pH 2.5, temperature 25 ± 2 °C). The Langmuir isotherm model was more suitable to describe the adsorption behavior of Cr(VI) by Fe-BC, and the fitted adsorption capacity achieved 10.03 mg/g. The experimental process was better described by the pseudo-second-order kinetic model, indicating that the adsorption process chemical adsorption was the rate-limiting step. The thermodynamic experiments revealed that the adsorption process of Cr(VI) by Fe-BC was spontaneous and endothermic. Column experiments demonstrated that a lower flow speed was beneficial to adsorption performance. Mechanistic studies highlighted the synergistic roles of electrostatic attraction, ion exchange, and reduction in Cr(VI) removal. These findings provide novel perspectives and innovative approaches for the development and application of adsorbents. Full article

Olive mill wastewater (OMW) is deemed a substantial environmental pollutant, particularly in Mediterranean regions. Lower and middle-income countries, including Jordan, suffer from water scarcity and increasing demand for water, especially for drinking and irrigation purposes. Subsequently, the management and treatment of OMW represents a major concern. This study investigates the feasibility of utilizing Jordanian kaolinite as a simple, readily available, green, and sustainable adsorbent to mitigate the environmental impact of untreated or partially treated OMW. In this work, purified kaolinite (PK) was activated with sodium ions at room temperature. The characterization of PK and sodium-activated kaolinite (PK-NaCl) was accomplished using FTIR, XRD, TGA, and BET surface area analyses. The adsorption performance of both PK and PK-NaCl for OMW treatment were evaluated through batch and column experiments. The key physiochemical parameters of OMW were systematically analyzed in all influent and effluent samples to evaluate the treatment efficiency. In all cases, sodium-activated kaolinite significantly enhances treatment efficiency. The adsorption of total phenolic compounds (TPCs) onto both PK and PK-NaCl adsorbents was studied with respect to initial concentration, adsorbent dosage, and temperature. The maximum adsorption capacity was 8.88 mg/g for PK-NaCl, which was higher than that of PK, at an adsorbent dose of 1.0 g and a temperature of 323 K. The Langmuir and Freundlich isotherm models to describe the adsorption equilibrium were implemented, and both displayed good fit with the experimental data. Additionally, the removal efficiencies of heavy metal (i.e., Zn, Fe and Mn) ions were also evaluated. The findings demonstrated that the PK-NaCl completely removed all tested heavy metal ions, regardless of their initial concentrations. Therefore, the cost-effective and easily prepared PK-NaCl significantly improved the adsorption capacity and presents a promising treatment solution for OMW. This approach could be highly beneficial for olive mills across the Mediterranean regions to mitigate the environmental impact of OM waste. Full article

The increasing environmental concerns over and demand for sustainable solutions have driven research into the efficient recovery and reuse of waste materials, particularly from photocatalysts used in wastewater treatment. This study addresses the critical challenge posed by used PVDF/TiO₂ photocatalysts, which, if not properly managed, contribute to environmental pollution. A practical recovery technique based on the phase inversion method was developed to separate and purify PVDF, TiO₂, and the solvent NMP from used composite materials. This method led to recovery rates of 95.17% for PVDF, 98.35% for NMP, and 67% for TiO₂. The recycled photocatalyst was then reassembled and tested for its ability to degrade methylene blue, a common dye pollutant. A Box–Behnken design was employed to optimize the treatment conditions, ensuring the process was both efficient and reproducible. The regenerated material achieved up to 99.6% efficiency in the first cycle, with a slight reduction in efficiency observed across subsequent cycles, maintaining over 92% efficiency after 10 cycles. These findings confirm that effective recovery of photocatalytic materials is not only feasible but also beneficial in reducing waste and maintaining high treatment performance. Full article

Management of sewage sludge is of ongoing concern because this waste product is generated continuously and contains high levels of harmful constituents. Among these constituents, fungal pathogens are of increasing concern. Vermicomposting can reduce the amounts of bacterial pathogens in sewage sludge; however, information about the effects of earthworms on fungal pathogens is limited or non-existent. We therefore aimed to determine whether vermicomposting can control fungal pathogens present in sewage sludge. Using next-generation sequencing techniques, we characterized fungal communities in sewage sludge from eight wastewater treatment plants (WWTPs) and in casts (feces) of earthworms feeding on sewage sludge. Fungal communities in earthworm casts primarily included taxa that were absent from sewage sludges, indicating a significant change in fungal composition. Changes in fungal diversity depended on the source of sewage sludge (WWTP). All of the sewage sludges contained low levels of fungal pathogens, most of which were significantly reduced or eliminated by earthworms, such as Armillaria, Cystobasidium, Exophiala and Ophiosthoma. Moreover, earthworm gut transit enhanced beneficial (saprotrophic) fungi like Arthrobotrys, Aseroe, Crepidotus and Trichurus. Overall, digestion of sewage sludge by earthworms alone generated a mainly pathogen-free fungal community with a high proportion of saprotrophic taxa, which would enhance nutrient cycling rates. Full article

Printing and dyeing wastewater is known for its high color intensity, complex composition, and low biodegradability, making its treatment a significant challenge in environmental protection. Dolomite is a natural mineral with abundant reserves and can be effectively used as an adsorbent carrier. In this study, the dolomite loaded by Fe₂O₃ composites (DFC) was synthesized and systematically characterized using XRD, SEM, TEM, BET, XPS, and IR to evaluate its structural and surface properties. The adsorption performance of DFC on Congo Red (CR) was then investigated. The maximum adsorption amount of CR by DFC was 3790.06 mg⋅g⁻¹, and the removal rate was still stable at 97% after five cycles of adsorption test, which demonstrated that DFC exhibited exceptional adsorption efficacy and regeneration capability. The loaded Fe³⁺ was beneficial to improve the adsorption effect on the DFC. In addition, to evaluate the type of adsorption, kinetic calculations were performed, which indicated that the Weber–Morris diffusion modeling study showed the adsorption behavior was influenced by the interplay of many diffusion mechanisms. The study offers an innovative method for the efficient utilization of dolomite in creating renewable adsorbent materials for dye wastewater remediation. Full article

Processing wastewater of yuba (PWY), a by-product of yuba production, contains valuable bioactive compounds such as soy isoflavones. However, its utilization remains limited. This study investigated the effects of Lactiplantibacillus plantarum fermentation on the bioactivity of PWY, focusing on its antioxidant properties and gut microbiota modulation. The fermentation resulted in a significantly increased amount of free flavonoids from 63.62 μg/mL to 145.91 μg/mL, and transformed glycosylated isoflavones into their more bioavailable aglycone forms. FPWY exhibited stronger antioxidant activity than non-fermented PWY (NFPWY) as indicated by DPPH, ABTS, and FRAP assays. Furthermore, FPWY promoted the growth of beneficial gut bacteria, including Bifidobacterium, Akkermansia, Ruminococcus, and butyrate bacteria, while inhibiting Escherichia coli. FPWY also enhanced the production of short-chain fatty acids (SCFAs), with propionic acid increasing from 5.01 to 9.30 mmol/L and butyric acid increasing from 0.11 to 2.54 mmol/L. These findings suggest that FPWY has a beneficial effect in relation to gut health and oxidative stress. Full article

Hydrogel-based wastewater treatment technologies show certain outstanding features, which include exceptional efficiency, sustainability, reusability, and the precise targeting of specific contaminants. Moreover, it becomes possible to minimize the environmental impact when using these materials. Their flexibility, low energy consumption, and adaptability to meet specific requirements for different purposes offer significant advantages over traditional methods like activated carbon filtration, membrane filtration, and chemical treatments. Recent advancements in hydrogel technology, including new production methods and hybrid materials, enhance their ability to efficiently adsorb contaminants without altering their biocompatibility and biodegradability. Therefore, innovative materials that are ideal for sustainable water purification were developed. However, these materials also suffer from several limitations, mostly regarding the scalability, long-term stability in real-world systems, and the need for precise functionalization. Therefore, overcoming these issues remains a challenge. Additionally, improving the efficiency and cost-effectiveness of regeneration methods is essential for their practical use. Finally, assessing the environmental impact of hydrogel production, use, and disposal is crucial to ensure these technologies are beneficial in the long run. This review summarizes recent advancements in developing polymer-based hydrogels for wastewater treatment by adsorption processes to help us understand the progress made during recent years. In particular, the studies presented within this work are compared from the point of view of the synthesis method, raw materials used such as synthetic/natural or hybrid networks, and the targeted class of pollutants—dyes or heavy metal ions. In several sections of this paper, discussions regarding the most important properties of the newly emerged adsorbents, e.g., kinetics, the adsorption capacity, and reusability, are also discussed. Full article

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

The presence of pharmaceuticals in wastewater raises concerns about the toxicological risks associated with its discharge and reuse. During the COVID-19 pandemic, widespread use of antivirals (ATVs), along with plastic gloves and masks, further contributed to pharmaceuticals in wastewater. Chlorination, commonly used for wastewater disinfection, may alter the toxicity of antivirals in the presence of microplastics (MPs) and complex organics in secondarily treated wastewater. To investigate this, synthetic secondary effluent containing Favipiravir (FAV) and Oseltamivir (OSE) was exposed to various chlorination conditions, both with and without MPs. The changes in the concentrations of FAV and OSE were measured using LC-MS/MS with isotopically labeled standards. Chlorination was more effective in removing Favipiravir (42 ± 4%) than Oseltamivir (26 ± 3%). The ecotoxicological effects were assessed on two species—Aliivibrio fischeri (a bacterium) and Enchytraeus crypticus (a soil invertebrate)—to evaluate potential impacts on aquatic and soil environments, though discharge of or irrigation with treated wastewater, respectively. Results indicated that chlorination of wastewater itself increased toxicity more significantly than the chlorination of antivirals to either species, suggesting that chlorination may not be as beneficial despite its cost-effectiveness. The effects of MPs in chlorinated wastewater on toxicity highlighted the importance of sample matrices in environmental toxicity studies. Full article