Search Results (1,723)

This is a pioneering study on the main drainage system in Gujranwala District, where untreated mixed wastewater is discharged and subsequently used for vegetable irrigation, leading to potential health and environmental risks. This study seeks to develop the spatial pattern of toxic metal accumulation in soil across an 11 km stretch of land used for vegetable cultivation. By using 90 samples of mixed wastewater and sludge, as well as 10 quadruplicate samples of rhizospheric soils and crops from ten vegetable fields, it was observed that the concentrations of Cr, Cu, Cd, Zn, Fe, Pb, Mg, and Ni in cauliflower (Brassica oleracea var. botrytis L.), coriander (Coriandrum sativum L.), radish (Raphanus sativus L.), mustard (Brassica juncea L.), spinach (Spinacia oleracea L.), meadow clover (Trifolium sp. L.), sorghum (Sorghum bicolour L.), garlic (Allium sativum L.), brinjal (Solanum melongena L.), and mint (Mentha L.) were beyond the permissible limits set by the FAO/WHO, 2001. The declining trend of the toxic metal concentrations in the effluent was Mg > Cr > Ni > Zn > Pb > Cd > Cu > Fe, and in sludge, soil, and plants, it varied in the order of Mg > Fe > Cr > Ni > Zn > Pb > Cd > Cu. Radish, mint, and brinjal had the highest quantities of toxic metals. The spatial pattern of toxic metals was determined by using proximity interpolation, Inverse Distance Weighted (IDW), the fine tuning of the interpolation characteristics, and the kriging of selected sample variograms. Toxic metals were found in the following order: plants > soil > sludge > effluents. The most prevalent cause of metal pollution was soil irrigation with polluted water. This study provides crucial information about the extent of contamination, which could help in the identification of public health risk, the assessment of environmental impacts, and also sustainable water management. Full article

Municipal wastewater treatment plants produce vast amounts of sewage sludge as waste, with more than 80% dewatered sludge (DS). DS is a polymer-based sludge containing flocculant and extracellular polymeric substances, including lipids. Lipids can be converted into biodiesel as an alternative energy that reduces dependency on fossil fuels while helping cities manage waste more sustainably. Past studies explored the potential of lipids from various sewage sludges in biodiesel production. However, the potential of DS remains largely unexplored. This study evaluates the lipid extracted from DS and the potential of its fatty acid methyl ester (FAME) to be used as biodiesel. Lipid extraction was conducted under varying parameters, including temperatures of 70, 80, and 90 °C, extraction time of 2, 4, 6, and 8 h, and sludge-to-solvent (S/L) ratios of 0.05, 0.075, 0.1, 0.125, 0.15, and 0.175 g/mL. The optimal extraction conditions of 70 °C for 4 h at S/L of 0.175 g/mL yielded 1.71 ± 0.10% lipid. FTIR and TGA revealed that the DS lipids contain triglycerides, fatty acids, glycerol, and proteins. Transesterification of DS lipids produced DS FAME with a fatty acid profile ranging from C4:0 to C22:0. The evaluation of DS FAME revealed a high ester content (94.7%) of fatty acids ranging from C14:0 to C24:1, surpassing the minimum standard of 90% for biodiesel. The elevated proportion of unsaturated fatty acids in DS FAME is expected to result in a low melting point, reducing the solidifying effect and enhancing its performance as biodiesel. Full article

The lack of access to centralized technologies and economic resources in rural communities makes wastewater management a critical challenge. Decentralized systems such as constructed wetlands offer sustainable solutions by leveraging natural processes for effluent treatment. However, their success and sustainability require active community participation. Currently, there is little evidence of community involvement in the implementation, maintenance, and management of constructed wetlands. Existing strategies for community collaboration in environmental and sanitation projects were analyzed through a literature review covering research conducted in the last 20 years. Only peer-reviewed research in English and Spanish was considered. Based on the findings, a triple helix model integrating academia, government, and society is proposed, compiling the most functional strategies from initial awareness raising to maintenance and dissemination. A case study of community participation is presented under this approach in the Salvador Díaz Mirón rural community, Veracruz, Mexico. The results of this study provide key information for effective strategies designed to manage constructed wetlands, emphasizing that their success depends on both the technology and the genuine commitment of communities to their operation and long-term sustainability. Furthermore, these findings can serve as a reference for decision-makers and project planners seeking to integrate participatory models into decentralized sanitation and water resource conservation. Full article

Zero Liquid Discharge (ZLD) is a wastewater management strategy that eliminates liquid waste while maximizing water use efficiency. This article reviews the primary ZLD technologies used for desulfurization wastewater (DWW) treatment in coal-fired power plants. These technologies include the thermal process and the membrane process. The thermal process includes “concentrated crystallization” technology and “gas evaporation and drying” technology. The paper also highlights recent advances in membrane technology for power plant wastewater treatment. The advantages and limitations of each technique are discussed. Membrane technology is considered a promising solution for wastewater recycling, while thermal technology offers easy operation and maintenance without the need for pretreatment. Finally, the paper outlines possible future directions for the treatment of DWW. Full article

Most people in the world now live in urban areas and their shared quest for better cities is embodied in several Sustainable Development Goals of the United Nations. These indicate that successful cities need jobs, adequate housing stock, effective governance, and other support systems. At the most basic level, they need a basket of core public works services like clean water and efficient transit, among others. These must be provided to improve public trust in government by addressing equity and affordability while also improving operational and cost efficiency. These targets are moving as transitions are occurring from stove-piped to integrated services, even while social contracts between government and the private sector are also shifting. Essential tools to improve cities include urban planning and infrastructure development, but applying them effectively faces challenges like climate change, inequality, social disorder, and even armed conflicts. This paper focuses on seven core public works services for drinking water, wastewater, stormwater, trash collection, mass transit, streets and traffic control, and disaster management. It reviews how these have evolved in the US, how they are organized under the federalism system, and how the goal of integrated management is being pursued. Challenges to integrated approaches include increasing responsibilities but lack of funding, political stress, and rule-driven and internally oriented management. Methods for performance assessment are explained under legacy systems based on methods like indicators and benchmarking applied to public works systems. Current methods focus on regulatory targets and the details; information has been shallow and not always timely. This paper projects how the performance assessment of core public works systems can be broadened to address goals like those of the SDGs and assesses why it is difficult to rate major systems. Examples of the activities of NGOs are given and an example of how progress toward SDG6 is included to show why performance management of integrated management applied to linked systems is needed. Performance dashboards with open government are currently the most common pathways, but emerging methods based on data analytics and visualization offer new possibilities. Reviewing the status of public works management shows that it is an important branch of the field of public administration, and it can be presented as a professional field with its own identity. The findings will support educators and researchers as well as provide policy insights into public works and stakeholder engagement. Full article

The increasing generation of industrial solid wastes, such as red mud and phosphogypsum, poses significant environmental challenges due to their complex chemical compositions and low utilization rates. This study aims to develop an innovative composite material by combining RM and PG, modified with ferric chloride (FeCl₃) and sodium silicate (Na₂SiO₃), to address their environmental risks and enhance their potential for soil and ecological remediation. The modification mechanisms and immobilization of toxic ions were investigated through leaching behavior analysis and advanced microscopic techniques, including BET and XRD. Under the optimal ratio (RM:PG = 7:3), the composite material exhibited excellent performance, with stable pH (8.03), low electrical conductivity (4.89 mS/cm), and significantly reduced concentrations of phosphate (PO₄³⁻: 0.36 mg/L) and fluoride ions (F⁻: 1.34 mg/L), achieving an upgrade from industrial Class II to Class I slag. The modification process increased the specific surface area, optimized pore structure, and enhanced surface activity and structural stability. Pot experiments demonstrated that the modified composite supported normal plant growth, with leachate meeting Grade I wastewater discharge standards. This study not only provides a sustainable approach for the utilization of RM and PG, but also offers valuable insights into the development of eco-friendly materials for soil remediation and ecological restoration, benefiting both the scientific community and environmental management practices. Full article

Synthetic and natural fibers are widely used in the textile industry. Natural fibers include cellulose-based materials like cotton, and regenerated fibers like viscose as well as protein-based fibers such as silk and wool. Synthetic fibers, on the other hand, include PET and polyamides (like nylon). Due to significant differences in their chemistry, distinct dyeing processes are required, each generating specific waste. For example, cellulose fibers exhibit chemical inertness toward dyes, necessitating chemical auxiliaries that contribute to wastewater contamination, whereas synthetic fibers are a major source of non-biodegradable microplastic emissions. Addressing the environmental impact of fiber processing requires a deep molecular-level understanding to enable informed decision-making. This manuscript emphasizes potential solutions, particularly through the biodegradation of textile materials and related chemical waste, aligning with the United Nations Sustainable Development Goal 6, which promotes clean water and sanitation. For instance, cost-effective methods using enzymes or microbes can aid in processing the fibers and their associated dyeing solutions while also addressing textile wastewater, which contains high concentrations of unreacted dyes, salts, and other highly water-soluble pollutants. This paper covers different aspects of fiber chemistry, dyeing, degradation mechanisms, and the chemical waste produced by the textile industry, while highlighting microbial-based strategies for waste mitigation. The integration of microbes not only offers a solution for managing large volumes of textile waste but also paves the way for sustainable technologies. Full article

The adsorption capacity of a biochar (BC) obtained from pine wood residues was evaluated for its ability to remove two pharmaceuticals: fluoxetine (FLX) and sulfamethizole (SMZ). The material showed promising results in FLX removal, but a limited capacity in the case of SMZ. In order to improve these results, BC surface modifications were made by doping with nitrogen, as well as using acid, basic and electrochemical treatments. A three-dimensional electrosorption treatment proved to be the most effective, increasing the adsorption rate from 0.45 to 13.46 mg/g after evaluating different operating conditions, such as the electrodes used or the BC dosage. Consecutive cycles of BC use were performed through desorption and electro-regeneration techniques to test its capacity for reuse, and it was observed that application in the 25 mA electric field increased the useful life of the material. Finally, the effect of ionic strength was studied, highlighting that the presence of ions did not significantly affect the efficiency of SMZ removal, although a slight increase was observed at a high ion concentration, probably due to a salinization effect. Full article

Nitrogen pollution poses significant environmental challenges, contributing to eutrophication, soil acidification, and greenhouse gas emissions. This study explores advanced methods for nitrogen removal and recovery from municipal and industrial wastewater, with a focus on biological, chemical, and physical processes. Key processes, such as nitrification–denitrification and emerging technologies like shortcut nitrogen pathways, were analyzed for their efficiency, cost-effectiveness, and environmental benefits. This review highlights the integration of innovative techniques, including membrane systems and ammonia stripping, with traditional approaches to enhance nitrogen management. Emphasis is placed on optimizing operational conditions, such as pH, temperature, and carbon-to-nitrogen ratios, to achieve high removal rates while minimizing energy consumption and environmental impact. These findings underline the critical role of interdisciplinary strategies in addressing the challenges of nitrogen pollution and promoting sustainable wastewater management. Full article

This study examined significant changes in phosphogypsum, a byproduct of the phosphoric acid industry, induced via mechanical activation through intensive grinding using a planetary ball mill. Alterations in crystallinity, surface area, and zeta potential were monitored using X-ray diffraction, Brunauer–Emmett–Teller analysis, zeta potential measurements, X-ray photoelectron spectroscopy, and scanning electron microscopy. The severe grinding of this mining waste led to the conversion of gypsum (CaSO₄·2H₂O) to anhydrite (CaSO₄), an increase in surface area from 5.8 m²/g to 17.8 m²/g, and a decrease in pore radius from 76.6 nm to 9.3 nm. The zeta potential shifted as the isoelectric point changed from pH 8.5 to pH 4.3. These modifications enhanced the material’s potential as a cost-effective and eco-friendly adsorbent for wastewater treatment. The enhanced adsorption capabilities for Cd and Pb were evaluated, revealing a higher adsorption capacity (~40 mg/g for both) and removal efficiency (~90% for Cd and ~80% for Pb) for activated phosphogypsum. The adsorption process followed the Freundlich isotherm and pseudo-second-order kinetic model, indicating its physisorption nature and spontaneous thermodynamic characteristics, and highlighting its potential for wastewater treatment. The mechanically activated adsorbent demonstrated over 90% desorption efficiency over five cycles, ensuring effective regeneration and reusability for Cd and Pb removal. Real tannery wastewater was treated using mechanically activated phosphogypsum at pH 6 and 70 °C for 60 min, achieving a 94% Cd and 92% Pb removal efficiency, with an overall heavy metal removal efficiency of up to 83%. This study demonstrates the sustainable utilization of phosphogypsum, contributing to green wastewater management and environmental protection. Full article

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

The discharge of wastewater containing persistent organic pollutants presents significant ecological and health challenges due to their toxicity and resilience. Recent advances in advanced oxidation processes (AOPs) and other remediation mechanisms, notably utilizing natural mineral materials (NMMs), offer promising solutions to these challenges. NMMs, with their cost-effectiveness, accessibility, eco-friendly nature, non-toxicity, and unique structural properties, have shown significant promise in environmental remediation and could effectively replace conventional catalysts in related applications. These minerals enable the activation of oxidants, generating reactive oxygen species crucial for the degradation of pollutants. This article reviews the mechanisms of NMMs in various AOPs, including photocatalysis, Fenton-like reactions, and persulfate-activation-based processes, and discusses the potential of these materials in enhancing pollutant degradation efficiency, with a focus on the activation of persulfates and the photo-induced redox processes. The synergy between photocatalytic properties and catalytic activation provided by NMMs offers a robust approach to managing water pollution without the drawbacks of secondary waste production, thus supporting sustainable remediation efforts. Full article

The presence of toxic and hazardous chemical species in municipal wastewater poses a significant environmental and public health challenge, necessitating innovative, sustainable, and cost-effective treatment solutions. This study pioneers the recovery and valorisation of polycationic metals from real acid mine drainage (AMD) for municipal wastewater treatment, demonstrating a novel approach that integrates resource recovery with wastewater remediation. A key strength of this study is the use of real municipal wastewater (authentic MWW) in the treatment phase, ensuring that the findings accurately reflect real-world conditions. Advanced analytical techniques were employed to characterise both aqueous and solid samples, and batch experiments were conducted to assess the removal efficiency of polycationic metals for key contaminants: ammonium (NH₄⁺), sulphate (SO₄²⁻), phosphate (PO₄³⁻), and nitrate (NO₃⁻). The optimised conditions are 2 g of polycationic metals per 100 mL, 90 min of contact time, and 35 °C. The yielded exceptional removal efficiencies are PO₄³⁻ (>99.9%), NH₄⁺ (>99.7%), NO₃⁻ (>99%), and SO₄²⁻ (>96%), achieving final concentrations of <0.5 mg/L for PO₄³⁻ and NH₄⁺, 2.1 mg/L for NO₃⁻, and 9.1 mg/L for SO₄²⁻. Adsorption kinetics followed a pseudo-first-order model, indicating physisorption, while the Two-Surface Langmuir model suggested a combination of homogeneous and heterogeneous adsorption mechanisms. FTIR, SEM-EDX mapping, and XRF analyses confirmed the retention of P, S, and N in the product sludge, validating the adsorption process. This study is the first of its kind to recover Al-rich Fe species from real AMD and activate them for municipal wastewater remediation using authentic MWW, bridging the gap between laboratory-scale research and real-world applications. By simultaneously addressing AMD pollution and municipal wastewater treatment, this research advances circular economy principles, promotes sustainable water management, and contributes to national and global efforts toward water security and environmental protection. Full article

The rapid expansion of industrial and agricultural activities in recent years has significantly contributed to water pollution leading to a decline in water quality and the need for effective treatment and reuse strategies. Metal contamination in water bodies poses severe environmental and health risks, making the development of cost-effective and sustainable remediation methods essential. Among the various treatment approaches, biosorption using biological adsorbents has emerged as a promising alternative due to its low cost and high efficiency. However, while the adsorption mechanisms of single metals are well understood, the competitive interactions between multiple metal ions during the sorption process remain less explored. In this review, we analyze the competitive biosorption of metals in multi-metallic wastewater systems. Key factors influencing metal removal, such as pH, contact time, biosorbent dosage, and initial metal concentration, are discussed, along with the intrinsic properties of biosorbents and metal ions that affect sorption efficiency. Additionally, we highlight recent studies on agroforestry byproducts as effective biosorbents for metal removal, showcasing their potential for sustainable water treatment. Heavy metals pose significant risks even at low concentrations, necessitating robust regulations and advanced treatment technologies; biomass byproducts, as cost-effective biosorbents, can be optimized through pre-treatment, activation, pH and temperature control, and particle size reduction, while effectively managing competitive multi-metal adsorption remains crucial for industrial effluent treatment. Full article

It is urgent for the wastewater treatment sector to respond to global climate change. Although studies related to the water–energy–carbon (WEC) nexus have been widely conducted, the application of the coupling coordination indicator is still limited in the wastewater treatment sector. This study fills such a research gap by linking water footprint (WF), energy footprint (EF), and carbon footprint (CF) together and testing these indicators in 140 wastewater treatment plants (WWTPs) in Shandong province, China. Both the EF and CF of these WWTPs were calculated by conducting hybrid life cycle assessments, while WF was calculated by using a WF method. The results show that gray WF generated from 1 m³ of wastewater ranged from 9.58 to 12.90 m³, while EF generated from 1 m³ of wastewater ranged from 9.42 × 10⁻² to 0.22 kg oil eq and CF generated from 1 m³ of wastewater ranged from 0.58 to 1.27 kg CO₂ eq. Also, the total WF, EF, and CF of these WWTPs in Shandong were 4.26 × 10¹⁰ m³, 5.32 × 10⁸ kg oil, and 3.35 × 10⁹ CO₂ eq in 2021, respectively. Key factors contributing to the overall greenhouse gas (GHG) emissions were the on-site GHG emissions and off-site electricity-based GHG emissions. Meanwhile, total nitrogen was the dominant contributor to the gray WF. In addition, the coupling coordination indicators of WF, EF, and CF ranged from 0.7571 to 0.9293. Finally, this study proposed several policy recommendations to improve the overall sustainability of this wastewater treatment sector by considering local realities, including adopting multi-dimensional indicators, decarbonizing current electricity grids, promoting the utilization of renewable energy, and initiating various capacity building efforts. Full article