Search Results (10,330)

Zeolites and molecular sieves have demonstrated remarkable potential in adsorption, ion exchange, and separation processes since their industrial revolution in the 1950s. Zeolites and molecular sieves are materials of choice in separation applications because of their well-defined microporous architecture, remarkable shape-selectiveness, and tunable characteristics. The adsorption process can be evaluated using an isotherm to determine the feasibility of gas mixture separation for practical applications. We will also discuss the basic structure of zeolites and molecular sieves based on different metals, along with their distinctive properties in detail. The purpose of this review is to contextualize the importance of zeolites and molecular sieves in adsorption and separation applications. The review has been divided into groups based on how zeolites as well as molecular sieves are established in the adsorption and separation processes. The fundamental adsorption characteristics, structures, and various separation methods that make zeolites appealing for different uses are covered. By incorporating knowledge of adsorption mechanisms, isotherms, and material changes, this review discusses the most recent developments. To augment zeolite-based materials for certain pollutant removal applications, it offers a strategic framework for future study. In this review, we will comprehensively discuss a range of separation and adsorption applications, including wastewater purification, CO₂ capture from flue gases, and hydrogen storage. Furthermore, the review will explore emerging prospects of zeolites and molecular sieves in innovative fields such as energy storage, oil refining, and environmental remediation. Emphasis will be placed on understanding how their tunable pore structures, surface chemistry, and metal incorporation can enhance performance and broaden their applicability in sustainable and clean energy systems. Full article

Constructed wetlands (CWs), increasingly adopted as nature-based solutions (NBS) for wastewater treatment, require a rigorous assessment of the durability and structural performance of the materials used in their supporting systems. In contrast to the extensive literature addressing hydraulic efficiency and contaminant removal, the structural behavior of CWs has been scarcely examined, with existing studies offering only general references to reinforced concrete and masonry and lacking explicit design criteria or deterioration analyses. This study integrates evidence from real-world CW installations with a systematic review of 31 studies on the degradation of cementitious materials in analogous environmental conditions, following PRISMA 2020 guidelines, with inclusion criteria based on quantified wastewater-related exposure conditions (e.g., chemical aggressiveness, persistent saturation, and biogenic activity). Results indicate that reinforced concrete, despite its structural capacity, is susceptible to biogenic corrosion, accelerated carbonation, and sulfate–chloride attack under conditions of persistent moisture, with reported degradation rates in analogous wastewater infrastructures on the order of millimeters per year for concrete loss and tens of micrometers per year for reinforcement corrosion. Masonry structures, similarly, exhibit performance constraints when exposed to mechanical overloads and repeated wetting–drying cycles. In contrast, emerging alternatives—such as nanomodified matrices and concretes incorporating supplementary cementitious additives—demonstrate potential to enhance durability while contributing to a reduced carbon footprint, without compromising mechanical strength. These findings reinforce the need for explicit structural design criteria tailored to CW applications to improve sustainability, durability, and long-term performance. Full article

Sludge, a by-product of wastewater treatment, contains harmful components that negatively impact the environment. One of the most ecologically viable and cost-effective methods for sludge treatment is anaerobic digestion, which produces biogas and stabilized digestate that can be applied to agricultural land. However, anaerobic digestion has certain limitations that reduce biogas yield. To address these issues, various improvement methods have been developed, including the addition of biochar. Biochar, a carbon-rich biomass, enhances the decomposition of organic matter, reduces ammonia toxicity, and supports the growth of methanogenic archaea. Additionally, biochar improves the quality of the resulting digestate, making it more suitable for agricultural use and plant growth. This sustainable approach to sludge management not only benefits the wastewater sector, but also contributes to the energy and agricultural industries. Full article

This study estimates the levels of chemical contamination and the responses of biochemical and cytogenetic biomarkers in Unio pictorum from the Nemunas River after a large-scale fire at a tire storage and processing warehouse (in October 2019), as well as after the subsequent discharge of partially cleaned water used for firefighting. The impact of firefighting water (FW) on the River Nemunas ecosystem was assessed. Elevated levels of trace metals (Pb, Cu, Co, Cr, Al, Zn) in U. pictorum mussels collected downstream from the wastewater treatment plant (WTP) discharger were measured in the first year after the accident. Genotoxic aberrations in gill cells were significantly more frequent in mussels collected downstream of the WTP discharger, along with higher frequencies of cytotoxic damage and changes in acetylcholinesterase activity. PAH metabolite concentrations, including naphthalene (Nap) and benzo(a)pyrene (B(α)P), were also elevated in haemolymph in U. pictorum gathered downstream from the discharger, but differences were not statistically significant. The total sum of 16 PAH concentrations in mussels collected in 2021 and 2022 was over 5 times higher than those in 2020, and the profile of accumulated metals shifted, with Ni, Cd, Cr, and Pb concentrations decreasing while Zn increased significantly. Mussel haemolymph in 2021 contained the highest levels of B(α)P-type PAH metabolites, indicating increased oxidative stress and neurotoxic impact. The results of chemical analysis and the values of genotoxic aberrations determined in gill cells of U. pictorum collected in 2021 and 2022 indicate an increase in PAH contamination and geno-cytotoxic impact compared to the results of 2020; these changes might be related to the gradual cancellation of COVID-19 restrictions and restoration of routine activities. The study provided an opportunity to demonstrate the unique response of a less anthropogenically stressed ecosystem to the extreme impact of contamination related to the fire on the tire recycling plant. Full article

Anaerobic digestion of sewage sludge generates large volumes of liquid digestate, which is often returned to wastewater treatment plants (WWTPs) due to the presence of pathogens and pollutants, limiting its safe reuse in agriculture. This study evaluated plasma-based post-treatment as a method to improve the sanitary quality of digestate. The liquid phase from mesophilic digesters at WWTP “Ravda” was treated for 5 min using two plasma sources, the β-device and the Surfaguide WR340 (SAIREM, Décines-Charpieu, France). Disinfection effectiveness was assessed for aerobic and anaerobic heterotrophs, fecal and total coliforms, Escherichia coli, Salmonella sp., and Clostridium sp. Physicochemical parameters measured included pH, COD, NH₄⁺, NO₂⁻, NO₃⁻, and PO₄³⁻. The β-device achieved partial disinfection, with reductions ranging from 16.3% to 89.8% for different microbial groups, whereas coliforms persisted and Clostridium sp. reappeared. The Surfaguide produced near-complete disinfection, eliminating coliforms, E. coli, Salmonella sp., and Clostridium sp., and markedly reduced microbial diversity. Both treatments caused slight pH increases, COD decreases, release of NH₄⁺ and PO₄³⁻, and rises in NO₂⁻ and NO₃⁻. Plasma-based disinfection, particularly with the Surfaguide, effectively improves the sanitary quality of the digestate and modifies its chemical properties, supporting the potential for sustainable digestate valorization and its safe reuse in agriculture. Full article

Wastewater management plays a critical role in advancing the circular economy, as wastewater is increasingly considered a recoverable resource rather than a waste product. This paper reviews physical, chemical, biological, and combined treatment methodologies, highlighting a lack of a holistic framework in current research which includes both the operational phases of wastewater treatment and proper risk analysis tools. To address this gap, an innovative methodological framework for wastewater recovery and risk management within an integrated logistic–production process is proposed. The framework is structured in five steps: description of the logistic–production process, hazard identification, risk assessment through the Failure Modes, Effects, and Criticality Analysis (FMECA), prioritization of interventions using the Action Priority (AP) method, and definition of corrective actions. The application of the proposed methodology can optimize the usage of available resources across various sectors while minimizing waste products, thus supporting environmental sustainability. Furthermore, political, economic and social implications of adopting the proposed approach in the field of energy transition are discussed. Full article

The objective of this study was to valorise eggshell waste (ESW) by investigating its biosorption properties and evaluating its efficiency as a sustainable biosorbent for the removal of the synthetic dye Congo Red (CR) from model CR solutions and synthetic wastewater with the addition of CR. Batch biosorption experiments were conducted to investigate the influence of several factors on the biosorption process, including ESW concentration (1–15 g L⁻¹), contact time (1–360 min), temperature (15, 25, 35, 45 °C) and initial CR concentration (10–100 mg L⁻¹). Desorption experiments were performed using ultrapure water, 0.1 M NaCl, 50% ethanol, 0.1 M HCl, or 0.1 M NaOH as solvents. A higher ESW concentration improved CR removal, but the amount of CR adsorbed on ESW decreased. The dye uptake by ESW was increased with prolonged contact time and temperature increase. When the effect of CR initial concentration was investigated, the results indicated that the process is concentration-dependent and that overall, CR uptake by ESW was higher in synthetic wastewater than in the model dye solution. The biosorption process was better described by the Langmuir isotherm model than by the Freundlich model, indicating monolayer adsorption. Kinetic analysis showed that the pseudo-second-order model provided a better fit than the pseudo-first-order model. Desorption of CR from ESW under the applied experimental conditions was generally low (0.67–27.13%). Full article

Piggery farming is the largest source of livestock manure in South Korea, yet greenhouse gas (GHG) data from piggery wastewater treatment systems remain limited. This study quantified methane (CH₄) and nitrous oxide (N₂O) fluxes from a full-scale treatment facility to develop stage-, seasonal-, and diurnal-specific emission factors. Continuous laser-based monitoring using a PVC air-pool chamber was applied across raw wastewater storage, an anoxic nitrogen-conversion reactor, and strongly aerated nitrification units. Mean CH₄ fluxes ranged from 1.1 to 15.6 mg s⁻¹ m⁻² peaking in summer, while N₂O fluxes ranged from 0.01 to 17,971 mg s⁻¹ m⁻², with maxima in fall. Emissions were dominated by two functional zones: aerated basins where vigorous mixing enhanced CH₄ stripping, and an upstream anoxic reactor where oxygen instability and nitrite accumulation produced extreme N₂O peaks. Derived emission factors were 0.11 kg CH₄ head⁻¹ yr⁻¹ and 45.2 kg N₂O head⁻¹ yr⁻¹, equivalent to 3.1 and 12,300 kg CO₂-eq head⁻¹ yr⁻¹. CH₄ variability was controlled mainly by treatment stage and temperature, whereas N₂O was governed by internal redox conditions. These results refine emission factors for inventories and underscore the need for improved aeration stability and denitrification control to reduce GHG emissions from piggery wastewater systems. Full article

Constructed wetlands (CWs), which combine biological and physicochemical processes and adhere to circular economy principles, are increasingly recognized as nature-based wastewater treatment solutions. With an emphasis on resource valorization and pollutant removal efficiency, this review assessed the use of organic residues as substrates in CWs. In total, 44 peer-reviewed open-access case studies in English were obtained from 325 documents that were retrieved from Scopus using PRISMA-based eligibility criteria. Information about the wastewater source, substrate, CW type, and results was extracted. The results indicated that biochar (66.7%) predominated because of its high adsorption capacity and microbial support, while shell or forest residues and agricultural residues (20.5%) helped remove micropollutants and phosphorus. CWs with vertical subsurface flow were most prevalent (54%). According to studies, the removal efficiencies of biochar and agricultural or shell residues were 10–15% higher than those of inorganic substrates for phosphorus, TSS (total suspended solids), NH₄⁺ (ammonium), and BOD (biochemical oxygen demand) in wastewater. Through innovative designs and the application of circular economy strategies, including revalorize, reuse, reutilize, reintegrate, rethink and reconnect, organic substrates enhance pollutant removal and improve the overall sustainability of CWs. Overall, CWs with organic residues provide cost-effective and environmentally sustainable wastewater treatment; further research on local resources, hybrid systems, and supportive policies is recommended to promote broader implementation. Full article

Sewer corrosion driven by sulfur metabolism threatens infrastructure durability. Current study examined the effect of conductive lining materials on microbial communities and sulfide control under simulated sewer conditions. Three lab-scale reactors (3.5 L total volume, 2.1 L working volume) were prepared with amorphous carbon (SAN-EARTH) and magnetite-black (MTB) linings, while a Portland cement reactor with no coating served as the control. Each reactor was operated for 120 days at room temperature and fed with artificial wastewater. The working volume consisted of 1.4 L of synthetic wastewater mixed with 0.7 L of sewage sludge used as the inoculum source. Sulfate, sulfide, hydrogen sulfide, nitrogen species, pH, and organic carbon were monitored, and microbial dynamics were analyzed via 16S rRNA sequencing and functional annotation. SAN-EARTH and MTB reactors completely suppressed sulfide and hydrogen sulfide, while Portland cement showed the highest accumulation. Both conductive linings maintained alkaline conditions (pH 9.0–10.5), favoring sulfide oxidation. Microbial analysis revealed enrichment of sulfur-oxidizing bacteria (Thiobacillus sp.) and electroactive taxa (Geobacter sp.), alongside syntrophic interactions involving Aminobacterium and Jeotgalibaca. These findings indicate that conductive lining materials reshape microbial communities and sulfur metabolism, offering a promising strategy to mitigate sulfide-driven sewer corrosion. Full article

Despite being frequently proposed as a low-carbon solution for wastewater treatment and solar fuel production, the feasibility of photocatalytic processes in large-scale deployments remains unclear. This review evaluates the scalability of photocatalytic technologies by synthesizing a decade (2015–2025) of techno-economic analysis (TEA) and life-cycle assessment (LCA) studies. Using a systematic search and programmatic screening, 77 assessment-focused publications were identified from an initial corpus of 854 studies. Across applications, TEA and LCA consistently highlight two dominant barriers to scale-up: high electricity demand in UV-driven systems and significant cradle-to-gate impacts associated with catalyst synthesis, particularly for nanostructured materials. When solar irradiation replaces artificial light, environmental and economic hotspots shift from energy use to material production, catalyst durability, and reuse assumptions. Wide variability in reported costs and impacts reflects heterogeneous methodologies, limited pilot-scale data, and a lack of standardized reporting. Overall, assessment-based evidence indicates that photocatalysis is not yet ready for widespread industrial deployment as a large industrial process. However, continuous advances in solar-driven reactor design, low-impact and circular catalyst synthesis, hybrid process integration, and harmonized TEA/LCA frameworks could substantially improve its prospects for scalable, climate-positive implementation, especially in the context of emerging green energy alternatives. Full article

Phosphorus recovery from wastewater as struvite via electrochemical magnesium dosing is a promising approach to address the growing demand for fertilizers. However, its large-scale implementation is often constrained by energy requirements. To overcome this limitation, this study investigates electroless struvite precipitation from cheese whey wastewater using sacrificial magnesium anodes. Under optimal conditions, up to 90% of the phosphorus was recovered within 4–6 h. In this process, spontaneous magnesium dissolution acts as the driving force for phosphorus precipitation and is strongly influenced by the wastewater’s ionic composition. To identify conditions that favor efficient recovery, the effects of ammonium, chloride, and sulfate ions were evaluated by monitoring phosphorus removal and magnesium corrosion behavior. Sulfate ions enhanced magnesium corrosion more strongly than chloride during the initial stages, likely due to stronger coulombic interactions with Mg²⁺ at the electrode–electrolyte interface, whereas chloride ions were more effective at disrupting the passivation layer that develops over time. Based on these observations, a mechanistic interpretation of ion-specific effects on anodic corrosion is proposed. Solid-phase analyses using multiple characterization techniques confirmed struvite formation, with ammonium sulfate and ammonium chloride systems yielding the highest product purity. Overall, these findings improve the understanding of electroless struvite precipitation and highlight its potential as an energy-efficient approach for nutrient recovery. Full article

Dewatering of sewage sludge is a key operational element of wastewater treatment plants and has major economic implications, as it entails the costs of thickening, transport, and disposal. The aim of this study was to determine the influence of selected polyelectrolytes and their dosages on dewatering efficiency and to present an innovative, multicriteria method of result evaluation using radar charts. In this research, 10 different polyelectrolytes were assessed in terms of sludge dewaterability, considering conditioning parameters including Specific Resistance to Filtration (SRF), Capillary Suction Time (CST), and centrifugation performance. The results were presented in the form of radar charts, enabling both an overall evaluation of the effectiveness of each product and an assessment of their suitability for specific dewatering technologies, such as belt filter presses and centrifuges. The analysis showed that polyelectrolytes with higher cationic charge provided better dewatering performance. The proposed visualization method allows us to analyze the effects across different conditioners and technologies. The best sludge conditioning effect (maximum radar chart area) was achieved with Praestol 665, a polyelectrolyte with a high cationic charge level. This method is a practical tool for selecting the optimal agent for sewage sludge dewatering. Full article

Wastewater treatment (WWT) is among the main challenges in environmental engineering. However, conventional wastewater treatment methods are limited by several aspects, mostly related to efficiency, excessive energy requirements, and surplus sludge production. Thus, the alternative use of biofilms (instead of suspended biomass/activated sludge systems) has garnered particular interest, especially due to their ability to sustain high microbial activity and withstand extreme conditions. This review aims to provide an interdisciplinary and comprehensive approach to understanding the main interactions occurring in biofilms, emphasizing, specifically, the quorum sensing (QS) and the quorum quenching (QQ) mechanisms, as well as to address their relative applications in controlling biofouling problems, e.g., during the operation of membrane bioreactors (MBRs). The review summarizes and analyzes the latest developments, highlights the relevant research gaps in the literature, and links microbiological knowledge with related technological applications. Full article

Pharmaceuticals such as paracetamol and diclofenac (DCF) are among the most extensively consumed drugs worldwide and are continuously released into municipal and hospital wastewater due to incomplete human metabolism. Their persistent presence in aquatic environments, typically ranging from ng/L to µg/L, raises concerns due to endocrine disruption, chronic toxicity, and the promotion of antimicrobial resistance. Conventional wastewater treatment plants (WWTPs) remove 70–90% of ACT but less than 30% of DCF, primarily because these systems were not designed to target low-concentration, recalcitrant micropollutants. As a result, pharmaceuticals frequently pass into treated effluents, highlighting the need for advanced, sustainable, and passive treatment solutions. Permeable reactive barriers (PRBs) have emerged as a promising technology for the interception and removal of pharmaceuticals from both wastewater treatment plant effluents and groundwater. This review provides a comprehensive assessment of ACT and DCF occurrence, environmental behavior, and ecotoxicological risks, followed by a detailed evaluation of PRB performance using advanced reactive media such as geopolymers, activated carbon, carbon nanotubes, and hybrid composites. Reported removal efficiencies exceed 90% for ACT and 70–95% for DCF, depending on media composition and operating conditions. The primary removal mechanisms include adsorption, ion exchange, π–π interactions, hydrogen bonding, and redox transformation. The novelty of this review lies in systematically synthesizing recent laboratory- and pilot-scale findings on PRBs for pharmaceutical removal, identifying critical knowledge gaps—including long-term field validation, media regeneration, and performance under realistic wastewater matrices—and outlining future research directions for scaling PRBs toward full-scale implementation. The study demonstrates that PRBs represent a viable and sustainable tertiary treatment option for reducing pharmaceutical loads in aquatic environments. Full article