Search Results (293)

This study investigated the influence of two years of ultrafiltration (UF) on the separation properties of tubular polyvinylidene fluoride membranes used for treating carwash wastewater, particularly with regard to bacterial rejection. Fouling was mitigated by washing the membranes with alkaline cleaning agents (pH > 11.5). Repeated applications of these agents enlarged the membrane pores to approximately 300 nm. This affected bacterial retention, and for feed containing bacteria (determined as colony-forming units, CFU) at a concentration of 3.11 × 10⁶ CFU/mL, over 13,000 CFU/mL were detected in the permeate. Interestingly, fouling improved retention, reducing bacterial counts present in the permeate from 13,689 to 2889 CFU/mL. Fouling also enhanced the retention of surfactants (80%), chemical oxide domain (60%), and turbidity (below 0.5 NTU), yielding results comparable to new membranes. Daily 60-min membrane washing with Wheel Cleaner solution (pH = 11.5) improved the membranes performance; however, it did not remove deposits from large pores, allowing good rejection performance and a permeate flux of 65 LMH to be maintained. It was found that bacteria also developed on the permeate side. Disinfection of the module housing with a NaOH/NaOCl solution reduced the number of bacteria in the permeate from 5356 to 66 CFU/mL. Microbiological tests revealed that some of these bacteria were antibiotic-resistant. Full article

The escalating global water crisis demands the development of cost-effective and environmentally sustainable treatment technologies. Among various advanced oxidation processes (AOPs), peracetic acid (PAA) has emerged as a promising oxidant, owing to its high redox potential, chemical stability, and potent disinfection capability. Nevertheless, the lack of highly efficient catalysts remains a major obstacle to achieving the effective degradation of contaminants of emerging concern in wastewater. Heterogeneous catalysis has proven to be a viable strategy for enhancing PAA activation, highlighting the urgent need for catalysts with superior activity, stability, and recyclability. Metal–organic frameworks (MOFs), with their large surface areas, tunable porosity, and structural diversity, provide versatile platforms for catalyst design. Recently, MOF-derived materials have attracted increasing attention for PAA activation, offering a new frontier in advanced oxidation technologies for efficient and sustainable wastewater remediation. This review systematically examines the role of MOFs in PAA activation, from pristine frameworks to MOF-based composites and MOF-derived catalysts. Mechanistic insights into PAA activation are highlighted, strategies for engineering MOF-based composites with synergistic catalytic properties are discussed, and the transformation of MOFs into robust derivatives with improved stability and reactivity is explored. Special attention is given to the identification and quantification of reactive species generated in PAA systems, providing a critical understanding of reaction pathways and catalytic performance. Finally, current challenges and future directions are outlined for designing highly efficient, recyclable, and environmentally compatible MOF-based catalysts, emphasizing their potential to significantly advance PAA-based AOPs. Full article

Enteric viruses in wastewater remain a persistent public health threat. Conventional treatments often achieve only modest viral log₁₀ reductions and can generate toxic disinfection byproducts, but high-energy advanced processes are often unaffordable. Antiviral phytoremediation, which involves virus removal mediated by plants and their rhizosphere microbiota, offers a low-cost, low-energy alternative; however, it has scarcely been studied. A bibliometric analysis of ~23,000 wastewater treatment studies (1976–2025) identified only 30 virus-targeted records within plant-based treatment branches, representing ~0.13% of the total corpus. This critical review structures antiviral phytoremediation into a four-barrier framework: (i) sorption/filtration, (ii) rhizosphere-mediated inactivation, (iii) plant internalization, and (iv) intracellular degradation. Pilot and full-scale studies provide strong support for the first two barriers, whereas evidence for internalization and intracellular degradation is limited, mainly laboratory-based, and often inferred from molecular rather than infectivity assays. Standalone constructed wetlands typically achieve ~1–3 log₁₀ virus reductions, but hybrid configurations that combine wetlands with complementary processes achieve ~3–7 log₁₀ reductions, with performance varying between enveloped and non-enveloped viruses and across climates. This review distills design principles for cost-effective hybrid systems and identifies methodological and governance priorities, positioning rigorously designed phytoremediation as a scalable part of climate- and pandemic-resilient wastewater infrastructure. 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

This study investigates the effectiveness of cold atmospheric plasma (CAP) treatment for improving the microbiological and physicochemical quality of wastewater generated in tourism-affected coastal regions. Experiments were performed on influent and effluent samples from the Ravda Wastewater Treatment Plant (WWTP) collected in April, August, and November 2024, representing different seasonal loading conditions. The plasma pre-treatment of influent aimed to minimize toxic micropollutants that inhibit activated sludge activity, reduce pathogenic and opportunistic microorganisms, and enhance oxidative potential before biological processing. The post-treatment of effluent focused on the elimination of residual pathogens, mainly Enterobacteriaceae, and the oxidative degradation of xenobiotics resistant to conventional treatment. Combined fluorescent (CTC/DAPI) and culture-based analyses were used to assess microbial viability and activity. Plasma exposure (1, 3 and 5 min) caused measurable changes in metabolic potential and bacterial abundance across all sampling periods. The results demonstrate that 1 min CAP treatment does not increase pathogen removal, but enhances oxidation capacity of the influent, while 3 min of CAP treatment ensures the disinfection of the effluent. Both can be combined to improve the effluent safety prior to Black Sea discharge. CAP is showing strong potential as a sustainable technology for wastewater management in tourism-intensive coastal zones. Full article

Cationic surfactants from the group of quaternary ammonium compounds (QACs) are widely used in disinfectants, cosmetics, and household and industrial products. Their strong antimicrobial activity and chemical stability make them valuable in applications but also highly persistent and toxic when released into aquatic environments. This problem has become increasingly relevant during and after the COVID-19 pandemic, when global use of QAC-based disinfectants increased drastically, resulting in their frequent detection in municipal, hospital, and industrial effluents. The concentrations of QACs reported in wastewater range from trace levels to several mg/L, often reaching inhibitory thresholds for biological treatment processes. Although surfactants are not listed in any current European directive, the revised Directive (EU) 2024/1440 classifies micropollutants as a priority group, imposing stricter environmental quality standards and mandatory monitoring requirements. Within this regulatory framework, QACs are recognized as compounds of emerging concern, and their effective removal from wastewater has become a critical challenge. This review summarizes the current knowledge on conventional treatment technologies (coagulation, adsorption, ion exchange, advanced oxidation, and biological processes) and membrane-based methods (ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, and hybrid systems) for the removal of cationic surfactants from water and wastewater. Mechanisms of separation, performance, and operational limitations are discussed. Full article

The aim of this paper is to investigate the measures adopted by higher education institutions (HEIs) for sustainable water management in university campuses. Rain and storm water harvesting and treatment, rain and storm water reuse, wastewater treatment and reuse and technologies for runoff reduction were found to be frequently undertaken. Sustainable approaches to water supply such as water-efficient appliances, irrigation algorithms and the use of drought-resistant plants have been adopted as well. In support, monitoring of consumed water and of rain and storm waters has been a widespread practice. Important considerations were given to the impact of the identified measures on campuses’ energy consumption and greenhouse gas emissions. Nature-based solutions, employment of renewable energies and sustainable disinfection methods are measures to prioritize. Some wastewater technologies may deserve priority in virtue of their positive contribution to circular economy. Drawbacks such as groundwater and soil contamination due to wastewater reuse and the release of pollutants from fertilized nature-based technologies were identified. Despite their variety, it must be noted that many of these measures have generally involved rather limited portions of campuses, taken more for demonstration or pilot/full-scale research purposes. Additional measures not identified in the current review—for instance the prevention of pollution from micropollutants and waste mismanagement—should be implemented to boost HEIs’ environmental sustainability. The findings of this review pave the way for a more structured implementation of water sustainability measures in university campuses. Full article

Chlorine contact tanks are crucial for wastewater disinfection, with performance strongly influenced by internal hydraulic characteristics. This study applies Computational Fluid Dynamics (CFD) to analyze and improve the hydraulics of the chlorination contact tank in a Wastewater Treatment Plant in the Southern Italy. A three-dimensional transient CFD model was developed using the Reynolds-Averaged Navier–Stokes (RANS) equations with the Renormalized Group (RNG) turbulence closure. The model simulated flow patterns, tracer transport, and chlorine decay kinetics under the existing configuration and two alternative configurations. Conservative tracer pulse simulations enabled the calculation of Residence Time Distributions (RTDs) and hydraulic efficiency indicators, including the Baffling Factor (θ₁₀), Morrill index (Mo), and Aral–Demirel index (AD). A typical contact tanks geometry exhibits specific hydraulic characteristics, including recirculation behind baffles and stagnant zones in sharp corners, which inevitably affects the contact time. The first alternative, namely featuring rounded corners, moderately reduced dead zones, but did not substantially mitigate recirculation. The second alternative, herein called combining rounded corners with perforated baffle walls, substantially improved hydraulic performance, yielding flow patterns closer to plug-flow. RTD peaks were higher and narrower for the modified designs, and hydraulic indices improved, with Mo decreasing by approximately 5%. These hydraulic enhancements are expected to increase disinfection efficiency by providing more uniform chlorine exposure. The results demonstrate that geometric modifications effectively optimize contact tank hydraulics and highlight the role of CFD as a design and retrofit tool for water and wastewater disinfection systems. Full article

This paper presents a review of current trends and challenges in greywater use in buildings, with particular emphasis on toilet = flushing applications. It discusses the quantitative and qualitative characteristics of greywater, including its generation sources, share in total domestic wastewater volume (50–89%), and flow variability depending on residents, building type, and user habits. Implementation of greywater recycling technologies faces several challenges, such as parameter variability, stringent sanitary and epidemiological standards, and the presence of micropollutants, including pharmaceuticals. Technological barriers include the integration of multi-stage treatment systems (physical, biological, and chemical) and ensuring effective disinfection for indoor use. The paper also highlights the lack of uniform international regulations and the significant variation in recovered water quality requirements. Key physicochemical and microbiological indicators that determine treatment system requirements are presented, with particular emphasis on the removal of organic pollutants and indicator bacteria. Various physical, chemical, and biological treatment technologies are described, with hybrid systems offering high efficiency and user safety. The implementation of greywater recycling systems encounters technical, regulatory, and social barriers. Social acceptance and transparent monitoring are identified as key challenges for widespread adoption. This critical literature review summarises current knowledge on effective greywater management in buildings, representing an increasingly important issue for sustainable water resource management. Full article

Green silver nanoparticles (AgNPs) have been increasingly recognized for their antimicrobial properties and environmental compatibility. In this study, AgNPs were synthesized using an aqueous extract of Manacá-da-Serra (Pleroma sellowianum) flowers as a natural reducing and stabilizing agent and subsequently incorporated into a chitosan matrix to produce functionalized composites for industrial wastewater disinfection. Optimal synthesis conditions were achieved at pH 12.0, 25 °C, and 0.01 mol/L AgNO₃, yielding uniformly dispersed spherical NPs (20–30 nm) with moderate colloidal stability (zeta potential ≈ −14 mV) and a minimum inhibitory concentration of 5 μL/mL against Escherichia coli and Staphylococcus aureus. The effective integration of AgNPs into the biopolymer was verified by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). The interaction between AgNPs and chitosan was confirmed by the data, while successful NP incorporation was further supported by homogeneous Ag distribution and improved thermal stability. Inhibition zones of 11 ± 1 mm (S. aureus) and 9 ± 1 mm (E. coli) were revealed by antimicrobial assays. For industrial wastewater disinfection, a total coliform reduction of >99.9% was achieved within 180 min, with Ag release remaining at 0.01 mg/L, below the regulatory threshold. The synergistic effect between chitosan and green-synthesized AgNPs was highlighted by these findings, demonstrating the potential of this environmentally friendly material for efficient, safe, and sustainable wastewater disinfection and reuse. Full article

Photocatalytic oxidation of microorganisms is a powerful alternative to established disinfection approaches, applicable to a variety of water matrices. Bacterial vegetative cells, spores, fungi, and viruses, represent potential biopathogens and photocatalysis targets. Inactivation efficiency is usually evaluated by assessing viability through culture. However, additional inactivation assessment approaches are needed, as some microbes, despite being unculturable, remain metabolically active and pathogenic. Nucleic acid quantification approaches (qPCR) can assess nucleic acid release and degradation during photocatalysis. We developed a novel multiplex qPCR assay for simultaneous detection/quantification of genomic DNA from different bacterial and fungal species and of MS2 bacteriophage load. Following small-scale solar titanium dioxide photocatalysis on a microbial suspension mixture containing different biopathogen classes, we assessed photocatalytic efficiency by conventional microbiological assays (culture) and our novel molecular assay. Microbiological assays show a significant reduction in microbe viability within one hour of processing, following previously reported patterns of microbial species resistance. Molecular analysis data show that nucleic acids released in solution due to microbial oxidative damage were significantly reduced due to oxidative degradation within six hours. Through targeting different biopathogen classes, our assay could be a useful tool for assessment of photocatalytic microbe inactivation both in laboratory and real-wastewater applications. Full article

Tetracycline (TC), commonly utilized in medicine and aquaculture, frequently enters aquatic environments, raising ecological concerns. This study examined TC-contaminated wastewater treated through ultraviolet (UV), potassium persulfate (PS), and combined UV/PS disinfection processes. The degradation of TC followed pseudo-first-order kinetics, with removal efficiency ranked as UV/PS > UV > PS. High-performance liquid chromatography–mass spectrometry (HPLC-MS) identified 20 disinfection byproducts (DBPs) across all processes. Based on the identified intermediates, the degradation pathways of TC under different disinfection processes (UV, PS, and UV/PS) were elucidated. Using the ECOSAR program, both acute and chronic aquatic toxicities of TC and its DBPs were predicted. The biological effects on Chlorella were also investigated. DBPs from UV and PS treatments inhibited algal growth, reducing it by 4.8–9.4% relative to the control. Conversely, DBPs formed under UV/PS disinfection stimulated growth, increasing rates by 3.4–6.6%. To counteract oxidative stress from TC and its DBPs, Chlorella enhanced superoxide dismutase (SOD) and catalase (CAT) activities. These findings highlight that while TC degradation occurs efficiently, the nature of DBPs and their ecological impacts vary significantly depending on the disinfection method. Overall, the UV/PS process not only improved TC removal but also reduced harmful effects on microalgal growth compared with UV or PS alone. Full article

Chlorinated benzoquinones, such as 2,6-dichlorobenzoquinone (DCBQ), are toxic disinfection byproducts of growing concern in aquatic environments. Advanced oxidation processes, particularly photo-Fenton treatment, provide sustainable alternatives for their degradation. However, optimization is required to ensure not only the removal of the parent compound but also the reduction in harmful intermediates. This study evaluated the degradation of DCBQ (1.0 mM H₂O₂, 150 W UV, pH 3.0, 25 °C) with ferrous ion between 0 and 1.0 mg/L. DCBQ removal followed a second-order kinetic model, reaching complete degradation. Aromaticity-loss and water color degradation adjusted to kinetics of second-order, reflecting the sequential reduction in chlorinated hydroquinones and chlorophenols type intermediates, with marked decreases after 120 min at 0.8 mg/L. Results showed that increasing iron dosage enhanced both the rate of DCBQ disappearance and the removal of aromaticity, with complete pollutant degradation. Importantly, optimal ferrous ion dosages (20 mol DCBQ: 70 mol H₂O₂: 1 mol Fe²⁺) effectively limited the persistence of intermediates, as evidenced by significant decreases in color and aromaticity, while avoiding excessive turbidity. These findings demonstrate that fine-tuning iron dosage in photo-Fenton systems can maximize contaminant elimination and minimize secondary byproducts, reinforcing their role as sustainable solutions for wastewater remediation. Full article

Antibiotic-resistant bacteria (ARB) such as Escherichia coli and Enterococcus released into surface waters have strong potential to impact human health. We assessed the prevalence of antibiotic-resistant bacteria (ARB) and multidrug-resistant (MDR) bacteria in undisinfected wastewater effluent in a tropical estuary that receives the discharge from a major wastewater treatment plant (WWTP) in Costa Rica. Methods: We quantified culturable ampicillin-resistant (ampR) and (MDR) E. coli and Enterococcus in wastewater influent from hospital and residential sources, effluent, and estuarine receiving waters of the secondary-treated effluent of a WWTP. AmpR isolates confirmed to species or genus were tested for resistance against six additional antibiotic classes. Results: The proportion of ampR E. coli (18%) was significantly greater than that of ampR enterococci (4%) but neither differed among sites. AmpR E. coli concentrations were significantly different by site (estuary, 3.9 log₁₀ CFU/100 mL vs. untreated residential wastewater, 6.4 log₁₀ CFU/100 mL), but ampR enterococci concentrations were consistent among sites. MDR E. coli and Enterococcus were most prevalent in hospital wastewater (57% and 45% of ampR isolates, respectively), but were found at all sites. MDR E. coli and Enterococcus isolates resistant to five antibiotics were isolated from the estuary, and gentamicin-resistant Enterococcus were isolated only from effluent. Conclusions: Undisinfected effluent is a source of ARB and MDR opportunistic pathogens in the tropical estuary and has the potential to impact the health of beachgoers. Our findings highlight the importance of rigorous treatment of wastewater effluent, including disinfection, as a contribution to efforts to achieve effective stewardship of antibiotics. Full article

We evaluated the effectiveness of three locally available disinfectants in reducing Escherichia coli (E. coli) contamination of wastewater-irrigated lettuce while preserving structural integrity. We conducted a quasi-experimental study using lettuce from two farms (Accra and Tamale) in Ghana. Disinfectants tested included (i) salt combined with vinegar, (ii) sequential salt and potassium permanganate, and (iii) sequential vinegar and potassium permanganate. Structural integrity (stem crispness and leaf mushiness) was assessed at 5, 10, and 15 min. E. coli counts and antibiotic resistance were determined pre- and post-disinfection. All three disinfectants preserved structural integrity of lettuce at 5 and 10 min. At 15 min, sequential disinfectants preserved 100% structural integrity, while the salt–vinegar mix caused mushiness in 16%. Pre-disinfection E. coli counts were 9720 cfu/g for Accra (Inter Quartile range, IQR: 3915–14,175) and 72 cfu/g (IQR: 36–189) for Tamale. All disinfectants eliminated E. coli after 15 min. Multi-drug-resistant isolates were common (45% in Accra and 30% in Tamale), particularly against “Watch, restricted use” antibiotics. A 15 min exposure of lettuce to locally available disinfectants, particularly when used sequentially, can eliminate E. coli contamination while preserving structural quality. This practical, low-cost intervention can empower households, vendors, and farmers to limit lettuce-borne diarrheal diseases and antimicrobial resistance transmission. Full article