A mass balance approach for quantifying the role of natural decay and fate mechanisms on SARS-CoV-2 genetic marker removal during water reclamation.

The recent SARS-CoV-2 outbreak yielded substantial data regarding virus fate and prevalence at water reclamation facilities (WRFs), identifying influential factors as natural decay, adsorption, light, pH, salinity, and antagonistic microorganisms. However, no studies have quantified the impact of these factors in full scale WRFs. Utilizing a mass balance approach, we assessed the impact of natural decay and other fate mechanisms on genetic marker removal during water reclamation, through the use of sludge and wastewater genetic marker loading estimates. Results indicated negligible removal of genetic markers during P/PT (primary effluent (PE) p value: 0.267; preliminary and primary treatment (P/PT) accumulation p value: 0.904; and thickened primary sludge (TPS) p value: 0.076) indicating no contribution of natural decay and other fate mechanisms toward removal in P/PT. Comparably, adsorption and decomposition was found to be the dominant pathway for genetic marker removal (thickened waste activated sludge (TWAS) log loading 9.75 log10 GC/day); however, no estimation of log genetic marker accumulation could be carried out due to high detections in TWAS. PRACTITIONER POINTS: The mass balance approach suggested that the contribution of natural decay and other fate mechanisms to virus removal during wastewater treatment are negligible compared with adsorption and decomposition in P/PT (p value: 0.904). During (P/PT), a higher viral load remained in the (PE) (14.16 log10 GC/day) compared with TPS (13.83 log10 GC/day); however, no statistical difference was observed (p value: 0.280) indicting that adsorption/decomposition most probably did not occur. In secondary treatment (ST), viral genetic markers in TWAS were consistently detected (13.41 log10 GC/day) compared with secondary effluent (SE), indicating that longer HRT and the potential presence of extracellular polymeric substance-containing enriched biomass enabled adsorption/decomposition. Estimations of total solids and volatile solids for TPS and TWAS indicated that adsorption affinity was different between solids sampling locations (p value: <0.0001).

Innovative porous mortar filters: wastewater purification for clean water.

Water scarcity is a major global challenge that affects both developed and developing countries, with Indonesia serving as a prime example. Indonesia's archipelagic nature, combined with its dense population, exacerbates the severity of water scarcity. The increased population density in these areas raises the demand for water resources, putting a strain on the available supply. The purpose of this research was to create porous mortar filters (PMFs) with different ratios (1:4, 1:5, and 1:6) by incorporating 10, 15, and 20% adsorbent material by weight of fine aggregate. The research was carried out in three stages: determining PMF properties, preparing synthetic wastewater, and assessing treatment effectiveness. Various PMF compositions consistently achieved notable success, with reductions in total dissolved solids and turbidity exceeding 25 and 75%, respectively. The PMF performed admirably in eliminating bacterial concentrations, achieving a 100% removal rate, and was critical in efficiently reducing metals, with compositions achieving over 80% reduction for manganese (Mn) and 38% reduction for iron (Fe). PMF emerges as a practical solution as a cost-effective and simple water treatment technology, particularly suitable for areas with limited technological infrastructure and resources, providing accessible water treatment for communities facing challenges in this regard.

The impact of recycling polyaluminium chloride and anionic polyacrylamide water treatment residuals on heavy metal adsorption in soils: implications for stormwater bioretention systems.

Despite the high adsorption capacity of polyaluminum chloride and anionic polyacrylamide water treatment residuals (PAC-APAM WTRs) for Pb2+, Cd2+, Cu2+, and Zn2+, their influence on the adsorption behavior of heavy metals in traditional bioretention soil media remains unclear. This study investigated the impact of PAC-APAM WTRs at a 20% weight ratio on the adsorption removal of Pb2+, Cd2+, Cu2+, and Zn2+ in three types of soils. The results demonstrated improved heavy metal adsorption in the presence of PAC-APAM WTRs, with enhanced removal observed at higher pH levels and temperatures. The addition of PAC-APAM WTRs augmented the maximum adsorption capacity for Pb2+ (from 0.98 to 3.98%), Cd2+ (from 0.52 to 10.99%), Cu2+ (from 3.69 to 36.79%), and Zn2+ (from 2.63 to 13.46%). The Langmuir model better described the data in soils with and without PAC-APAM WTRs. The pseudo-second-order model more accurately described the adsorption process, revealing an irreversible chemical process, although qe demonstrated improvement with the addition of PAC-APAM WTRs. This study affirms the potential of PAC-APAM WTRs as an amendment for mitigating heavy metal pollution in stormwater bioretention systems. Further exploration of the engineering application of PAC-APAM WTRs, particularly in field conditions for the removal of dissolved heavy metals, is recommended.

Maximum desorption of perfluoroalkyl substances adsorbed on granular activated carbon used in full-scale drinking water treatment plants.

Activated carbon adsorption is an effective method for removing perfluoroalkyl substances (PFAS) from water. However, the observation that higher concentrations of PFAS are observed after treatment than before (i.e., desorption) is an important, unsolved issue. In this study, to elucidate PFAS desorption and its relationship with PFAS properties, we conducted solvent extraction and long-term desorption experiments using granular activated carbon (GAC) that had been loaded with PFAS in two actual drinking water treatment plants. The amount of PFAS extracted from GAC depended on the depth in the GAC filter; longer-chain and hydrophobic PFAS were present in relatively higher amounts in the shallow part compared to the deep part of the GAC filter, whereas shorter-chain and hydrophilic PFAS were present in relatively higher amounts in the deep part compared to the shallow part. This pattern was probably due to a chromatographic effect by which hydrophilic PFAS adsorbed once, subsequently desorbed, and migrated from the shallow part of the GAC filter to the deeper part. The desorption potential of PFAS to water (i.e., the maximum amount of PFAS desorbed to water per unit mass of GAC) was estimated by conducting long-term bottle-point desorption tests and analyzing the relationship between the equilibrium water-phase concentration of PFAS in a bottle containing GAC and the amount of PFAS desorbed to water per unit GAC mass. The desorption ratio (ratio of desorption potential to loading) was the highest for PFAS for which the logarithm of the octanol/water distribution coefficient (Log DOW) ranged from -1 to 1. The implication was that most of those PFAS removed by GAC were likely to return to the water as the external water-phase concentrations dropped. The decrease of the desorption ratio to 20 % as Log DOW increased suggested irreversible adsorption due to hydrophobic affinity.

Elucidating the impacts of cobalt (II) ions on extracellular electron transfer and pollutant degradation by anodic biofilms in bioelectrochemical systems during industrial wastewater treatment.

Electrogenic biofilms in bioelectrochemical systems (BES) are critical in wastewater treatment. Industrial effluents often contain cobalt (Co2+); however, its impact on biofilms is unknown. This study investigated how increasing Co2+ concentrations (0-30 mg/L) affect BES biofilm community dynamics, extracellular polymeric substances, microbial metabolism, electron transfer gene expression, and electrochemical performance. The research revealed that as Co2+ concentrations increased, power generation progressively declined, from 345.43 ± 4.07 mW/m2 at 0 mg/L to 160.51 ± 0.86 mW/m2 at 30 mg/L Co2+. However, 5 mg/L Co2+ had less effect. The Co2+ removal efficiency in the reactors fed with 5 and 10 mg/L concentrations exceeded 99% and 94%, respectively. However, at 20 and 30 mg/L, the removal efficiency decreased substantially, likely because of reduced biofilm viability. FTIR indicated the participation of biofilm functional groups in Co2+ uptake. XPS revealed Co2+ presence in biofilms as CoO and Co(OH)2, indicating precipitation also aided removal. Cyclic voltammetry and electrochemical impedance spectroscopy tests revealed that 5 mg/L Co2+ had little impact on the electrocatalytic activity, while higher concentrations impaired it. Furthermore, at a concentration of 5 mg/L Co2+, there was an increase in the proportion of the genus Anaeromusa-Anaeroarcus, while the genus Geobacter declined at all tested Co2+ concentrations. Additionally, higher concentrations of Co2+ suppressed the expression of extracellular electron transfer genes but increased the expression of Co2+-resistance genes. Overall, this study establishes how Co2+ impacts electrogenic biofilm composition, function, and treatment efficacy, laying the groundwork for the optimized application of BES in remediating Co2+-contaminated wastewater.

A Potential Therapeutic Approach According to Traditional Thai Medicine Theory for Post-COVID-19 Syndrome Treatment: An Observational Retrospective Clinical Study.

Background: Most post-COVID-19 patients had physiological health problems, which differed for each patient. The potential treatment for post-COVID-19 syndrome must require multi-disciplinary approaches that focus on individualized treatment. Therefore, traditional Thai Medicine (TTM) clinical practice guidelines for post-COVID-19 treatment are developed by the Traditional Thai Medicine Hospital, Prince of Songkla University, to care for post-COVID-19 patients. Objective: This current study aimed to investigate the effect of the guidelines on post-COVID-19 patient's physical health. Methods: This research was a retrospective clinical study, carried out from June 2022 to July 2022. Setting: The study was conducted at the Traditional Thai Medicine Hospital, Prince of Songkla University, and La Flora Khao Lak TTM clinic, Thailand. Participants: Data (n=17) were collected from the medical record. They were included if they met the following criteria: patients were more than 18 years old, had a medical history of COVID-19 disease, had fully recovered from the disease (ATK for COVID-19 is negative) at least a week before starting the guideline, and had complete medical information such as post-COVID-19 symptoms, vital signs, pain score, cough severity score, and quality of life examination. Intervention: Approaches for post-COVID-19 treatment included herbal Thai medicine recipes, Thai massage, herbal steam inhalation, herbal hot steam, herbal hot water immersion, acupressure massage for breathing stimulation, and a breathing exercise. All procedures were applied for 7 days continually or until they have recovered. Primary Outcome Measures: The effects of TTM approaches on the symptoms of post-COVID-19 patients on pain score, quality of life, cough severity were measured using a visual analog score (VAS), SF-36 questionnaire, and cough severity index (CSI), respectively. Results: The average duration time of post-COVID-19 syndrome was 25.76 days, and the most common symptom was muscle pain/stress (10; 71.43%). Yahom-Navakot (6; 42.86%) is the most common recipe used for the treatment. Interestingly, the pain score was significantly reduced by 3 days of the treatment (4.88±2.03 vs 2.29±2.08 ). Moreover, the cough severity index (12.86±11.55 vs 3.31±6.38) was significantly lessened by 7 days of the treatment. Remarkably, most symptoms vanished entirely after 7 days of the intervention, leading to a better quality of life for the patients (53.24±22.15 vs 65.59±23.64). Conclusions: The TTM clinical practice guideline for treating post-COVID-19 syndrome effectively improved the overall physical health capacity and symptoms associated with post-COVID-19 syndrome. Therefore, the implementation of this guideline, together with other approaches, could strengthen the treatment for post-COVID-19 to be more effective.

Efficient removal of microcystin-LR from contaminated water using water-stable MIL-100(Fe) synthesized under HF-free conditions.

Cyanobacterial algal hepatotoxins, called microcystins (MCs), are a global health concern, necessitating research on effective removal methods from contaminated water bodies. In this study, we synthesized non-fluorine MIL-100(Fe) using an environmentally friendly room-temperature method and utilized it as an adsorbent to effectively remove microcystin-LR (MC-LR), which is the most toxic MC congener. MIL-100(Fe) was thoroughly characterized, and its adsorption process was investigated under various conditions. Results revealed rapid MC-LR adsorption, achieving 93% removal in just 5 min, with the pseudo-second-order kinetic model indicating chemisorption as the primary mechanism. The Langmuir isotherm model demonstrated a monolayer sorption capacity of 232.6 µg g-1 at room temperature, showing favorable adsorption. Furthermore, the adsorption capacity increased from 183 µg g-1 at 20 °C to 311 µg g-1 at 40 °C, indicating an endothermic process. Thermodynamic parameters supported MC-LR adsorption's spontaneous and feasible nature onto MIL-100(Fe). This study highlights MIL-100(Fe) as a promising method for effectively removing harmful biological pollutants, such as MC-LR, from contaminated water bodies in an environmentally friendly manner.

Domestic wastewater treatment by Pistia stratiotes in constructed wetland.

The objective of the study was to evaluate the performance of Pistia stratiotes for treatment of domestic wastewater in a free surface water flow constructed wetland. The objective of the study was to evaluate contaminants removal efficiency of the constructed wetland vegetated with P. stratiotes in treatment of domestic wastewater against Hydraulic retention time (HRT) of 10, 20 and 30 days was investigated. This asks for newer and efficient low-cost nature-based water treatment system which along with cost takes into consideration the sustainability of the ecosystem. Five constructed wetland setups improved the wastewater quality and purify it significantly by reducing the TDS by 83%, TSS by 82%, BOD by 82%, COD by 81%, Chloride by 80%, Sulfate by 77%, NH3 by 84% and Total Oil and Grease by 74%. There was an increase in pH of about 11.9%. Color and odor of wastewater was also improved significantly and effectively. It was observed that 30 days' HRT was optimum for the treatment of domestic wastewater. The final effluent was found to be suitable as per national environmental quality standards and recycled for watering plants and crop irrigation but not for drinking purposes. The treatment in constructed wetland system was found to be economical, as the cost of construction only was involved and operational and maintenance cost very minimal. Even this research was conducted on the sole purpose of commuting the efficiency of pollutant removal in short span time.

The Mechanism of Polygonum Hydropiper L-Coptis Chinensis in the Treatment of Ulcerative Colitis Based on Network Pharmacology and Experimental Validation.

BACKGROUND: Polygonum hydropiper L (PH) was widely used to treat dysentery, gastroenteritis, diarrhea and other diseases. Coptis chinensis (CC) had the effects of clearing dampness-heat, purging fire, and detoxifying. Study confirmed that flavonoids in PH and alkaloids in CC alleviated inflammation to inhibit the development of intestinal inflammation. However, how PH-CC affects UC was unclear. Therefore, the aim of this study is to analyze the mechanism of PH-CC on ulcerative colitis (UC) through network pharmacology and in vivo experiments. METHODS: The active ingredients and targets of PH-CC and targets of UC were screened based on related databases. The core targets of PH-CC on UC was predicted by protein-protein interaction network (PPI), and then the Gene Ontology-biological processes (GO-BP) function enrichment analysis was conducted using the Database for Annotation, Visualization and Integrated Discovery (DAVID) database. The binding activity between pyroptosis proteins, core targets and effective ingredients were verified based on molecular docking technology. Finally, combined with the results of network pharmacology and literature research, the mechanism of PH-CC against UC was verified by in vivo experiments. RESULTS: There were 23 active components and 191 potential targets in PH-CC, 5275 targets in UC, and 141 co-targets. GO-BP functional analysis of 141 co-targets showed that the first 20 biological processes were closely related to inflammation and lipopolysaccharide (LPS) stimulation. Furthermore, core targets had good binding activity with the corresponding compounds. Animal experiment indicated that PH-CC effectively prevented weight loss in UC mice, reduced the disease activity index (DAI) score, maintained colon length, suppressed myeloperoxidase (MPO) activity, inhibited pyroptosis protein expression, and downregulated the levels of IL-18 and IL-1ß to alleviate intestinal inflammation. CONCLUSIONS: The results of network pharmacology and animal experiments showed that PH-CC suppressed the inflammatory response, restored colon morphology, and inhibited pyroptosis in UC mice. Thus, PH-CC may improve UC by regulating the NOD-like receptor protein domain 3 (NLRP3)/Caspase-1 signaling pathway.

Removal of organic micropollutants in biologically active filters: A systematic quantitative review of key influencing factors.

Biofiltration utilizes natural mechanisms including biodegradation and biotransformation along with other physical processes for the removal of organic micropollutants (OMPs) such as pharmaceuticals, personal care products, pesticides and industrial compounds found in (waste)water. In this systematic review, a total of 120 biofiltration studies from 25 countries were analyzed, considering various biofilter configurations, source water types, biofilter media and scales of operation. The study also provides a bibliometric analysis to identify the emerging research trends in the field. The results show that granular activated carbon (GAC) either alone or in combination with another biofiltration media can remove a broad range of OMPs efficiently. The impact of pre-oxidation on biofilter performance was investigated, revealing that pre-oxidation significantly improved OMP removal and reduced the empty bed contact time (EBCT) needed to achieve a consistently high OMP. Biofiltration with pre-oxidation had median removals ranging between 65% and >90% for various OMPs at 10-45 min EBCT with data variability drastically reducing beyond 20 min EBCT. Biofiltration without pre-oxidation had lower median removals with greater variability. The results demonstrate that pre-oxidation greatly enhances the removal of adsorptive and poorly biodegradable OMPs, while its impact on other OMPs varies. Only 19% of studies we reviewed included toxicity testing of treated effluent, and even fewer measured transformation products. Several studies have previously reported an increase in effluent toxicity because of oxidation, although it was successfully abated by subsequent biofiltration in most cases. Therefore, the efficacy of biofiltration treatment should be assessed by integrating toxicity testing into the assessment of overall removal.

Purification of dredged water by magnetic coagulation: Response surface optimization and dissolved organic matter removal characteristics.

In the present study, magnetic coagulation was used to treat dredged water and the response surface method was used to optimize process parameters. The dissolved organic matter (DOM) removal characteristics were characterized by three-dimensional fluorescence spectrometry and ultra-high resolution mass spectrometry. During the magnetic coagulation process, the suspended solids (SS) removal rate increased initially and then decreased under conditions of increasing magnetic powder dosage and stirring rate. After magnetic coagulation and precipitation for 20 min, the contents of SS, ammonia nitrogen, chemical oxygen demand, and total phosphorus in the treated dredged water met the requirements of the discharge standard (GB8978-1996, China). Three-dimensional fluorescence results showed that magnetic coagulation selectively removed fulvic acids and humic acid substances. After magnetic coagulation with precipitation for 10 min and 20 min, the total relative content of lignins, tannins, proteins, lipids, aminosugars, unsaturated hydrocarbons, condensed aromatic structures, and carbohydrates decreased by 26.3% and 39.4%, respectively. After magnetic coagulation, the distribution range of small molecule DOM shifted to the low H/C and high O/C regions. This study provides a novel perspective for studies on the removal of DOM in dredged water by magnetic coagulation. PRACTITIONER POINTS: SS and DOM removal were significantly enhanced by the use of magnetic coagulation. SS removal efficiency was affected by stirring rate and magnetic powder dosage. Magnetic coagulation selectively removed fulvic acids and humic acid substances. DOM molecule shifted to low H/C and high O/C regions after magnetic coagulation.

Biochar-modified constructed wetlands using Eclipta alba as a plant for sustainable rural wastewater treatment.

Constructed wetlands (CWs) provide a low-cost, effective solution for domestic wastewater treatment in developing nations compared to costly traditional wastewater systems. Biochar which is an organic material created by pyrolysis offers straightforward, affordable methods for treating wastewater and lowering carbon footprint by acting as a substrate in CWs. Batch mode biochar-amended subsurface flow (SSF) CWs planted with Eclipta alba (L) with a hydraulic retention time (HRT) of 3 days were used for the treatment of rural domestic wastewater in the present investigation. Two control CWs, without plants (C1) and with plants (C2), and five different amendments of biochar 5% (B5), 10% (B10), 15% (B15), 20% (B20) and 25% (B25) in ratio with soil were set up to check the treatment efficiency of CWs. Removal efficiency (RE%) of the CWs for parameters namely chemical oxygen demand (COD), biochemical oxygen demand (BOD), phosphate (PO42-), sulphate (SO42-), nitrate (NO3-) and total Kjeldhal nitrogen (TKN) was determined using standard methods. Removal efficiency of 93%, 91%, 74% and 77% was observed for BOD, COD, nitrate and sulphate, respectively, in the B25 amendment at HRT 72 h. The highest removal of TKN (67%) was also observed in the B25 amendment at HRT of 72 h. No stable trend for the removal of phosphates was found during the study, and maximum removal was observed at HRT 48 h; afterward, phosphate was slightly inclined with the increasing HRT. The findings of one-way ANOVA using Tukey's test show significant variations (p < 0.05) in the removal efficiencies of pollutants after 72 h between two controls (C1 and C2) and various biochar amendments in CWs, indicating a significant role of the wetland plants and concentration of the biochar as substrate. Biochar shows a positive impact on the removal of organic pollutants and nitrates. Hence, biochar-amended CWs can be a sustainable way of treating rural domestic wastewater.

Water insecurity among seasonal agriculture workers: perspectives from Spanish professionals.

BACKGROUND: Migrant seasonal agricultural workers face conditions of material vulnerability such as inadequate housing difficulties prevent access to running water supplies. The purpose of this study is to explore the perceptions of professionals involved in the care and support of seasonal migrant agricultural workers, as it relates to water access and water consumption and their impact on these workers' health, in a context of COVID-19 pandemic. METHODS: A qualitative exploratory and descriptive study was conducted in 2021 as part of a larger research project, based on 63 personal semi-structured interviews with professionals who provided support to seasonal migrant agricultural workers in three Spanish autonomous regions. COREQ checklist was used for reporting. The interviews were recorded, transcribed, and imported into ATLAS.ti-9 for an inductive thematic analysis. RESULTS: The results have been structured into two main themes: (1) Accessing and obtaining water; and (2) Health problems related to water consumption. Seasonal migrant agricultural workers experience barriers to obtaining safe water for hygiene, cleaning, food preparation and drinking. The implementation of regulations to reduce COVID-19 transmission resulted in improved hygiene levels in the migrants' quarters, including access to safe drinking water. CONCLUSION: This study suggests that water insecurity experienced by migrant seasonal agricultural workers in Spain results from their poor living conditions and causes health problems related to a lack of hygiene and the use of unsafe water. Sustainable solutions are needed beyond the pandemic in order to provide migrant workers with adequate living conditions and ensure their water needs are fulfilled.

Foam control in lakes and sewage receiving water bodies: A pre-emptive approach using decentralized inline water treatment design.

Hideous and persistent foams on surface water bodies are global issues with far-reaching environmental consequences. This study examines Bellandur Lake (Bengaluru, India) plagued by foam since 2005 due to surfactant-laden untreated sewage ingress. Bellandur Lake receives 258 million liters of inadequately treated sewage daily, constituting 47% of its total volume. Yearlong water quality monitoring reveals that a) high surfactant levels (up to 17.8 ± 1 ppm) and b) prevalent anoxic conditions at lake inlets. Laboratory experiments show that controlled aeration achieved >90% surfactant degradation within 30 h at 3.5 ppm of dissolved oxygen conditions, indicating the need for an aeration chamber design based on the required residence time for inline water treatment. Based on these findings, a design of an inline wastewater treatment system to be installed at sewage entry points into the lake is presented in this work. The inline system was based on experimentally validated BioWin software. Simulations show that recirculating sludge enhances treatment efficiency, achieving effective surfactant degradation in 20 h (2/3rd original time) of residence time. Predictions suggest <1 ppm surfactant levels in the receiving water body, meeting local discharge norms to prevent frothing. This holistic approach, proposed for the first time, could serve as a blueprint for managing foam-related challenges in other waterbodies, offering insights into design, stakeholder engagement, and process optimization.

Biofilm rigidity, mechanics and composition in seawater desalination pretreatment employing ultrafiltration and microfiltration membranes.

The choice of appropriate biofilm control strategies in membrane systems for seawater desalination pretreatment relies on understanding the properties of the biofilm formed on the membrane. This study reveals how the biofilm composition, including both organic and inorganic, influenced the biofilm behavior under mechanical loading. The investigation was conducted on two Gravity-Driven Membrane reactors employing Microfiltration (MF) and Ultrafiltration (UF) membrane for the pretreatment of raw seawater. After a stabilization period of 20 days (Phase I), a biofilm behavior test was introduced (Phase II) to evaluate (i) biofilm deformation during the absence of permeation (i.e., relaxation) and (ii) biofilm resistance to detachment forces (i.e., air scouring). The in-situ monitoring investigation using Optical Coherence Tomography (OCT) revealed that the biofilms developed on MF and UF membrane presented a rigid structure in absence of filtration forces, limiting the application of relaxation and biofilm expansion necessary for cleaning. Moreover, under shear stress conditions, a higher reduction in biofilm thickness was observed for MF (-60%, from 84 to 34 µm) compared to UF (-30%, from 64 to 45 µm), leading to an increase of permeate flux (+60%, from 9.1 to 14.9 L/m2/h and +20 % from 7.8 to 9.5 L/m2/h, respectively). The rheometric analysis indicated that the biofilm developed on MF membrane had weaker mechanical strength, displaying lower storage modulus (-50 %) and lower loss modulus (-55 %) compared to UF. These differences in mechanical properties were linked to the lower concentration of polyvalent ions and the distribution of organic foulants (i.e., BB, LMW-N) found in the biofilm on the MF membrane. Moreover, in the presence of air scouring led to a slight difference in microbial community between UF and MF. Our findings provide valuable insight for future investigations aimed at engineer biofilm composition to optimize biofilm control strategies in membrane systems for seawater desalination pretreatment.

Influence of ozonation and UV/H2O2 on the genotoxicity of secondary wastewater effluents.

The implementation of novel wastewater treatment technologies, including Advanced Oxidation Processes (AOPs) such as ozonation and ultraviolet radiation (UV) combined with hydrogen peroxide (H2O2), can be a promising strategy for enhancing the quality of these effluents. However, during effluent oxidation AOPs may produce toxic compounds that can compromise the water reuse and the receiving water body. Given this possibility, the aim of this study was to evaluate the genotoxic potential of secondary effluents from two different Wastewater Treatment Plants (WWTP) that were subjected to ozonation or UV/H2O2 for periods of 20 (T1) and 40 (T2) minutes. The genotoxic potential was carried out with the Comet assay (for clastogenic damage) and the Micronucleus assay (for clastogenic and aneugenic damage) in HepG2/C3A cell culture (metabolizing cell line). The results of the comet assay revealed a significant increase in tail intensity in the Municipal WWTP (dry period) effluents treated with UV/H2O2 (T1 and T2). MN occurrence was noted across all treatments in both Pilot and Municipal WWTP (dry period) effluents, whereas nuclear buds (NBs) were noted for all Pilot WWTP treatments and UV/H2O2 treatments of Municipal WWTP (dry period). Moreover, the UV/H2O2 (T1) treatment of Municipal WWTP (dry period) exhibited a noteworthy incidence of multiple alterations per cell (MN + NBs). These findings imply that UV/H2O2 treatment demonstrates higher genotoxic potential compared to ozonation. Furthermore, seasonal variations can have an impact on the genotoxicity of the samples. Results of the study emphasize the importance of conducting genotoxicological tests using human cell cultures, such as HepG2/C3A, to assess the final effluent quality from WWTP before its discharge or reuse. This precaution is essential to safeguard the integrity of the receiving water body and, by extension, the biotic components it contains.

Adsorption of anti-inflammatory and analgesic drugs traces in water on clay minerals.

The aim of this study was to assess the adsorption of four non-steroidal anti-inflammatory drugs (NSAIDs), namely Paracetamol (PRC), Diclofenac (DIC), Ibuprofen (IBU), and Ketoprofen (KET), using both batch and continuous experiments with clay. Various analytical techniques, including XRD, FTIR, SEM coupled to EDX, and Zeta potential, were employed to characterize both raw and calcined clay. XRD and FTIR analyses confirmed the kaolinite nature of the clay. SEM data revealed a lamellar structure formed in the clay after calcination at 550 °C. Adsorption tests were conducted to determine the optimal adsorption conditions. Batch kinetics of adsorption demonstrated rapid adsorption of all four NSAIDs, with the highest adsorption occurring at pH 4 (DIC, IBU, and KET) and pH 6 for PRC, using a concentration of 20 mg L-1 of calcined clay. Additionally, the pseudo-second-order model provided the best fit for all NSAIDs adsorption processes. Maximum adsorption capacities, as determined by the Langmuir model, were 80 mg g-1 for PRC, 238 mg -1g for DIC, 138 mg g-1 for IBU, and 245 mg g-1 for KET. In fixed bed column studies, three dynamic models (Thomas, Adams-Bohart, and Yoon-Nelson) were utilized to describe the breakthrough curves, with linear regression used to identify key characteristics for process design. The fixed bed column adsorption study revealed that DIC exhibited the highest removal efficiency at 98%, while KET, IBU, and PRC were more persistent, with removal efficiencies of 77.1%, 76.7%, and 67.1%, respectively. The Thomas model was deemed appropriate for describing the breakthrough curve. These findings offer valuable insights into the interactions between clay and pharmaceuticals with varying physicochemical properties. They also provide information on the adsorption models, saturation, and adsorption capacities of various pharmaceuticals on natural clays, which can be crucial for further research and environmental remediation efforts.

Demonstrating scale-up of a novel water treatment process using super-bridging agents.

Fiber-based materials have emerged as a promising option to increase the efficiency of water treatment plants while reducing their environmental impacts, notably by reducing the use of unsustainable chemicals and the size of the settling tank. Cellulose fiber-based super-bridging agents are sustainable, reusable, and versatile materials that considerably improve floc separation in conventional settling tanks or via alternative screening separation methods. In this study, the effectiveness of fiber-based materials for wastewater treatment was evaluated at lab-scale (0.25 L) and at pilot-scale (20 L) for two separation methods, namely settling and screening. For the fiber-based method, the performance of floc separation during settling was slightly affected by an 80x upscaling factor. A small decrease in turbidity removal from 93 and 86 % was observed for the jar and pilot tests, respectively. By contrast, the turbidity removal of the conventional treatment, i.e., no fibers with a settling separation, was largely affected by the upscaling with turbidity removals of 84 and 49 % for jar and pilot tests, respectively. Therefore, results are suggesting that fiber-based super-bridging agents could be implemented in full-scale water treatment plants. Moreover, the tested fibers increase the robustness of treatment by providing better floc removal than conventional treatment under several challenging conditions such as low settling time and screening with coarse screen mesh size. Furthermore, at both lab-scale and pilot-scale, the use of fiber-based materials reduced the demand for coagulant and flocculant, potentially lowering the operational costs of water treatment plants and reducing the accumulation of metal-based coagulants and synthetic polymers in sludge. Acute toxicity tests using the model organism Daphnia magna show that the cellulose fibers introduce insignificant toxicity at the optimized fiber concentration. Although dedicated mechanistic studies are required at various scales to understand in detail the influence of fibers on water treatment (coagulation/flocculation time, floc formation, floc size distribution velocity gradient, etc.), the efficacy and scalability of the fiber-based approach, along with its minimal environmental impact, position it as a viable and sustainable option for existing and future wastewater treatment plants.

When does infrastructure hybridisation outperform centralised infrastructure paradigms? - Exploring economic and hydraulic impacts of decentralised urban wastewater system expansion.

We explore the dynamics of centralised and decentralised wastewater infrastructure across various scenarios and introduce novel insights into their performance regarding structural vulnerability, hydraulic capacity, and costs. This study determines circumstances under which infrastructure hybridisation outperforms traditional centralised infrastructure paradigms. We combined system analysis to map out the modelling problem with the model-based exploration of the transition space using the novel TURN-Sewers model. System diagramming was used to identify the parameters or combinations of parameters that significantly influence the performance indicators being assessed. This allowed the creation of relevant simulation scenarios to identify circumstances where a decentralised sewer system could outperform a centralised one. TURN-Sewers was applied to model the infrastructure maintenance and generation of new infrastructure over 20 years for a municipality on the Swiss Plateau, considering a population growth rate of 0.03 a-1. Results show that decentralisation in expansion areas with higher densification can outperform the hydraulic performance and structural vulnerability of expanding centralised sanitary wastewater infrastructure. Decentralised systems can also offer economic advantages when capital expenditure costs for small-scale wastewater treatment plants are significantly reduced compared to current costs, particularly at higher discount rates, e.g. reaping effects of economies of scale. The findings of this study emphasise the potential of transition pathways towards decentralisation in urban water infrastructures and the value of models that allow the exploration of this transition space.