Environmental Science: Water Research & Technology最新文献

The risk of heavy metal leaching from sorptive filter media in stormwater control measures (SCMs) treating road runoff is mainly assessed through lab-scale studies. In contrast, investigations with filter media prestressed under real conditions are crucial. Therefore, the leaching potential of five traffic-relevant heavy metals (Cr, Cu, Ni, Pb, and Zn) from field-scale and lab-scale prestressed sorptive filter media and road-deposited sediments (RDSs) from a decentralized treatment facility was assessed using quiescent batch leaching tests with and without adding de-icing salts. The hydraulic retention times of a maximum of 7 days should represent prolonged submerged conditions during dry periods. The leaching quantity order was Zn ≫ Cu > Ni, whereas no observed leaching was quantified for Cr and Pb for all tested materials. Considerable loads of Cu only leached from the field-scale prestressed sorptive filter media, which was mainly associated with the presence of dissolved organic matter. Regarding the tested filter media, zeolite and carbonate sand revealed significantly higher leaching of Zn under the influence of de-icing salts. The leaching of Cu and Zn concerning the mobile heavy metal fraction was less than 0.2%. The highest concentrations of heavy metals were observed for the RDSs, where up to 0.3% leached of the potential mobile fraction during one dry cycle.

Developing efficient Fenton catalysts for the remediation of emerging pollutants is one of the challenges for researchers. Herein, a novel cathode catalyst via the utilization of waste electro-coagulated (ECO) sludge was synthesized for the efficient abatement of tetracycline (TC) through the bio-electro-Fenton (BEF) process. The carbon-felt-coated heterogeneous catalyst (Fe₃O₄–MgO@C) resulted in more than 96.7 ± 2.2% removal of 10 mg L⁻¹ of TC during 420 min of operating time following pseudo-first-order kinetics at neutral pH. Moreover, 53.5 ± 2.5% mineralization in terms of total organic carbon removal was obtained for real municipal wastewater during the BEF treatment. Radical experimentation displayed ˙OH as the dominant oxidative species for TC degradation. Besides, the maximum power density achieved by Fe₃O₄–MgO@C-BEF was 114.5 ± 4.5 mW m⁻², which was 2.6-times more than BEF operated without any catalyst (44.2 ± 2.7 mW m⁻²). The co-precipitation in the cathodic chamber of BEF via external addition of Fe₃O₄–MgO@C (63.6 mg L⁻¹) resulted in 1.20 ± 0.08 g L⁻¹ of struvite recovery from synthetic urine. Overall, the sludge-derived catalyst might be beneficial for reducing the economics of future full-scale implementation of the technology, contributing to a circular economy, and fixing the lacunas of ECO technology for sludge management, thereby proposing an effective waste management strategy.

Sub-city, or sub-sewershed, wastewater monitoring for infectious diseases offers a data-driven strategy to inform local public health response and complements city-wide data from centralized wastewater treatment plants. Developing strategies for equitable representation of diverse populations in sub-city wastewater sampling frameworks is complicated by misalignment between demographic data and sampling zones. We address this challenge by: (1) developing a geospatial analysis tool that probabilistically assigns demographic data for subgroups aggregated by race and age from census blocks to sub-city sampling zones; (2) evaluating representativeness of subgroup populations for COVID-19 wastewater-based disease surveillance in Davis, California; and (3) demonstrating scenario planning that prioritizes vulnerable populations. We monitored SARS-CoV-2 in wastewater as a proxy for COVID-19 incidence in Davis (November 2021–September 2022). Daily city-wide sampling and thrice-weekly sub-city sampling from 16 maintenance holes covered nearly the entire city population. Sub-city wastewater data, aggregated as a population-weighted mean, correlated strongly with centralized treatment plant data (Spearman's correlation 0.909). Probabilistic assignment of demographic data can inform decisions when adapting sampling locations to prioritize vulnerable groups. We considered four scenarios that reduced the number of sampling zones from baseline by 25% and 50%, chosen randomly or to prioritize coverage of >65-year-old populations. Prioritizing representation increased coverage of >65-year-olds from 51.1% to 67.2% when removing half the zones, while increasing coverage of Black or African American populations from 67.5% to 76.7%. Downscaling had little effect on correlations between sub-city and centralized data (Spearman's correlations ranged from 0.875 to 0.917), with strongest correlations observed when prioritizing coverage of >65-year-old populations.

Efficient and environmentally friendly removal of Cu²⁺ from wastewater has been the focus of recent research. However, the acid mine drainage (AMD) produced during the mining process, characterized by low pH and high concentrations of toxic heavy metals, poses a significant challenge for Cu²⁺ removal. Therefore, in this study, corn stalks were selected as raw materials, and a goethite-modified biochar material (GMB) was prepared using the hydrolysis co-precipitation method at different temperatures and raw material ratios. Additionally, sodium alginate was used as a chelating agent to construct a composite material (SGB). The adsorption process, removal efficiency, and adsorption mechanism of Cu²⁺ in acidic mine wastewater by GMB and SGB were investigated through batch adsorption experiments and characterization. Results showed that GMB adsorption followed the second-order kinetic and Langmuir models, with a maximum capacity of 51.23 mg g⁻¹ at 25 °C, indicating single-layer homogeneous chemisorption. The Thomas model accurately described SGB's dynamic adsorption, with a high correlation (R² = 0.94) and a maximum capacity of 117.68 mg g⁻¹. Both materials performed well under acidic conditions (pH 2.0–5.5) and in the presence of competing ions (Na⁺, Ca²⁺, Cl⁻, NO₃⁻, SO₄²⁻). The characterization results indicated that the adsorption mechanism of GMB for Cu²⁺ primarily involved physical adsorption, electrostatic interactions, surface complexation, and co-precipitation. Additionally, after five adsorption–desorption cycles, GMB maintained a capacity of 29.55 mg g⁻¹, while SGB improved Cu²⁺ removal from 72.71% to 94.27% compared to GMB alone. In conclusion, GMB and SGB demonstrated significant potential for Cu²⁺ remediation in acid mine drainage.

Advanced oxidation processes like heterogeneous photocatalysis can degrade recalcitrant compounds. However, the overall potency of most semiconductor-based photocatalysts in continuous operation and real wastewater matrices remains inadequate. This study investigates the simultaneous removal of three contaminants, namely, acetaminophen (ACT), sulfamethoxazole (SMX), and iohexol (IOX), from actual municipal wastewater (MWW) and hospital wastewater (HWW) by utilizing a moving bed biofilm system coupled with a filtration unit, followed by a continuous photocatalytic reactor. Here, a sulfur-doped Bi₂O₃/MnO₂ Z-scheme heterojunction photocatalyst immobilized over low-cost and eco-friendly clay beads (2S-BOMO CCB) was employed to degrade an ACT–SMX–IOX mixture in a continuous photocatalytic reactor. Under optimal conditions, removal efficiencies of 87.1 ± 1.4%, 82.6 ± 1.9%, and 77.5 ± 2.3% were attained for ACT, SMX, and IOX, respectively. The feasibility of reusing the spent photocatalyst was also investigated over ten consecutive cycles. Further, this study confirmed that the superoxide anion, hydroxyl radical, and singlet oxygen were dominant oxidative species for ACT–SMX–IOX degradation. However, the removal efficiency of ACT–SMX–IOX by 2S-BOMO CCB was significantly reduced due to the presence of various interfering agents in real wastewater. Nonetheless, when the hybrid system was employed, approximately 93.8 ± 2.7% and 89.4 ± 3.6% of ACT, 89.6 ± 1.8% and 83.7 ± 1.1% of SMX, and 84.5 ± 1.7% and 81.5 ± 3.3% of IOX were eliminated from MWW and HWW, respectively. These results endorse the applicability of the developed integrated technology for removing pharmaceutical contaminants from real wastewater.

The bioremediation of pharmaceutical wastewater by microalgae has gained scientific attention due to its cost-effectiveness and environmental friendliness. However, limited information is available regarding the influence of co-substrates on the removal of antiretroviral (ARV) drugs by microalgae. This study was aimed at evaluating the NVP removal efficiency and antioxidant gene expression of microalga Tetradesmus obliquus under different cultivation modes (autotrophic, heterotrophic, and mixotrophic). The removal mechanism, biotransformation products, and changes in key algal metabolites were also investigated. The maximum removal of NVP (80.13%) was achieved on the 8th day of cultivation. Fourier-transform infrared (FTIR) spectroscopy confirmed the adsorption of NVP on the microalgae cell surface. The highest NVP removal was observed in the mixotrophic mode, followed by the heterotrophic and autotrophic cultivation. Gene expression analysis showed elevated antioxidant enzyme activity in autotrophic, heterotrophic and mixotrophic growth. Metabolomic analysis identified significant changes in key metabolites of T. obliquus in treatments compared to the control (p < 0.05). Additionally, a potential degradation pathway of NVP was predicted by using computation tools, eMolecules and EAWAG-BBD PPS database and discussed. The overall findings of this study suggest that T. obliquus can be used as a promising agent for environmental remediation and ARV drug removal.

Pharmaceuticals have been detected in water and wastewater, resulting in increasing research attention towards the elimination of these substances from aqueous environments. Due to the limitations of conventional processes in wastewater treatment plants (WWTPs) to fully eliminate these compounds, more research is needed on complementary advanced treatment technologies. This study aims to examine the removal efficiency for 24 selected pharmaceuticals and the fate of their 7 main metabolites including several oxidation transformation products by various technique combinations applied on the effluent from a full-scale WWTP. Investigated treatment options include ozonation (O₃) combined with either granular activated carbon (GAC), two different types of biochar, and anion exchange (AIX) in a continuously operated laboratory-scale system. The average removal of analyzed pharmaceuticals ranged between 8.8–97% with an O₃ dose of 0.28 g O₃/g DOC (dissolved organic carbon), whereas it ranged from 86–99% for higher O₃ dosages (0.96 and 2.17 g O₃/g DOC). Overall, the investigated metabolites of pharmaceuticals exhibited lower removal efficiency (between −33 and 99%) with ozone compared to the parent compounds at all O₃-dosages. Concentrations of oxidation transformation products such as citalopram N-oxide were increased after ozone treatment, whereas it was decreased after the columns at different rates. The bromate concentrations during all three O₃-dosages (0.28, 0.96 and 2.17 g O₃/g DOC) were below 5 μg L⁻¹. GAC was the best performing sorbent among all materials, where even after two weeks of continuous operation, nearly all compounds were removed below quantification levels. Although biochar 1 showed better performance (30–89%, mean = 68%) than biochar 2 (8.5–82%, mean = 38%), both sorption materials showed reduced sorption capacity over the time period of two weeks for most of the target compounds. On the other hand, AIX had lower removal rates ranging between 2–55% (mean = 20%). Regarding the combination of O₃ with the individual sorbent materials, GAC was the most successful combination with O₃ for the removal of pharmaceuticals (>99%) and oxidation transformation products (>60%). The combination of O₃ with biochar 1 was more successful (mean = 91%) than the combination with biochar 2 (mean = 79%), where the combination of O₃ with AIX showed the lowest removal rates (mean = 58%).

Carbon recovery and sustainable management of sewage sludge from wastewater treatment plants were reviewed regarding the technical and market supply potentials, environmental, economic, and social benefits, and technology readiness. The findings were used in a case study of a 75 000 PE water recycling plant to evaluate the potential benefits of implementing the most promising technological solutions via a triple bottom line approach. Implementation of rotating belt filtration for cellulose recovery in primary treatment would reduce the energy required for aeration, the sludge volume and thus the sludge management burden. Recovery of protein from the waste activated sludge would provide net revenue. Volatile fatty acid (VFA) extraction from the acidogenic phase of anaerobic digestion was economically sound. Co-digestion of food waste with the sludge would enhance VFA production or biogas generation, depending on the target product. Microalgal treatment of the digestate liquor would enable purification of the biogas through CO₂ fixation and generate biomass which could be returned to anaerobic digestion for biogas production. Conversion of the biosolids to biochar would lead to net generation of revenue due to cost savings for transportation and land application, the biochar is useful for adsorption, catalysis and soil amendment for nutrients and sequestering CO₂. Integration of promising recovery technologies into wastewater treatment would reduce sludge volume and create value-added products, and also reduce the environmental impact and health risks. However, integration must address the obstacles in terms of economy, value chain development, environment and wellbeing, as well as societal and policy limitations.

The use of constructed wetlands to remove pollutants from greywater is a viable solution, but seasonal variability of microbial activity and persistence of some of the organic compounds may impact their treatment efficiency. These shortcomings could be overcome using reactive media like manganese oxides (MnOx) that, as strong oxidants, extend the set of abiotic reactions. The reactivity of MnOx can be altered by the presence of dissolved oxygen, presence of vegetation and ammonium, among many other factors. In this study, constructed wetlands filled with commercial filtering material consisting of MnOx (specifically pyrolusite) or sand were used to treat greywater in an outdoor batch experiment exposed to natural seasonality. The effect of five variables (controlled ones: the presence of MnOx, plants, ammonium, the use of aeration, and uncontrolled: ambient temperature) on the removal of organic pollutants was evaluated. The four selected organic pollutants were: 5-methylbenzotriazole (5MBTR), metoprolol (MTP), bisphenol S (BPS), and diclofenac (DCF). The removal efficiency of DCF in the presence of MnOx was higher than 99% and unaffected by the temperature. The removal was confirmed to be associated with abiotic oxidation of DCF by MnOx. In contrast, sand-filled treatments outcompeted MnOx in removing 5MBTR, MTP, and BPS. The lower removal of 5MBTR, BPS, and MTP in the treatments with MnOx was probably due to organic carbon deficiency. This hypothesis was partially verified by the enantioselective analysis of MTP and the identification of its transformation product (MTP acid, MTPA) in both sand and MnOx treatments, indicating similar biotic removal mechanisms despite contrasting removal efficiencies (by 46–78%). The removal of the studied compounds by biodegradation correlated strongly with the determined electrophilicity index (EI), and the reactivity with MnOx with ionization potential (IP). The unaerated treatments with sand and plants were found the most effective and provided the greatest treatment resilience. In these treatments, the highest removals of the organic pollutants were 65%, 78%, 95% and 80% for 5MBTR, BPS, MTP and DCF, respectively.

We investigated basic bismuth subnitrate for removal of radioactive technetium-99 as pertechnetate (⁹⁹TcO₄⁻) from contaminated groundwater. This material removed 93% of the initial concentration of ⁹⁹TcO₄⁻ within a week via formation of pH-dependent mineral phases that were identified here, but not reported previously. Perrhenate (ReO₄⁻) removal was also studied because it is a widely used non-radiological analogue for ⁹⁹TcO₄⁻, considering their similar physicochemical properties. We found that removal of ReO₄⁻ was not identical to removal of ⁹⁹TcO₄⁻ and led to formation of an additional transitional phase. This demonstrates that perrhenate and pertechnetate have different kinetics of contaminant removal as a result of variations in mineral transformation.