Environmental Science: Water Research & Technology最新文献

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.

Limited studies to-date have assessed the impacts of disinfectants (chlorine and ultraviolet (UV)/H₂O₂) on microplastics (MPs), with most employing dosages and fluences that are much higher than typically applied during drinking water treatment. Formation of hydroxyl, carbonyl, and carbon–chlorine bonds on the surface of MP particles, as well as the potential for fragmentation and changes to surface roughness have been linked to an increase in toxicity. Additional knowledge regarding physicochemical changes to MPs under conditions representative of drinking water disinfection will aid our understanding of potential risk. In this study, changes to virgin low-density polyethylene (LDPE) and high-density polyethylene (HDPE) fragments (2–125 μm) were examined following exposure to 6 mg L⁻¹ free chlorine over a two-week period. Relative changes to hydroxyl, carbonyl, carbon–oxygen, and carbon–chlorine indices were determined using Attenuated Total Reflectance Fourier Transform Spectroscopy (ATR-FTIR). Following exposure, particle size distributions remained consistent, indicating that MPs did not fragment as reported in earlier studies by others. Neither polymer type nor pH level exhibited an impact on fragmentation or bond indices that was statistically significant (P > 0.05). These findings suggest that neither chlorination nor UV/H₂O₂ adversely impact LDPE or HDPE.

Recently, improving the mechanical properties of monolithic silica and alumina aerogels by incorporating polymers for various applications, particularly for adsorption, has been the focus of research. In this study, we report the modification of the high surface area γ-aluminum oxy-hydroxide (γ-AlOOH) aerogel with biopolymer chitosan having nitrogen functional groups to improve the efficiency of adsorption. The chitosan + γ-AlOOH aerogel was synthesized using the sol–gel method via a supercritical drying process. The monolithic chitosan–γ-AlOOH aerogel was optimized at 1% (w/w) chitosan for all aluminum precursors used. The XRD pattern of the synthesized monolithic chitosan–γ-AlOOH aerogel shows an amorphous nature, while the FTIR peaks at 1065 cm⁻¹ and 1387 cm⁻¹ indicated the presence of –OH and –NH (amide) bonds. TEM images show the nanoneedle-shaped morphology of chitosan within the γ-AlOOH aerogel with specific surface area of 562.11 m² g⁻¹ and pore volume of 3.68 cc g⁻¹. The as-synthesized monolithic chitosan–γ-AlOOH aerogel was used for the removal of azo dyes, such as methylene blue (MB) and crystal violet (CV), heavy metal ions [Pb(II), As(III)], and rare earth metals [U(VI)]. The maximum adsorption capacities obtained from the adsorption isotherms are 167 ± 3 mg g⁻¹ for MB, 164 ± 2 mg g⁻¹ for CV, 644 ± 5 mg g⁻¹ for U(VI), and 102 ± 2 mg g⁻¹ for As(III) at pH 7. However, at pH 7 Pb(II) is found to precipitate; therefore, the adsorption capacity is obtained at pH 5 with 228 ± 1 mg g⁻¹. The recyclability of the monolithic chitosan–γ-AlOOH aerogel was 94.55% (MB), 94.48% (CV), 94.65% (Pb(II)), 94.8% (U(VI)), and 95.15% (As(III)). These results highlight the potential of heteroatom-rich biopolymers tailored to alumina aerogels for achieving superior multifunctional adsorption properties.

Adenoviruses present challenges for traditional surveillance methods since there are more than 60 types that infect humans. Wastewater-based surveillance can supplement traditional surveillance methods for gastrointestinal-associated adenoviruses, but the ability to detect trends of respiratory-associated adenoviruses in wastewater remains unclear. We quantified human adenovirus type 4 (HAdV-4) in wastewater settled solids and compared wastewater measurements to clinical cases from an outbreak investigation beginning in late September 2022. The human adenovirus type 4 target was positively correlated with clinical cases (Spearman's rho = 0.5470, p < 0.0001) and followed a similar trend during the outbreak. We also quantified human adenovirus types 3, 7, 14, 21, 40/41, and a pan-adenovirus assay that targets all types that infect humans. The respiratory adenoviruses comprised a small fraction of the adenoviruses in wastewater and types 40/41, which typically cause gastrointestinal disease, comprised the majority of the detected adenoviruses. The efficacy of adenovirus wastewater surveillance will depend on assay specificity and the public health action available for adenovirus types.

The use of UV light to prevent or mitigate the development of biofilms is an area of emerging research that spans numerous industries. We reviewed 58 papers published between 1998 and 2024 reporting UV/biofilm experiments. Unlike earlier literature reviews on this topic, we included studies from many areas of practice including water, healthcare, and food safety. We focused on experimental methods and the types of information reported in different studies. Major research gaps included a lack of comparison between different approaches to biofilm growth and/or UV exposure, poor reporting of the chemical and/or optical characteristics of the biofilm growth and UV exposure media, little to no investigation into the impact(s) of support surface characteristics on treatment efficacy, few attempts to meaningfully compare the effects of different UV wavelengths on biofilms, and limited use of advanced methods to quantify and characterize of biofilms exposed to UV light. No existing studies have explored how UV light travels through biofilms or whether existing UV characterization methods can be meaningfully applied to UV/biofilm studies. The impacts of hydraulic conditions during biofilm growth and UV exposure also remain unexplored. Through this review we determined that a prescriptive standard experimental method for UV/biofilm experiments would be unable to encompass the wide range of industries and potential applications of the technology. Instead, recommendations for minimum reporting requirements were developed and examples of advanced methods to enhance future for UV/biofilm experiments were identified along with a proposed terminology framework to improve comparability between studies.