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The wastewater treatment performance in an inverted A 2 /O reactor supplemented with fermentation liquid of primary sludge was explored comparing to commercial carbon sources sodium acetate and glucose. Similar COD removal rate was observed with the effluent COD stably reaching the discharge standard for those 3 carbon sources. However, the fermentation liquid distributed more carbon source in the anaerobic zone. Fermentation liquid and sodium acetate tests achieved better nitrogen removal rate than glucose test. The fermentation liquid test showed the best biological phosphorus removal performance with the effluent phosphorus barely reaching the discharge standard. The microbial community characterization revealed that the fermentation liquid test was dominated by phylum Proteobacter in all the anoxic, anaerobic and aerobic zones. Denitrifying phosphorus accumulating organisms (PAOs) (i.e., genera Dechloromonas and unclassified_f__Rhodocyclaceae) were selectively enriched with high abundances (over 20%), which resulted in improved phosphorus removal efficiency. Moreover, the predicted abundances of enzymes involved in nitrogen and phosphorus removal were also enhanced by the fermentation liquid., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this study, highly antimicrobial CuNPs were integrated into a hydrophilic polydopamine (PDA) coating and immobilized on a RO TFC membrane via a mild and facile reduction approach to form a stable and durable dual-functional layer. Based on the XDLVO analysis, the introduction of PDA increased the membrane-foulant total interaction energy (ΔG mwf ) to 14.13 mJ/m 2 , resulting in improved anti-adhesive properties as demonstrated by a 37% decrease in BSA adsorption for the modified membranes. The well dispersed and high loadings of CuNPs induced by PDA conferred strong bacterial toxicity to the modified membranes, reducing the viability of E. coli by 76%. Furthermore, the presence of catechol groups on PDA favors the formation of covalent bond with CuNPs, thus prolonging the durability of the copper-based anti-biofouling membranes. The combination of PDA coating and CuNPs functionalization imparts the membrane with simultaneous anti-adhesive and anti-microbial properties, leading to a substantial reduction in biofouling propensity in dynamic biofouling experiments. Specifically, the flux decline due to biofouling observed for the modified membranes significantly decreased from 65% to 39%, and biofilm thickness and TOC biomass were 58%, and 55% lower, respectively. This study provides a facile and versatile strategy to construct high performance RO membranes with excellent anti-biofouling functionality., (Copyright © 2022. Published by Elsevier Ltd.)

Engineered nanoparticles (ENPs) will inevitably enter wastewater treatment plants (WWTPs) due to their widespread application; thus, it is necessary to study the migration and transformation of nanoparticles in sewage treatment systems. Extracellular polymeric substances (EPSs) such as polysaccharides, proteins, nucleic acids, humic acids and other polymers are polymers released by microorganisms under certain conditions. Intracellular polymeric substances (IPSs) are microbial substances contained in the body with compositions similar to those of extracellular polymers. In this review, we summarize the characteristics of EPSs and IPSs from sewage-collecting microbial aggregates containing pure bacteria, activated sludge, granular sludge and biofilms. We also further investigate the dissolution, adsorption, aggregation, deposition, oxidation and other chemical transformation processes of nanoparticles, such as metals, metal oxides, and nonmetallic oxides. In particular, the review deeply analyzes the migration and transformation mechanisms of nanoparticles in EPS and IPS matrices, including physical, chemical, biological interactions mechanisms. Moreover, various factors, such as ionic strength, ionic valence, pH, light, oxidation-reduction potential and dissolved oxygen, influencing the interaction mechanisms are discussed. In recent years, studies on the interactions between EPSs/IPSs and nanoparticles have gradually increased, but the mechanisms of these interactions are seldom explored. Therefore, developing a systematic understanding of the migration and transformation mechanisms of ENPs is significant., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Supersaturation of total dissolved gas (TDG) is a common occurrence in high dams during the spill process, which can lead to fish bubble disease and threaten aquatic organisms. As a result, many scholars have taken a keen interest in this issue. Research into the gas-liquid mass transfer mechanism has improved the accuracy of TDG prediction models. This article investigates the factors affecting TDG dissipation through laboratory experiments. Especially, the mass transfer coefficient across the bubble interface based on the slip penetration model was calibrated, and the coaxial bubble coalescence added to the coefficient was studied. The results show that the aeration rate has the most significant impact, followed by water depth, and then the aeration aperture. The TDG dissipation rate increases with the parameter β, and the parameter of 0.35 shows the highest correlation with the experimental data. Furthermore, the concentration change rate after coalescence is lower than before, suggesting that aggregation negatively impacts mass transfer. This study improves TDG concentration prediction accuracy and proposes measures for mitigating supersaturation to avoid fish bubble disease. [ABSTRACT FROM AUTHOR]

[Display omitted] • BC/FBC made from agricultural waste were pre-deposited in GDM systems. • BC pre-deposition improved biofouling layer heterogeneity thus higher stable flux. • Presence of biochar significantly enhanced microbial activity and pollutant removal. • The presence of Fe in FBC inhibits microbial activity of the biofouling layer. The relatively unstable dissolved organic removal efficiency and low water flux during long-term filtration of gravity-driven membrane (GDM) are major barriers to its widespread application in decentralized water treatment. In this study, the role of pre-deposited biochar (BC) and iron-modified biochar (FBC) layers in GDM for treating surface water were firstly investigated, aiming to explore the feasibility of cost-effective agricultural waste as pre-deposition materials. Compared to the relatively low removal efficiency of GDM control group (DOC 18.1 %, UV 254 10.6 %), both BC pre-deposited GDM (BC-GDM: DOC 36.0 %, UV 254 39.9 %) and FBC pre-deposited GDM (FBC-GDM: DOC 31.9 %, UV 254 32.4 %) show considerably enhanced removal efficacy. Also, pre-deposited BC/FBC layers accelerated the start-up process for NH 4 +-N removal. The enhancement of functional bacteria such as Proteobacteria and Nitrospirota was accountable for pollutant removal efficacy. Regarding the flux stabilization, compared to the GDM control system, the final stable flux of BC-GDM increased by 3.61 % while FBC-GDM decreased by 9.55 %. The presence of BC layer increased the bacterial activity, porosity of the formed biofouling layer, thus favored the flux enhancement, resulting in a lower water production cost. Conversely, the presence of Fe in FBC may inhibit the microbial activity and diminish its pore structure, leading to reduced flux transport. Our study suggests simple pre-deposition of BC shows positive effect on ultra-low pressure GDM filtration, highlighting the potential application of low-cost agriculture waste in decentralized drinking water treatment. [ABSTRACT FROM AUTHOR]

Owing to the high toxicity and mobility, the removal of arsenite (As(III)) is significantly more difficult than arsenate (As(V)), thus representing a major challenge in arsenite-contaminated water treatment. For efficient elimination of As(III), we successfully fabricated a novel Ti-Mn binary oxide via a simultaneous oxidation and coprecipitation process. The amorphous oxide was aggregated from nanosized particles with a high specific surface area of 349.5 m 2 /g. It could effectively oxidize As(III) to As(V) and had a high As(III) sorption capacity of 107.0 mg/g. As(III) sorption occurred rapidly and equilibrium was achieved within 24 h. The kinetic data was well fitted by the pseudo-second-order equation, indicating a chemical sorption process. The material was almost independent upon the presence of competitive ions. The As(III) removal by the sorbent is a combined process coupled oxidation with sorption, where the MnO 2 content is mainly responsible for oxidizing As(III) to As(V) and the formed As(V) is then adsorbed onto the surface of amorphous TiO 2 content, through replacing the surface hydroxyl group or the adsorbed As(III) and forming inner-sphere surface complexes. Furthermore, the arsenic-containing oxide could be effectively regenerated and reused. The bi-functional sorbent could be used as a potentially attractive sorbent for As(III) removal in drinking water treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • There are 26 types of NF/RO membranes in use or under investigation for PFAS removal. • Under environmentally relevant pH and concentration, NF and RO can effectively remove long chain PFAS from water. • More study should focus on overlooked compounds with smaller size, shorter C-F chain, and higher hydrophilicity. • Novel membrane materials, modifications, and hybrid treatment trains with improved PFAS selectivity/fouling resistance are expected. Per- and polyfluoroalkyl substances (PFAS) have been ubiquitously detected in the aquatic environment which poses a risk for human exposure. The recalcitrant behavior of PFAS to most traditional water treatment processes calls for development of novel or modified treatment approaches for effective PFAS elimination. Currently, high-pressure membrane systems, including nanofiltration (NF) and reverse osmosis (RO) are among the most promising and readily applied technologies for PFAS removal. In this review, we summarized peer-reviewed scientific articles on the development and use of 20 different types of commercial and 6 synthesized/modified NF and RO membranes in terms of PFAS removal efficacy. Synthesizing of existing knowledge shows that under environmentally relevant pH and concentration, NF and RO can effectively remove PFAS from water. The impact of PFAS molecular weight (MW) and functionality, membrane characteristics, feed water constitution, natural organic matters and operational conditions were systematically reviewed and evaluated. Moving forward, we recommend additional research dedicated to understanding the behaviors of PFAS alternatives and other overlooked compounds (e.g., PFAS with chain length C 2 and C3) during NF and RO processes. Further, it is critical to develop or optimize existing membrane products with strong selectivity for specific PFAS species, while being resistant to fouling. Overall, this review is expected to assist researchers and water quality managers investigating membrane processes for PFAS removal. [ABSTRACT FROM AUTHOR]

Abstract In order to attain a high-efficiency and low-cost adsorbent for both arsenate (As(V)) and arsenite (As(III)) removal from As-contaminated water, a novel nanostructured Fe-Ti-Mn composite oxide (FTMO) was fabricated through a one-step simultaneous oxidation and co-precipitation method. Batch control experiments and series of spectroscopy detection technologies were carried out to investigate the surface change of the FTMO adsorbent and the respective role of Fe, Ti and Mn content in the arsenic adsorption process. The results showed that the FTMO adsorbent had a high adsorption capacity for both As(V) and As(III) (especially for the latter one) via the formation of inner-sphere complexes at the water/oxide interface under both darkness and light conditions. The material could effectively oxidize As(III) to As(V) and light illumination could further apparently enhance the As(III) oxidation, thus achieving high adsorption efficiency of As(III). Combined with the characterizations from FTIR, ESR and XPS, it was assumed that the predominant As(III) removal mechanism could be attributed to the coupling of various processes including photooxidation, oxidation and adsorption. The Ti and Mn contents were dominant for the As(III) oxidation, while the Fe content mainly played an important role for the adsorption of newly formed As(V). However, the involvement of surface hydroxyl groups and the formation of inner-sphere surface complexes were primarily responsible for the As(V) adsorption mechanism. Moreover, the successful removal of arsenic from real water matrices made the FTMO a potentially attractive adsorbent for both As(V) and As(III) removal. Graphical abstract Image 1 Highlights • A novel synthesized FTMO could effectively remove both As(V) and As(III). • The As(V) adsorption was mainly achieved through forming the inner-sphere complexes. • The predominant As(III) removal was a photooxidation, oxidation coupled with adsorption. • The Ti and Mn contents were contribute to As(III) oxidation. • The Fe content was mainly responsible for the formed As(V) adsorption. [ABSTRACT FROM AUTHOR]

The regulation behavior of oxygen vacancies (Vo) at different spatial positions (surface or bulk) in catalysts for selective O 3 catalyzation, along with the reaction pathways evolution was well-investigated in α-MnO 2−x /O 3 systems. Combined characterization methods, systematic organic removal experiments, structure-activity relationship analysis, and theoretical calculations were employed to unveil O 3 decomposition and electron transfer behaviors regulated by surface or bulk Vo. The contribution of electron transfer process (ETP) to atrazine (ATZ) removal was reinforced from 5.2 % to 34.8 % with the formation of bulk Vo, and Vo-rich α-MnO 2−x -2/O 3 system achieved ∼96.5 % ATZ removal along with improved TOC mineralization (∼38 % vs. ∼20 %). Surface Vo facilitated O 3 adsorption, promoting its decomposition into •OH, while bulk Vo not only accelerated •OH production but also withdrew electrons from organics to build ETP. This study shed light on precise modification of metal-based catalysts with Vo to modulate •OH/ETP synergistic processes in catalytic ozonation for efficient water purification. [Display omitted] • Rational Vo modification in catalysts promoted selective ozone catalyzation. • The reaction pathways (•OH and ETP) were modulated by surface and bulk Vo. • Both surface and bulk Vo boosted electrons transfer to decompose O 3 into •OH. • Bulk Vo preferred to withdraw electrons from the organics to build ETP. • •OH and ETP synergistic process facilitated the stoichiometry efficiency of O 3. [ABSTRACT FROM AUTHOR]

Very recently, several studies have found that homogeneous reducing agents (e.g., sodium thiosulfate (Na 2 S 2 O 3), and sodium sulfite (Na 2 SO 3)) can activate ferrate to enhance the degradation of selected contaminants. In this work, it was found that heterogeneous carbon nanotube (CNT) could accelerate ferrate (Fe(VI)) for the degradation of bromophenols (BrPs) of environmental concerns and alleviate the appearance of undesired by-products in effluent. Fe(VI) could react with BrPs over a wide pH range of 6–10 with apparent second-order rate constants of 1.8–1850 M−1 s−1. Electrospray ionization-triple quadrupole mass spectrometry (ESI-QqQMS) analysis showed that dibrominated dihydroxylated biphenyls and dibrominated phenoxyphenols were possibly formed via coupling reaction of BrPs radicals generated from Fe(VI) oxidation through one-electron transfer. The presence of CNT could remarkably accelerate the degradation rates of BrPs by Fe(VI) in a wide pH range from 7 to 10. Moreover, the formed undesired polybrominated products during Fe(VI)/CNT oxidation were absorbed on CNT surface and thus removed from treated water. The Fe(VI)/CNT system was capable of selectively oxidizing electron-rich pollutants (e.g., BrPs, and sulfamethoxazole (SMX)), but reluctant to iopamidol (IPM) and nitrobenzene (NB). High-valent metal-oxo intermediates Fe(V)/Fe(IV) formed in situ from the reaction of CNT with Fe(VI) were likely responsible for this activation effect of CNT, which was further confirmed via using methyl phenyl sulfoxide (PMSO) as a probe compound. Comparatively, homogeneous reducing agent Na 2 S 2 O 3 could enhance Fe(VI) degradation of BrPs at pH 7 and 8, while undesired polybrominated products were detected in effluent from Fe(VI)/Na 2 S 2 O 3 system. These findings have crucial implications for the development of a promising oxidation process by combination of Fe(VI) and CNT for water and wastewater treatment. Image 1 • Fe(VI) could degrade bromophenols in a wide pH range. • Undesired polybrominated products of concern were formed during Fe(VI) oxidation. • CNT significantly accelerated the degradation of bromophenols by Fe(VI). • The formed polybrominated products of concern were absorbed on CNT surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • NF can simultaneously remove traditional PFOS/PFOA and emerging PFAS homologous. • MW and logK ow are the most significant molecular parameters affecting PFAS removal. • Membrane intrinsic structural characteristics affect the PFAS removal significantly. • Adsorption and rejection of PFAS may occur via similar driving forces. Although nanofiltration (NF) has been widely reported for removing long-chain per- and polyfluoroalkyl substances (PFAS) from water, little is known about the correlations between removal efficacy and PFAS/membrane characteristics, especially for emerging PFAS with shorter polyfluoroalkyl chain or containing fluoroether moieties. A systematic study of treatment of structurally diverse PFAS by NF can help predict the behavior of more unknown compounds during NF process. In this study, we conducted filtration experiments with five commercial NF membranes. Results show that seven legacy PFAS, three emerging perfluoroalkyl ether acids (PFEA) and two fluorotelomer sulfonates (FTS) can be removed simultaneously during the NF process, with rejection ranging from 66.0% to > 99.9%. The removal efficiency of five membranes decreased successively as DK > NF90 > XN45 > NF270 > DL. Rejection of FTS and PFEA by DK membranes were 88.3% to 97.1% and 81.7% to > 99.9%, respectively. Correlation analysis revealed that PFAS molecular structure and membrane characteristics significantly affect PFAS rejection. PFAS molecular weight (MW) and hydrophobicity (logK ow) and membrane intrinsic structural characteristics (e.g., molecular weight cut-off (MWCO), water permeability, and salt selectivity) are among the most significant parameters impacting PFAS removal. The findings imply that both steric hindrance and hydrophobic interactions contribute to PFAS rejection. Moreover, the mass of PFAS adsorbed on the membrane was positively correlated with their molecular parameters (i.e., MW and logK ow) and weakly correlated with membrane properties, suggesting that the adsorption and rejection of PFAS have similar driving forces. This study provides critical insights into the application of NF for emerging PFAS removal for both the scientific community and private industry, concerning water purification processes and remediation of thousands of PFAS-impacted sites. [ABSTRACT FROM AUTHOR]