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The effects of trace sulfadiazine (SDZ) and cast-iron corrosion scales on the disinfection by-product (DBP) formation in drinking water distribution systems (DWDSs) were investigated. The results show that under the synergistic effect of trace SDZ (10 μg/L) and magnetite (Fe 3 O 4 ), higher DBP concentration occurred in the bulk water with the transmission and distribution of the drinking water. Microbial metabolism-related substances, one of the important DBP precursors, increased under the SDZ/Fe 3 O 4 condition. It was found that Fe 3 O 4 induced a faster microbial extracellular electron transport (EET) pathway, resulting in a higher microbial regrowth activity. On the other hand, the rate of chlorine consumption was quite high, and the enhanced microbial EET based on Fe 3 O 4 eliminated the need for microorganisms to secrete excessive extracellular polymeric substances (EPS). More importantly, EPS could be continuously secreted due to the higher microbial activity. Finally, high reactivity between EPS and chlorine disinfectant resulted in the continuous formation of DBPs, higher chlorine consumption, and lower EPS content. Therefore, more attention should be paid to the trace antibiotics polluted water sources and cast-iron corrosion scale composition in the future. This study reveals the synergistic effects of trace antibiotics and corrosion scales on the DBP formation in DWDSs, which has important theoretical significance for the DBP control of tap water., 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.)

The biofilm stress response of biological activated carbon (BAC) was investigated under prolonged exposure to sulfadiazine and 2,4-Dichlorophenoxyacetic acid, simulating complex emerging organic contaminants (EOCs) that are mainly involved in the formation of nitrogenous disinfection byproducts (N-DBPs) and antibiotic resistance genes (ARGs). Under trace complex EOCs condition (2 µg/L), N-DBP precursors and abundance of ARGs increased significantly in BAC effluent. The total formation potential of haloacetonitriles (HANs) and halonitromethanes (HNMs) was 751.47 ± 2.98 ng/L, which was much higher than the control group (440.67 ± 13.38 ng/L without EOCs). Similarly, the relative abundance of ARGs was more than twice that in the control group. The complex EOCs induce excessive extracellular polymeric substance secretion (EPS), thereby causing more N-DBP precursors and stronger horizontal gene transfer. Metagenome analysis revealed that functional amino acid and protein biosynthesis genes were overexpressed compared to the control group, causing more EPS to be secreted into the external environment. Complex EOCs promote Cobetia, Clostridium, and Streptomyces dominance, contributing to the production of N-DBP precursors and ARGs. For the first time, in addition to the direct hazards of the EOCs, this study successfully revealed the indirect water quality risks of complex EOCs from the microbial stress response during BAC treatment. Synergistic regulation of EOCs and microorganisms is important for tap water security., 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 B.V. All rights reserved.)

Bifunctional photocatalytic nanofiltration (PNF) membrane has become a reliable frontier technique for removing refractory organic micropollutants. However, the active mitigated fouling mechanism from the microscopic perspective during its long-term operation of purifying real micro-polluted water is rarely studied. Herein, with an integrated use of QSense Explorer and confocal laser scanning microscope techniques, self-cleaning foulant attachment on an activated and customized near-infrared responsive polymeric PNF (termed as nPNF) membrane with good service performance for continuous dynamic removing antibiotics in sewage effluent environment was firstly elucidated. Time-dependent changes in dissipation oscillation frequency, sensed mass and the visualized foulant spatial distribution all indicated that there were only sporadic foulant attachment, an extremely low fouling layer thickness and irreversible fouling rate on/of the activated nPNF membrane top surface, thereby endowing it with excellent self-cleaning characteristic. This is probably because the reactive oxygen species (mainly •O 2 - and •OH) concurrently destroys the integrity of fouling layer and its internal adhesion structure, transforming part of the irreversible fouling on nPNF membrane surface into reversible one that is easy to wash off. These new horizons provided useful insight on the fate of selected antibiotics in the to-be-removed stage and self-cleaning foulant attachment of PNF membrane., 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.)

The use of catalyst materials to mediate the enhancement of microbial degradation in wastewater is a new economic and energy saving breakthrough in water treatment technology. In this study, γ-Al 2 O 3 , which is commonly used as catalyst/carrier, is used as biological filler to treat kitchen-oil wastewater with low biodegradability, and the COD removal rate is about 50 %. It is found that the complexation of cationic vacancies on Al 2 O 3 surface with extracellular polymeric substance (EPS) secreted by microorganisms in wastewater lead to the polarization of electron distribution on biofilm. The efficient degrading bacteria are enriched on reaction interface and obtain electrons to maintain electron dynamic balance by enhancing the transmembrane metabolism of pollutants. The aluminum vacancies on Al 2 O 3 surface accelerate the microbial degradation of pollutants. The cationic vacancies in the structure of catalyst accelerate the acquisition of exogenous electrons by microorganisms without the addition of external energy, which provides a new idea for catalytic fillers to enhance wastewater degradation., 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. Published by Elsevier B.V.)

For the sustainable reutilization of poultry feces (PF) to reduce environmental pollution, we present a novel approach for converting PF into a highly effective catalyst, consisting of trace copper (Cu) and sulfur (S) linked with ordered graphitized carbon (CS/CPF) for wastewater purification. Raman and EPR results verified that the disorderly organic matters in PF are transformed into orderly graphene structures that complexed with Cu to form large numbers of electron-poor/rich microregions on CS/CPF surface. The electrons from electron-rich organic pollutants can be directly captured by dissolved oxygen (DO) to produce abundant reactive oxygen species due to the enhanced electron polarization via the construction of Cu-S-C bond bridge on CS/CPF surface, which greatly enhance the removal efficiency of pollutants. CS/CPF achieves 100% removal for 2,4-dichlorophenoxyacetic acid (2,4-D) in just 10 min after adding trace peroxymonosulfate (PMS), keeping efficient catalytic activity after continuous reactions for 240 h. This strategy offers a practical and sustainable solution for the efficient resource recovery of poultry feces., 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.)

Cyanobacteria and their metabolites are one of the primary precursors of disinfection by-products (DBPs) in natural water environments. However, few studies have investigated whether the production of DBPs by cyanobacteria changes under complex environmental conditions and possible mechanisms underlying these changes. Therefore, we investigated the effects of algal growth phase, water temperature, pH, illumination and nutrients on the production of trihalomethane formation potential (THMFPs) by Microcystis aeruginosa in four algal metabolic fractions, that is, hydrophilic extracellular organic matter (HPI-EOM), hydrophobic EOM (HPO-EOM), hydrophilic intracellular organic matter (HPI-IOM) and hydrophobic IOM (HPO-IOM). Additionally, correlations between THMFPs and some typical algal metabolite surrogates were analyzed. The results showed that the productivity of THMFPs by M. aeruginosa in EOM could be affected significantly by the algal growth phase and incubation conditions, while the IOM productivity varied insignificantly. M. aeruginosa in the death phase could secrete more EOM and have a higher THMFP productivity than those in the exponential or stationary phases. Cyanobacteria grown under harsh conditions could have increased THMFP productivity in EOM by increasing the reactivity of algal metabolites with chlorine, for example, under low pH conditions, and secreting more metabolites in EOM, for example, under low temperature or nutrient limitation conditions. Polysaccharides were responsible for the enhanced THMFP productivity in HPI-EOM fraction, and a significant linear correlation was found between the concentration of polysaccharides and THMFPs (r = 0.8307). However, THMFPs in HPO-EOM did not correlate with dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV 254 ), specific UV absorbance (SUVA) and cell density. Thus, we could not specify the kind of algal metabolites that contribute to the increased THMFPs in the HPO-EOM fraction under harsh growth conditions. Compared with the case in EOM, the THMFPs in IOM were more stable and correlated with the cell density and total amount of IOM. The results implied that the THMFPs in the EOM were sensitive to growth conditions and were independent of algal density. Considering the fact that traditional water treatment plants cannot remove dissolved organics as efficiently as algal cells, the increased THMFP productivity in EOM by M. aeruginosa under harsh growth conditions could be a potentially serious threat to the safety of the water supply., Competing Interests: Declaration of competing interest I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for any other journals, in whole or in part. All authors are aware of, and accept responsibility for the manuscript., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Excessive consumption of energy and resources is a major challenge in wastewater treatment. Here, a novel heterogeneous Fenton-like catalyst consisting of Cu-doped graphene-like catalysts (Cu-GCD NSs) was first synthesized by an enhanced carbothermal reduction of β-cyclodextrin (β-CD). The catalyst exhibits excellent Fenton-like catalytic activity for the degradation of various pollutants under neutral conditions, accompanied by low H 2 O 2 consumption. The results of structural characterization and theoretical calculations confirmed that the dual reaction centers (DRCs) were constructed on Cu-GCD NSs surface through C-O-Cu bonds supported on zero-valent copper species, which play a significant role in the high-performance Fenton-like reaction. The pollutants that served as electron donors were decomposed in the electron-poor carbon centers, whereas H 2 O 2 and dissolved oxygen obtained these electrons in the electron-rich Cu centers through C-O-Cu bonds, thereby producing more active species. This study demonstrates that the electrons of pollutants can be efficiently utilized in Fenton-like reactions by DRCs on the catalyst surface, which provides an effective strategy to improve Fenton-like reactivity and reduce H 2 O 2 consumption., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationship that could have appeared to influence the work reported in this article., (Copyright © 2022. Published by Elsevier B.V.)

The stable structure and toxic effect of refractory organic pollutants in wastewater lead to the problem of high energy consumption in water treatment technology. Herein, we propose a synergistic purification of refractory wastewater driven by microorganisms and surface microelectric fields (SMEF) over a dual-reaction-center (DRC) catalyst HCLL-S8-M prepared by an in situ growth method of carbon nitride on the Cu-Al 2 O 3 surface. Characterization techniques demonstrate the successful construction of SMEF with strong electrostatic force over HCLL-S8-M based on cation-π interactions between metal copper ions and carbon nitride rings. With the catalyst as the core filler, an innovative fixed bed bioreactor is constructed to purify the actual kitchen-oil wastewater. The removal efficiency of the wastewater even with a very low biodegradability (BOD 5 /COD = 0.33) can reach 60% after passing through this bioreactor. An innovative reaction mechanism is revealed for the first time that under the condition of a small amount of biodegradable organic matter, the SMEF induces the enrichment of electric active microorganisms (Desulfobulbus and Geobacter) in the wastewater, accelerates the interspecies electron transfer of intertrophic metabolism with the biodegradable bacteria through the extracellular electron transfer mechanism such as cytochrome C and self-secreted electron shuttle. The electrons of the refractory organic pollutants adsorbed on the surface of the catalyst are delocalized by the SMEF, which can be directly utilized by microorganisms through EPS conduction. The SMEF generated by electron polarization can maximize the utilization of pollutants and microorganisms in wastewater and further enhance degradation without adding any external energy, which is of great significance to the development of water self-purification technology., 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 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Improper disposal of waste biomass and an increasing number of emerging contaminants (ECs) in water environment are universal threats to the global environment. Here, we creatively propose a sustainable strategy for the direct resource transformation of livestock manure (LM) into an innovative catalyst (Fe-CCM) for water self-purification with zero external consumption. ECs can be rapidly degraded in this self-purification system at ambient temperature and atmospheric pressure, without any external oxidants or energy input, accompanied by H 2 O and dissolved oxygen (DO) activation. The performance of the self-purification system is not affected by various types of salinity in the wastewater, and the corresponding second-order kinetic constant is improved 7 times. The enhanced water self-purification mechanism reveales that intermolecular forces between anions and pollutants reinforce electron exchange between pollutants and metal sites on the catalyst, further inducing the utilization of the intrinsic energy of contaminants, H 2 O, and DO through the interfacial reaction. This work provides new insights into the rapid removal of ECs in complicated water systems with zero external consumption and is expected to advance the resource utilization of livestock waste.

Bifunctional photocatalytic nanofiltration (PNF) membrane is increasingly concerned in practical micro-polluted water purification, but there are still several bottlenecks that inhibit its practicality. In this context, the feasibility of a novel metal-free and visible light-responsive surface-anchored PNF membrane for simultaneously removing target antibiotics in real sewage effluent in a continuous dynamic process was explored. The results showed that the optimal PNF-4 membrane was expectedly consisted of an inside tight sub-nanopore structured separation layer and an outside thinner, smoother, super hydrophilic mesoporous degradation layer, respectively. Consequently, the activated PNF-4 membrane could synergistically reduce trimethoprim and sulfamethoxazole concentrations to below two orders of magnitude, accompanying with almost constant high water permeability, suggesting that the hydrophilic modification of the mesoporous degradation layer basically offsets its inherent hydraulic resistance. Also, after repeating the fouling-physical rinsing process three times lasted for 78 h, only sporadic adherent contaminants remained onto the top surface, together with the minimal total and irreversible fouling ratios (as low as 7.2% and 1.2%, respectively), strongly demonstrated that PNF-4 membrane displayed good self-cleaning performance. Undoubtedly, this will significantly reduce its potential cleaning frequency and maintenance cost in long-term operation. Meanwhile, the acute and chronic biotoxicities of its permeate to Virbrio qinghaiensis sp. -67 were also reduced sharply to 2.22% and 0.45%, respectively. All of these evidences suggest that the dual functions of PNF-4 membrane are synergetic in an uninterrupted permeating process. It will provide useful insights for continuously enhancing the practicality and effectiveness of PNF membrane in actual micro-polluted water purification scenarios., 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 © 2022. Published by Elsevier Ltd.)

Herein, a novel metal-free catalyst consisting of multiporous oxygen-rich carbon-nitrogen graphene-like nanosheets (O LAA -CN NSs) is first developed through a staged temperature-programmed calcination of l-ascorbic acid (LAA)-modified dicyandiamide precursor. It is found that the oxygen species from l-ascorbic acid (O LAA ) are introduced into the graphene-like basic matrix and replace partial N atoms to form the COC-R structure, leading to the non-uniform distribution of electrons on the catalyst surface, and the formation of electron-rich centers around the COC microareas according to a series of characterization techniques. As a result, O LAA -CN NSs exhibits excellent performance for refractory pollutant removal in the presence of peroxymonosulfate (PMS) and dissolved oxygen. Some pollutants with complex structures are even completely degraded within only 1 min. The interface reaction mechanism is further revealed that PMS mainly acts as an active inducer to drive the electron donation of pollutants over O LAA -CN NSs. These electrons are finally utilized by dissolved oxygen to generate reactive oxygen species (ROS) through the interface process. This reaction system results in pollutants that can either be cleaved directly by surface oxidation process or degraded by the attack of the generated ROS, such as singlet oxygen ( 1 O 2 ) and superoxide radicals (O 2 •- ), through oxygen activation, which significantly reduces the resource and energy consumption in advanced wastewater treatment by harnessing the energy of pollutants and dissolved oxygen in the water., 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 © 2022 Elsevier Inc. All rights reserved.)

Removing micropollutants in real water is a scientific challenge due to primary dissolved organic carbon (DOC) and high energy consumption of current technologies. Herein, we develop a self-purification process for the preferential destruction of various micropollutants in municipal wastewater, raw drinking water, and ultrapure water with humic acid (HA) driven by the surface microelectronic field of Fe 0 -Fe y C z /Fe x -GZIF-8-rGO without any additional input. It was verified that a strongly polar complex consisting of an electron-rich HA/DOC area and an electron-poor micropollutant area was formed between HA/DOC and micropollutants, promoting more electrons of micropollutants in the adsorbed complex to delocalizing to electron-rich Fe species area and be trapped by O 2 , which resulted in their surface cleavage and hydrolyzation preferentially. The higher micropollutant degradation efficiency observed in real wastewaters was due to the greater complex polarity of DOC. Moreover, the electron transfer process ensured the stability of the surface microelectronic field and continuous water purification. Our findings provide a new insight into low-energy combined-micropollution water treatment.

As an efficient active oxidant for the selective degradation of pollutants in wastewater, the high-valent copper species Cu(III) with persulfate activation has attracted substantial attention in some Cu-based catalysts. However, the systematic study of a catalyst structure and mechanism about Cu(III) with peroxydisulfate (PDS) activation is challenging owing to the coexistence of multiple Cu species and the structural symmetry of PDS. Herein, we anchored a Cu atom with two pyridinic N atoms to synthesize a single-atom Cu catalyst (Cu SA -NC). Experimental characterizations and theoretical calculations complemented each other well because of the uniform atomic active sites. The single-atom Cu was identified as the active site, and the unsaturated Cu-N 2 configuration was more conductive to PDS activation than the saturated Cu-N 4 configuration. Benefiting from the generation of Cu(III), Cu SA -NC exhibited an obvious selective and anti-interference performance for pollutant degradation in a complex matrix. The superior catalytic activity of Cu SA -NC compared with that of other reported Cu-based catalysts and good durability in a continuous-flow experiment further revealed the potential of Cu SA -NC for practical applications. This work strongly deepens the understanding of the generation of Cu(III) in a single-atom Cu catalyst with unsaturated Cu-N 2 sites under PDS activation and develops an efficient approach for actual water purification.

The effects of cast iron pipe corrosion on nitrogenous disinfection by-products formation (N-DBPs) in drinking water distribution systems (DWDSs) were investigated. The results verified that in the effluent of corroded DWDSs simulated by annular reactors with corroded cast iron coupons, typical N-DBPs, including haloacetamides, halonitromethanes, and haloacetonitriles, increased significantly compared with the influent of DWDSs. In addition, more dissolved organic carbon, adenosine triphosphate, and iron particles were simultaneously detected in the bulk water of corroded DWDSs, thereby indicating that abundant iron particles acted as a "protective umbrella" for microorganisms. Under the condition of corroded DWDSs, the extracellular polymeric substances gradually exhibited distinct characteristics, including a higher content and lower flocculation efficiency, thereby resulting in a large supply of N-DBPs precursors. Corroded cast iron pipes, equivalent to a unique microbial interface, induced completely distinct microbial community structures and metabolic functions in DWDSs, thereby enhancing the formation of N-DBPs. This is the first study to successfully reveal the interactions among iron particles, biofilms, and chlorine in DWDSs, which may help to fully understand the biofilm transformation and microbial community succession in DWDSs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The main function of quartz sand in drinking water treatment has been to remove turbidity, while the microbial effect of its solid-liquid interface has been ignored. In order to solve the limitations of control of the disinfection by-products (DBPs) and opportunistic pathogens (OPs) in common quartz sand, the common quartz sand was modified to iron sand. The maximum DBPs formation potential of typical nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products was determined using gas chromatography-ECD. Compared with those of sand, the inhibition effects of halonitromethanes, haloacetamides, and haloacetonitriles by the Fe-sand were increased by 51.51%, 43.66%, and 90.6%, respectively. In addition, the gene copy numbers of Hartmanella vermiformis, Legionella spp., Mycobacterium spp., M. avium , and Naegleria spp. were detected via quantitative qPCR, and the results indicated that the Fe-sand did have a similar significant inhibitory effect on OPs. The Fe-sand had limited ability to enhance the removal of NOM. However, the Fe-sand effectively inhibited the continuous contribution of biofilm to N-DBPs and opportunistic pathogens. The distribution of biofilms on the surface of the Fe-sand filter media was uniform, not likely to fall off, and more stable; however, the suspended biofilms in the effluent were more difficult to aggregate. In addition, the α -helix of the secondary structure in the extracellular protein disappeared in the effluent of the Fe-sand. Therefore, the whole suspended biofilm was easily penetrated by chlorine. The Fe-sand solid-liquid interface did significantly change the microbial community structure and suspended biofilm characteristics, which provides a new concept to ensure the safety of drinking water quality and plays a good theoretical supporting role in the improvement and transformation of the existing process in drinking water treatment plants.

Change in water quality was investigated with laboratory-scale ozone-biological activated carbon filters using copper-modified granular activated carbon (Cu/GAC) and unmodified granular activated carbon (GAC). In the first seven days of the experimental period, Cu/GAC removed organic matter more efficiently owing to its enhanced adsorption capacity. As the running time increased, the amount of disinfection by-products (DBPs), dissolved organic carbon, and extracellular polymeric substances (EPS) increased sharply in the effluent of the Cu/GAC filter (CCW). More importantly, the EPS suspended in the CCW exhibited weaker flocculating efficiency and hydrophobicity, causing more active chemical reactions between chlorine and EPS substances. The copper species significantly limited the microbial biomass (0.01 nmol/L adenosine triphosphate) but stimulated the secretion of significant amounts of EPS by microorganisms for self-protection. Furthermore, the microbial community in the bulk water was successfully shaped by Cu/GAC, resulting in a continuous supply of EPS-derived DBP precursors and a sharp rise in chlorine consumption in the downstream drinking water distribution. Therefore, use of modified GAC materials, similar to Cu/GAC, as carrier materials for biological activated carbon (BAC) treatment remains controversial, despite enhanced pollutant adsorption capacity. This is the first study to reveal the mechanism of BAC-modified materials for water quality stability. The study potentially contributes to a comprehensive understanding of the effects of biofilm transformation and microbial community succession on drinking water quality. These results showed that tap water safety risks could be reduced by improving BAC pretreatment in drinking water treatment plants., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In common advanced oxidation processes, excess reagents and energy are often added to the reaction system to maintain the continuity of the reaction. These additions result in a large waste of resources and energy, which has become a bottleneck in the development of water treatment technology. In this study, we propose a new strategy to solve this problem based on a novel dual-reaction-center (DRC) Fe-ZnS quantum dots (Fe-ZnS QDs) catalyst that forms a non-equilibrium surface with an electron-polarized distribution. Through experimental and theoretical studies, it was verified that the activation of trace amounts of H 2 O 2 could break the energy barrier for pollutants to transfer electrons. The dissolved oxygen (DO) in the reaction system could be activated by gaining energy on the surface of the Fe-ZnS QDs catalyst, and was converted to 1 O 2 to attack organic pollution. In addition, the pollutants themselves supplied electrons to H 2 O 2 through the surface of the Fe-ZnS QDs catalyst to generate more •OH radicals for pollutant degradation, thus providing two fast paths for pollutant degradation. The system could drive the reaction through a trace amount of H 2 O 2 , thereby activating DO to generate 1 O 2 while effectively using the energy of pollutants. Therefore, the proposed system offers a new direction for the development of environmentally-friendly catalysts and greatly reduces the consumption of resources and energy., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The effects of trace phosphate concentrations (0, 0.3 and 0.6 mg/L) in water source were investigated on microbial stability of the drinking water distribution systems (DWDSs). Obviously, the results verified that in the effluent of DWDSs simulated by annular reactors (ARs), the total microbial biomass and the absolute concentration of opportunistic pathogens such as Legionella pneumophila, Mycobacterium avium, and Hartmanella vermiformis increased significantly with phosphate concentration increasing. Based on X-ray powder diffractometer and zeta potentials measurement, trace phosphate did change physicochemical properties of corrosion products, hence promoting microbes escape from corrosion products to bulk water to a certain extent. Stimulated by chlorine disinfectant and phosphate, the extracellular polymeric substances (EPS) from the suspended biofilms of AR-0.6 gradually exhibited superior characteristics including higher content, flocculating efficiency, hydrophobicity and tightness degree, contributing to formation of large-scale suspended biofilms with strong chlorine-resistance ability. However, the disinfection by-products concentration in DWDSs barely changed due to the balance of EPS precursors contribution and biodegradation effect, covering up the microbiological water quality risk. Therefore, more attention should be paid to the trace phosphorus polluted water source though its concentration was much lower than wastewater. This is the first study successfully revealing the influence mechanism of trace phosphate on microbial stability in DWDSs, which may help to fully understand the biofilms transformation and microbial community succession in DWDSs., 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 © 2021 Elsevier Ltd. All rights reserved.)

The effects of biological activated carbon treatment using Fe 2 O 3 modified coconut shell-based activated carbon (Fe/CAC) were investigated on the occurrence of opportunistic pathogens (OPs) and formation of disinfection by-products (DBPs) in simulated drinking water distribution systems (DWDSs) with unmodified CAC as a reference. In the effluent of annular reactor (AR) with Fe/CAC, the OPs growth and DBPs formation were inhibited greatly. Based on the differential pulse voltammetry and dehydrogenase activity tests, it was verified that extracellular electron transfer was enhanced in the attached biofilms of Fe/CAC, hence improving the microbial metabolic activity and biological removal of organic matter especially DBPs precursors. Meanwhile, the extracellular polymeric substances (EPS) on the surface of Fe/CAC exhibited stronger viscosity, higher flocculating efficiency and better mechanical stability, avoiding bacteria or small-scale biofilms falling off into the water. Consequently, the microbial biomass and EPS substances amount decreased markedly in the effluent of Fe/CAC filter. More importantly, Fe/CAC did significantly enhance the shaping role on microbial community of downstream DWDSs, continuously excluding OPs advantage and inhibiting EPS production. The weakening of EPS in DWDSs resulted in decrease of microbial chlorine-resistance ability and EPS-derived DBPs precursors supply. Therefore, the deterioration of water quality in DWDSs was inhibited greatly, sustainably maintaining the safety of tap water. Our findings indicated that optimizing biological activated carbon treatment by interface modification is a promising method for improving water quality in DWDSs., 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 © 2020 Elsevier Ltd. All rights reserved.)

The change of water quality was investigated in pilot-scale ozone-biological activated carbon (O 3 -BAC) filters using an emerging coconut shell-based granular activated carbon (CAC) or traditional granular activated carbon (GAC), respectively. More dissolved organic carbon (DOC) and disinfection by-products (DBPs) precursors were removed, meanwhile, less microbes, less metabolites and smaller microbial clusters were detected in the effluent of CAC compared with GAC. Sequentially, lower DBPs formation and higher disinfection efficiency were achieved in drinking water distribution systems (DWDSs). Furthermore, it was observed that extracellular electron transfer was enhanced in the attached biofilms of CAC, hence improving the microbial metabolic activity and biological removal of DOC. The results were attributed to the strong interaction of extracellular polymeric substances (EPS) with highly graphitized CAC. In addition, CAC resulted in totally different EPS in attached biofilms with superior characteristics including stronger viscosity, higher flocculating efficiency, mechanical stability and numerous binding sites for bacterial cells. Consequently, a wide range of compact interconnected biofilms formed on the surface of CAC and exhibited certain binding effect for microbial flocs and metabolites. Therefore, CAC resulted in higher microbial metabolic activity and lower release of microbes and metabolites, which was beneficial to maintain water quality safety in downstream DWDSs., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interests., (Copyright © 2020. Published by Elsevier B.V.)

Graphitic carbon nitride (g-C 3 N 4 ) has enormous potentials for photocatalysis, yet it only possesses moderate activity because of excitonic effects and sluggish charge transfer. Here, we develop a novel two-dimensional g-C 3 N 4 /WO 3 /MoS 2 (CWM) ternary nanocomposite through a facile co-calcination and a hydrothermal process to reach a highly-efficient photocatalyst for organic pollutant elimination under visible light. The WO 3 and MoS 2 nanoparticles were dispersed on the ultra-thin g-C 3 N 4 nanosheets, in which the electronegative g-C 3 N 4 facilitates formation of oxygen vacancies in WO 3 . Compared to pure g-C 3 N 4 , WO 3 , and binary composites, CWM exhibited higher photocatalytic activities for various organic pollutants removal under visible light irradiation. For instance, the CWM showed a removal ratio of ∼99% for RhB after only 10 min irradiation of visible light (λ > 420 nm) and nearly 100% for ciprofloxacin after 2 h of operation. The results showed that OH radicals are the main active species for organic degradation, which suggests a direct Z-scheme heterojunction in CWM that improved spatial separation of charge carries. Furthermore, the collection of electrons is significantly enhanced by MoS 2 for oxygen reduction reaction, and the increased oxygen vacancies of WO 3 further enhanced the separation of electron-hole pairs; therefore, it led to an effective suppression of charge carriers recombination. The above synergistic effects of ternary photocatalyst result in higher photocatalytic oxidation performance for wastewater treatment compared with pure WO 3 , g-C 3 N 4 and their binary composites., (Copyright © 2019. Published by Elsevier Ltd.)

Sodium hypochlorite (NaClO) solution is a typical cleaning agent for membrane fouling. However, it can damage membrane chemical structures and produce toxic disinfection byproducts, which in turn reduces the membrane performance. This study focuses on the fabrication of active membranes thereby overcoming the limitations of chemical cleaning. A hierarchical active poly(vinylidene fluoride) membrane with polydopamine/polyethyleneimine (PEI) co-supported iron nanoparticle (Fe NP) catalysts was successfully constructed and denoted as a Fe-HP-membrane. The Fe-HP-membrane exhibited excellent advanced oxidation activity with maximum flux recoveries (∼85% with bovine serum albumin [BSA] and ∼95% with humic acid [HA] solutions). After the static experiment of ∼30 days, the BSA proteins and HA successfully desorbed from the membrane surface. Especially, with a trace amount of hydrogen peroxide (H 2 O 2 ) flowing over the surface of the Fe-HP-membrane, highly exposed active sites were observed. Membrane cleaning showed that the "outside-to-in" active surfaces generated considerable amounts of • OH radicals at the interface of BSA or HA and the fouled membrane. As a result, the unwanted foulants were successfully removed from the membrane interface, enabling multiple use of the Fe-HP-membrane. Therefore, backwashing with a small amount of H 2 O 2 (0.33 wt %) covered ∼20% of the flux. In contrary, backwashing with NaClO (1 wt %) can only achieve a flux recovery of ∼10% after six consecutive BSA filtration cycles. The Fe-HP-membrane exhibited better HA foulant removal (a flux recovery of ∼51%) after backwashing with H 2 O 2 than using NaClO (a flux recovery of ∼43%). Our findings demonstrate a new platform for water treatment and regeneration of fouled membranes.

The effects of disinfection efficiency on microbial communities and the corrosion of cast iron pipes in drinking water distribution systems (DWDSs) were studied. Two annular reactors (ARs) that simulated actual running conditions with UV/Cl 2 disinfection and chlorination alone were used. High chlorine consumption and corrosion rate were found in the AR with UV/Cl 2 . According to functional genes and pyrosequencing tests, a high percentage of iron recycling bacteria was detected within the biofilm of the AR with Cl 2 at early running stage, whereas siderophore-producing bacteria were dominant in the biofilm of the AR with UV/Cl 2. At the early running stage, the sequential use of UV light and an initial high chlorine dosage suppressed the biomass and iron-recycling bacteria in both bulk water and biofilms, thereby forming less protective scales against further corrosion, which enhanced chlorine consumption. Non-metric multidimensional scaling analysis showed that the bacterial communities in the ARs shaped from within rather than being imported by influents. These results indicate that the initial high disinfection efficiency within the distribution system had not contributed to the accumulation of iron-recycling bacteria at the early running stages. This study offer certain implications for controlling corrosion and water quality in DWDSs., (Copyright © 2019. Published by Elsevier B.V.)

Drinking water distribution systems (DWDS) may be a "Trojan Horse" for some waterborne diseases caused by opportunistic pathogens (OPs). In this study, two simulated DWDS inoculated with groundwater were treated with chlorine (Cl 2 ) and ultraviolet/chlorine (UV/Cl 2 ) respectively to compare their effects on the OPs distributed in four different phases (bulk water, biofilms, corrosion products, and loose deposits) of DWDS. 16S rRNA genes sequencing and qPCR were used to profile microbial community and quantify target genes of OPs, respectively. Results showed that UV/Cl 2 was more effective than single Cl 2 to control the regrowth of OPs in the water with the same residual chlorine concentration. However, the OPs inhabiting the biofilms, corrosion products, and loose deposits seemed to be tolerant to UV/Cl 2 and Cl 2 , demonstrating that OPs residing in these phases were resistant to the disinfection processes. Some significant microbial correlations between OPs and Acanthamoeba were found by Spearman correlative analysis (p < 0.05), demonstrating that the ecological interactions may exist in the DWDS. 16S rRNA genes sequencing of water samples revealed a significant different microbial community structure between UV/Cl 2 and Cl 2 . This study may give some implications for controlling the OPs in the DWDS disinfected with UV/Cl 2 ., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Using sodium alginate hydrogel as skeleton, in combination with chitosan and magnetic Fe 3 O 4 , a new type of magnetic chitosan/sodium alginate gel bead (MCSB) was prepared. Adsorptive removal of Cu(II) from aqueous solutions was studied by using the MCSB as a promising candidate in environmental application. Different kinetics and isotherm models were employed to investigate the adsorption process. Based on Fourier transform infrared spectroscopy, field-emission scanning electron microscope, CHNS/O elements analysis, vibration magnetometer, and various means of characterization, a comprehensive analysis of the adsorption mechanism was conducted. The MCSB had a good magnetic performance with a saturation magnetization of 12.5 emu/g. Elemental analysis proved that the addition of chitosan introduced a considerable amount of nitrogen-rich groups, contributing significantly to copper adsorption onto gel beads. The contact time necessary for adsorption was optimized at 120 min to achieve equilibrium. Experimental data showed that the adsorption process agreed well with the Langmuir isotherm model and the pseudo-second-order kinetics model. The theoretical maximum adsorption capacity of MCSB for Cu(II) could reach as high as 124.53 mg/g. In conclusion, the MCSB in this study is a novel and promising composite adsorbent, which can be applied for practical applications in due course.

The effects of ozone-biologically activated carbon (O 3 -BAC) treatment with various phosphate doses (0, 0.3 or 0.6 mg/L) were investigated on the formation of disinfection by-products (DBPs) and occurrence of opportunistic pathogens (OPs) in drinking water distribution systems (DWDSs) simulated by annular reactors (ARs). It was found that the lowest DBPs and the highest inactivation of OPs such as Mycobacterium spp., Mycobacterium avium, Aeromonas spp., Pseudomonas aeruginosa and Hartmanella vermiformis, occurred in the effluent of the AR with 0.6 mg/L phosphate addition. Based on the results of different characterization techniques, for the AR with 0.6 mg/L phosphate-enhanced O 3 -BAC treatment, dissolved organic carbon in the influent exhibited the lowest concentration and most stable fraction due to the improved biodegradation effect. Moreover, the total amount of suspended extracellular polymeric substances (EPS) in the bulk water of the AR decreased greatly, resulting in the lowest chlorine consumption and DBPs formation in the AR. In Fourier transform infrared spectra of the suspended EPS, the amide II band (1600-1500 cm -1 ) disappeared and the protein/polysaccharide ratio decreased remarkably, indicating the destruction of protein and a decrease in hydrophobicity. Moreover, β-sheets and α-helices in the protein secondary structures were degraded while the random coils increased sharply as phosphate addition increased to 0.6 mg/L, inhibiting microbial aggregation and hence weakening the chlorine-resistance capability. Thus, most of the OPs in suspended biofilms were more easily inactivated by residual chlorine, resulting in the lowest OPs occurrence in the effluent of the AR. Our findings indicated that enhancing the efficiency of the BAC filter by adding phosphate is a promising method for improving water quality in DWDSs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Bacterial community structure and iron corrosion were investigated for simulated drinking water distribution systems (DWDSs) composed of annular reactors incorporating three different treatments: ozone, biologically activated carbon and chlorination (O 3 -BAC-Cl 2 ); ozone and chlorination (O 3 -Cl 2 ); or chlorination alone (Cl 2 ). The lowest corrosion rate and iron release, along with more Fe 3 O 4 formation, occurred in DWDSs with O 3 -BAC-Cl 2 compared to those without a BAC filter. It was verified that O 3 -BAC influenced the bacterial community greatly to promote the relative advantage of nitrate-reducing bacteria (NRB) in DWDSs. Moreover, the advantaged NRB induced active Fe(III) reduction coupled to Fe(II) oxidation, enhancing Fe 3 O 4 formation and inhibiting corrosion. In addition, O 3 -BAC pretreatment could reduce high-molecular-weight fractions of dissolved organic carbon effectively to promote iron particle aggregation and inhibit further iron release. Our findings indicated that the O 3 -BAC treatment, besides removing organic pollutants in water, was also a good approach for controlling cast iron corrosion and iron release in DWDSs., (Copyright © 2017. Published by Elsevier B.V.)

Sewage sludge and bagasse were used as raw materials to produce cheap and efficient adsorbent with great adsorption capacity of Pb(2+). By pyrolysis at 800 °C for 0.5 h, the largest surface area (806.57 m(2)/g) of the adsorbent was obtained, enriched with organic functional groups. The optimal conditions for production of the adsorbent and adsorption of Pb(2+) were investigated. The results of adsorb-ability fitted the Langmuir isotherm and pseudo-second-order model well. The highest Pb(2+) (at pH = 4.0) adsorption capacity was achieved by treating with 60% (v/v) HNO3. This is a promising approach for metal removal from wastewater, as well as recycling sewage sludge and bagasse to ease their disposal pressure., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The effectiveness of UV and chlorination, used individually and sequentially, was investigated in killing pathogenic microorganisms and inhibiting the formation of disinfection by-products in two different municipal wastewaters for the source water of reclaimed water, which were from a microfilter (W1) and membrane bioreactor (W2) respectively. Heterotrophic plate count (HPC), total bacteria count (TBC), and total coliform (TC) were selected to evaluate the efficiency of different disinfection processes. UV inactivation of the three bacteria followed first-order kinetics in W1 wastewater, but in W2 wastewater, the UV dose-response curve trailed beyond approximately 10 mJ/cm2 UV. The higher number of particles in the W2 might have protected the bacteria against UV damage, as UV light alone was not effective in killing HPC in W2 wastewater with higher turbidity. However, chlorine was more effective in W2 than in W1 for the three bacteria inactivation owing to the greater formation of inorganic and organic chloramines in W1 wastewater. Complete inactivation of HPC in W1 wastewater required a chlorine dose higher than 5.5 mg/L, whereas 4.5 mg/L chlorine gave the equivalent result in W2 wastewater. In contrast, sequential UV and chlorine treatment produced a synergistic effect in both wastewater systems and was the most effective option for complete removal of all three bacteria. UV disinfection lowered the required chlorine dose in W1, but not in W2, because of the higher chlorine consumption in W2 wastewater. However, UV irradiation decreased total trihalomethane formation during chlorination in both wastewaters., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Several disinfection processes of ultraviolet (UV), chlorine or UV followed by chlorine were investigated in municipal wastewater according to the inactivation of Escherichia coli, Shigella dysenteriae and toxicity formation. The UV inactivation of the tested pathogenic bacteria was not affected by the quality of water. It was found that the inactivated bacteria were obviously reactivated after one day in dark. Fluorescent light irradiation increased the bacteria repair. The increase of UV dosage could cause more damage to bacteria to inhibit bacteria self-repair. No photoreactivation was detected when the UV dose was up to 80 mJ/cm2 for E. coli DH5alpha, and 23 mJ/cm2 for S. dysenteriae. Nevertheless, sequential use of 8 mJ/cm2 of UV and low concentration of chlorine (1.5 mg/L) could effectively inhibit the photoreactivation and inactivate E. coli below the detection limits within seven days. Compared to chlorination alone, the sequential disinfection decreased the genotoxicity of treated wastewater, especially for the sample with high NH3-N concentration.

A new biomimetic absorbent, cellulose acetate (CA) embedded with triolein (CA-triolein), was prepared and applied for the removal of persistent organic pollutants (POPs) from micro-polluted aqueous solution. The comparison of CA-triolein, CA and granular activated carbon (GAC) for dieldrin removal was investigated. Results showed that CA-triolein absorbent gave a lowest residual concentration after 24 h although GAC had high removal rate in the first 4 h adsorption. Then the removal efficiency of mixed POPs (e.g. aldrin, dieldrin, endrin and heptachlor epoxide), absorption isotherm, absorbent regeneration and initial column experiments of CA-triolein were studied in detail. The linear absorption isotherm and the independent absorption in binary isotherm indicated that the selected POPs are mainly absorbed onto CA-triolein absorbent by a partition mechanism. The absorption constant, K, was closely related to the hydrophobic property of the compound. Thermodynamic calculations showed that the absorption was spontaneous, with a high affinity and the absorption was an endothermic reaction. Rinsing with hexane the CA-triolein absorbent can be regenerated after absorption of POPs. No significant decrease in the dieldrin removal efficiency was observed even when the absorption-regeneration process was repeated for five times. The results of initial column experiments showed that the CA-triolein absorbent did not reach the breakthrough point at a breakthrough empty-bed volume (BV) of 3200 when the influent concentration was 1-1.5 microg/L and the empty-bed contact time (EBCT) was 20 min.

A type reactor with on-line O3 was used to do further research of the disinfection of total bacteria, E. coli and degradation of 2,4-DCP. The result was obtained in the following conditions. Only UV-radiation, O3 applied by other machine and by the reactor itself, and other conditions were changed to study the disinfection and degradation. The result showed the satisfied effect of disinfection and degradation would be achieved by using UV/O3 applied outside and when the flow rate was about 400 L.h-1, on-line O3 could be produced and make high efforts to enhance disinfection and degradation. The method of UV/O3 was a promising technology in the treatment of drinking water.

Conventional water purification technologies struggle to simultaneously address purification efficiency and energy consumption. Molecular orbital level surface micro-electric field (MEF)-driven water purification is an original and innovative concept conceived and developed by our group in recent years. The core idea involves creating electron-rich and electron-poor micro-areas on the nanomaterial surface, which drive pollutants or H2O molecules to provide electrons in the electron-poor micro-areas while other environmental factors (such as H2O2 and O2) obtain electrons in the electron-rich micro-areas. This process effectively utilizes the internal energy contained within wastewater and emerging contaminants (ECs). Centered on this core, this review systematically examines the discovery, construction, and characteristics of MEF and MEF-like systems and summarizes their application directions. The challenges, bottlenecks, and future development directions of MEF technology are also analyzed and discussed. Reviews of MEFs can facilitate the development of low-consumption, high-efficiency water purification technologies.

Emerging single‐atom catalysts (SACs) are promising in water remediation through Fenton‐like reactions. Despite the notable enhancement of catalytic activity through increasing the density of single‐atom active sites, the performance improvement is not solely attributed to the increase in the number of active sites. The variation of catalytic behaviors stemming from the increased atomic density is particularly elusive and deserves an in‐depth study. Herein, single‐atom Fe catalysts (FeSA‐CN) with different distances (dsite) between the adjacent single‐atom Fe sites are constructed by controlling Fe loading. With the decrease in dsite value, remarkably enhanced catalytic activity of FeSA‐CN is realized via the electron transfer regime with peroxymonosulfate (PMS) activation. The decrease in dsite value promotes electronic communication and further alters the electronic structure in favor of PMS activation. Moreover, the two adjacent single‐atom Fe sites collectively adsorb PMS and achieve single‐site desorption of the PMS decomposition products, maintaining continuous PMS activation and contaminant removal. Moreover, the FeSA‐CN/PMS system exhibits excellent anti‐interference performance for various aquatic systems and good durability in continuous‐flow experiments, indicating its great potential for water treatment applications. This study provides an in‐depth understanding of the distance effect of single‐atom active sites on water remediation by designing densely populated SACs. [ABSTRACT FROM AUTHOR]

An innovative strategy for synthesizing novel dual-reaction-center (DRC) catalysts from chicken manure (CM) biochar to purify wastewater that contained emerging contaminants (ECs) is proposed to synchronously address the release of ECs and improper disposal of livestock manure. A series of characterization techniques reveal the formation of a special C-O-Ca bond bridge (cation-π) structure on resourcelized CM nanosheets (RCM NSs). RCM NSs exhibit distinct selectivity and anti-interference capability for various ECs removal in complex matrices, and the water purification system remains stable after 1735 hours (equivalent to 3470 cycles) of operation. Density Functional Tomography (DFT) calculations reveal that trace of peroxymonosulfate as an inducer initiates the continuous donation of electrons from electron-rich ECs and the C-O-Ca bond bridges provide a favorable pathway for electron transfer, which facilitates the electron capture effect of dissolved oxygen in the system. This study provides a novel strategy to convert livestock manure into DRC-catalysts for developing energy-saving and high-efficiency environmental remediation technologies. Highlights: • The chicken manure biochar was converted into a water purification catalyst through a graphitization process. • Resourcelized catalyst RCM NSs had superior removal capability for various ECs triggering by trace of PMS. • RCM NSs could quickly eliminate ECs and simultaneously drive NOM removal, even with NOM interference. • The key role of dissolved oxygen for water purification was illustrated in RCM NSs system. [ABSTRACT FROM AUTHOR]

Rural pollution is largely caused by the accumulation of waste biomass, such as livestock manure and crop straw, which is extremely difficult to dispose of due to the simultaneous need to non-destructively treat metal and organic matter. Untreated fecal waste fluxes have contributed to more than 870,000 sanitation-related deaths annually worldwide. The existing disposal methods are accompanied by large amounts of energy and resource consumption and GHG emissions, which are not conducive to achieving the UN Sustainable Development Goals (SDGs). Herein, we pioneer a new approach to sustainable resource utilization by subjecting unprocessed livestock manure to a Dual-Reaction-Center (DRC) Fenton-like catalyst directly through the ordered bonding of intrinsic metal-organic species via an in situ 2-stage calcination-annealing process with zero emissions and zero pollution. The directional electron transfers along with the generated metal cation–π interactions during the resourcelized process led to the formation of electron-rich/-poor microregions. Through triggering by a small amount of hydrogen peroxide (H2O2), the removal of refractory pollutants reaches 100% within a very short time in this system, which also shows a long-term purification effect on actual wastewater, accompanied by the utilization of intrinsic energy from the pollutants and dissolved oxygen. This study is expected to advance the resource utilization of rural waste and the sustainable development of environmental factors. [ABSTRACT FROM AUTHOR]

A low-consumption water purification system is firstly constructed based on a new dual-reaction-center (DRC) catalyst molybdenum-doped zinc sulfide (Mo-ZnS, MZS) with a confined nonequilibrium surface. The extremely strong electron trapping ability of the Mo site is realized by the substitution of Mo for ZnS lattice. In this way, the electrons of emerging contaminants (ECs) are efficiently transferred to the nonequilibrium surface through the oriented interface process (Mo-S-Zn bond bridge), and obtained by the natural dissolved oxygen (DO) to generate hydrogen peroxide (H 2 O 2) under trace H 2 O 2 trigger without light and electricity assistant. The highest yield of H 2 O 2 is even up to ∼230 % of the initial value, and the ECs removal can reach 100 % within 60 min, which is far superior to conventional Fenton catalysts. This work realized the efficient utilization of the contaminant electrons through the construction of Mo-S-Zn bond bridge, which greatly reduced the energy consumption of water purification and improved the resourcefulness of ECs. [Display omitted] • DRC catalyst MZS with the confined nonequilibrium surface is first prepared. • MZS shows excellent performance for water purification. • Efficient H 2 O 2 generation is achieved without light and electricity assistant. • The highest H 2 O 2 concentration reaches up to ∼230 % of the initial concentration. • ECs electrons are efficiently utilized in ORR processes and water purification. [ABSTRACT FROM AUTHOR]

In the present work, direct ink writing (DIW) technology was utilized to fabricate geopolymer-based anisotropic membranes from metakaolin precursors. For evaluation of filtration performance in water treatment, the 3D-printed membranes were characterized, tested systematically, compared with a molded membrane and benchmarked against other geopolymer and ceramic membranes reported in the literature. With a novel approach, geopolymer-yttria stabilized zirconia (YSZ) ultrafiltration (UF) membrane with configuration of relatively dense rejection layer and gradient macroporous support was obtained via a one-step process of alkaline activation, DIW and curing, starting from a computer aided design (CAD) figure of an isotropic solid plate. The achievement of such structure resulted from the printing procedure leveraging both rheological properties of geopolymer ink and printing principle of DIW. The printed membrane displayed very high permeances (1453 L/(m2hbar) for pure water and 1311 L/(m2hbar) for suspension of 80-nm alumina particles), high rejection efficiency (98.4% for suspension of 80-nm alumina particles) and good chemical stability in alkaline solution. The present work provided the first-time report on additive manufacturing of geopolymer-based asymmetric UF membranes with superb performance for water treatment. [Display omitted] • Geopolymer-based membranes with anisotropic structures were fabricated from a process mainly comprising direct ink writing. • Ink rheological property and printing process were leveraged to achieve such configuration. • The produced membrane displayed high permeance and rejection efficiency in water treatment. • The first-time report on 3D printing of geopolymer-based asymmetric membranes was provided in this work. [ABSTRACT FROM AUTHOR]

Abstract: Ag–AgBr was deposited onto mesoporous alumina (MA) and titanium-doped MA by a deposition–precipitation method. The photocatalytic activity and the dissolution of Ag+ from different catalysts were investigated during the photodegradation of 2-chlorophenol (2-CP) and phenol in ultrapure water and tap water with visible-light irradiation. With the increase in doped titanium, the Ag+ dissolution decreased with a decrease in the photocatalytic activity. Ag–AgBr/MA-Ti1 was considered the better catalyst for practical applications because its Ag+ dissolution was minimal (0.4mgL−1 in ultrapure water and 5μgL−1 in tap water), although its photoactivity was slightly less than that of Ag–AgBr/MA. The dissolution of Ag+ was related to a charge–transfer process based on the study of cyclic voltammetry analyses under a variety of experimental conditions. The results suggested that several types of anions in the water, including CO3 2−, SO4 2−, and Cl−, could act as electron donors that trap the photogenerated holes on Ag nanoparticles to facilitate electron circulation; this would decrease the release of Ag+. Our studies indicated that the catalyst had a higher activity and stability in water purification. [Copyright &y& Elsevier]

• Mesoporous reduction state cobalt species-doped silica nanospheres are first prepared. • Excellent activity is realized in mp -RSCo-SiO 2 NSs/H 2 O 2 system. • Efficient dual-pathway degradation of pollutant is achieved in Fenton-like process. • Pollutants replace H 2 O 2 as electron donors for the mp -RSCo-SiO 2 NSs system. • A new interfacial Fenton-like reaction mechanism involving pollutants is proposed. A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO 2) nanospheres (mp -RSCo-SiO 2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1–10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co 3 O 4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO 2 framework through forming Co O Si bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of "Pollutants → Co2+/0-SiO 2 ". The obtained electrons from pollutants were transferred to the catalyst surface and captured by H 2 O 2 , resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-atom Fe, Co, and Cu on the supports with similar properties are synthesized. • Single-atom catalysts were efficient in degradation of the pollutants. • The durability of single-atom metal is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4. • Co(IV) = O was evidenced to be contribute predominantly to pollutant degradation. Single-atom metal catalyzed peroxymonosulfate (PMS) activation shows great potential in water treatment; and the activity of various metal centers have been explored. The properties of the support contribute significantly to the catalytic performance of the metal centers. The knowledge on the intrinsic distinctions of the elements in single-atom catalyzed PMS activation is, however, relatively in lack. In this work, via a facile one-step method, three representative elements of Fe, Co, and Cu were configured in a metal − N 4 structure and anchored on N-doped carbon matrix with similar composition and structure. The atomic dispersity of the metal centers was experimentally substantiated by electronic microscopic technique in atomic scale and X-ray absorption spectroscopy. All these single-atom metal centers exhibit high activity in PMS activation for selective degradation of the organic pollutants, while the durability of the single-atom metal centers is vastly distinct as examined in continuous flow-mode. The water treatment capacity is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4 for the elimination of 0.1 mM 4-chlorophenol from water. Based on the analysis of the qunching effect by various probe molecules and electron spin resonance spectra at various reaction conditions, the high-valent Co(IV) O species is proposed to be the predominant active species for pollutant degradation in Co − N 4 catalyzed PMS activation. The findings in this work sheds light on the desgin of efficent and durable single-atom catalyst for water treatment. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Iodide was inserted in the interlayer of the multilayered Bi 2 WO 6 for better activity. • I 0.30 -Bi 2 WO 6 was highly effective for pollutants removal under visible light. • The enlarged layer spacing enhanced effective charge separation and transfer. • The main active species were holes whose oxidative power was enhanced after I− insertion. Abstract An iodine intercalated Bi 2 WO 6 was fabricated by a facile hydrothermal method (160 °C, 2 h) and characterized by field emission scanning electron microscope, high resolution transmission electron microscopy, nitrogen adsorption/desorption isotherms, X-ray diffraction and X-ray photoelectron spectroscopy, Fourier-transform infrared and UV-Vis diffuse reflectance spectra. The I 0.30 -Bi 2 WO 6 with an I/W molar ratio of 0.30 was highly effective for the degradation and mineralization of 2-chlorophenol, rhodamine B, bisphenol A, phenol, ciprofloxacin and sulfamethoxazole in water under visible light. Furthermore, the visible-light-driven photocatalytic activity of Bi 2 WO 6 was enhanced 3.1 times by the introduction of I−. The characterized results indicated that I− mainly inserted into the interlayer of Bi 2 WO 6 , expanding the layer spacing, favoring the efficient charge separation and transfer and prohibiting the recombination of the photogenerated electrons and holes. Specially, the XPS analysis indicated the I− ions substitued the absorbed oxygen to chemically bond in the layered Bi 2 WO 6 , resulting in the change of the electric charge distribution of Bi 2 WO 6. Moreover, the BET surface area was increased from 25.2 m2 g−1 for Bi 2 WO 6 to 66.7 m2 g−1 for I 0.30 -Bi 2 WO 6 for more surface active sites. In addition, the band gap was narrowed for expanded optical absorption in the visible light region. ESR and radicals trapping experiments verified holes were the main active species for the degradation of organic pollutants. Simultaneously, the more positive potential of valence band in iodine intercalated Bi 2 WO 6 could enhance the oxidative power of the photogenerated holes, resulting in the efficient removal of refractory organic pollutants in water. [ABSTRACT FROM AUTHOR]

Single-atom Fe catalysis has exhibited remarkable potentials in water treatment applications. However, rational design of single-atom Fe catalysts with controlled catalytic performance is still challenging, due to the lack of the fundamental understanding on the corelated factors of structure, property, and catalytic behavior. Herein, PMS activation performance of the single-atom Fe sites is successfully boosted by molecular-engineering on the polymeric carbon nitride (CN) framework. Benzene-1,4-diamine regulates the polymerization process, and rises the ratio of carbon/nitrogen; the valence of the single-atom Fe is thereby positively shifted, leading to favorable thermal dynamics of the high-valent Fe(IV)=O involved oxidation reaction. The carbon-rich CN supported single-atom Fe catalyst thus exhibits remarkable performance in selective degradation of a series of organic pollutants via high-valent Fe(IV)=O oxidation pathway. The findings in this work implicate the significance of electronic properties of the support as one of the essential descriptors for a robust single-atom catalyst for pollutants abatement. [Display omitted] • Benzene diamine in precursor for synthesis of single-atom Fe catalyst could positively shift the valence of Fe center. • A 5.1 times of performance improvement in bisphenol A degradation reaction was realized. • The single atom Fe catalyst with optimized valence is durable in a fixed-bed reactor. • Theoretical simulation states that positive valence of Fe center lowered the energy barrier of the catalytic reaction. [ABSTRACT FROM AUTHOR]

A visible-light-driven photocatalyst AgBr@Ag/nitrogen-doped reduced graphene oxide (AgBr@Ag/N-RGO) was prepared by a hydrothermal- in situ oxidation method, and characterized by scanning and transmission electron microscope, X-ray diffraction, Fourier-transform infrared spectra, Raman and X-ray photoelectron spectroscopy. AgBr@Ag/N-RGO exhibited high photoactivity and photostability to degrade and mineralize various organic pollutants, as demonstrated with 2-chlorophenol, phenol, bisphenol A and diphenhydramine in water under visible light. Its photoactivity was 20, 5.3, and 2.9 times higher than that of Ag/N-RGO, TiO 2- x N x , and AgBr@Ag, respectively for the photodegradation of 2-chlorophenol. The characterized results verified that Ag nanoparticles (NPs) was first chelated by N-groups of N-RGO and then enwrapped by AgBr by in-situ oxidation, which was contributed to the enhancement of interfacial electron transfer in AgBr@Ag/N-RGO. Furthermore, the two charge transfer processes were elucidated that the plasmon-induced electrons on Ag NPs core transferred to AgBr shell, and could be further transferred away together with the photoexcited electrons on AgBr by N-RGO to interact with O 2 to form O 2 − , while the electrons of pollutants were accerelated to transfer to the plasmon-induced Ag NPs by the Ag-N complex along the π-π graphitic carbon network of N-RGO, which was responsible for the photoactivity and stability of AgBr@Ag/N-RGO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zero-added conversion of chicken manure into water treatment catalyst (RCM) is realized. • Electron-poor/rich microregions are successfully constructed on RCM. • Pollutant degradation processes can be driven by a little bit of peroxymonosulfate. • RCM has excellent performance on actual wastewater treatment. • Water treatment with low consumption is achieved by utilization of pollutants. Fecal pollution in rural areas and water pollution caused by emerging contaminants (ECs) are two international environmental problems. Here, we propose a new strategy to address the two problems simultaneously through the resource utilization and harmless transformation of poultry manure as a kind of water purification catalyst with zero addition. The ordered bonding of intrinsic metal-organic species is realized in the resourcelized procedure by a one-stage calcination-annealing method, which results in the formation of electron-rich/poor microregions. With the triggering of a small amount of peroxymonosulfate (PMS), the energy/electrons of ECs are utilized by the dissolved oxygen in water driven by the electron-rich/poor microregions on the catalyst surface. As a result, the system exhibits excellent performance in removing various ECs. The degradation rate can even be maintained above 94.3 % after 10,000 cycles. This work indicates a sustainable approach to the effective utilization and treatment of rural waste and pollutants. [ABSTRACT FROM AUTHOR]

Solid solution of BiOBr and BHO (BiO(OH) 0.06 Br 0.94 ) with abundant oxygen vacancies was supported on Ag/AgBr using precipitation and deposition–precipitation methods. The photocatalyst showed high and stable photocatalytic activity for the degradation of chlorophenols and azodyes in water under visible to NIR light irradiation without any release of Ag + , which came from visible-excited AgBr and the SPR of Ag NPs in the visible and NIR region. The different interfacial charge-transfer processes were verified on the basis of cyclic voltammetry analyses and all experimental information. The conduction band (CB) electrons of photoexcited AgBr reacted with the adsorbed oxygen forming O 2 •− , while the valence band (VB) holes of AgBr were transported the VB of BiO(OH) 0.06 Br 0.94 to oxidize organic pollutants or H 2 O to • OH. The plasmon-induced electrons from Ag NPs transferred to the CB of AgBr reacting with the adsorbed oxygen to O 2 •− , while the electrons trapped on the oxygen vacancies of BiO(OH) 0.06 Br 0.94 transferred to Ag NPs recombining with the plasmon-induced holes, inhibiting the release of Ag + , and the resulted VB holes of BiO(OH) 0.06 Br 0.94 oxidized organic compound. These interfacial charge transfers evidenced the high photoactivity and photostability of BiO(OH) 0.06 Br 0.94 /Ag/AgBr. [ABSTRACT FROM AUTHOR]

A twofold cation-π-assembled catalyst consisting of honeycomb microsphere-like MoS 2 cross-linking g-C 3 N 4 hybrid (HM-MS/CN) is first developed to address the bottleneck of excessive resource and energy consumption in Fenton chemistry. A series of modern characterization techniques combined with theoretical calculation are used to reveal and verify the twofold cation-π interaction (Mo-O-C and Mo-S-C bonding bridges). It is found that the electrons of pollutants can be captured by H 2 O 2 and O 2 through the twofold cation-π interaction during Fenton-like reaction, which inhibits the oxidative decomposition of H 2 O 2 and promotes its hydroxylation. As a result, HM-MS/CN shows excellent performance for water purification by initiating pollutants as electron donors substituting H 2 O 2 consumption under mild natural conditions, and the actual consumption of H 2 O 2 in this system is only 6–8% of that in the common Fenton systems. This discovery is of great significance for the development of novel water purification technology with high efficiency and low consumption. [Display omitted] • A twofold cation-π-assembled catalyst consisting of HM-MS/CN is first prepared. • HM-MS/CN shows excellent performance for actual water purification. • The actual consumption of H 2 O 2 is only 6–8% of that in the common Fenton systems. • Twofold cation-π interaction based on Mo-O-C and Mo-S-C is responsible for excellent performance. • Pollutants act as electron donors substituting H 2 O 2 consumption via twofold cation-π. [ABSTRACT FROM AUTHOR]

[Display omitted] • HA was efficiently mineralized in an Fe0-Fe y C z /Fe x -GZIF-8-rGO aqueous suspension. • The polar alkane-alcohol complex was formed with more single electrons on –OH group. • The polar alkane-alcohol complex enhanced its surface cleavage and •OH formation. • The reaction kinetics depends on the surface complex characteristic. Natural organic matter (NOM) has diverse negative impacts on water purification, however, preventing them occurrence very difficult. Herein, humic acid (10 mg/L), as the main component of NOM, is completely destructed within 120 min in the Fe0-Fe y C z /Fe x -GZIF-8-rGO air-saturated aqueous suspension without additional energy input, while its mineralization is followed by three kinetic constants within 480 min. During the process, HA was first complexed with Fe0-Fe y C z /Fe x -GZIF-8-rGO by π-π interaction and H-bonding interaction and cleaved to aromatic compounds and then to alkanes and alcohols with some small acids before 120 min. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations confirmed that a strongly polarized alkane-alcohol complex was formed after 150 min with an electron-rich hydroxyl group area in alcohol and an electron-poor alkane area. Moreover, the more electrons of alkane in the complex are delocalized and trapped by O 2 , with the adsorption of the alkane-alcohol complex on the catalyst surface based on the analyses of both electrochemical impedance spectroscopy (EIS) and chronoamperometry, greatly promoting the surface cleavage and hydrolytic process of alkane in the complex and producing more •OH for pollutant degradation than it does from the HA surface complex, which results in the highest mineralization rate in the period of 150–390 min. Our findings demonstrated that the current system is very promising for complex mixture-containing water purification without additional energy. [ABSTRACT FROM AUTHOR]