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Abstract Effects of sulfadiazine and ciprofloxacin on microorganisms in biofilm of drinking water distribution systems (DWDSs) were studied. The results verified that the increases of 16S rRNA for total bacteria and bacterial genus Hyphomicrobium were related to the promotion of antibiotic resistance genes (ARGs) and class 1 integrons (int1) in DWDSs with sulfadiazine and ciprofloxacin. Moreover, the bacteria showed higher enzymatic activities in DWDSs with sulfadiazine and ciprofloxacin, which resulted in more production of extracellular polymeric substances (EPS). The higher contents of EPS proteins and secondary structure β -sheet promoted bacterial aggregation and adsorption onto surface of pipelines to form biofilm. EPS can serve as a barrier for the microorganisms in biofilm. Therefore, the biofilm bacterial communities shifted and the 16S rRNA for total bacteria increased in DWDSs with antibiotics, which also drove the ARGs promotion. Furthermore, the two antibiotics exhibited stronger combined effects than that caused by sulfadiazine and ciprofloxacin alone. Graphical abstract Image 1 Highlights • Response of biofilm to sulfadiazine and ciprofloxacin in DWDSs was studied. • Bacterial community shift and total bacteria increase related to ARGs promotion. • The bacteria exhibited higher enzymatic activity and produced more EPS. • The higher contents of proteins and β -sheet in EPS promoted biofilm formation. • Sulfadiazine and ciprofloxacin exhibited stronger combined effects on biofilm. [ABSTRACT FROM AUTHOR]

Abstract: The cathodic reduction of complex-state copper(II) was investigated in a dual chamber microbial fuel cell (MFC). The inner resistance of MFC system could be reduced in the presence of ionizing , however, mass transfer was hindered at higher ammonia concentration. Thermodynamic and electrochemical analyses indicated that the processes of complex dissociation and copper reduction were governed by the ratio of T[Cu]:T[NH3] and the pH of solution. The reduction of could be achieved via two possible pathways: (1) releasing Cu2+ from , then reducing Cu2+ to Cu or Cu2O and (2) accepting an electron and forming , and depositing as Cu or Cu2O consequently. At initial concentration of 350mg T[Cu] L−1, copper removal efficiency of 96% was obtained at pH=9.0 within 12h (with △Cu/△COD=1.24), 84% was obtained at pH=3.0 within 8h (with △Cu/△COD=1.72). was reduced as polyhedral deposits on the cathode. [Copyright &y& Elsevier]

Abstract 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. Graphical abstract Image 1 Highlights • Opportunistic pathogens in the water, biofilms, corrosion products, and loose deposits of DWDS were quantified respectively. • UV/free chlorine controlled the opportunistic pathogens in water more efficiently than single chlorine. • Opportunistic pathogens in the biofilms, corrosion products and loose deposits were tolerant to UV/free chlorine. • Potential microbial correlations existed between the target opportunistic pathogens. • Apparent shift of bacterial community was captured in both ARs disinfected with UV/free chlorine and chlorine. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Effect of cast iron pipe corrosion on N-DBPs formation in simulated DWDSs was investigated. • More N-DBPs, DOC, ATP and iron particles were detected in the bulk water of corroded DWDSs. • Corroded cast iron pipes were equivalent to a unique microbial interface in DWDSs. • The EPS characteristics of corroded DWDSs caused a large supply of N-DBPs precursors. • The interaction among iron particles, biofilms, and chlorine in DWDSs significantly affected water quality stability. [ABSTRACT FROM AUTHOR]

The effects of synchronous variations of influent salinity with the elevation of NH 4 +-N concentration on nitrification performance and microbial community structure of bioreactor are often ignored. In this study, we investigated the dynamic response of nitrifying activated sludge to synchronously increased salinity and ammonia loading rate (ALR) in a nitrification membrane bioreactor (MBR). We found that the increase in influent salinity above 1% (from 0.91 to 1.32%) led to the deterioration of the nitrification performance of the MBR. The combined inhibition effect of salinity (1.32%), free ammonia (FA, an average of 1.37 mg/L), and free nitrous acid (FNA, an average of 0.155 mg/L) on nitrite-oxidizing bacteria (NOB) resulted in long-term (35 days) nitrite accumulation. The further increase of salinity and ALR exhibited little influence on the nitrification performance of MBR after the activated sludge had adapted to high salinity (>1%), effective nitrification performance was achieved at high ALR up to 1.71 kg NH 4 +-N/m3·d and high salinity (2.13%). The microbial analysis showed that the elevated salinity and accumulation of FNA reshaped the microbial community structure of ammonia-oxidizing bacteria (AOB) and NOB. The dominant species of AOB and NOB shifted from the salinity-resistant species Nitrosomonas aestuarii to the species Nitrosomonas mobilis with dual resistant to salinity and FNA, and from non-salinity-resistant species Candidatus Nitrospira defluvii to salinity-resistant species Nitrobacter winogradskyi and Nitrospira marina , respectively. Therefore, the salinity of 1% may be a critical level for the nitrification performance and the shift in the nitrifier community of activated sludge without salinity acclimation. [Display omitted] • The elevation of salinity above 1% deteriorated the nitrification performance. • The elevation of salinity above 1% reshaped the nitrifier community. • The dominant AOB shifted from Nitrosomonas aestuarii to Nitrosomonas mobilis. • Nitrobacter winogradskyi and Nitrospira marina are predominant NOB at high salinity. [ABSTRACT FROM AUTHOR]

Abstract Algae and mercury (Hg) are ubiquitous in marine environments. In this study, we investigated the effects of a typical marine algae of diatom Skeletonema costatum on Hg methylation by an iron-reducing bacterium of Geobacter sulfurreducens (G. sulfurreducens) PCA. In the absence of Skeletonema costatum , the bacterial MeHg production rate maximized at 104.06 ± 11.7 ng L−1 h−1 with a high Hg level, while the highest methylation efficiency was achieved at a low Hg concentration. The existence of Skeletonema costatum greatly inhibited the capability of G. sulfurreducens PCA to methylate Hg. With the increase in algal biomass, there was a significant mitigation of MeHg formation and Hg0 release, leaving a considerable proportion of immobilized Hg2+ species (up to 47%) associated with algal cell materials. These results suggest that marine algae are crucial in determining the bioavailability of Hg contaminants and the methylating potential of G. sulfurreducens PCA. Highlights • Marine algae of Skeletonema costatum was insignificant in Hg methylation. • G. Sulfurreducens PCA was capable of bacterial methylation of Hg. • Bacterial methylation depended on initial Hg level and active algal biomass. • Bacterial methylation of Hg was inhibited by Skeletonema costatum. • Algal biomass was crucial in determining the distribution and transformation of Hg. [ABSTRACT FROM AUTHOR]

Information on the association between tea drinking and semen quality is limited. Little is reported on whether tea drinking is benefit to sperm quality. This cross-sectional and longitudinal study was conducted between April 2017 and July 2018. Participants were healthy men who were screened as potential sperm donors recruited at the Hubei Province Human Sperm Bank of China. A structured questionnaires containing sociodemographic information, daily habits, sperm collection-related information was completed for each participant at interview. Repeated semen samples were taken to examine the sperm parameters, including sperm volume, sperm concentration, sperm count, progressive motility, and total motility. A total of 1385 men with 6466 sperm samples were included in this study. Two groups were compared: tea drinking men (389, 28.1%) and non-tea drinking men (996, 71.9%). Compared with subjects who never drink tea, the analyses showed that sperm concentration and total sperm count were higher in tea-consuming subjects. A 10-year period or more duration of tea drinking significantly increased semen concentrations by 16.27% (P < 0.05). Sperm concentration was increased in subjects with a frequency of tea drinking of 3 days or more per week (P < 0.05) or, among men who were occasional alcohol drinkers, when tea concentration was weak (P < 0.05). No evidence of trend effects (P for trend > 0.05) or interaction effects (P for interaction > 0.05) between tea consumption and sperm quality, respectively. Our findings provide evidence that tea drinking may improve male reproductive health. Long-term, frequent, weak tea drinking tends to increase sperm quality among men with low BMI or health-related behaviors like smoking or alcohol intake. [Display omitted] • Long-term of tea drinking significantly increased sperm concentration. • Frequent of tea drinking was associated with a higher sperm count in occasional alcohols consumers. • Frequent of tea drinking was associated with a higher progressive sperm motility in occasional alcohols consumers. • Weak tea drinking was associated with greater total sperm count among occasional alcohols consumers. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Effect of biofiltration with Cu/GAC on DBPs and pathogenic bacteria were investigated. • Cu/GAC exhibited enhanced organic pollutants adsorption capacity compared with GAC. • More DOC, DBPs precursors, and EPS were detected in the effluent of Cu/GAC biofilter. • Cu/GAC successfully shaped the microbial community in the bulk water. • It is controversial that Cu/GAC can be used as BAC carrier materials. [ABSTRACT FROM AUTHOR]

Abstract: AgBr was creatively immobilized on a magnetic substrate (SiO2-coated Fe3O4 nanoparticle, SFN) to achieve magnetic separation after visible light-driven photocatalytic oxidation (PCO). The resulted Ag/AgBr/SFN was characterized by TEM, vibrating sample magnetometer and other techniques. It is found that the average diameter of the Ag/AgBr/SFN particle is less than 20nm. The typical superparamagnetic behavior of Ag/AgBr/SFN implies that the catalyst can be magnetically separated. The physicochemical features of the used Ag/AgBr/SFN after visible light irradiation were not dramatically changed by X-ray diffraction, UV–Vis diffuse reflectance spectra and Fourier transform-infrared analysis. SiO2 interlayer was proven to slightly increase the degradation efficiency for an azo dye Acid Orange 7. UV–Vis spectra and HPLC analysis indicated that the dye was oxidized and decomposed. The photoactivity of Ag/AgBr/SFN was partly maintained after successive PCO under visible light. In order to evaluate the roles of e−–h+ pairs and reactive oxygen species, the quenching effect was examined by employing Ag/AgBr/SFN and commercial TiO2 (P-25) under visible light (λ >400nm) and UV-A irradiation, respectively. Active h+ and the resulting OH played the major roles for degradation. The effect of active h+ and OH were proven to be highly dependent on the concentration of photocatalysts. The effect of OH was more obvious for P-25, while that of active h+ was more predominant for Ag/AgBr/SFN. [Copyright &y& Elsevier]

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. [Display omitted] • Trace phosphate did promoted microbial regrowth in drinking water distribution systems. • The extracellular polymeric substances (EPS) exhibited higher content and molecular weight due to trace phosphate. • Higher flocculating efficiency and tightness degree of EPS contributed to strong chlorine-resistance ability. • The balance of EPS production and biodegradation caused disinfection by-products stabilization. • Trace phosphorus polluted water source intensified the microbiological risk of tap-water. [ABSTRACT FROM AUTHOR]

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. Efficiently improved organics and dyes degradation system is acquired using a 2-D g-C 3 N 4 /WO 3 /MoS 2 ternary nanocomposite which has improved spatial separation of charge carries and facilitated collection of electrons under visible light. Image 1 • 2-D CWM was constructed through a facile co-calcination and a hydrothermal process. • Electronegative g-C 3 N 4 facilitates the formation of oxygen vacancies in WO 3. • High rates of degradation are obtained for various organic contaminants under visible light. • The CWM shows Z-scheme heterostructure in photogenerated charges separation. • MoS 2 further hinders the charge recombination by consuming electrons for ORR. [ABSTRACT FROM AUTHOR]