In this study, the effects of pre-oxidants permanganate (PM), persulfate (PS), hydrogen peroxide (PO), and ozone (OZ)) and/or adsorption on pseudoboemite-chitosan shell magnetic nanoparticles (ACMNs) on haloacetonitrile (HAN) and trichloronitromethane (TCNM) formation from aspartic acid (Asp; positive charge) and/or histidine (His; negative charge) were compared. Asp and His apparently do not interact in aqueous solution during chlorination. Asp and/or His can undergo partially oxidation by PM, but are recalcitrant to direct oxidation by PS and PO. Pre-oxidation with OZ decreases the formation of HANs but increases the formation of TCNM. ACMN prefers to adsorb Asp over His in the competitive sorption of coexisting Asp and His because of attractive electrostatic interactions. The rank order for the effect of the pre-oxidants and ACMN adsorption on dichloroacetonitrile and trichloroacetonitrile formation is OZ and ACMN adsorption > PM and ACMN adsorption > PS and ACMN adsorption > PO and ACMN adsorption; that for the effect of the pre-oxidants and ACMN adsorption on TCNM formation is PM and ACMN adsorption > PS and ACMN adsorption > PO and ACMN adsorption > OZ and ACMN adsorption. The favored adsorption of Asp over His by ACMN is weakened by pre-oxidation.

•Ultrafiltration membrane has a potential to treat ACFBW.•Micro-flocculation/sedimentation removed most particles in ACFBW.•Ozonation changed characteristics of organic matters and killed bacteria in ACFBW.•Ozonation changed characteristics of membrane material in the long run.•Ozonation alleviated membrane fouling in the long run according to calculation.The reuse of activated carbon filter backwash water (ACFBW) was performed using an ultrafiltration (UF) system. The feed water was pretreated by the micro-flocculation/sedimentation, followed by ozonation, prior to its entry into the UF system. The dose of 2 mg/L PACl and subsequent 10 min sedimentation were involved in the pretreatment, which resulted in the removal of most particles and bacteria in ACFBW, causing a decrease of transmembrane pressure (TMP) and the mitigation of membrane fouling. In the parallel experiment with or without preozonation, the influence of dosing ozone at 0.15 mg/L on membrane fouling was investigated. The results showed that the preozonation restrained bacteria breeding on the membrane surface and maintained the membrane permeability. The preozonation reduced the hydrophobic organic matters and changed the molecular weight distribution of organics in the influent ACFBW, reflecting macromolecular organic compounds to form small fractions. In addition, the preozonation narrowed the pore size of membrane, the virgin membrane varying from 2.1 to 26.3 nm compared with the used membrane with preozonation from 1.5 to 23.6 nm. The preozonation improved the hydrophobicity of membrane material in a long-running filtration, which could aggravate the membrane fouling. However, the preozonation enhanced UF performance due to the characteristics change of organic matters, which was dominant in alleviating membrane fouling compared with the adverse influence of the increased hydrophobicity of membrane material.

•A Microcystis-laden water treatment was studied via oxidation-assisted coagulation.•Persulfate/Fe(II), KMnO4 and O3 were compared for cell lysis and organic removal.•Persulfate/Fe(II) and KMnO4 contribute to a larger floc size and more compact floc.•Ozonation causes more severe cell breakage and release of 2-MIB and GSM.•The SiDS is more favorable than the SuDS for Microcystis-laden water coagulation.In this study, the application of enhanced coagulation with persulfate/Fe(II), permanganate and ozone for Microcystis-laden water treatment was investigated. Two oxidant dosage strategies were compared in terms of the organic removal performance: a simultaneous dosing strategy (SiDS) and a successive dosing strategy (SuDS). To optimize the oxidant species, oxidant doses and oxidant dosage strategy, the zeta potential, floc size and dimension fraction, potassium release and organic removal efficiency during the coagulation of algae-laden water were systematically investigated and comprehensively discussed. Ozonation causes most severe cell lysis and reduces organic removal efficiency because it releases intracellular organics. Moreover, ozonation can cause the release of odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). With increasing doses, the performance of pollutant removal by coagulation enhanced by persulfate/Fe(II) or permanganate did not noticeably improve, which suggests that a low dosage of persulfate/Fe(II) and permanganate is the optimal strategy to enhance coagulation of Microcystis-laden water. The SiDS performs better than the SuDS because more Microcystis cell lysis occurs and less DOC is removed when oxidants are added before the coagulants.

A magnetic molecularly imprinted polymer (MSEP@MIP) adsorbent was prepared by using magnetic Fe3O4-modified sepiolite (MSEP) particles as magnetic carrier for the efficient removal of herbicide atrazine from aqueous solution. The composition, thermal stability, chemical structure, specific surface area, morphology, and magnetic properties of MSEP@MIP adsorbent were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method, scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Absorption isothermal and kinetics experiments were employed to investigate the adsorption capacity of atrazine onto MSEP@MIP. The prepared MSEP@MIP adsorbent was mesoporous. Compared with magnetic non-imprinted polymer (MSEP@NIP) and MSEP, MSEP@MIP showed greater removal efficiency for atrazine (about 91.3% for an initial concentration of 0.1 mg L−1). Kinetic studies demonstrated that the adsorption process onto MSEP@MIP followed a pseudo-second-order rate equation. Isotherm studies indicated that the atrazine adsorption onto MSEP@MIP was a monolayer molecular adsorption with a maximum adsorption amount of 69.53 mg g−1. Scatchard analysis showed that there are two different kinds of binding sites in MSEP@MIP. Furthermore, the thermodynamics parameters indicated that the reaction between MSEP@MIP and atrazine was physical, exothermic, and nonspontaneous in nature.

A novel clay mineral biocomposite, chitosan-modified sepiolite (CMSEP), was prepared and used as adsorbent to remove atrazine from water. The adsorption behaviors including thermodynamic and kinetic parameters, effect factors and mechanisms of atrazine adsorption on CMSEP were studied. The results show that the adsorption capacity of atrazine on CMSEP increases with increasing temperature. Protonation of chitosan in biocomposite can improve adsorption ability of the composite to a certain extent. The parameters ΔGΘ, ΔHΘ and ΔSΘ are −1.48—2.69 kJ/mol, 7.54 kJ/mol and 30.28 J/mol, respectively. Langmuir isotherm is proved to describe the adsorption data better than other isotherms with a maximum adsorption capacity of 17.92 mg/g, suggesting that the adsorption process is homogeneous. Pseudo-second-order kinetic model can fit the adsorption kinetic processes well although intraparticle diffusion can not be discarded. Briefly, CMSEP has potential value in the removal of atrazine from water and wastewater.

We investigated the photocatalytic inactivation of free Escherichia coli and E. coli attached to carbon particles using granulated activated carbon filter effluent as a water sample. The inactivation rates of both free and attached E. coli exposed to UV/TiO2 were higher than that using UV irradiation alone. However, attached E. coli was barely inactivated because of the protection of particles, which acted as hotspots for protection against inactivation of attached E. coli in the effluent. During inactivation, a lower UV irradiation intensity favored inactivation by UV/TiO2 for a given UV irradiation dose (irradiation intensity over time), because a longer irradiation period favored higher disinfection efficiency. Particles with a diameter >8 μm were predominantly responsible for protecting attached E. coli, and a higher particle concentration was associated with lower inactivation. The reactivation of E. coli after UV/TiO2 disinfection was lower than that after UV irradiation alone, and the reactivation rate decreased with increasing UV irradiation dose.

In this study, Ce and B co-modified TiO2 nanoparticles were prepared using an ultrasonic-assisted sol–gel method. The prepared sample was characterized by X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy and BET analysis. In order to detect the effect of dopants on the titania, the photocatalytic activity of these as-prepared titania nanoparticles was determined by following the degradation of the reactive dye methylene blue under solar light irradiation. The activity was compared to that of pure titania. It was revealed that the photocatalytic activity of the Ce and B co-modified titania nanoparticles produced a significant enhancement compared to pure titania. The apparent rate constant of the as-prepared co-modified titania was 3 times higher than that of pure titania.Highlights► Ce, B co-modified titania nanoparticles synthesized by ultrasonic assisted sol–gel method. ► The preparation processes are all under mild condition (low temperature). ► The samples exhibited high photocatalytic activity under solar light irradiation.

Lake Taihu is the third largest freshwater lake in China and is contaminated with xenoestrogens associated with high population density, intensive livestock and aquatic breeding activities. A field study in Lake Taihu was conducted using the goldfish (Carassius auratus) as an indicator organism. Several biological markers were selected to assess the extent of estrogenic contamination. Changes in serum vitellogenin (VTG), and gill 7-Ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and reduced glutathione (GSH) were measured in caged juvenile goldfish for 28 days in seven locations in northern Lake Taihu. Bioassay showed VTG increased 0.64–2.42 folds over time in goldfish collected from five stations and GSH decreased in samples from all seven stations after 7 days of exposure. EROD levels increased continually in fish collected at all the seven stations and the highest concentrations occurred at day 21. GST activity increased significantly at 7 days. The concentration of the target estrogens estrone (E1), 17β-estradiol (E2), ethinylestradiol (EE2), octylphenol (OP), diethylstilbestrol (DES), nonylphenol (NP) and bisphenol A (BPA) were determined in lake water at the sampling stations. Each individual estrogen concentration measured was multiplied by its relative potency to gain the estrdiol equivalent (EEQ). There was an obvious correlation between the concentration of VTG and the total EEQ for all seven locations (P < 0.001). The biomarker VTG, EROD, GST and GSH assays and chemical analysis might be used to illustrate the potential risk in Lake Taihu.

The effectiveness of a magnetic ion exchange resin (MIEX) for the treatment of Hongze Lake water in China was evaluated. The kinetics of natural organic matter (NOM) removal at various MIEX doses and contact time, multiple-loading experiments, impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX, pre-chlorination and coagulation were investigated. Kinetic experimental results show that more than 80% UV254 and 67% dissolved organic carbon (DOC) from raw water can be removed by the use of MIEX alone. 94% sulfate, 69% nitrate and 98% bromide removals are obtained after the first use of MIEX in multiple-loading experiments. It is suggested that MIEX can be loaded up to 1 250 bed volume (BV, volume ratio of tested water to resin) or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57% chlorine demand and 77% trihalomethane formation potential (THMFP) for raw water. Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals. The results suggest that MIEX provides a new method to solve the problem algae reproduction.

In this paper, the drinking water biotic safety of particles and bacteria attached to fines in activated carbon process was investigated by actual treatment process and advanced treatment pilot trial with granular activated carbon. In the experiment, the particles were detected by IBR particle calculating instrument, the activated carbon fines were counted on the basis of the most probable number (MPN) with a microscope, the total number of bacteria was analyzed between the conventional agar culture medium and the one with R2A, and the bacteria attached to activated carbon fines was resolved by the homogenization technique. The experimental results showed that the average total number of particles was 205 CNT/mL in the activated carbon effluent during a filter cycle, of which the number of particles with sizes > 2 μm was 77 CNT/mL more than the present particle control criterion of the American drinking water product standard (50 CNT/mL). The backwash of low density and long duration lowered particle number in the effluent. The MPN of activated carbon fines in the effluent was between 400 and 600 CNT/L, which accounted for less than 5‰ of the total particles from activated carbon filtration for a poor relative level (R2 = 0.34). The microorganisms in activated carbon effluent consisted mostly of heterotrophic bacillus and the total bacteria number was five times as high as that of the inflow, i.e. the effluent from sand filter. The actual bacteria number may be truly indicated by the detection technique with R2A culture medium compared with the traditional agar cultivation. The inactivation efficiency of bacteria attached to activated carbon fines was less than 40% under 1.1 mg/L of chlorine contacting for 40 min. Results showed that the particles and bacteria attached to activated carbon fines may influence drinking water biotic safety, and that the effective control measures need to be further investigated.

•Chlorine as a preoxidant for UFsystem pretreatment.•We examine the mechanism of membrane fouling with preoxidation by chlorine.•The chlorine oxidation changed the characteristics of organic pollutants.•The chlorine pretreatment indicated some potential for mitigating transmembrane pressures.•The chlorine combined with UF system can affect the qualities of the membrane materials.An ultrafiltration (UF) system for the purification of raw water from the Yangtze River was used as an advanced treatment, following a conventional purification process. We investigated the performance of membrane fouling control, using chlorine for the pre-oxidation of the raw water. The former process was implemented via direct continuous dosing of chlorine prior to coagulation, during which the supernatant was used as an influent into a UF system. Investigations into this option indicated that the optimal dose of chlorine is 1.5 mg/L. These conclusions were reinforced by results from an investigation into molecular weight distribution and hydrophilic and hydrophobic fractions in the water treated with and without chlorine in the UF system. Scanning electron microscopy indicated that loose fragments were formed on the filtration cake during the chlorine/UF process, which was easy to remove by hydraulic washing. The analysis of tensile strength shows that the tensile ability of material is weakened during the chlorine pretreatment of the raw water in the UF system. Meanwhile, the contact angle and the field emission scanning electron microscopy experiment also indicated that the membrane material could be affected by the chlorine, which oxidizes the raw water in the UF system.

•The XDLVO approach is effective for predicting UF membrane fouling caused by NOM.•Hydrophility and polarity of membrane are benefits to alleviate membrane fouling.•Particle size and total surface energy of colloid influences membrane fouling•LW is dominant to total interaction energy contribution if separation is beyond 5 nm.•AB is a main contributor to total interaction energy if separation is under 3 nm.The Extended Derjaguin Landau Verwey Overbeek (XDLVO) approach was introduced to predict organic colloid fouling of membranes in an initial ultrafiltration (UF) phase. Two polymeric UF membranes, made of polyvinylchloride (PVC) and polyvinylidene fluoride (PVDF) respectively, were selected to investigate membrane fouling by filtering water samples with different organic colloid compositions. The experiment was performed to determine the fouling contributions of van der Waals (LW) interactions, electrostatic (EL) interactions, as well as double layer and short-range acid–base (AB) interactions, to the total interaction energy caused by organic colloids attaching to UF membrane surfaces. The results showed that LW interaction energy predominated when the distance between the membrane surface and organic colloid was > 5 nm, while AB accounted for a key contribution to total interaction energy over short distances (< 2.5 nm). The influence of EL interaction energy was ignored in the total interaction energy composition. The surface energy, among all characteristics of membrane material, was a dominant factor affecting membrane fouling. The experimental results of initial ultrafiltration of raw water from the actual water source were in accordance with the predictions based on XDLVO theory, indicating that it was a feasible option for predicting membrane fouling during the initial ultrafiltration phase.

•XDLVO approach can predict membrane fouling.•Particle size and total surface energy of colloid influence membrane fouling.•Increasing calcium ion concentration resulted in a larger colloid size.•Increasing concentrations of calcium ions caused greater membrane fouling.•Prechlorination reduced the interaction between calcium ions and humic acid.The Extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) approach was used to predict the mechanisms regarding the influence of humic acid together with calcium ions on membrane fouling in an ultrafiltration (UF) system. The polymeric UF membranes composed of polyvinylchloride (PVC) were selected to investigate membrane fouling. The results indicated that membrane fouling was aggravated when the total interaction energy caused by humic acid combined with calcium ions decreased. Calcium ions aggravated membrane fouling, compared with water samples without calcium ions. Increasing concentrations of calcium ions resulted in greater membrane fouling due to their chelation with humic acid. Increased pH influenced the interaction between calcium ions and humic acid, resulting in an increase in the total interaction energy, which reduced membrane fouling. Prechlorination reduced the interaction between calcium ions and humic acid, and resulted in an increase in the total interaction energy of the water sample, indicating that prechlorination may reduce membrane fouling, due to characteristic changes in organic matter.