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Abstract This work studied simultaneous bromate (BrO 3 −) reduction and adsorption of perchlorate (ClO 4 −) by FeCl 3 -impregnated granular activated carbon (Fe-GAC) and the mutual co-solute effects. We report that BrO 3 − reduction by Fe-GAC was coupled with enhanced adsorption of ClO 4 − by the material. The Langmuir maximum adsorption capacity for ClO 4 − by Fe-GAC was increased from 0.179 mmol g−1 (without BrO 3 −) to 0.256 mmol g−1 in the presence of 0.2 mmol L−1 of BrO 3 − (a 43% increase) at pH 6.0. While the activated carbon alone was able simultaneously remove both BrO 3 − and ClO 4 −, Fe-GAC offered much greater removal efficacy and synergistic effect, likely because the immobilized Fe3+ acted as a catalyst and provided a local acidic environment, both being in favor of accelerated BrO 3 − reduction. Mechanistic analyses revealed that BrO 3 − removal was through a two-step process: ion exchange with OH− and Cl− on Fe-GAC, and then Fe-catalyzed reduction of BrO 3 − to Br− by carbon. The carbon-BrO 3 - redox reaction generated more Fe-O and C-O groups on the material surface, which can bind with ClO 4 − by surface complexation and electrostatic interactions. To our knowledge, this is the first report that metal modified activated carbon may facilitate synergistic removal of both BrO 3 − and ClO 4 −, which are common co-solutes in contaminated waters. Graphical abstract Image 1 Highlights • Fe-impregnated GAC (Fe-GAC) rapidly and completely reduces BrO 3 − to Br− in water. • Reduction of BrO 3 − enhances adsorption of ClO 4 − as a co-contaminant. • Fe-GAC offers much higher removal efficacy than GAC alone for BrO 3 − and ClO 4 − • Fe3+ as a catalyst and local acidic environment in Fe-GAC promote BrO 3 − reduction. • Enhanced ClO 4 − adsorption is due to Fe-O and C-O groups from BrO 3 − reduction. [ABSTRACT FROM AUTHOR]

Typical spinel ferrites of CoFe 2 O 4 and MnFe 2 O 4 were studied as heterogeneous catalysts of peroxymonosulfate (PMS) for the degradation of paracetamol (APAP) in water. The APAP degradation followed a pseudo-first-order kinetics pattern (R 2 > 0.95) under conditions tested. In the presence of 0.2 g/L catalyst, APAP with initial concentration of 10 mg/L would be 90.5% and 100% removed in CoFe 2 O 4 /PMS and MnFe 2 O 4 /PMS system, respectively. Higher catalyst dosage, higher PMS dosage, neutral pH and lower concentration of HA favored APAP degradation in each system. After being recycled for three times, MnFe 2 O 4 and CoFe 2 O 4 could still effectively catalyze PMS to react with APAP, with the removal efficiencies of 100% and 76.1%, respectively. The production of sulfate radical and hydroxyl radical was validated from the scavenging tests, results showed that sulfate radical was the main reactive species responsible for APAP degradation. Plausible mechanisms on the activation processes were proposed based on the radical identification tests and XPS analysis, showing that Mn 2+ -Mn 3+ /Fe 3+ -Fe 2+ recycle and Co 2+ -Co 3+ /Fe 3+ -Fe 2+ recycle on catalyst were responsible for the radical generation. The results demonstrated that both CoFe 2 O 4 and MnFe 2 O 4 MNPs activated PMS were promising technologies for water pollution caused by pharmaceuticals. [ABSTRACT FROM AUTHOR]

Trihalomethane (THMs) and haloacetonitriles (HANs) are typical and frequently detected carbonaceous (C–) and nitrogenous (N–) disinfection by-products (DBPs) in water treatment, and amine acids (AAs) are important precursors of DBPs. However, previous researches mainly focused on free AAs and few investigations evaluated the DBPs formation potential of combined AAs, especially combined histidine. The formation of THMs and HANs from free and combined histidine and glycine during chlorination was firstly examined and compared in this study with an emphasis on their differences. The impacts of chlorine dose, pH, ammonia nitrogen and bromide were evaluated and mechanistic formation pathways were proposed. In comparison with free AAs, combined AAs generated more chloroform (CF, 125%–671%) but less dichloroacetonitrile (DCAN, 4.66%–87.5%) at all chlorine doses. The effect of solution pH on combined AAs was slighter than that on free AAs. During chloramination, both free AAs and combined AAs generated much smaller amounts of DBPs, especially DCAN (<9.01%), compared with chlorination. At any bromide dose, there was more bromine merging into THMs than DHANs, especially for combined AAs. At the beginning of chlorination, the combined AAs decomposed in three different ways: hydrolysis, decarboxylation and scission, leading to differing amounts of CF and DCAN compared with the free AAs. [ABSTRACT FROM AUTHOR]

Three typical fluoroquinolones (FQs), ciprofloxacin, norfloxacin and enrofloxacin were degraded using the thermal activation of persulfate (PS). The degradation rates of FQs generally increased with the rise of PS/fluoroquinolone ratio (20:1–80:1) and temperature but decreased with the increase of initial pH values. The major degradation mechanisms of fluoroquinolones by thermally activated PS were proposed. Abundant intermediates identified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) indicated that the oxidation would occur mainly on the C–F bonds (for ciprofloxacin and enrofloxacin) or the C–H (for norfloxacin) bonds on the quinolone groups, causing hydroxyl substitution as well as hydrogen abstraction, and on the piperazine groups following a series of substitutions, additions and eliminations resulting in the final open-loop reactions. [ABSTRACT FROM AUTHOR]

Perchlorate reduction kinetics and effects of various environmental conditions on removal of perchlorate from synthetic water were investigated to seek high-strength perchlorate removal using mixed perchlorate reducing bacteria. Results demonstrated that perchlorate (50–1500 mg L −1 ) could be degraded rapidly within 28 h under the optimal conditions. The maximum specific perchlorate reduction rate ( q max ) and half saturation constant ( K s ) were 0.92 mg-perchlorate (mg-dry weight) −1 h −1 and 157.7 mg L −1 , respectively. In the ClO 4 − – NO 3 − systems obvious but recoverable lags were caused in perchlorate reduction and the lag time increased with the ratio of nitrate to perchlorate concentration increasing from 0.5 to 3. While in the ClO 4 − – SO 4 2 − systems inhibitions didn't occur until the ratio of sulfate to perchlorate concentration exceeded 10. The optimum temperature and pH value were 35 °C and 6.85, respectively. The optimal acetate-to-perchlorate ratio that could consume all perchlorate and acetate simultaneously was about 2. Dechloromonas , one of the most prominent perchlorate reducing bacteria, was identified as the dominant bacterium in the acclimated culture (69.33% of the whole clones). The study demonstrated that the perchlorate-acclimated mixed microorganisms can readily and efficiently realize reduction of highly concentrated perchlorate in wastewater. [ABSTRACT FROM AUTHOR]

Bentazon (BTZ) in water, a broadly used herbicide in agriculture, is toxic to human beings and has a negative impact on ecosystem. In this study, zero-valent iron (ZVI) activation of persulfate (PS) for the oxidation of BTZ was investigated. More active sulfate radicals produced from the system were principally responsible for the BTZ degradation. The BTZ removal well followed a pseudo-first-order (PFO) kinetics pattern. Key factors affecting the treatment were tested, including ZVI concentration, PS dose, initial BTZ concentration, initial solution pH, temperature and common coexisting ions in water. Under the optimal ZVI (4.477 mM) and PS (0.262 mM) concentrations, 0.021 mM BTZ was totally removed at an initial pH ⩽ 7. Generally, lower BTZ concentration, lower pH and higher temperature favored the treatment. Different coexisting ions exhibited different effects. Al 3+ , Cl − and NO 3 − improved the treatment; NH 4 + , Ca 2+ , and Mg 2+ did not significantly influence the BTZ removal; and, Mn 2+ , Cu 2+ , CO 3 2− , HCO 3 − , PO 4 3− , HPO 4 2− and H 2 PO 4 − inhibited the BTZ degradation. Most of BTZ were not mineralized, and instead degraded into three major degradation products including 2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide (P1, C 7 H 6 N 2 O 3 S), 2-aminobenzoic acid (anthranilic acid) (P3, C 7 H 7 NO 2 ), and 2-amino-2-sulfobenzoic acid (P5, C 7 H 7 NO 5 S). This study demonstrates that ZVI/PS is a viable alternative for controlling BTZ-induced water pollution. [ABSTRACT FROM AUTHOR]

In this study, the perchlorate sorption behaviors of three various representative anion resins were systematically investigated with respect to sorption kinetics, equilibrium capacity, perchlorate selectivity, thermodynamics and isotherms. Results showed that the equilibrium capacity of the three investigated resins followed the order of Purolite A530E≈magnetic ion exchange resin > Purolite A532E due to the effect of structure type, while magnetic ion exchange resin (MIEX) reached the equilibrium much faster than Purolite A530E and Purolite A532E, which can be attributed to its smaller particle size and larger surface area. Furthermore, the two Purolite resins showed superior perchlorate selectivity than MIEX resin because of matrix and functional groups. The adsorption kinetics for each of three selected resins fitted best with the pseudo-second-order model, indicating the adsorption process was controlled by chemical sorption. While the fitting of intra-particle model implied that intra-particle diffusion was not the only rate-limiting step of the whole process. The isotherm data can be best described by the Freundlich isotherm and the value of intensity of adsorption was larger than 1, suggesting the process was heterogenous and favorable adsorption. The negative Δ G ° manifested that the adsorption of perchlorate by each of the three resins was a spontaneous process, and the positive indicated it was also an endothermic and entropy driven process. Besides, the effects of independent variables on the perchlorate sorption of the three resins were also evaluated completely. Results suggested that the removal of perchlorate increased with the increase of resin dosage and temperature for each of the three resins, and the sorption process was nearly independent of solution pH in a wide range of 4–10 for each of the resins. [ABSTRACT FROM AUTHOR]

• Reactive nitrogen species contribute to 56.6% of the Sulfamethazine degradation. • Degradation intermediates were proposed by DFT calculation. • Theoretical toxicity and BCF of SMT increased after UV/NH 2 Cl process. • DBPs formation in UV/NH 2 Cl was much lower than UV/Cl 2. • Bromide ions significantly increased total DBPs yields. Ultraviolet combined monochloramine (UV/NH 2 Cl) process is a promising advanced oxidation process (AOP) to remove organic micropollutants effectively through the generation of various reactive species e.g., hydroxyl radicals (HO•), reactive chlorine species (RCS), and reactive nitrogen species (RNS). This study investigated the kinetics, transformation pathways, DBPs formation, and toxicity alternation in the degradation of sulfamethazine (SMT). Based on the calculation of degradation kinetic models, RNS was proved to be the most important reactive species in the degradation of SMT in UV/NH 2 Cl. The contribution of RNS, HO• and RCS were approximately 56.6%, 38.8%, and 4.5%, respectively. With the NH 2 Cl dosage increased from 100 to 800 µmol L-1, degradation rate increased from 37% to 73% in 10 min. Significantly alternation was not observed with the changing of pH. Natural organic matter (NOM) remarkably inhibited the degradation rate to 48.6% and 32.8% in the presence of 1 and 2 mg L-1 NOM. Degradation reactions of SMT in UV/NH 2 Cl system primarily comprised of hydroxylation, nitrosation, and ring opening reactions. The total theoretical toxicity of degradation system increased in the first 20 min and decreased eventually. Comparing with UV/free chlorine (UV/Cl 2) process, less disinfection by-products (DBPs) generated in UV/NH 2 Cl treatment. Thus, the theoretical toxicity of DBPs formed in UV/NH 2 Cl was much lower than UV/Cl 2. Within 40 min degradation, the theoretical toxicity value reached maximum at pH 7.1 due to the mass production of dicloroacetonitrile (DCAN). Bromide ions (10 µmol L-1) significantly promoted the formation of brominated DBPs especially dibromoacetonitrile (DBAN). This study provided insight into the important role of RNS in the SAs' transformation in UV/NH 2 Cl process and reference to benefits and disadvantages when selecting the process for disinfection in drinking water treatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] The antipyrine decomposition exhibited a pseudo-first-order kinetics pattern well. [•] The k obs with irradiance or oxidant dosage presented a linear relationship well. [•] The k obs exhibit an exponential trend as a function of [AP]0 for three systems. [•] UV/H2O2 behaved best at pH 2.5–10, while UV/PS behaved best at pH 10.0–11.5. [•] Cost for chemicals was firstly taken into account in calculation of the EE/O values. [Copyright &y& Elsevier]

Highlights: [•] Formation of haloacetamides function of DON/DOC, SUVA254 and bromide. [•] DON/DOC may act as an indicator of HAcAm yields during chlorination. [•] More formation during chloramination in low-SUVA waters with no bromide. [•] More formation of dihalogenated species than tri- or mono-halogenated species. [•] Bromine incorporation increased with increasing bromide with either disinfectant. [Copyright &y& Elsevier]

Highlights: [•] The antipyrine degradation exhibited a pseudo-first-order kinetics pattern in tests. [•] More alkalinity species and dissolved organic matter lead to greater inhibition. [•] lead to greater inhibition than Cl− on system at the same molar ratio to PS. [•] predominant at acidic conditions and OH at basic conditions. [•] Anaerobic condition favored degradation for the generated along with . [Copyright &y& Elsevier]

Perchiorate is widely known as an inorganic endocrine disruptor. In this study, MgAI-C03 layered double hydroxides with different Mg/Al molar ratios were prepared using a coprecipitation method and followed by a calcination process at a temperature range of 300 to 700°C. Results showed that the best synthesis conditions were a calcination temperature of 550°C and Mg/Al molar ratio of 3. Further, the adsorbent and its adsorption product were characterized by x-ray diffraction, Fourier transforminfrared spectroscopy, and thermogravi-metric-differential thermal analysis. The layered double hydroxides structures in the adsorbent were lost during calcination at 550°C but were reconstructed subsequent to adsorption of perchlorate, indicating that the "memory effect" appeared to play an important role in perchlorate adsorption. The perchlorate adsorption pattern was best described by the pseudo-second-order kinetics model, while the Freundlich isotherms appropriately explained perchlorate adsorption data. [ABSTRACT FROM AUTHOR]

Abstract: Disinfection by-products (DBPs) are a great challenge to our drinking water security. Particularly, nitrosamines (NAms), as emerging DBPs, are potently carcinogenic, mutagenic, and teratogenic, and have increasingly attained public attention. This study was to evaluate the performance of the NAms degradation by the ultraviolet (UV) irradiation (253.7nm) in the presence of hydrogen peroxide (H2O2). In the UV/H2O2 system, hydroxyl radicals (OH of nonselective and powerful oxidant, was produced to attack the molecules of NAms. Factors affecting the treatment efficiency, including the H2O2 dosage, initial NAms concentration, UV irradiation intensity, initial solution pH, and inorganic anions present in water, were evaluated. All the NAms degradation exhibited a pseudo-first-order kinetics pattern. Within 60min, 0.1mg/L of any NAms could be almost decomposed except NDPhA that required 120min for complete removal, at 25μmol/L H2O2 and at initial pH 7. Results demonstrate that the UV/H2O2 treatment is a viable option to control NAms in water. [Copyright &y& Elsevier]

Abstract: Heat-activated persulfate oxidation of diuron, a commonly found herbicide in groundwater, was evaluated in this study. Sulfate radicals was the principal oxidizing agent responsible for the diuron degradation. The diuron decomposition exhibited a pseudo-first-order kinetics pattern at all the conditions tested. The observed rate constants determined at 50–70°C well fit the Arrhenius equation, yielding an activation energy of 166.7±0.8kJmol−1. Temperature, persulfate dose, initial diuron concentration, pH, and three common groundwater solutes (, and Cl−), to different degrees, influenced the degradation. Typically, high temperature, high persulfate dose, and low initial diuron concentration increased the decomposition rate of diuron. At the tested pH range of 5.5–8.1, the highest degradation rate (kobs =0.18min−1) occurred at pH 6.3. The three groundwater anions inhibited the diuron decomposition with the following order: . The major oxidation products in this study were C15H15ON3Cl4 (P3, m/z =376.2), C16H16O4N3Cl4 (P4, m/z =420.3), and C17H17O7N3Cl4 (P5, m/z =465.4), different from those produced during hydroxyl radical-induced advanced oxidation. The in situ chemical oxidation (ISCO) technology can be achieved in practice through combination with in situ thermal remediation. [Copyright &y& Elsevier]

Abstract: In this study, a new calcined iron-based layered double hydroxide material was synthesized to adsorb perchlorate from water. The MgFe–CO3 layered double hydroxides (MgFe-LDH) were prepared at pH 9–10 and with different molar Mg/Fe ratios (2–5) using a co-precipitation method, and then calcined at a temperature range of 300–900°C. Results showed that the best synthesis conditions to maximize the perchlorate adsorption capacity of the calcined MgFe–CO3 layered double hydroxide (MgFe-CLDH) were the calcination temperature of 550°C and [Mg]/[Fe]=3. Furthermore, the adsorbents and their adsorption products were characterized by X-ray, FT-IR and thermogravimetric analyses. The layered double hydroxide structures in the adsorbent were lost during calcination at 550°C, but were reconstructed subsequent to adsorption of perchlorate, indicating that the ‘memory effect’ appeared to play an important role in perchlorate adsorption. The perchlorate adsorption pattern was well described by the pseudo-second-order kinetic model, while the Freundlich isotherm provided the best fitting of adsorption isotherms with the experimental data at chemical equilibrium at 25°C. Indeed, an initial solution pH of 4–10, a higher adsorbent dose, and a lower initial perchlorate concentration typically favored the removal of perchlorate from water. Furthermore, co-existing anions, including PO4 3−, SO4 2−, Cl− and NO3 −, inhibited the perchlorate adsorption, to different degrees. At 25°C, MgFe-3 CLDH=1.33g/L (calcination temperature=550°C and [Mg]/[Fe]=3), and the initial solution pH of 4–10, 2000μg/L of perchlorate was almost all adsorbed within 720min. This study demonstrated that the new calcined iron-based layered double hydroxide was a promising adsorbent for control of the perchlorate pollution in water. [Copyright &y& Elsevier]

Aqueous solutions of atrazine (ATZ, 2-chloro-4-ethylamino-6-isopropylamino-1, 3, 5-triazine) were photolysed (λ = 254 nm) by low pressure UV/H2O2 process (LP/UV/H2O2) under a variety of parameters including hydrogen peroxide, the initial concentration of ATZ, pH, and humic acid. The results show that the most favourable reaction condition appears to be a moderate concentration of H2O2 from 100 mg/L to 120 mg/L. The presence of humic acid in the solution has a negative impact on the LP/UV/H2O2 treatment because of scavenging effects. Ninety percent of ATZ is destroyed in one hour under the optimum conditions. In this study, LP/UV/ H2O2 treatment of ATZ yielded several organic by products which are identified, including DIA, DEA, OHDIA, OHDEA, DAA and OAAT. They are quantified over the range of treatment tested and the ATZ degradation scheme is proposed combined with by products information. [ABSTRACT FROM AUTHOR]

Abstract: The degradation of diuron by persulfate (S2O8 2−, PS) activated with ferrous ion (Fe2+) was investigated. The PS–Fe2+ system achieved high levels of reduction of diuron (90%). The optimal PS/Fe2+ molar ratio for diuron reduction was found to be 1:1. A chelating agent, sodium citrate, was used to control the amount of Fe2+ in solution for activation of the oxidant, with the optimum results obtained when the molar ratio of citrate and Fe2+ was 1:1. A reductive chemical, hydroxylamine, was also applied into the PS–Fe2+ system, and the hydroxylamine/Fe2+ molar ratio of 2:1 significantly increased the degradation of diuron due to enhancement of redox of Fe3+ to Fe2+. The main degradation product of diuron was 1-(3,4-Dichlorophenyl)-3-methylurea(DCPMU); SO4 − attack did not cause the opening of the aromatic ring of diuron. [Copyright &y& Elsevier]

Abstract: The immediate and long-term impacts of potassium permanganate (KMnO4) as pre-oxidant on Microcystis aeruginosa and microcystin-LR (MC-LR) release risk were investigated. The cell density and the integrity of M. aeruginosa were determined by a flow cytometry, and typical photosynthetic parameters were measured by a pulse amplitude modulated fluorometer. The photosynthetic parameters were reduced to different degrees, accompanied with slight cytoclasis and complete degradation of extracellular MC-LR immediately after various dosages KMnO4 oxidation (2–20mgL−1). In a 6-d cultivation following 5mgL−1 KMnO4 oxidation, the cell density decreased from 3.9×106 to 0.6×106 cellsmL−1, and then increased to 0.9×106 cellsmL−1, while the extracellular MC-LR increased from 0 to 51.2μgL−1. In the cultivation after 10mgL−1 KMnO4 treatment, the intracellular MC-LR and cell activity significantly declined, while significant cytoclasis (cell density from 3.8×106 to 0cellsmL−1) and MC-LR release (increase from 0 to 15.2μgL−1) were observed. The photosynthetic parameters were found to be useful tools to predict the recovery tendency of M. aeruginosa cells, and the MC-LR release risk should be considered during KMnO4 pre-oxidation in water-treatment plants. [Copyright &y& Elsevier]

In the context of water treatment, the ferrate ([FeO4]2−) ion has long been known for its strong oxidizing power and for producing a coagulant from its reduced form [i.e., Fe(III)]. However, it has not been widely applied in water treatment, because of preparation difficulties and high cost. This article describes a low-cost procedure for producing solid potassium ferrate. In this synthetic procedure, NaClO was used in place of chlorine generation; and 10 M KOH was used in place of saturated KOH in the previous procedures. In addition, this study investigated the reactions of potassium ferrate with tetracycline hydrochloride (TC) at different pH and molar ratios. Results showed that the optimal pH range for TC degradation was pH 9-10, and TC could be mostly removed by Fe(VI) in 60 s. However, results showed >70% of TC degraded and <15% of dissolved organic carbon (DOC) reduction at molar ratio of 1:20. The main degradation pathway of TC is proposed based on the experimental data. [ABSTRACT FROM AUTHOR]

Abstract: The haloacetamides (HAcAms) are disinfection by-products (DBPs) in drinking water which are currently receiving increased scientific attention due to their elevated toxicity relative to regulated disinfection by-products. A simultaneous determination method of 13 HAcAms, combining solid-phase extraction (SPE) enrichment, liquid chromatographic (LC) separation, and triple quadrupole mass spectrometry (tqMS) detection with atmospheric pressure chemical ionization (APCI) using selective reaction monitoring in positive mode, was developed to measure HAcAms, including chlorinated, brominated, and iodinated analogs. Ammonium chloride and Oasis HLB were selected as the dechlorinating reagent and polymeric SPE sorbent of HAcAm samples. The used tqMS apparatus showed higher sensitivity for the studied HAcAms in the APCI mode than electrospray ionization. 13 HAcAms were separated by LC in 9.0min, and the detection limits ranged from 7.6 to 19.7ng/L. The SPE-LC/tqMS method was successfully applied to quantify 13 HAcAms in drinking water samples for the first time, and first indentified tribromoacetamide and chloroiodoacetamide as DBPs in drinking water. [Copyright &y& Elsevier]

Abstract: The calcination products containing Mg(II), Al(III), and Fe(III) in the brucite-like layers with varying Mg/Al/Fe molar ratios at 550°C were used as the adsorbent to remove perchlorate from aqueous solution, while the Mg/(Al–Fe) hydrotalcite compounds were synthesized by co-precipitation method at a constant pH value. The Mg/(Al–Fe) hydrotalcite compounds (HMAF) were characterized by XRD, FT-IR and TG–DTA. The characteristics showed that the layered double hydroxides structures in the HMAF were lost during calcination at 550°C, but were reconstructed subsequent to adsorption of perchlorate, indicating that the ‘memory effect’ appeared to play an important role in perchlorate adsorption. Batch adsorption studies were conducted under various equilibration conditions, such as molar ratios of Mg/Al/Fe, calcined temperature, different initial solution pH, adsorbent dose, initial perchlorate concentration, and co-existing anions. It was found that the existence of ferric iron in calcined Mg/(Al–Fe) hydrotalcite compound (CHMAF) was favorable to removal of perchlorate from water, and the best ratio of Mg/Al/Fe is 3:0.8:0.2 (CHMAF5%). This study demonstrated that the calcination product of Mg/(Al–Fe) hydrotalcite-like compound was a promising adsorbent for control of the perchlorate pollution in water. [Copyright &y& Elsevier]

Abstract: In this study, the immediate and long-term impacts of shortwave ultraviolet (UV-C) irradiation on photosynthetic capacity, survival, and recovery of Microcystis aeruginosa were investigated. The risk of microcystin-LR (MC-LR) release during irradiation was also estimated. The cell density was determined by a flow cytometry, and typical chlorophyll fluorescence parameters, including the effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse amplitude modulated (PAM) fluorometer. Under various UV-C dosages (140–4200 mJ cm−2), photosynthetic capacities were reduced, to different degrees, accompanied by slight cytoclasis and complete degradation of extracellular MC-LR immediately after irradiation. In a 6-d cultivation following UV-C irradiation, cell density and extracellular MC-LR in the samples treated by 140 mJ cm−2 UV-C irradiation increased from 4.0 × 106 cells mL−1 and 8 μg L−1 to 5.1 × 106 cells mL−1 and 20 μg L−1, respectively. Significant M. aeruginosa cytoclasis (cell density from 4.0 × 106 to 1.0 × 106 cells mL−1) and MC-LR release (2–25 μg L−1) occurred when the UV-C dosage reached 350 mJ cm−2. Cell cytoclasis and MC-LR release were enhanced in the cultivated samples under higher UV-C dosages. Results revealed that photosynthetic parameters were useful tools to predict the recovery profiles of M. aeruginosa cells, and the MC-LR release risk should be considered after UV-C inactivation. [Copyright &y& Elsevier]

Abstract: Algae organic matters (AOM), including intracellular organic matters (IOM) and extracellular organic matters (EOM), are causing numerous water quality issues, among which formation of disinfection byproducts (DBPs) and odor & taste (O&T) compounds are of particular concern. In this study, physiochemical properties of IOM and EOM of Microcystic aeruginosa under an exponential growth phase (2.01 × 1011/L) were comprehensively characterized. Moreover, the yields of DBPs during AOM disinfection and O&T-causing compounds were quantified. Hydrophilic organic matters accounted for 86% and 63% of DOC in IOM and EOM, respectively. Molecular weight (MW) fractions of IOM in <1 kDa, 40–800 kDa, and >800 kDa were 27%, 42%, and 31% of DOC, respectively, while EOM primarily contained 1–100 kDa molecules. Besides, a low SUVA (0.84 L/mg m) and the specific fluorescence spectra suggested that AOM (especially IOM) was principally comprised of protein-like substances, instead of humic-like matters. The formation potentials of chloroform, chloroacetic acid, and nitrosodimethylamine were 21.46, 68.29 and 0.0096 μg/mg C for IOM, and 32.44, 54.58 and 0.0189 μg/mg C for EOM, respectively. Furthermore, the dominant O&T compound produced from EOM and IOM were 2-MIB (68.75 ng/mg C) and β-cyclocitral (367.59 ng/mg C), respectively. Of note, dimethyltrisulfide became the prevailing O & T compound following anaerobic cultivation. [Copyright &y& Elsevier]

Abstract: Pilot-scale tests were performed to reduce the formation of several nitrogenous and carbonaceous disinfection by-products (DBPs) with an integrated ozone and biological activated carbon (O3–BAC) treatment process following conventional water treatment processes (coagulation–sedimentation–filtration). Relative to the conventional processes alone, O3–BAC significantly improved the removal of turbidity, dissolved organic carbon, UV254, and dissolved organic nitrogen from 98–99%, 58–72%, 31–53%, 16–93% and 35–74%, respectively, and enhanced the removal efficiency of the precursors for the measured DBPs. The conventional process was almost ineffective in removing the precursors of trichloronitromethane (TCNM) and dichloroacetamide (DCAcAm). Ozonation could not substantially reduce the formation of DCAcAm, and actually increased the formation potential of TCNM; it chemically altered the molecular structures of the precursors and increased the biodegradability of N-containing organic compounds. Consequently, the subsequent BAC filtration substantially reduced the formation of the both TCNM and DCAcAm, thus highlighting a synergistic effect of O3 and BAC. Additionally, O3–BAC was effective at controlling the formation of the total organic halogen, which can be considered as an indicator of the formation of unidentified DBPs. [Copyright &y& Elsevier]

Abstract: The formation of disinfection by-products (DBPs), including both nitrogenous DBPs (N-DBPs) and carbonaceous DBPs (C-DBPs), was investigated by analyzing chlorinated water samples following the application of three pretreatment processes: (i) powdered activated carbon (PAC) adsorption; (ii) KMnO4 oxidation and (iii) biological contact oxidation (BCO), coupled with conventional water treatment processes. PAC adsorption can remove effectively the precursors of chloroform (42.7%), dichloroacetonitrile (28.6%), dichloroacetamide (DCAcAm) (27.2%) and trichloronitromethane (35.7%), which were higher than that pretreated by KMnO4 oxidation and/or BCO process. The removal efficiency of dissolved organic carbon by BCO process (76.5%) -was superior to that by PAC adsorption (69.9%) and KMnO4 oxidation (61.4%). However, BCO increased the dissolved organic nitrogen (DON) concentration which caused more N-DBPs to be formed during subsequent chlorination. Soluble microbial products including numerous DON compounds were produced in the BCO process and were observed to play an essential role in the formation of DCAcAm in particular. [Copyright &y& Elsevier]

Abstract: In this study, the mechanisms and factors affecting the inactivation and degradation efficiency during UV-C irradiation of Microcystis aeruginosa, a harmful cyanobacteria strain, were investigated. Under different experimental conditions, the concentrations of three bioactivity materials, including protein, phycocyanin and chl-a, were measured, and fluorescence regional integration (FRI) was used to quantify the results of excitation emission matrix fluorescence spectroscopy. Furthermore, any alternation occurring in cell ultrastructure was determined using transmission electron microscopy. Results showed that UV-C could effectively damage the M. aeruginosa cells, most likely via a 3-step procedure, including impairment of photosynthesis system, decomposition of cytoplasmic inclusions, and cell cytoclasis. Comparison of FRI values and biochemical parameters in the presence of H2O2 and under the UV-C irradiation revealed the importance of photolysis and reactive oxygen species (ROS)-induced oxidation. UV-C/H2O2 treatment was more efficient due to enhanced ROS generation, while adding inhibited the ROS-induced oxidation, resulting in suppression on reaction. Humic acid and , two common water solutes, somewhat inhibited the inactivation and degradation processes, due to the ROS scavenging and “inner filter” effect. [Copyright &y& Elsevier]

Abstract: Poly-synchronous techniques were performed to investigate the inactivation and degradation mechanisms of Microcystic aeruginosa under UV-C irradiation and chlorination. Extracellular dissolved organic matter (EDOM) and intracellular dissolved organic matter (IDOM) properties were analyzed using excitation emission matrix (EEM) fluorescence spectroscopy, while the concentration of biochemical parameters including protein, phycocyanin, chlorophyll-a, and microcystin-LR was determined. Transmission electron microscopy was also used to obtained ultrastructural images. EEM analysis revealed that protein-like matters were the major EDOM fluorescence component, while amino acid-like and protein-like matters constituted IDOM with little amount of humic-like substances. In addition, the monitor of biochemical parameters showed that they had different susceptibility under the inactivation reactions. Poly-synchronous techniques confirmed that UV-C irradiation was more appropriate than chlorination for M. aeruginosa inactivation and degradation. The primary mechanism of UV-C irradiation was direct photo-degradation and indirect oxidation by reactive oxygen species, which effectively degraded the fluorescence EDOM and IDOM and caused decomposition of cytoplasmic inclusions and intracellular bioorganic substances. Different from UV-C, the inactivation during chlorination was due to the formation of HOCl, which permeated into the cyanobacteria cells and caused intracellular damage, accompanied with incomplete degradation of IDOM and harmful MC-LR. [Copyright &y& Elsevier]

Abstract: The removal of DDT[(1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane)] with synthetic waters was carried out on a nanofiltration (NF) pilot unit. The influence of initial DDT concentration, pH, flux and recovery on the removal of DDT was studied. The presence of humic acid and some inorganic (CaCl2, NaCl, and CaSO4) matters was also tested in the experiment. The removal percent and that of their adsorption on the membrane have been calculated. The results reveal that DDT was easy to be adsorbed on the membranes and the higher the applied pressure the more rapidly saturation of the membrane was achieved. At the initial concentration of 77μg/L, the equilibrium for DDT adsorption can be achieved in 30min. With the initial DDT concentration from 5 to 20μg/L, the removal percent was from 95 to 85%. On condition that recovery was not changed, higher flux can lead to low rejection of DDT. On the other hand, low recovery can have a high rejection when the fluxes were the same. Humic acid can hinder DDT from passing through the membrane by adsorption and inorganic matter (NaCl, CaCl2 and CaSO4) can improve the removal percent by reducing the pore size of the membrane. [Copyright &y& Elsevier]

Abstract: Bormate (BrO3-) is a carcinogenic chemical produced in ozonation or chlorination of bromide-containing water. Although its formation in seawater with or without sunlight has been previously investigated, the formation of bromate in dilute solutions, particularly raw water for water treatment plant, is unknown. In this article, the results of bench scale tests to measure the formation rates of bromate formation in dilute solutions, including de-ionized water and raw water from Yangtze River, were presented in dark chlorination and ultraviolet (UV)/chlorination processes. And the effects of initial pH, initial concentration of NaOCl, and UV light intensity on bromate formation in UV/chlorination of the diluted solutions were investigated. Detectable bromate was formed in dark chlorination of the two water samples with a relatively slow production rate. Under routine disinfecting conditions, the amount of formed bromate is not likely to exceed the national standards (10 μg/L). UV irradiation enhanced the decay of free chlorine, and, simultaneously, 6.6%–32% of Br- was oxidized to BrO3-. And the formation of bromate exhibited three stages: rapid stage, slow stage and plateau. Under the experimental conditions (pH = 4.41–11.07, CCl2= 1.23–4.50 mg/L), low pH and high chlorine concentration favored the generation of bromate. High light intensity promoted the production rate of bromate, but decreased its total generation amount due to acceleration of chlorine decomposition. [Copyright &y& Elsevier]

Graphical abstract Highlights • Influence of bromide ion on the degradation of typical sulfonamides in UV/chlorine process was studied. • The concentration of degradation products and pathways of SAs was proposed using LC-ESI/MS. • The DBPs formation during degradation process was evaluated. • Toxicity change during UV/chlorine process in the presence of Br− was determined. Abstract The degradation of sulfonamides (SAs) in the presence of bromide during the UV/free chlorine process was investigated in this study. The reactions followed pseudo first-order kinetics. With increasing bromide concentrations of 1, 5, 10–20 µM, the degradation rate was gradually raised. The contribution of different reactive species has been calculated. The degradation products and DBPs formed by SAs were determined. The mechanisms of the degradation of SAs in the presence of bromide included hydroxylation, cleavage of the pyrimidinyl group, and bromine and chlorine electrophilic addition. The concentration of brominated disinfection by-products, including DBCM, TBM and DBAN, increased with increasing bromide dosage and degradation time, while 1, 1, 1-TCP and 1, 1-DCP decreased. In an acute toxicity test, the inhibition rate decreased in the first 5–10 min then increased after 10 min degradation when 10 µM Br− was added to the system. The initial decrease may due to the formation of low toxicity substances after the cleavage of the pyrimidinyl group, while the subsequent increase may be attributable to the increased formation of DBPs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Heat-activated PS degraded DBP and DEP efficiently and DBP was degraded faster. • Both SO 4 - · and OH were involved in oxidation process. • The effects of reaction parameters on PAEs degradation were studied. • Bromate and brominated disinfection byproducts were formed in the presence of Br−. • The proposed DEP and DBP degradation paths were analyzed by the DFT. Abstract The degradation kinetics of two phthalate esters (PAEs) (i.e., diethyl phthalate (DEP) and dibutyl phthalate (DBP)) in heat-activated persulfate (PS) system were studied and followed pseudo-first-order kinetics. Results demonstrated that both sulfate radical (SO 4 - ·) and hydroxyl radical (HO) were responsible for degrading DEP and DBP. The pseudo-first-order rate constant (k obs) enhanced remarkably as reaction temperature and PS dosages increased, while it decreased as the initial PAEs concentrations increased. Lower pH values promoted the degradation over the pH range chosen here (5.0–8.0). Natural organic matter (NOM) and HCO 3 - showed inhibitory effects on PAEs degradation by quenching SO 4 - · and HO. At any pH value studied here, Cl− enhanced PAEs degradation at lower concentrations while it suppressed degradation as Cl− concentration further increased. The coexisting Br− hindered the degradation of PAEs mainly by suppressing SO 4 - ·. Significant formation of dibromoacetonitrile (DBAN) and bromoform (TBM) was verified with Br− and NOM in the degradation system, while only TBM was detected without NOM. Bromate was also detected in the Br− containing degradation system. Generally, NOM facilitated the formation of brominated disinfection byproducts (Br-DBPs), while it suppressed the generation of bromate. Additionally, it is noteworthy that the degradation efficiency of DBP was higher than that of DEP probably owing to the longer alkyl side chain of DBP. The DBP degradation system was observed to form slightly more Br-DBPs than DEP, while bromate had an opposite trend. Besides, the potential initial degradation pathways of DEP and DBP were discussed by the computational analysis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Perchlorate reduction rate was greatly increased in the presence of humic acids or AQDS. • The proposed redox reactions in the "bacteria-quinone-ClO 4 −" system were confirmed. • Quinone alleviated the inhibition of long oxygen exposure and high levels of NO 3 − on ClO 4 − reduction. • Perchlorate reduction rate was further increased with the combination of quinone and Fe (III) oxide. • Thaeura was predominant in perchlorate-acclimated inocula regardless of the presence of quinones. Abstract Humic acids (HA) and anthraquinone-2,6-Disulfonate (AQDS) are conceived as quinone-based redox mediators (QRM) in contaminant transformation processes, however, their effects on perchlorate (ClO 4 −) reduction remain unclear. This study explored the efficacy of quinone-mediated perchlorate reduction and the redox reactions occurred in QRM-amended systems. Relative to the average perchlorate reduction rate (k) in the control system, k was increased by 1.8, 1.9, and 2.3-fold in the presence of 100 mg/L commercial HA, extracted HA, and AQDS, respectively. Moreover, in AQDS-amended systems, k was further increased by 66.3% and 158.6%, respectively, with the addition of 0.003 g and 0.032 g hematite to the 200 mL culture. The critical redox reactions implying the electron transferring mechanism were explored and proven to be enzymatically driven. The presence of AQDS shortened the nitrate-induced lag of perchlorate reduction by stimulating nitrate exhaustion rate (2.83 mM NO 3 − h−1 compared to 1.26 mM NO 3 − h−1 in the control). Also, the inhibition of the 5-h aeration was alleviated (36.6% compared to 52.5% in the control) due to the higher redox-buffer capacity in AQDS-amended systems. Thaeura was predominant in all perchlorate-acclimated inocula, while the presence of QRM contributed to the enrichment of Desulfuromonas and Geobacter. [ABSTRACT FROM AUTHOR]

UV/persulfate (UV/PS) has been as an efficient method to remove many organic contaminants in water. However, little is known about the impact of UV/PS pretrement on the formation of disinfection byproducts (DBPs) during chlorination of 2,4-Di-tert-butylphenol (2,4-D). This research evaluated that UV/PS preoxidation of 2,4-D greatly decreased the DBPs generation during following chlorination. In the 2,4-D solution without any treatment system (O system), trichloromethane (TCM) as the only detected DBP increased with the increase of chlorine dosage. While the formation of TCM declined with the increase of PS dosage in the PS and UV/PS preoxidation systems and decreased the estimated toxicity accordingly. And it was found the residual PS in system could combine free chlorine to further oxidize 2,4-D. And intermediate products were analysed by high-performance liquid chromatography combined with triple quadrupole mass spectroscopy analysis. In the presence of bromine, the bromodichloromethane augmented first and then slowly decreased while dibromochloromethane and tribromethane increased both in O and UV/PS systems with the increase of [Br − ]. Bromine substitution was decreased by preoxidation of UV/PS. UV/PS could decrease the total-DBPs formation when used in the real water matrix contained 100 μg/L 2,4-D. [ABSTRACT FROM AUTHOR]

The degradation of diuron by chlorination and UV/chlorine process and the formation of disinfection by-products (DBPs) was investigated in this study. The degradation of diuron followed the pseudo first-order kinetics model. In UV/chlorine process, hydroxyl radical were proved to provide more contribution in the oxidation. The degradation kinetics increased with the increasing of chlorine dosage and the decreasing of natural organic matter (NOM) dosage. However, the degradation pathways were defined using high performance liquid chromatography coupled with a TSQ Quantum quadrupole mass spectrometer (HPLC-ESI/MS). The formation of DBPs after chlorination and chloramination was defined using gas chromatography with elect ion capture detector (GC-ECD) and gas chromatography–mass spectrometer (GC–MS). Several kinds of DBPs including chloroform (TCM), 1,1-dichloroacetone (1,1-DCP), 1,1,1-trichloroacetone (1,1,1-TCP), trichloronitromethane (TCNM), dichloroacetamide (DCAcAm) and trichloroacetamide (TCAcAm) was identified in this study. [ABSTRACT FROM AUTHOR]

The ultraviolet/persulfate (UV/PS) process was used to degrade dibutyl phthalate (DBP) at different reaction conditions and a steady-state kinetic model was established based on the elementary reactions involved as well. UV/PS process, which can generate both sulfate radical (SO 4 − ) and hydroxyl radical (HO ) proved by the evidence that methanol had a larger inhibition impact on the degradation than tert -butyl, could effectively degrade DBP. The second-order rate constant of (1.2 ± 0.1) × 10 8  M −1  s −1 between DBP and SO 4 − and the second-order rate constant of (6.3 ± 0.1) × 10 9  M −1  s −1 between DBP and HO were determined by competition kinetics. The degradation efficiency of DBP was affected by PS dosage, initial DBP concentration, solution pH value, natural organic matter (NOM) and inorganic anions. Increasing PS dosage could enhance the degradation of DBP before PS dosage reaching 1.6 mM. However, the pseudo-first-order rate constants (k o ) decreased as initial DBP concentration increased probably owing to the radical scavenging effect of DBP. Generally, the k o value decreased slightly at pH values ranged from 4.0 to 6.0 while decreased significantly as pH increased from 6.0 to 8.0, which might be due to the scavenging effect on SO 4 − and HO by OH − and increasing concentration of HPO 4 2 - (with higher scavenging capacity than H 2 PO 4 - ) from the phosphate buffer with rising pH value. NOM and HCO 3 - showed an inhibition effect on the degradation of DBP through quenching SO 4 − and HO . However, Cl − had a dual role on the degradation of DBP in the UV/PS system, which enhanced the degradation at lower concentration (0–1 mM) and suppressed as Cl − concentration further increased to 2 mM. Additionally, a simple steady-state kinetic model involving SO 4 − and HO was developed to simulate the k o values and the radical contributions in this reaction system. Generally, HO had a higher contribution to DBP degradation than SO 4 − . The total cost including the electrical energy per order and oxidant cost was increased with increasing PS dosage and the oxidant cost was the major one. The results in this study can serve as a guide and indicate that UV/PS process is feasible for the treatment of water contaminated with DBP. [ABSTRACT FROM AUTHOR]

The degradation of phenacetin (PNT) by the combination of low-pressure mercury lamp and chlorine (UV/chlorine), an advanced oxidation process (AOP) of recent interest, was systematically investigated in terms of degradation kinetics, effects of chlorine dosage and water parameters, oxidation products as well as toxicity evaluation. The degradation of PNT followed pseudo first-order kinetics. The first-order rate constant ( k obs ) in the UV/chlorine AOP was 4.3, 8.4, and 11.1 times that of dark chlorination, UV/H 2 O 2 , and UV/PS, respectively, with the same molar dosage of oxidant at pH 7.2. Radical quenching tests suggested that chlorination, OH and reactive chlorine species were responsible for the UV/chlorine oxidation of PNT with contributions of 26.33%, 14.6% and 59.07%, at pH 7.2. As chlorine dosage gradually increased from 100 to 500 μM, the corresponding k obs monotonically increased from 0.0229 to 0.216 min −1 . k obs was not apparently affected by the pH and coexisting chloride, but decreased by 56.5% and 75.4% in the presence of 10 mM HCO 3 − and 10 mg/L NOM. Slight decreases (around 15%) of k obs occurred in the raw water and tap water tests, while little effect was observed in filtered water samples compared with ultrapure water tests. Six typical disinfection byproducts including trichloromethane (TCM), chloral hydrate, dichloropropanone, trichloropropanone, trichloronitromethane, and dichloroacetonitrile were detected. The TCM yields increased to 159.95 μg/L within 20 min reaction of UV/chlorine, comprising 13.3% of the degraded PNT (per mole of carbon). The acute toxicity to luminescent bacterium Q67 by UV/chlorine was lower than chlorination under similar reaction conditions. [ABSTRACT FROM AUTHOR]

Degradation of diethyl phthalate (DEP) by ultraviolet/persulfate (UV/PS) process at different reaction conditions was evaluated. DEP can be degraded effectively via this process. Both tert-butyl (TBA) and methanol (MeOH) inhibited the degradation of DEP with MeOH having a stronger impact than TBA, suggesting sulfate radical ( Image 1 ) and hydroxyl radical (HO ) both existed in the reaction systems studied. The second-order rate constants of DEP reacting with Image 1 and HO were calculated to be ( 6.4 ± 0.3 ) × 10 7 M −1 s −1 and ( 3.7 ± 0.1 ) × 10 9 M −1 s −1 , respectively. To further access the potential degradation mechanism in this system, the pseudo-first-order rate constants (k o ) and the radical contributions were modeled using a simple steady-state kinetic model involving Image 1 and HO . Generally, HO had a greater contribution to DEP degradation than Image 1 . The k o of DEP increased as PS dosages increased when PS dosages were below 1.9 mM. However, it decreased with increasing initial DEP concentrations, which might be due to the radical scavenging effect of DEP. The k o values in acidic conditions were higher than those in alkaline solutions, which was probably caused by the increasing concentration of hydrogen phosphate (with higher scavenging effects than dihydrogen phosphate) from the phosphate buffer as pH values rose. Natural organic matter and bicarbonate dramatically suppressed the degradation of DEP by scavenging Image 1 and HO . Additionally, the presence of chloride ion (Cl − ) promoted the degradation of DEP at low Cl − concentrations (0.25–1 mM). Finally, the proposed degradation pathways were illustrated. [ABSTRACT FROM AUTHOR]

The abundance of chloramphenicol (CAP), a representative antibiotic, was investigated in drinking water sources of the Yangtze River Delta region with detection frequencies of 16–45%. Considering the abuse of CAP, understanding its fate in the water treatment process was necessary. The kinetics and by-products formation of 5 mg L −1 CAP by means of chlorination and photocatalytic oxidation were studied. The degradation of CAP follows approximately a pseudo-first-order kinetics for both chlorination and photocatalytic oxidation, with pseudo first-order rate constants k obs = 0.164 min −1 and k obs = 0.031 min −1 respectively. The reaction rate of CAP chlorination is higher in alkaline solution, while the extent of degradation for photocatalytic oxidation is much greater at pH 4. Transformation intermediates were identified using liquid chromatography-tandems mass spectrometry (LC-MS/MS) and the possible degradation pathways were proposed. Furthermore, disinfection by-products (DBPs) formation potentials were studied by gas chromatograph-mass mass spectrometry GC-MS/MS. [ABSTRACT FROM AUTHOR]

The priority pollutant antimony (Sb) exists primarily as Sb(V) and Sb(III) in natural waters, and Sb(III) is generally with greater mobility and toxicity than Sb(V). The bio-reduction of Sb(V) would not become a meaningful Sb-removal process unless the accumulation of produced dissolved Sb(III) could be controlled. Here, we examined the dissimilatory antimonate bio-reduction with or without the coexistence of sulfate using Sb-acclimated biomass. Results demonstrated that 0.8 mM Sb(V) was almost completely bio-reduced within 20 h along with 48.6% Sb(III) recovery. Kinetic parameters q max and K s calculated were 0.54 mg-Sb mg-DW −1 h −1 and 41.96 mg L −1 , respectively. When the concentrations of coexisting sulfate were 0.8 mM, 1.6 mM, and 4 mM, the reduction of 0.8 mM Sb(V) was accomplished within 17, 9, and 5 h, respectively, along with no final Sb(III) recovery. Also, the bio-reduction of sulfate occurred synchronously. The precipitated Sb 2 O 3 and Sb 2 S 3 were characterized by scanning electron microscopy coupled with energy dispersive spectrometer, X-ray diffraction, and X-ray photoelectron spectroscopy. Compared with bacterial compositions of the seed sludge obtained from anaerobic digestion tank in a wastewater treatment plant, new genera of Pseudomonas and Geobacter emerged with large proportions in both Sb-fed and Sb-sulfate-fed sludge, and a small portion of sulfate reduction bacteria emerged only in Sb-sulfate-fed culture. [ABSTRACT FROM AUTHOR]

This study investigated the UV/persulfate (UV/PS) and UV/chlorine processes as alternative method for the removal of clofibric acid (CA). The formation of disinfection byproducts (DBPs) during subsequent chlor(am)ination was also evaluated. The degradation of CA followed the pseudo-first order kinetics. The second-order rate constants of CA with SO4 − , OH and Cl were respectively determined as k SO 4 - ,CA = (1.73 ± 0.01) × 10 9 M −1 s −1 , k OH ,CA = (2.72 ± 0.08) × 10 9 M −1 s −1 and k Cl ,CA = (9.76 ± 0.15) × 10 10 M −1 s −1 . The degradation rate constant increased with increasing oxidant dosage in UV/PS and UV/chlorine processes. The degradation rate constant was found to be the highest at pH 9 and decreased dramatically at pH 11 in UV/PS process. For UV/chlorine, the rate constant continuously decreased with increasing pH from 3 to 11. Presence of HCO 3 − and Cl − had different effects (promotion and/or inhibition) on CA degradation in both processes. An inhibition effect was observed in the presence of NOM for the two UV-based processes. The higher CA removal in real water suggested the two processes were suitable for treating water containing CA, and the UV/chlorine was more cost-effective than UV/PS based on the total cost of electrical energy. Compared with the chlor(am)ination of CA, the UV/PS and UV/chlorine pre-oxidation significantly impacted the DBP formation during subsequent chlor(am)ination, which indicated the application of the two UV-based processes needs to be carefully balanced against the downstream effect on DBP formation. [ABSTRACT FROM AUTHOR]

Al 2 O 3 -based CoFe 2 O 4 (CoFe 2 O 4 /Al 2 O 3 ) as a catalyst was prepared to activate peroxymonosulfate (PMS) for degradation of sulfachloropyridazine (SCP). In general, the catalytic performance of CoFe 2 O 4 /Al 2 O 3 in activation PMS was demonstrated more effective than CoFe 2 O 4 . Several influence factors were inspected, including scavengers, PMS concentration, pH, anions, nature organic matter (NOM) and temperature. The oxidation of SCP fitted a pseudo-first-order kinetics model and was efficient with the pH from 5.00 to 8.00. The influence of scavengers demonstrated that SO 4 - · played a more significant role than HO · in the oxidation process. The removal was strongly inhibited by adding NOM or HCO 3 - , and almost unaffected by adding NO 3 - , while chloride could enhance the degradation in the system. The increasing temperature greatly promoted the degradation of SCP. After four recycles, CoFe 2 O 4 /Al 2 O 3 still showed preferable catalytic performance with 97.6% removal rate of SCP. Furthermore, the degradation mechanism was explored based on the XPS results. In the composit of CoFe 2 O 4 /Al 2 O 3 , Al 2 O 3 had no additional catalytic performance but just as a matrix base. [ABSTRACT FROM AUTHOR]

Two selected fluoroquinolones (FQs), norfloxacin (NOR) and enrofloxacin (ENR) were degraded using the UV/persulfate process. The degradation of FQs was mainly enhanced with the increasing dosages of persulfate (0.05 mM–0.5 mM) and lower FQs concentration (0.0026–0.052 mM). pH 9.0 was demonstrated as the optimal condition with the apparent rate constants at 0.186 ± 0.018 min −1 and 0.250 ± 0.029 min −1 for NOR and ENR respectively. The detailed degradation mechanisms for FQs by UV/persulfate were proposed. 9 (for NOR) and 12 (for ENR) intermediates were identified by high performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). It is indicated that the degradation occurred mainly through defluorination, hydroxyl substitution and decarboxylation on the C–F bond or carboxylic acid by photon attack, and carbonyl-addition, hydroxyl substitution as well as decarboxylation on the piperazine group also constituted the decontamination, which was followed by the further oxidation, deamination and subsequent dehydrogenation. For NOR, the ethyl of the C–N heterocyclic ring was activated, while the alpha-C atom on the ethyl of the piperazine group was vulnerable for ENR. It was demonstrated that the UV/persulfate process has a great effect on the mineralization (up to 61.2–62.5%) and toxicity control (14.6–32.6%) for the fluoroquinolone antibiotics. [ABSTRACT FROM AUTHOR]

Performances of chloramphenicol (CAP) degradation by direct ultraviolet (UV) irradiation, persulfate (PS) oxidation alone and UV irradiation-activated persulfate process (UV/PS) were systematically studied. UV/PS oxidation was superior over direct UV irradiation or PS oxidation alone. Both SO 4 − and HO were existing in UV/PS system, and SO 4 − was proved to be the primary radical species through the scavenging tests. The secondary order reaction rate constant between CAP and SO 4 − was estimated to be 1.33 × 10 10 M −1 s −1 . The CAP degradation fitted the pseudo-first-order kinetics well (R 2 > 0.95) in tests. Higher PS dosage, lower initial CAP concentration and acid pH promoted the CAP degradation. A maximum TOC removal of 31.7% was observed in 120 min at conditions of [CAP] 0 = 0.03 mM and [PS] 0 = 1.0 mM. At last, the electrical energy per order (EE/O) value in system was demonstrated to be 16.76 kWh/m 3 /order. Results indicated that the UV/PS system is potential alternative to control water pollution caused by emerging contaminants such as CAP. [ABSTRACT FROM AUTHOR]

The sensitivity of perchlorate reduction and microbial composition to varied nitrate and acetate loadings was studied in a biologically activated carbon reactor with perchlorate loading and empty bed contact time fixed at 5 mg/L and 226 min, respectively. In stage 1, the sole electron acceptor ClO 4 − realized complete removal with ≥21.95 mg C/L of acetate supply. As nitrate loading gradually increased to 5 mg/L (stage 2), perchlorate reduction was slightly promoted and both ClO 4 − and NO 3 − were completely removed at an acetate loading of 29.7 mg C/L. When nitrate loading continued increasing to 10–60 mg/L (stage 3), perchlorate reduction converted to be inhibited, along with nondetectable NO 3 − and approximately exhausted DOC in effluent. When acetate loading increased to 43.9 mg C/L in stage 4, both ClO 4 − and NO 3 − were again removed, though lags still existed in perchlorate reduction. β-Proteobacteria accounted for about 60%, 55%, 58%, 61% and 12% in samples from the base and top of the filter in stage 1 and those from the base, middle and top in stage 4, respectively. These findings implied that ratio of NO 3 − to ClO 4 − loadings and acetate loading were two key factors impacting ClO 4 − reduction and microbial structure along the filter. [ABSTRACT FROM AUTHOR]

In this study, the degradation performance of 2,4-Di-tert-butylphenol (2,4-D) by the ultraviolet/persulfate (UV/PS) process was evaluated for the first time. To better understand the possible degradation mechanism in the UV/PS advance oxidation process system, a kinetic model involved hydroxyl and sulfate radicals was developed for predicting pseudo-first order rate constants (k o ) and radical contributions. The results showed that the degradation of 2,4-D was promoted by increasing dosages of PS. H 2 PO 4 - almost had no significant impact on the degradation of 2,4-D, whereas the removal of 2,4-D was suppressed when NO 3 - dosage was added up to 50 mM. HCO 3 - , HPO 4 2 - and natural organic matter significantly inhibited the degradation of 2,4-D. The reaction rate constants between SO 4 - and 2,4-D were not affected by pH. However, the degradation was suppressed with the increasing pH due to the increasing HPO 4 2 - from the phosphate buffer in alkaline. The degradation of 2,4-D was promoted by adding Cl − . The proposed degradation pathways were elucidated on the basis of results obtained by high-performance liquid chromatography combined with triple quadrupole mass spectroscopy analysis. [ABSTRACT FROM AUTHOR]

This study demonstrates the use of MIEX resin as an efficient adsorbent for the removal of clofibric acid (CA) and diclofenac (DCF). The adsorption performance of CA and DCF are investigated by a batch mode in single-component or bi-component adsorption system. Various factors influencing the adsorption of CA and DCF, including initial concentration, contact time, adsorbent dosage, initial solution pH, agitation speed, natural organic matter and coexistent anions are studied. The Langmuir model can well describe CA adsorption in single-component system, while the Freundlich model gives better fitting in bi-component system. The DCF adsorption can be well fitted by the Freundlich model in both systems. Thermodynamic analyses show that the adsorption of CA and DCF is an endothermic (ΔH o > 0), entropy driven (ΔS o > 0) process and more randomness exists in the DCF adsorption process. The values of Gibbs free energy (ΔG o < 0) indicate the adsorption of DCF is spontaneous but nonspontaneous (ΔG o > 0) for CA adsorption. The kinetic data suggest the adsorption of CA and DCF follow the pseudo-first-order model in both systems and the intra-particle is not the unique rate-limiting step. The adsorption process is controlled simultaneously by external mass transfer and surface diffusion according to the surface diffusion modified Biot number (Bi s ) ranging from 1.06 to 26.15. Moreover, the possible removal mechanism for CA and DCF is respectively proposed based on the ion exchange stoichiometry. [ABSTRACT FROM AUTHOR]

Worldwide, the increasing occurrence of microcystin-LR (MC-LR) in water bodies used as source waters for drinking water has become an important public health issue. The present study surveying the MC-LR concentration of natural water in water resources from the Yangtze River Delta region of China was performed from 2013 to 2014. Many of the samples analyzed were found to have high concentration. The highest concentration of MC-LR was 27.79 μg/L, which was observed at Xijiu River in August of 2013. MC-LR is chemically stable, but disinfection by chlorine is known to reduce concentration of MC-LR. In this work, behavior of MC-LR with regard to chlorine has been studied. The decomposition of MC-LR followed first-order kinetics with average first-order constants of about 1.90 × 10 −4 s −1 of a [Chlorine]:[MC-LR] molar ratio of 20:1. The Mdha amino acid in the cyclic structure, the diene bonds and benzene ring in the Adda side chain were the reacted sites of MC-LR. The intermediates and byproducts formed during the chlorination of MC-LR and the probable degradation pathway were investigated, 16 different intermediates were found. Furthermore, the formation potential of carbonaceous disinfection by-products (C-DBPs) and nitrogenous disinfection by-products (N-DBPs) were detected by GC/MSMS. [ABSTRACT FROM AUTHOR]

Dichloroacetamide (DCAcAm), a disinfection byproduct, has been detected in drinking water. Previous research showed that amino acids may be DCAcAm precursors. However, other precursors may be present. This study explored the contribution of the antibiotic chloramphenicol (CAP) and two of its analogues (thiamphenicol, TAP; florfenicol, FF) (referred to collectively as CAPs), which occur in wastewater-impacted source waters, to the formation of DCAcAm. Their formation yields were compared tofree and combined amino acids, and they were investigated in filtered waters from drinking-water-treatment plants, heavily wastewater-impacted natural waters, and secondary effluents from wastewater treatment plants. CAPs had greater DCAcAm formation potential than two representative amino acid precursors. However, in drinking waters with ng/L levels of CAPs, they will not contribute as much to DCAcAm formation as the μg/L levels of amino acids. Also, the effect of advanced oxidation processes (AOPs) on DCAcAm formation from CAPs in real water samples during subsequent chlorination was evaluated. Preoxidation of CAPs with AOPs reduced the formation of DCAcAm during postchlorination. The results of this study suggest that CAPs should be considered as possible precursors of DCAcAm, especially in heavily wastewater-impacted waters. [ABSTRACT FROM AUTHOR]

Pilot-scale tests were performed to reduce the formation of a range of carbonaceous and nitrogenous disinfection by-products (C-, N-DBPs), by removing or transforming their precursors, with an integrated permanganate oxidation and powdered activated carbon adsorption (PM–PAC) treatment process before conventional water treatment processes (coagulation–sedimentation–filtration, abbreviated as CPs). Compared with the CPs, PM–PAC significantly enhanced the removal of DOC, DON, NH 3 + –N, and algae from 52.9%, 31.6%, 71.3%, and 83.6% to 69.5%, 61.3%, 92.5%, and 97.5%, respectively. PM pre-oxidation alone and PAC pre-adsorption alone did not substantially reduce the formation of dichloroacetonitrile, trichloroacetonitrile, N-nitrosodimethylamine and dichloroacetamide. However, the PM–PAC integrated process significantly reduced the formation of both C-DBPs and N-DBPs by 60–90% for six C-DBPs and 64–93% for six N-DBPs, because PM oxidation chemically altered the molecular structures of nitrogenous organic compounds and increased the adsorption capacity of the DBP precursors, thus highlighting a synergistic effect of PM and PAC. PM–PAC integrated process is a promising drinking water technology for the reduction of a broad spectrum of C-DBPs and N-DBPs. [ABSTRACT FROM AUTHOR]

There has been a series of research work on exploring how disinfection by-products (DBPs) are formed from free amino acids (AAs) during chlorination in drinking water. Yet there is very limited information about the formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs) from the chlorination of those AAs in combined forms which are more abundant than free AAs in source waters. In this study, we compared the differences on the formation of trihalomethanes (THMs, representing C-DBPs) and haloacetonitriles (HANs, representing N-DBPs) from free AAs and combined AAs (short oligopeptides) during chlorination. And, the influence of the selected pre-oxidation processes (permanganate, persulfate, hydrogen peroxide) on THM and HAN formation during subsequent chlorination was also examined. There were significant differences in chloroform (CF), dichloroacetonitrile (DCAN) and trichloroacetonitrile (TCAN) formation between free AAs and short oligopeptides, which was probably ascribed to the presence of peptide bond. Of note, the combined tyrosine (Tyr) in tripeptides (Tyr–Tyr–Tyr) formed more TCAN compared with free Tyr and other combined Tyr in dipeptides, and a novel possible formation pathway of TCAN from Tyr–Tyr–Tyr was proposed. In addition, the effect of three pre-oxidation on DBP formation was different, and their rank order was permanganate > persulfate > hydrogen peroxide. The permanganate is a better choice than persulfate and hydrogen peroxide for controlling AA derived HANs, but this benefit should be weighed against the potential drawback of increased regulated THMs. [ABSTRACT FROM AUTHOR]