Electron Redistribution in Iridium-Iron Dual-Metal-Atom Active Sites Enables Synergistic Enhancement for H2O2 Decomposition.

Developing efficient heterogeneous H2O2 decomposition catalysts under neutral conditions is of great importance in many fields such as clinical therapy, sewage treatment, and semiconductor manufacturing but still suffers from low intrinsic activity and ambiguous mechanism understanding. Herein, we constructed activated carbon supported with an Ir-Fe dual-metal-atom active sites catalyst (IrFe-AC) by using a facile method based on a pulsed laser. The electron redistribution in Ir-Fe dual-metal-atom active sites leads to the formation of double reductive metal active sites, which can strengthen the metal-H2O2 interaction and boost the H2O2 decomposition performance of Ir-Fe dual-metal-atom active sites. Ir-Fe dual-metal-atom active sites show a high second-order reaction rate constant of 3.53 × 106 M-1·min-1, which is ∼106 times higher than that of Fe3O4. IrFe-AC is effective in removing excess intracellular reactive oxygen species, protecting DNA, and reducing inflammation under oxidative stress, indicating its therapeutic potential against oxidative stress-related diseases. This study could advance the mechanism understanding of H2O2 decomposition by heterogeneous catalysts and provide guidance for the rational design of high-performance catalysts for H2O2 decomposition.

Biology and morphometric relationship of gall inducers Contarinia sp. and corresponding parasitoids for swollen galls of Nitraria sibirica pall.

Galls function as provide shelter for gall inducers, guarding them against their natural enemies. Previous research has illuminated the interactions between galls, gall inducers, and their corresponding parasitoids within various caltrop plants. However, less is known about these relationships within Nitraria sibirica, particularly regarding the efficacy of parasitism. Therefore, this study aimed to identify the morphometric relationships among the swollen galls, gall inducers, and their parasitoids. Two species of gall inducers and three species of parasitoids were obtained from the swollen galls of N. sibirica. The correlations of the parasitization indexes, the lifespan of gall inhabitants, and temperature and the morphometric relationships between the galls and their inhabitants were analyzed. The dominant gall inducer identified was Contarinia sp. (Diptera: Cecidomyiidae). Furthermore, it was observed that three solitary parasitoids attacked Contarinia sp. in the swollen galls, with only Eupelmus gelechiphagus acting as an idiobiont ectoparasitoid. The dominant parasitoids were Platygaster sp. and Cheiloneurus elegans at sites 1 and 2, respectively, with Platygaster sp. displaying greater abundance than C. elegans in the swollen galls. The lifespan of the gall inhabitants shortened gradually as the temperature increased. Moreover, the optimal number of gall chambers ranged from two to four per swollen gall with maximized fitness, which can be considered the optimal population density for the gall inducer Contarinia sp. Morphometric analysis exhibited a strong linear correlation between gall size and chamber number or the number of gall inhabitants, as well as a weak correlation between gall size and body size of the primary inhabitants of swollen galls. Our results highlight the importance of the biological investigation of parasitoids and gall inducers living in closed galls with multiple chambers and may pave the way for potential application in biological control.

Comparison of disinfection-residual-bacteria (DRB) after seven different kinds of disinfection: Biofilm formation, membrane fouling and mechanisms.

Membrane fouling is the Achilles' heel of the reverse osmosis (RO) system for high-quality reclaimed water production. Previous studies have found that after the significant selection effect of traditional disinfection, the remaining disinfection-residual bacteria (DRB) may possess more severe biofouling potentials. To provide more constructive advice for the prevention of biofouling, we compared the RO membrane fouling characteristics of DRB after using five commonly used disinfection methods (NaClO, NH2Cl, ClO2, UV, and O3) and two novel disinfection methods (K2FeO4 and the flow-through electrode system (FES)). Compared with the control group (undisinfected, 21.1 % flux drop), the UV-DRB biofilm aggravated biofouling of the RO membrane (23.4 % flux drop), while the FES, K2FeO4, and NH2Cl treatments showed less severe biofouling, with final flux drops of 6.9 %, 8.1 %, and 8.1 %, respectively. Adenosine triphosphate (ATP) was found to be a capable indicator for predicting the biofouling potential of DRB. Systematic analysis showed that the thickness and density of the DRB biofilms were most closely related to the different fouling degree of RO membranes. Moreover, the relative abundance of bacteria with higher extracellular polymeric substance (EPS) secretion levels, such as Pseudomonas and Sphingomonas, was found closely related with the biofouling degree of RO membranes.

Identification of surrogates for rapid monitoring of microbial inactivation by ozone for water reuse: A pilot-scale study.

The complex contaminants in reclaimed water sources and delayed feedback of microbial detection have brought tremendous challenges to disinfection process control. The identification of sensitive and online surrogates for indicating microbial inactivation efficacy is vital to evaluate and optimize the disinfection technologies and processes. This study analyzes the inactivation of microbial indicators during ozone disinfection at a pilot-scale study over 5 months. It is identified that total fluorescence (TF) intensity, ultraviolet absorbance at 254 nm (UV254) and intracellular adenosine triphosphate (cATP) concentration can act as surrogates in predicting microbial inactivation by ozone. Particularly, the empirical linear correlations for log removal values (LRV) of TF, UV254 and cATP concentration are developed for the inactivation of four widely applied microbial indicators, namely the total coliforms, fecal coliforms, Escherichia coli (E. coli) and heterotrophic plate count (HPC) (R2 = 0.86-0.96). Validation analyses are further conducted to verify the robustness and effectiveness of empirical models. Notably, TF is considered as the most efficient surrogate due to its high sensitivity, accuracy and reliability, whereas cATP concentration is an efficient supplement to directly reflect total microbial counts. The study is important to provide a rapid and reliable approach for ozone disinfection efficiency evaluation and prediction.

Elimination of amino trimethylene phosphonic acid (ATMP) antiscalant in reverse osmosis concentrate using ozone: Anti-precipitation property changes and phosphorus removal.

Amino trimethylene phosphonic acid (ATMP) was widely used as an antiscalant in reverse osmosis (RO) systems to prevent membrane scaling, and entered RO concentrate at elevated levels. However, phosphonate antiscalants in RO concentrate might aggravate phosphorus pollution, remobilize heavy metals, and adversely affect the sedimentation treatment of RO concentrate. Ozonation was found an efficient method for ATMP treatment. The ATMP removal efficiencies with 8 mg/L ozone were 100% and 86.5% for ultrapure water and RO concentrate, respectively. The ATMP mineralization efficiency reached 46.5% with 8 mg/L ozone. The rate constant for the reaction between ATMP and ozone was 1.92 × 106 M-1 s-1. Increasing the pH from 3 to 9 decreased the ATMP removal efficiency from 90% to 30.9% but increased the orthophosphate formation to ATMP removal ratio from 0.11 to 0.48. The ATMP intermediates generated with low ozone dosages exhibited moderate chelation and anti-precipitation capacity, and their chelation and anti-precipitation capacity could be further attenuated by increasing the ozone dosage. Ozonation alone enhanced the growth potential for microalgae in RO concentrate because orthophosphate formed. Combining ozonation and coagulation effectively removed 83.0% of the total phosphorus from RO concentrate. The maximum algal density of Scenedesmus sp. LX1 decreased by 78.7% by ozonation and coagulation.

Assessment and mechanisms of microalgae growth inhibition by phosphonates: Effects of intrinsic toxicity and complexation.

The effects of phosphonates, the heavily-used antiscalants in reverse osmosis systems, on microalgae are controversial, although they are harmless to most aquatic organisms. Herein, we assessed the inhibitory effects of etidronic acid (HEDP) and diethylenetriamine penta(methylene phosphonic acid) (DTPMP) on algal growth and revealed the mechanisms involved in both intrinsic toxicity and complexation. The phosphonates showed weak influences on Scenedesmus sp. LX1 in the first 4 d of cultivation. In contrast, a significant growth inhibition was observed subsequently with half maximal effective concentrations of 57.6 and 35.7 mg/L for HEDP and DTPMP, respectively, at 10 d. The phosphonates had little effect on cellular energy transfer and oxidative stress, quantified by adenosine triphosphate level and superoxide dismutase activity, respectively, demonstrating weak intrinsic toxicities to algal cells. Phosphonates blocked the algal assimilation of iron ions through complexation. Severe iron deficiency limited photosynthetic activity and caused chlorophyll decline, resulting in a functional loss of the photosystem followed by complete algal growth inhibition at the late cultivation stage. Our findings point to a potential ecological impact wherein harmful algal blooms are induced by the natural degradation of phosphonates due to the release of both iron and phosphate ions that stimulate algal regrowth after disinhibition.

Cell Transport Prompts the Performance of Low-Voltage Electroporation for Cell Inactivation.

The inactivation of pathogens in liquids has broad applications, ranging from water disinfection to food pasteurization. However, common cell inactivation methods (e.g., chlorination, ultraviolet radiation and thermal treatment) have significant drawbacks such as carcinogenic byproduct formation, energy intensiveness and/or nutrient structure destruction. Here, we fabricated a new approach to address these challenges by applying a low-voltage electroporation disinfection cell (EDC) and investigate the critical mechanisms of cell transport to allow high inactivation performance. The EDC prototypes were equipped with two one-dimensional (1D) nanostructure-assisted electrodes that enabled high electric field strength (>107 V m-1) near the electrode surface with a low applied voltage (1 V). We have identified that during electroporation disinfection, electrophoresis, dielectrophoresis and hydraulic flow are the three major mechanisms which transport cells into the vicinity of the electrode surface to achieve superior disinfection performance. The EDC treated 70 ml of bacteria sample with an initial cell concentration of 107 CFU ml-1 and achieved complete bacteria inactivation (survival rate <0.00001%; no live bacteria detected). Our findings will help to establish a foundation for the future development and implementation of low-voltage electroporation for cell inactivation.

Interaction between 1,2-benzisothiazol-3(2H)-one and microalgae: Growth inhibition and detoxification mechanism.

Isothiazolinones, such as 1,2-benzisothiazol-3(2H)-one (BIT), are widely used as biocides for bacterial growth control in many domestic and industrial processes. Despite their advantages as biocides, they are highly toxic and pose a potential risk to the environment. This study investigated the inhibition process and detoxification mechanism involved in microalgal survival and growth recovery after BIT poisoning. BIT could seriously inhibit the growth of Scenedesmus sp. LX1, Chlorella sp. HQ, and Chlamydomonas reinhardtii with half maximal effective concentrations at 72 h (72h-EC50) of 1.70, 0.41, and 1.16 mg/L, respectively. The primary inhibition mechanism was the BIT-induced damage to microalgal photosynthetic systems. However, the inhibited strains could recover when their growth was not completely inhibited. The influence of this inhibiting effect on subsequent algal regrowth was negligible or weak. BIT consumption was the primary reason for their recovery. Notably, algae did not die even if their growth was completely inhibited. If the BIT concentration did not exceed a certain high level, then the inhibited algae could recover their growth relatively well. Microalgal generation of reduced glutathione (GSH) and the oxygen radical scavenging enzymes, superoxide dismutase (SOD) and catalase (CAT), played a key role in detoxification against BIT poisoning.

Response of microbial community structure and metabolic profile to shifts of inlet VOCs in a gas-phase biofilter.

The effects of inlet VOCs (Volatile Organic Compounds) shifts on microbial community structure in a biofiltration system were investigated. A lab-scale biofilter was set up to treat eight VOCs sequentially. Short declines in removal efficiency appeared after VOCs shifts and then later recovered. The number of OTUs in the biofilter declined from 690 to 312 over time. At the phylum level, Actinobacteria and Proteobacteria remained dominant throughout the operation for all VOCs, with their combined abundance ranging from 60 to 90%. The abundances of Planctomycetes and Thermi increased significantly to 20% and 5%, respectively, with the intake of non-aromatic hydrocarbons. At the genus level, Rhodococcus was present in the highest abundance (≥ 10%) throughout the experiment, indicating its wide degradability. Some potential degraders were also found; namely, Thauera and Pseudomonas, which increased in abundance to 19% and 12% during treatment with ethyl acetate and toluene, respectively. Moreover, the microbial metabolic activity declined gradually with time, and the metabolic profile of the toluene-treating community differed significantly from those of other communities.

Tolerance and resistance characteristics of microalgae Scenedesmus sp. LX1 to methylisothiazolinone.

Methylisothiazolinone (MIT) has been widely used to control bacterial growth in reverse osmosis (RO) systems. However, MIT's toxicity on microalgae should be determined because residual MIT is concentrated into RO concentrate (ROC) and might have a severe impact on microalgae-based ROC treatment. This study investigated the tolerance of Scenedesmus sp. LX1 to MIT and revealed the mechanism of algal growth inhibition and toxicity resistance. Scenedesmus sp. LX1 was inhibited by MIT with a half-maximal effective concentration at 72 h (72 h-EC50) of 1.00 mg/L, but the strain recovered from the inhibition when its growth was not completely inhibited. It was observed that this inhibition's effect on subsequent growth was weak, and the removal of MIT was the primary reason for the recovery. Properly increasing the initial algal density significantly shortened the adaptation time for accelerated recovery in a MIT-containing culture. Photosynthesis damage by MIT was one of the primary reasons for growth inhibition, but microalgal cell respiration and adenosine triphosphate (ATP) synthesis were not completely inhibited, and the algae were still alive even when growth was completely inhibited, which was notably different from observations made with bacteria and fungi. The algae synthesized more chlorophyll, antioxidant enzymes of superoxide dismutase (SOD) and catalase (CAT), and small molecules, such as reduced glutathione (GSH), to resist MIT poisoning. The microalgae-based process could treat the MIT-containing ROC, since MIT was added for only several hours a week in municipal wastewater reclamation RO processes, and the MIT average concentration was considerably lower than the maximum concentration that algae could tolerate.

Development of an ATP luminescence-based method for assimilable organic carbon determination in reclaimed water.

Assimilable organic carbon (AOC) is an important indicator of the biological stability of reclaimed water. In this study, a new rapid and more stable method for AOC measurement in reclaimed water was proposed. Indigenous microbial culture from secondary effluent was used as the inoculum, and bacterial growth was determined by the quantity of adenosine triphosphate (ATP) in the form of luminescence instead of plate count. ATP luminescence had a high correlation with biogrowth both in pure acetate solutions and reclaimed waters. ATP luminescence analysis could be determined in 5 min. Three days of 10000 cells/mL inoculum incubated at 25 °C were enough for the bacteria to reach the stationary phase. The good correlations between ATP luminescence and the added acetate-C concentration illustrated the applicability of monitoring AOC level by luminescence method. And in reclaimed water samples, indigenous microbial culture produces the highest AOC results compared with the pure strains. This indicated that the integrity of indigenous microbial culture ensured the full utilization of matrix carbons, which demonstrated the advantage of indigenous microbial culture compared with the selected pure bacteria in the traditional AOC test. The average ATP content per cell of 3.95 × 10-10 nmol/cell was derived, and this value was stable in both the acetate solutions and reclaimed waters. Furthermore, the average yield coefficient of 1.5 × 105 RLU/µg acetate-C (4.1 × 10-3 nmol ATP/µg acetate-C) was obtained from different indigenous cultures. Additionally, the indigenous microbial cultures from different secondary effluents would produce the similar AOC results for the same water sample, indicating the consistency of this assay. The ATP luminescence-AOC assay provides a faster, more stable and accurate approach for monitoring the biological stability of reclaimed waters.

Primary Intraosseous Adenoid Cystic Carcinoma of the Mandible: A Comprehensive Review With Analysis of 2 Additional Cases.

PURPOSE: Primary intraosseous adenoid cystic carcinoma (IACC) of the mandible is poorly understood because of its rarity. This study performed a comprehensive literature review on IACC of the mandible. MATERIALS AND METHODS: Forty-five cases of IACC reported in the literature and 2 additional cases in the authors' hospital were reviewed. RESULTS: IACC of the mandible generally occurred in the fourth to sixth decades, with no meaningful gender predilection. Pain and swelling were the most common clinical manifestations. Radical surgery combined with postsurgical radiotherapy was recommended as the best treatment. CONCLUSIONS: The diagnosis of IACC should be based on clinical, radiologic, and pathologic examinations. Radical surgery combined with postsurgical radiotherapy seems to be the best treatment. In addition, the histologic subtype of the tumor is an important prognostic factor in patients with IACC.

Nanowire-Modified Three-Dimensional Electrode Enabling Low-Voltage Electroporation for Water Disinfection.

More than 10% of the people in the world still suffer from inadequate access to clean water. Traditional water disinfection methods (e.g., chlorination and ultraviolet radiation) include concerns about the formation of carcinogenic disinfection byproducts (DBPs), pathogen reactivation, and/or excessive energy consumption. Recently, a nanowire-assisted electroporation-disinfection method was introduced as an alternative. Here, we develop a new copper oxide nanowire (CuONW)-modified three-dimensional copper foam electrode using a facile thermal oxidation approach. An electroporation-disinfection cell (EDC) equipped with two such electrodes has achieved superior disinfection performance (>7 log removal and no detectable bacteria in the effluent). The disinfection mechanism of electroporation guarantees an exceedingly low operation voltage (1 V) and level of energy consumption (25 J L(-1)) with a short contact time (7 s). The low operation voltage avoids chlorine generation and thus reduces the potential of DBP formation. Because of irreversible electroporation damage on cell membranes, no regrowth and/or reactivation of bacteria occurs during storage after EDC treatment. Water disinfection using EDCs has great potential for practical applications.

The removal of estrogenic activity with UV/chlorine technology and identification of novel estrogenic disinfection by-products.

As a recently developed disinfection technology, ultraviolet (UV)/chlorine treatment has received much attention. Many studies have evaluated its effects on pathogen inactivation, contaminant removal, and formation of disinfection by-products (DBPs), but its potential for environmental estrogen removal and estrogenic DBP generation, which can also be a risk to both ecosystem and human health, have not been evaluated. In this study, UV/chlorine treatment resulted in a greater removal of estrogenic activity in synthetic effluent samples containing 17ß-estradiol (E2) than did UV or chlorine treatment alone regardless of the water quality. For both the UV/chlorine and chlorine treatments, there was significant interference from NH3-N, although the UV/chlorine treatment was less affected. Estrogen receptor based affinity chromatography was used to isolate the specific estrogenic DBPs, and a novel product, with high estrogenic activity compared to E2, Δ9(11)-dehydro-estradiol, was identified. It was generated by all three treatments, and might be previously mistakenly recognized as estrone (E1). This study demonstrated that UV/chlorine is a better treatment for the removal of 17ß-estradiol than chlorine and UV alone. The new identified estrogenic DBP, Δ9(11)-dehydro-estradiol, which can be isolated by affinity chromatography, could be an emerging concern in the future.

Investigation of the characteristics of biofilms grown in gas-phase biofilters with and without ozone injection by CLSM technique.

Recently, ozone injection technique was developed as a novel biomass control method to reduce bed clogging in biofilters treating volatile organic compounds (VOCs). However, the effects of ozone on the characteristics of biofilms are still unknown. In this study, two identical lab-scale biofilters treating gaseous toluene were operated in parallel except that one was continuously injected with 200 mg/m(3) ozone. Four glass slides were placed inside each biofilter on day 57 and then were taken out sequentially after 1, 2, 4, and 6 weeks of cultivation. The biofilms grown on the glass slides were stained by the ViaGram™ Red + Bacterial Gram Stain and Viability Kit and observed through the confocal laser scanning microscopy (CLSM). According to the CLSM images of 1, 2, and 4 weeks, the ozonated biofilm was significantly thinner than the control biofilm, which demonstrated that ozone could effectively control the biomass in the biofilter. For the biofilter without ozone injection, the ratios of viable cells (0.51~0.89) and the ratios of Gram-positive bacteria (0.22~0.57) both decreased within 4 weeks of cultivation. The CLSM image analysis results also demonstrated that a continuous injection of 200 mg/m(3) ozone was able to significantly enhance the ratio of viable cells to 0.77~0.97 and allow the dominance of Gram-positive bacteria in the biofilms with the ratio 0.46~0.88 instead of Gram-negative bacteria. For the 6-week samples, the biofilm thickness of the control system was reduced significantly which indicated the detachment of accumulated biofilms might occur in the samples without ozone.

Evidence of ATP assay as an appropriate alternative of MTT assay for cytotoxicity of secondary effluents from WWTPs.

Biological tests are effective and comprehensive methods to assess toxicity of environmental pollutants to ensure the safety of reclaimed water. In this study, the canonical MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed to evaluate the cytotoxicity of dissolved organic matters (DOMs) of secondary effluents from wastewater treatment plants (WWTPs). It was surprising that most concentrated DOMs treated HepG2 cells yielded much higher signal compared with vehicle control regardless of difference of treatment technologies and seasons. However, there was actually no obvious enhancement of the cell proliferation by microscopy. In order to find out potential reason for the discrepancy, another three assays were performed. The results of ATP assay and flow cytometry showed expected toxicity, which was consistent with microscopy and previous studies, while DNA assay did not exhibit apparent change in treated cells. The possible mechanisms of abnormal MTT signal could be that some materials in secondary effluents isolated by solid extraction with HLB resin directly reacted with MTT and/or enhanced the activity of mitochondrial dehydrogenase. Therefore, the MTT assay is not suitable to assess cytotoxicity of complex mixtures such as secondary effluents, while ATP assay is an optional sensitive method. This study also suggests the importance of choosing both suitable extraction methods and detection assays for toxicity evaluation of component-unknown environmental samples.

Health risk assessment of phthalate esters (PAEs) in drinking water sources of China.

Phthalate esters (PAEs) with endocrine disruption effects and carcinogenicity are widely detected in water environment. Occurrences of PAEs in source water and removal efficiencies of PAEs by drinking water treatment plants (DWTPs) in China were surveyed from publications in the last 10 years. Concentration of diethylhexyl phthalate (DEHP) in source water with median value of 1.3 µg/L was higher than that of dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP). If the removal efficiencies of DEHP and DnBP reached 60 and 90 %, respectively, the calculated PAE concentration in drinking water can generally meet Standards for Drinking Water Quality in China. The health risks of PAEs, including non-carcinogenic and carcinogenic risks via the "water source-DWTP-oral ingestion/dermal permeation" pathway, were evaluated with Monte Carlo simulation and sensitivity analysis under certain removal efficiencies from 0 to 95 %. The carcinogenic risk of DEHP was lower than the upper acceptable carcinogenic risk level (10(-4)), while the probability of DEHP's carcinogenic risk between lower (10(-6)) and upper (10(-4)) acceptable carcinogenic risk level decreased from about 21.2 to 0.4 % through increasing DEHP removal efficiency from 0 to 95 %. The non-carcinogenic risk of DEHP was higher than that of DEP and DnBP. In all cases, the total non-carcinogenic risk of DEP, DnBP, and DEHP was lower than 1, indicating that there would be unlikely incremental non-carcinogenic risk to humans. Both carcinogenic risk and non-carcinogenic risk of PAEs in drinking water to female were a little higher than those to male.

Enhanced decomposition of 1,4-dioxane in water by ozonation under alkaline condition.

1,4-Dioxane is a probable human carcinogenic and refractory substance that is widely detected in aquatic environments. Traditional wastewater treatment processes, including activated sludge, cannot remove 1,4-dioxane. Removing 1,4-dioxane with a reaction kinetic constant of 0.32 L/(mol·s) by using ozone, a strong oxidant, is difficult. However, under alkaline environment, ozone generates a hydroxyl radical (•OH) that exhibits strong oxidative potential. Thus, the ozonation of 1,4-dioxane in water under different pH conditions was investigated in this study. In neutral solution, with an inlet ozone feed rate of 0.19 mmol/(L·min), the removal efficiency of 1,4-dioxane was 7.6% at 0.5 h, whereas that in alkaline solution was higher (16.3-94.5%) within a pH range of 9-12. However, the removal efficiency of dissolved organic carbon was considerably lower than that of 1,4-dioxane. This result indicates that several persistent intermediates were generated during 1,4-dioxane ozonation. The pseudo first-order reaction further depicted the reaction of 1,4-dioxane. The obvious kinetic constants (kobs) at pH 9, 10, 11 and 12 were 0.94, 2.41, 24.88 and 2610 L/(mol·s), respectively. Scavenger experiments on radical species indicated that •OH played a key role in removing 1,4-dioxane during ozonation under alkaline condition.

[Health risk induced by estrogens during unplanned indirect potable reuse of reclaimed water from domestic wastewater].

The estrogenic endocrine disruptors in reclaimed water from domestic wastewater may induce health risks to human being, when reclaimed water is used for augmentation of drinking water unplannedly and indirectly. This study investigated changes in concentrations of estrone, estradiol, 17alpha-ethinyl estradiol, bisphenol A, nonylphenol and octylphenol in reclaimed water during the reuse of reclaimed water for augmentation to water source such as lakes and reservoir via river. Thereafter, health risk induced by estrogens during the resue of reclaimed water was evaluated. The concentration of estrogen in secondary effluent ranged 0.1-100 ng x L(-1). The highest concentrations of bisphenol A and nonylphenol reached up to 1-10 microg x L(-1). During the indirect reuse of reclaimed water as potable water, the dilution and degradation in river and lake, and the removal by drinking water treatment process could change the concentrations of estrogen. The non-carcinogenic risks of estrone, estradiol, bisphenol A, nonylphenol and octylphenol were lower than 1. When the hydraulic retention time of 17alpha-ethinyl estradiol (EE2) in lakes and reservoir was higher than 30 days, the non-carcinogenic risk of EE2 was lower than 1 in most cases. When the hydraulic retention time of EE2 in lakes and reservoir was less than 30 days and the percentages of reclaimed water in drinking water were higher than 50%, the non-carcinogenic risk induced by EE2 was higher than 1 in 20%-50% samples. This indicated that the risks of EE2 should be concerned.

Antiestrogenic activity and related disinfection by-product formation induced by bromide during chlorine disinfection of sewage secondary effluent.

Chlorine disinfection, widely used in wastewater reclamation, can form toxic and harmful disinfection by-products (DBPs), some of which are associated with endocrine disruption. In this study, the presence of bromide was found to promote an increase in antiestrogenic activity using a yeast two-hybrid assay in the sewage secondary effluent during chlorine disinfection. Among the dissolved organic matters in the secondary effluent, hydrophobic acids and hydrophilic substance fractions were determined as potential precursors associated with increase in antiestrogenic activity in the secondary effluent induced by bromide. Further antiestrogenic activity evaluation and mass spectrum characterization following the semipreparative liquid chromatography fractionation of a natural organic matter precursor, tyrosine, after chlorination under the presence of bromide revealed, for the first time, that 2-(bromo-4-hydroxyphenyl) acetonitrile (Br-HPAN) and 2-(dibromo-4-hydroxyphenyl) acetonitrile (DBr-HPAN) exhibited antiestrogenic activity. Br-HPAN and DBr-HPAN were the DBPs involved in the increase in antiestrogenic activity in the tyrosine solution. Bromide was shown to induce the formation of Br-HPAN and DBr-HPAN in the secondary effluent during chlorine disinfection.