UV/H_2O_2/O_3联用降解饮用水中的三氯硝基甲烷

分别采用O3、H2O2、UV及其联用技术降解饮用水中的含氮消毒副产物三氯硝基甲烷(TCNM),考察了不同反应条件下对TCNM的降解效果及其影响因素,并探讨了其降解机理。结果表明,单独O3、H2O2和UV工艺对TCNM的去除效果不理想,而UV/H2O2和UV/H2O2/O3组合工艺能够有效去除TCNM。当TCNM初始浓度为20μg/L、紫外光强为31μW/cm2、H2O2投加量为15 mg/L、臭氧投加量为10 mg/L时,反应150 min后,UV/H2O2、UV/H2O2/O3组合工艺对TCNM的去除率分别为82.26%和97.28%,两种工艺对TCNM的降解均符合一级反应动力学。     

UV/PDS降解二苯甲酮-9的动力学及影响因素分析

为解决传统水处理工艺难以有效去除水中二苯甲酮类有机污染物的问题,采用紫外活化过硫酸盐(UV/PDS)工艺降解水中二苯甲酮-9。比较了单一UV、单一PDS及UV/PDS联用工艺对二苯甲酮-9的去除效果,并考察了初始浓度、PDS投加量、p H值、阴离子4种因素的影响。结果表明,与单一UV及单一PDS工艺相比,UV/PDS联用工艺大大提高了二苯甲酮-9的去除效果;在一定范围内,二苯甲酮-9去除率随着其初始浓度的增加而减小,且随着PDS投加量的增加而增大;酸性和碱性条件能促进二苯甲酮-9的降解,而硫酸根、碳酸氢根等阴离子均能抑制降解反应的进行,且碳酸氢根离子的抑制作用最明显。     

O_3/H_2O_2工艺去除饮用水中2-MIB的效能与机制

以2-甲基异莰醇(MIB)为嗅味物质的代表物,采用过氧化氢/臭氧氧化(O3/H2O2)工艺去除水中嗅味物质,考察了O3/H2O2工艺对水中2-MIB的去除效能与主导作用机制。研究表明,投加H2O2显著提高了单独O3氧化对2-MIB的去除效能,H2O2与O3最佳物质的量比为0.3∶1,且2-MIB去除效果随pH值的升高而升高。叔丁醇对2-MIB的去除表现出显著的抑制作用,在O3氧化2-MIB过程中,除O3分子氧化2-MIB外,O3在水中自分解产生的强氧化性的羟基自由基(HO.)也具有协同氧化作用。不同浓度的天然有机物(NOM)对2-MIB去除效果的影响不同,较低浓度的NOM促进了2-MIB的去除,但随着其浓度的升高,2-MIB去除率明显降低。O3/H2O2工艺对水中2-MIB表现出良好的去除效果,是强化去除水中2-MIB等致臭微量有机物的重要工艺。     

Fenton试剂降解邻苯二甲酸二甲酯及反应动力学的研究

针对邻苯二甲酸二甲酯(DMP)难降解的特性,采用Fenton试剂降解DMP.首先考察了Fe2+浓度、Fe2+与H2O2投量比、反应液初始pH、Fenton试剂投加量以及DMP初始浓度对Fenton试剂降解DMP效率的影响.并简要分析了Fenton和类Fenton体系在UV作用下对DMP的降解效果,然后研究了Fenton氧化降解DMP的反应动力学方程.实验结果表明,当DMP初始浓度为2mg/L、Fe2+浓度为2.5 mg/L、Fe2+与H2O2投量比为1∶10、溶液初始pH为3、反应30min,Fenton试剂降解DMP的效率可达96.08%.Fenton和类Fenton体系在UV作用下降解DMP效率与无UV作用相比提高率超过30%.以一级反应动力学模型建立Fenton降解DMP反应表观动力学方程,Fenton及DMP投加量的反应级数分别为2.337,0.2072.     

UV／H2O2用于中水回用预处理工艺试验研究

本试验采用UV／H2O2光氧化法处理含有较高浓度阴离子表面活性剂（LAS）的洗浴废水,研究了H2O2投加量、pH值、光照时间、紫外灯光强对LAS降解率的影响,并得出了一些有益的结论。     

臭氧/过氧化氢降解扑草净试验研究

采用O3/H2O2体系降解内分泌干扰物类除草剂扑草净,并对氧化产物进行色谱分析,考察了该体系去除扑草净的效果。结果表明,当扑草净初始浓度为2 mg/L时,在H2O2/O3(物质的量之比)为0.7、O3投量为16.8 mg/L、温度为25℃、pH值为6.2的最佳条件下,O3/H2O2体系对扑草净的去除率接近93%;在自来水本底条件下,对扑草净的去除率较纯水中的高约9%;腐殖酸对扑草净降解的影响表现为低浓度促进、高浓度抑制,碳酸氢根对扑草净降解的抑制作用较小;伴随扑草净的降解,有硝酸根和硫酸根离子产生,这表明O3/H2O2体系能够有效降解扑草净。     

O3／H2O2艺去除饮用水中2-MIB的效能与机制

以2-甲基异莰醇（MIB）为嗅味物质的代表物,采用过氧化氢／臭氧氧化（O3／H2O2）工艺去除水中嗅味物质,考察了O3／H2O2工艺对水中2一MIB的去除效能与主导作用机制。研究表明,投加H2O2显著提高了单独0,氧化对2-MIB的去除效能,H2O2与O3最佳物质的量比为0．3：1,且2-MIB去除效果随pH值的升高而升高。叔丁醇对2-MIB的去除表现出显著的抑制作用,在O3氧化2-MIB过程中,除O3分子氧化2-MIB外,O3在水中自分解产生的强氧化性的羟基自由基（HO·）也具有协同氧化作用。不同浓度的天然有机物（NOM）对2-MIB去除效果的影响不同,较低浓度的NOM促进了2-MIB的去除,但随着其浓度的升高,2-MIB去除率明显降低。O3／H2O2工艺对水中2-MIB表现出良好的去除效果,是强化去除水中2-MIB等致臭微量有机物的重要工艺。     

UV-H2O2工艺去除饮用水中二氯乙酸的研究

采用间歇式反应器考察了UV-H2O2高级氧化技术去除饮用水中二氯乙酸的效果及其影响因素，并进行了相关的动力学分析。结果表明，在紫外线辐照度为1048μW／cm^2、H2O2投加量为60mg／L、原水pH值为7．1、DOC浓度为5．13mg／L、二氯乙酸初始浓度约为100μg／L的条件下，UV-H2O2工艺对二氯乙酸的去除率〉90％。pH值为中性或偏酸性时，更有利于系统对二氯乙酸的去除；在其他条件一定的情况下，系统对二氯乙酸的去除效果随紫外线辐照度或H2O2投量的增加而增加，但当紫外线辐照度〉640μW／cm^2或H2O2投量〉40mg／L时，系统对二氯乙酸的去除率增加缓慢；在二氯乙酸初始浓度约为100μg／L及其他条件一定的情况下，当原水DOC浓度〈2．39mg／L时，180min内二氯乙酸即可被降解完毕；其他条件不变，当二氯乙酸的初始浓度〉109．48μg／L时，系统对二氯乙酸的去除率随其初始浓度的增加而变得非常缓慢。UV-H2O2工艺对二氯乙酸的降解符合一级反应动力学，UV与H2O2发生协同效应，使得在两者同时增加的情况下，反应速率常数大幅增加。     

铁粉类FENTON降解对硝基苯酚的研究

以硝基苯酚(PNP)为研究对象,分析了铁粉类FENTON体系降解硝基类有机物的反应参数,结果表明对于初始浓度为100 mg/L的PNP溶液最佳降解工艺条件是pH=3±0.1,30%的H2O2投加量为2 mL/L,铁粉投加量4.0 g/L,20 min的PNP去除率达95%以上。     

UV-H2O2工艺降解饮用水中阿特拉津的试验研究

采用紫外—过氧化氢（UV—H2O2）的光激发氧化工艺去除饮用水中的内分泌干扰物——阿特拉津，考察了影响降解效果的因素。试验结果表明：紫外—过氧化氢工艺对阿特拉津有较好的去除效果，阿特拉津的降解过程符合一级反应动力学模型。通过提高照射光强，可以提高对阿特拉津的去除速率。过氧化氯浓度对阿特拉津的降解具有促进和抑制的双重作用：当H2O2浓度〈60mg／L时，降解阿特拉津的一级反应速率常数随H2O2浓度的增加而线性增加；当H2O2浓度〉80mg／L时，该反应速率常数的增加速率变得缓慢；当H2O2浓度〉120mg／L时，阿特拉津的降解受到明显抑制。阿特拉津初始浓度对降解过程没有影响。自来水中羟基自由基捕获剂及有机物的存在，会降低阿特拉津的降解速率，而较低的pH值则有利于降解反应的进行。     

混凝联合O_3、O_3/UV深度处理焦化废水的研究

采用混凝联合O3、O3/UV深度处理焦化废水的生物处理出水。试验结果表明:当混凝剂Al2(SO4)3的投量为900 mg/L时,对TOC、COD、色度和UV254的去除率分别为23.2%、19.5%、33.6%和27.1%,相应的出水值分别为55.5 mg/L、196 mg/L、680倍和2.53 cm-1。混凝出水经O3/UV深度处理的效果优于单独O3氧化的,当臭氧投量为2.8 g/L、反应时间为80 min、UV照射强度为30 W时,对TOC、COD、色度和UV254的去除率分别达到91.8%、73.1%、96.1%和97.6%,相应的出水值分别为5.9 mg/L、60 mg/L、40倍和0.081 cm-1,出水COD浓度达到《污水综合排放标准》(GB 8978—1996)的一级标准,且大大提高了废水的可生化性。     

阴离子交换膜生物反应器反硝化性能的研究

考察了进水硝酸盐浓度对阴离子交换膜生物反应器反硝化性能的影响。试验结果表明,当进水NO3-为47.01～168.55mg/L时,流动池出水中的NO3-N浓度满足我国生活饮用水水质标准中小于10mg/L的要求(NO3-≤44.29mg/L)。厌氧生物反应器对硝酸盐具有较高的反硝化性能。流动池出水中的Cl-浓度随着进水NO3-浓度的增加而升高,但出水pH值稳定在6.8左右。出水总有机碳浓度与进水的保持一致,表明其未受到"二次污染"和"微生物污染"。     

三种预氧化剂在水处理中的应用评估

源水的富营养化将严重影响常规给水处理厂的运行,使得出水水质不能保证。为此,开展了KMnO4、H2O2、ClO2 的预氧化研究。结果表明,投加这三种氧化剂均能显著提高对水中藻类、浊度、有机物的去除率,对细菌及大肠菌群也有较好的去除效果,但投加KMnO4 会增加出水色度,采用ClO2 作氧化剂则成本较高,相比之下H2O2 是一种较为理想的预氧化剂。     

光助芬顿法降解印制电路板脱膜废液

研究表明,采用UV／Fenton均相光催化氧化体系降解印制电路板脱膜废液效果好。在H202用量为1倍理论药量,Fe^2＋：H2O2（摩尔比）=1：20,光照时间为80min,脱膜废液COD去除率可达80％。光助芬顿体系降解脱膜废液的诸多影响因素中,重要性次序依次为H2O2投药比〉FeSO4／H2O2的比值〉光照时间。     

Occurrence and formation potential of N-nitrosodimethylamine in ground water and river water in Tokyo

N-nitrosodimethylamine (NDMA), a disinfection byproduct of water and wastewater treatment processes, is a potent carcinogen. We investigated its occurrence and the potential for its formation by chlorination (NDMA-FP_2Cl) and by chloramination (NDMA-FP_2NHCl) in ground water and river water in Tokyo. To characterize NDMA precursors, we revealed their molecular weight distributions in ground water and river water. We collected 23 ground water and 18 river water samples and analyzed NDMA by liquid chromatography-tandem mass spectrometry. NDMA-FP_2Cl was evaluated by chlorinating water samples with free chlorine for 24 h at pH 7.0 while residual free chlorine was kept at 1.0-2.0 mgCl₂/L. NDMA-FP_2NHCl was evaluated by dosing water samples with monochloramine at 140 mgCl₂/L for 10 days at pH 6.8. NDMA precursors and dissolved organic carbon (DOC) were fractionated by filtration through 30-, 3-, and 0.5 kDa membranes. NDMA concentrations were <0.5-5.2 ng/L (median: 0.9 ng/L) in ground water and <0.5-3.4 ng/L (2.2 ng/L) in river water. NDMA concentrations in ground water were slightly lower than or comparable to those in river water. Concentrations of NDMA-FP_2Cl were not much higher than concentrations of NDMA except in samples containing high concentrations of NH₃ and NDMA precursors. The increased NDMA was possibly caused by reactions between NDMA precursors and monochloramine unintentionally formed by the reaction between free chlorine and NH₃ in the samples. NDMA precursors ranged from 4 to 84 ng-NDMA eq./L in ground water and from 11 to 185 ng-NDMA eq./L in river water. Those in ground water were significantly lower than those in river water, suggesting that NDMA precursors were biodegraded, adsorbed, or volatilized during infiltration. The molecular weight of NDMA precursors in river water was dominant in the <0.5 kDa fraction, followed by 0.5-3 kDa. However, their distribution was inconsistent in ground water: one was dominant in the <0.5 kDa fraction, and the other in 0.5-3 kDa. Molecular weight distributions of NDMA precursors were very different from those of DOC. This is the first study to reveal the widespread occurrence and characterization of NDMA precursors in ground water.     

Fe-H2O2深度处理造纸中段废水的研究

为解决零价铁法处理废水时效率偏低的问题,采用Fe-H2O2法对造纸中段废水的二级处理出水进行了深度处理,分别考察了pH值、反应时间、铁炭比、曝气量和H2O2投量对色度和COD去除率的影响.结果表明：在pH值为3.5、铁炭比（体积比）为1.2、曝气量为1.4 L/min、铁屑粒径为60～80目、H2O2投量为40～60 mg/L的最优条件下,当处理时间控制在35 min时,对色度和COD的去除率可分别达到98%和77%左右,出水可回用.     

Evaluating the impacts of membrane type, coating, fouling, chemical properties and water chemistry on reverse osmosis rejection of seven nitrosoalklyamines, including NDMA

Reverse osmosis (RO) treatment has been found to be effective for a wide range of organics but generally small, polar, uncharged molecules such as N-nitrosodimethylamine (NDMA) can be poorly rejected. The rejection of seven N-nitrosoalkylamines with molecular masses in the range of 78-158Da, including NDMA, N-nitrosodiethylamine (NDEA), N-nitrosomethylethylamine (NMEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip) by three commercial brackish-water reverse osmosis membranes was studied in flat-sheet cells under cross-flow conditions. The membranes used were ESPA3 (Hydranautics), LFC3 (Hydranautics) and BW-30 (Dow/Filmtec), commonly used in water reuse applications. The effects of varying ionic strength and pH, dip-coating membranes with PEBAX 1657, a hydrophilic polymer, and artificial fouling with alginate on nitrosamine rejection were quantified. Rejection in deionized (DI) water increased with molecular mass from 56 to 70% for NDMA, to 80-91% for NMEA, 89-97% for NPyr, 92-98% for NDEA, and to beyond the detection limits for NPip, NDPA and NDBA. For the nitrosamines with quantifiable transmission, linear correlations (r(2)>0.97) were found between the number of methyl groups and the log(transmission), with factor 0.35 to 0.55 decreases in transmission per added methyl group. A PEBAX coating lowered the ESPA3 rejection of NDMA by 11% but increased the LFC3 and BW30 rejection by 6% and 15%, respectively. Artificially fouling ESPA3 membrane coupons with 170g/m(2) alginate decreased the rejection of NDMA by 18%. A feed concentration of 100mM NaCl decreased rejection of NDMA by 15% and acidifying the DI water feed to pH=3 decreased the rejection by 5%, whereas increasing the pH to 10 did not have a significant (p<0.05) effect.     

Impact of UV/H(2)O(2) advanced oxidation treatment on molecular weight distribution of NOM and biostability of water

The presence of natural organic matter (NOM) poses several challenges to the commercial practice of UV/H₂O₂ process for micropollutant removal. During the commercial application of UV/H₂O₂ advanced oxidation treatment, NOM is broken down into smaller species potentially affecting biostability by increasing Assimilable Organic Carbon (AOC) and Biodegradable Organic Carbon (BDOC) of water. This work investigated the potential impact of UV/H₂O₂ treatment on the molecular weight distribution of NOM and biostability of different water sources. A recently developed flow cytometric method for enumeration of bacteria was utilized to assess biological stability of the treated water at various stages through measurement of AOC. BDOC was also assessed for comparison and to better study the biostability of water. Both AOC and BDOC increased by about 3-4 times over the course of treatment, indicating the reduction of biological stability. Initial TOC and the source of NOM were found to be influencing the biostability profile of the treated water. Using high performance size exclusion chromatography, a wide range of organic molecule weights were found responsible for AOC increase; however, low molecular weight organics seemed to contribute more. Positive and meaningful correlations were observed between BDOC and AOC of different waters that underwent different treatments.     

Aerobic treatment of N-nitrosodimethylamine in a propane-fed membrane bioreactor

N-Nitrosodimethylamine (NDMA) is a suspected human carcinogen that has recently been detected in wastewater, groundwater and drinking water. Treatment of this compound to low part-per-trillion (ng/L) concentrations is required to mitigate cancer risk. Current treatment generally entails UV irradiation, which while effective, is also expensive. The objective of this research was to explore potential bioremediation strategies as alternatives for treating NDMA to ng/L concentrations. Batch studies revealed that the propanotroph Rhodococcus ruber ENV425 was capable of metabolizing NDMA from 8 μg/L to <2 ng/L after growth on propane, and that the strain produced metabolites that do not pose a significant risk at the concentrations generated (Fournier et al., 2009). A laboratory-scale membrane bioreactor (MBR) was subsequently constructed to evaluate the potential for long-term ex situ treatment of NDMA. The MBR was seeded with ENV425 and received propane as the primary growth substrate and oxygen as an electron acceptor. At an average influent NDMA concentration of 7.4 μg/L and a 28.5 h hydraulic residence time, the reactor effluent concentration was 3.0 ± 2.3 ng/L (>99.95% removal) over more than 70 days of operation. The addition of trichloroethene (TCE) to the reactor resulted in a significant increase in effluent NDMA concentrations, most likely due to cell toxicity from TCE-epoxide produced during its cometabolic oxidation by ENV425. The data suggest that an MBR system can be a viable treatment option for NDMA in groundwater provided that high concentrations of TCE are not present.