污水中二甲基亚硝胺的形成及处理研究进展

二甲基亚硝胺(NDMA)是强致癌物质亚硝胺中的一种,由于其近年来在水环境中的高检出率引起了人们的广泛关注.综述了NDMA的基本性质、来源、各种不同的分析方法及检测限,并列出了目前主要的去除方法.NDMA广泛存在于各种水体中,但其分析检测和去除尚存在一定难度.传统的检测方法不能满足痕量NDMA的分析;GC-MS-MS和HPLC-MS-MS是目前应用比较广泛的两种分析方法.紫外照射能去除NDMA,但其费用较高.并且无法破坏其前体物的结构,处理后的水再经氯化处理时仍可能形成NDMA.亟需进一步研究有效去除NDMA及其前体物的方法.     

微污染水源水中消毒副产物前体物的去除

采用生物接触氧化法对北京某水库的微污染水源水中消毒副产物前体物的去除进行了研究。结果表明,水源水和生物接触氧化柱(简称生化柱)出水中的消毒副产物前体物氯化后形成的消毒副产物三卤甲烷(THMs)以CHCl3,CHCl2Br和CHBr2Cl为主,其中CHCl3含量最高,约占THMs的70％。水温对THMs前体物的去除有很大的影响,水温15．8℃时,生化柱对THMs前体物的去除率为65．2％;当水温由15．8℃降至12．8℃时,THMs前体物的去除率由65．2％降至18．8％。2002年11月至2003年1月间,生化柱UV254吸收值的平均去除率为11％。     

不同吸附剂对三氯乙醛及其前体物的去除

研究了粉末活性炭、硅藻土和膨润土等3种常用吸附剂对三氯乙醛(CH)的去除作用,并以南方某水源原水为研究对象,分析3种吸附剂对于CH前体物(CH1d和CHFP)的去除效果。结果表明,膨润土和粉末活性炭适用于对CH的去除,最大去除率分别为95.93%和86.86%。225 mg·L-1投加量条件下,前15 min膨润土和粉末活性炭对CH吸附效果最快,2种吸附剂对CH去除率分别为63.36%和51.84%;反应2 h后,对CH的吸附已达到饱和,此时膨润土和粉末活性炭对CH去除率分别为89.36%和61.75%。粉末活性炭和硅藻土适用于对CH前体物的去除,最适投加量均为30 mg·L-1,此时对CH1d和CHFP的去除率分别为57.49%和75.21%、28.27%和50.19%。可根据CH的风险程度高低选择硅藻土或粉末活性炭对CH前体物予以去除。     

河流型水源地源水典型氯化消毒副产物及其前体物的强化去除工艺

以长三角某典型河流型水源地源水为研究对象,设计了传统工艺及基于凹凸棒土处理单元的6种强化工艺,对各工艺及其处理单元应用于典型氯化消毒副产物(三卤甲烷和卤乙酸)及其前体物控制的技术和经济可行性进行了系统分析。结果表明,预O3+凹土强化混凝+O3-GAC强化的工艺对上述2种消毒副产物及其前体物的控制效果最佳;在传统工艺中单纯增加O3处理也能在一定程度上提高其对消毒副产物前体物的去除效果;KMnO4控制消毒副产物的效果一般,但KMnO4处理可强化后续单元对消毒副产物前体物的去除效果。各工艺处理出水中三卤甲烷和卤乙酸单项指标均能达标,但传统工艺和经凹土强化混凝+GAC强化的工艺出水三卤甲烷4种化合物的实测浓度与其各自限值的比值之和均大于1.0,不能满足水质要求,必须进行强化处理。凹土强化混凝单元在6种强化工艺条件下对三卤甲烷生成潜能(THMFP)和卤乙酸生成潜能(HAAFP)的去除率较传统混凝单元平均提高15.99%和4.92%;各强化工艺对THMFP和HAAFP的去除率较传统工艺均提高20%以上(除凹土强化混凝+GAC强化的工艺外),消毒副产物产生量降低40%以上,工艺成本降低20%以上。     

城市污水再生氯消毒过程中HAAs生成及迁移转化

针对城市污水再生处理工艺中卤乙酸类(HAAs)消毒副产物和卤乙酸生成潜能(HAAFP),结合三维荧光光谱,分析HAAs及其前体物的变化规律。结果表明,二级出水经2次加氯过程后,再生出水中的总卤乙酸浓度增加了90%,其中溴代乙酸的增幅最大,占增加量的82%。卤乙酸生成潜能较大的为氯代乙酸类物质,说明水中存在大量的氯代乙酸前体物。从工艺过程来看,总卤乙酸生成潜能与总有机物荧光强度分别下降了32%和28%,表明该再生处理工艺对HAAs前体物有一定的去除作用。     

O_3和ClO_2氧化NDMA前体的动力学和产物生成规律

以4种含有二甲胺(DMA)官能团的药物和个人护理品(PPCPs)为研究对象,通过研究其降解反应动力学和氧化产物生成规律,确定臭氧(O_3)和二氧化氯(ClO_2)对N-亚硝基二甲胺(NDMA)生成势的控制效果。O_3氧化PPCPs的二级反应速率常数(k)为10~5~10~6(mol·s)~(-1),ClO_2氧化PPCPs的k为10~1~10~2(mol·s)~(-1),ClO_2与O_3均可去除PPCP类NDMA前体。O_3与PPCP反应生成氮加氧产物,加氧在DMA官能团的氮上,该氮加氧产物不再具有NDMA生成势,且O_3与PPCP摩尔比为1:1时,加一氧产物的生成量最大。ClO_2与PPCPs反应时生成去DMA基产物,脱落的DMA也具有NDMA生成势,ClO_2氧化产物仍具有NDMA生成势,且ClO_2与PPCPs的摩尔比为3:1时,去DMA基产物生成量最大。O_3氧化可满足对NDMA生成势的控制,但ClO_2氧化不能满足对NDMA生成势的控制。     

基于响应面法的重金属螯合剂前体物合成条件优化研究

以小分子的乙二胺与环氧氯丙烷为原料,以黏度为考察对象,对高分子重金属螯合剂的前体物合成条件进行优化。采用单因素实验确定黏度的主要影响因素,然后采用响应面法对制备条件进行优化。结果表明:(1)拟合的模型回归项显著而失拟项不显著,拟合性良好。(2)最佳制备条件为环氧氯丙烷和乙二胺摩尔比1.1、反应温度82.8℃、反应时间9.2h、NaOH和乙二胺摩尔比1.2。(3)产物傅立叶红外光谱表明,特征官能团的存在证明了前体物的生成。(4)利用前体物进一步合成了螯合剂,该螯合剂的Pb去除和稳定效果明显优于市售螯合剂。     

臭氧氧化敌草隆生成亚硝基二甲胺的研究

初步探究了敌草隆在臭氧氧化下生成毒性更强的消毒副产物亚硝基二甲胺(NDMA)的可能性及机理。结果表明,臭氧氧化降解敌草隆过程中的NDMA生成问题不容忽视,NDMA生成量随敌草隆初始浓度增加而升高,并且随反应时间的延长迅速升高。中性(pH=7.5)条件下敌草隆降解速率虽然略慢,但反应15.0min仍能达到较高的敌草隆去除率,同时可以抑制NDMA的大量生成。自由基清除剂叔丁醇共存可以显著降低NDMA的生成。NDMA生成途径为:敌草隆被臭氧氧化成中间产物二甲胺后,二甲胺在臭氧和·OH共同作用下生成NDMA。     

天津市秋季臭氧浓度影响因素及相关关系研究

选择天津市秋季典型重污染时期2005年11月2～7日近地面大气O3、NO、NO2、CO、紫外线(UV)强度和温度等观测数据,研究O3浓度的时间变化特征及其与相关前体物、气象条件的相关关系.结果表明,在观测期间O3浓度存在明显的日变化周期,在13:00～14:00时浓度最大,夜间变化平缓;O3浓度与NO、NO2、NOx和CO等前体物呈较好的负相关关系;温度和UV与O3浓度密切相关,昼间O3与UV呈相同变化趋势,相关系数达0.71,O3浓度变化滞后于UV变化,将O3浓度与前1小时的UV对比分析,相关系数提高到0.81.     

基于树脂处理和电解联用的卤代消毒副产物控制

天然有机物(NOM)和溴离子是卤代消毒副产物的前体物,氯型阴离子交换树脂可以有效去除这2种前体物,同时交换出氯离子。交换出的氯离子与水源水中天然存在的氯离子通过电解可以产生自由氯用于消毒。将氯型阴离子交换树脂处理与电解联用,通过建立和优化树脂处理与电解消毒方法,实现饮用水中卤代消毒副产物的控制。结果表明:树脂依次经过碱/酸洗、甲醇抽提和5次去离子水清洗后,可以有效减少树脂溶出,并降低氯离子和甲醇的影响;在2 L的模拟水源水样中加入20 mL树脂反应1 h后,可以去除93.7%的NOM和91.2%的溴离子;由树脂交换至水样中的氯离子通过电解氧化,可以在3 min内产生5 mg·L~(-1)的氯。与单独的氯消毒相比,新方法可以削减86.4%的总有机卤素(TOX)。     

Sources and fate of nitrosodimethylamine and its precursors in municipal wastewater treatment plants.

To assess the occurrence and fate of nitrosodimethylamine (NDMA) and its precursors in wastewater treatment plants, samples from wastewater treatment plants and industrial sources were analyzed for NDMA, total NDMA precursors, and dimethylamine (DMA). The median concentration of NDMA in untreated wastewater was approximately 80 ng/L, with maximum concentrations up to 790 ng/L presumably occuring because of sources unrelated to domestic wastewater. Concentrations of DMA in untreated wastewater ranged from approximately 50 to 120 microg/L and accounted for a majority of the NDMA precursors. The removal of NDMA during secondary biological treatment exhibited considerable variability, with overall removal ranging from 0 to 75%. In contrast, removal of NDMA precursors and DMA generally exceeded 70%. The median concentration of NDMA in secondary effluent before disinfection was 46 ng/L. Although DMA was removed during secondary treatment, other NDMA precursors in wastewater effluent will result in formation of additional NDMA upon disinfection with chloramines.     

N-nitrosodimethylamine: a disinfectant byproduct and its occurrence in wastewater.

This paper will provide wastewater treatment utility professionals with a comprehensive synthesis of information pertinent to N-nitrosodimethylamine (NDMA) so that plant operators can make informed and cost-effective decisions regarding appropriate management techniques. A suspect disinfection byproduct, NDMA is a potential carcinogen and is presently under scrutiny from the U.S. Environmental Protection Agency because it poses a threat to groundwaters from reclaimed wastewaters. Recognizing that the current state of knowledge pertaining to the occurrence and treatment of NDMA from wastewater treatment is in its infancy, the information presented in this paper is timely and will help utility professionals develop confidence toward controlling NDMA during wastewater treatment. Given the increased probability of the formation of NDMA using current wastewater treatment technologies and also in the complex matrices of the wastewaters subjected to UV treatment, the investigation of occurrence pathways and means of suppression of NDMA formation before and after treatment needs to be investigated. This paper also summarizes strategies to minimize exposure such as modifying treatment or instituting waste and agricultural management practices that minimize inorganic and organic nitrogen discharges to wastewaters.     

火力发电厂废水处理的现状与展望

介绍了当前我国火力发电厂废水处理技术的现状,对火力发电厂各类废水的特点及其处理方法进行了相应的分析,并对火电厂废水处理的发展进行了展望。     

Influence of soluble microbial products (SMP) on wastewater disinfection byproducts: trihalomethanes and haloacetic acid species from the chlorination of SMP

Introduction  

Effluent organic matter from biological wastewater treatment plants is composed of degradation products and soluble microbial products (SMP). Protein, polysaccharide, humic acid, and DNA were major biomolecules of SMP. Little is known about the effects of SMP as microbially derived precursors on disinfection byproduct formation and speciation in biologically treated wastewater. In addition, there has never been any attempt to directly chlorinate the major biomolecules of SMP.     

南京市某城镇污水处理厂运行问题分析及对策

随着大量污水处理厂的建成投运,中国污水处理事业的重心必然会从以建设为主转向建设与运行并重,运行管理将发挥越来越重要的作用。文中以南京市某城镇污水处理厂为例,分析该污水处理厂运行过程COD、NH^3-N排放超标问题,并提出对策(健全配套污水收集管网,提升工艺参数DO、NO^3-、NO^2-的控制水平,规范运行台账管理等),以期为其他城镇污水处理厂的运行管理提供参考。     

Use of naturally growing aquatic plants for wastewater purification.

This paper examines potential uses of naturally growing aquatic plants for wastewater purification. These plants enhance the removal of pollutants by consuming part of them in the form of plant nutrients. This applies to urban and agricultural wastewater, in particular, where treatment units of different sizes can be applied at the pollution source. The effectiveness of wastewater purification by different plants was tested on laboratory and pilot scales. The growth rate of the plants was related to the wastewater content in the water. Batch and semicontinuous experiments verified that the plants are capable of decreasing all tested indicators for water quality to levels that permit the use of the purified water for irrigation. This applies to biochemical oxygen demand (BOD), chemical oxygen demand, total suspended solids. pH, and turbidity. In specific cases, the turbidity reached the level of drinking water. Comparison of BOD concentrations with typical levels in water treatment facilities across the country indicates the effectiveness of water purification with plants. A major effect of treatment with plants was elimination of the disturbing smell from the wastewater. It is shown that mixtures of wastewater and polluted water from the Kishon River are amenable in varying degrees to treatment by the plants. The higher the wastewater content in the mixture, the more effective the treatment by the plants. In this context, a scheme for rehabilitation and restoration of the Kishon River is presented and technical and economical aspects of the purification technology are considered.     

Formation of N-nitrosodimethylamine (NDMA) by ozonation of dyes and related compounds

Formation of N-nitrosodimethylamine (NDMA) by ozonation of commercially available dyes and related compounds was investigated. Ozonation was conducted using a semi-batch type reactor, and ozone concentration in gas phase and the ozone gas flow were 10 mg L(-1) and 1.0 L min(-1), respectively. NDMA was formed by 15 min of ozonation of seven out of eight selected target compounds (0.05 mM) at pH 7. All the target compounds with N,N-dimethylamino functions were NDMA precursors in ozonation. The lowest and highest NDMA concentrations after ozonation of the target compounds were 13 ng L(-1) for N,N-dimethylformamide (DMF) and 1600 ng L(-1) for N,N-dimethyl-p-phenylenediamine (DMPD), respectively. NDMA concentrations after 15 min of ozonation of 0.05 mM methylene blue (MB) and DMPD increased with an increase in pH in its range of 6-8. The effects of coexisting compounds on NDMA concentrations after 15 min of ozonation of 0.05 mM MB and DMPD were examined at pH 7. NDMA concentrations after ozonation of MB and DMPD increased by the presence of 0.05 mM (0.7 mg L(-1) as N) nitrite (NO(2)(-)); 5000 ng L(-1) for MB and 4000 ng L(-1) for DMPD. NDMA concentration after MB ozonation decreased by the presence of 5mM tertiary butyl alcohol (TBA), a hydroxyl radical (HO.) scavenger, but that after DMPD ozonation was increased by the presence of TBA. NDMA concentrations after ozonation of MB and DMPD were not affected by the presence of 0.16 mM (5.3 mg L(-1)) hydrogen peroxide (H(2)O(2)). When 0.05 mM MB and DMPD were added to the Yodo and Tone river water samples, NDMA concentrations after 15 min of their ozonation at pH 7 increased compared with those in the case of addition to ultrapure water samples.     

城市污水处理厂除臭技术

介绍了城市污水处理厂臭气来源、成分及产量.针对目前国内外除臭技术的研究和发展情况,分析了污水处理厂的各种物理、化学和生物除臭方法的技术原理、优缺点和应用现状.结合日本城市污水处理厂的运行实际,重点介绍了一种不产生臭气的新技术--腐殖活性污泥法的工艺流程、特点及其应用现状.     

浙江省污水处理厂现状、存在问题及对策建议

根据对浙江省37家城市污水处理厂和大型工业污水集中处理厂20个月的监督监测结果，评述了该省城市污水处理厂和大型工业污水集中处理厂的现状，分析了经处理后排放的尾水超标原因和存在问题，并提出对策和建议。     

城市污水处理厂除臭技术

介绍了城市污水处理厂臭气来源、成分及产量。针对目前国内外除臭技术的研究和发展情况，分析了污水处理厂的各种物理、化学和生物除臭方法的技术原理、优缺点和应用现状。结合日本城市污水处理厂的运行实际，重点介绍了一种不产生臭气的新技术——腐殖活性污泥法的工艺流程、特点及其应用现状。