Transformations of particles, metal elements and natural organic matter in different water treatment processes

Characterizing natural organic matter （NOM）, particles and elements in different water treatment processes can give a useful information to optimize water treatment operations. In this article, transformations of particles, metal elements and NOM in a pilot-scale water treatment plant were investigated by laser light granularity system, particle counter, glass-fiber membrane filtration, inductively coupled plasma-optical emission spectroscopy, ultra filtration and resin absorbents fractionation. The results showed that particles, NOM and trihalomethane formation precursors were removed synergistically by sequential treatment of different processes. Preozonation markedly changed the polarity and molecular weight of NOM, and it could be conducive to the following coagulation process through destabilizing particles and colloids; mid-ozonation enhanced the subsequent granular activated carbon （GAC） filtration process by decreasing molecular weight of organic matters. Coagulation-flotation and GAC were more efficient in removing fixed suspended solids and larger particles; while sand-filtration was more efficient in removing volatile suspended solids and smaller particles. Flotation performed better than sedimentation in terms of particle and NOM removal. The type of coagulant could greatly affect the performance of coagulation-flotation. Pre-hydrolyzed composite coagulant （HPAC） was superior to FeCl3 concerning the removals of hydrophobic dissolved organic carbon and volatile suspended solids. The leakages of flocs from sand-filtration and microorganisms from GAC should be mitigated to ensure the reliability of the whole treatment system.     

Haloacetic acids in swimming pool and spa water in the United States and China

The objective of this study is to investigate the occurrence of haloacetic acids （HAAs）, a group of disinfection byproducts, in swimming pool and spa water. The samples were collected from six indoor pools, six outdoor pools and three spas in Pennsylvania, the United States, and from five outdoor pools and nine indoor pools in Beijing, China. Five HAAs （HAA5）, including monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid were analyzed. Total chlorine, pH and total organic carbon concentration were analyzed as well. Results indicated that the levels of HAA5 in swimming pools and spas in the United States ranged from 70 to 3980μg·L^-1, with an arithmetic average at 1440μg·L^-1 and a median level at 1150μg·L^-1. These levels are much higher than the levels reported in chlorinated drinking water and are likely due to organic matters released from swimmers＇ bodies. The levels of HAA5 in swimming pools in China ranged from 13 to 332μg·L^-1, with an arithmetic average at 117μg·L^-1 and a median level at 114μg·L^-1. The lower HAA levels in swimming pools in China were due to the lower chlorine residuals. Results from this study can help water professionals to better understand the formation and stability of HAAs in chlorinated water and assess risks associated with exposures to HAAs in swimming pools and spas.     

水中天然有机物的分类特性及其卤代活性

利用XAD树脂对原水中的天然有机物进行富集分类 ,将其分为腐植酸、富里酸、亲水酸和其它亲水物质等 4种有机组分 .考察了原水中各有机组分的分布及其在加氯消毒过程中的三卤甲烷生成量、生成速度及耗氯量情况 .研究结果表明 ,原水中的主要成分是富里酸 ,占有机物总量的50.7% ,其它3种成分所占比例相对较小 ;原水具有较高的三卤甲烷生成能力 ,富里酸是生成三卤甲烷的主要有机组分 ;对各有机组分卤代活性的研究表明 ,腐植酸、富里酸和亲水酸具有较高的卤代活性 ,其它亲水物质的卤代活性较低 ;从各有机组分的三卤甲烷生成速度及与氯反应速度来看 ,腐植酸、富里酸及亲水酸具有较快的三卤甲烷生成速度 ,与氯的反应速度也较快 ,而其它亲水物质的三卤甲烷生成速度及与氯的反应速度均较低 .     

氯化对二级处理出水中溶解性有机物结构的影响

以哈尔滨市W污水处理厂污水为研究对象,利用XAD树脂对二级处理出水中的溶解性有机物(DOM)进行分级分离.按照DOM在不同树脂上的吸附特性将其分为5个部分:疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).考察了二级处理出水中有机组分的组成分布、三卤甲烷生成势、紫外光谱和红外光谱.结果表明,二级处理出水中的主要成分是HPO-A和HPI,两者含量之和达70.8%.HPO-A是加氯消毒时产生三卤甲烷的主要有机组分,其三卤甲烷生成活性(STHMFP)为232.9μg/mg.而HPO-N、TPI-A、TPI-N和HPI的STHMFP介于100～125μg/mg之间.氯化反应后,HPO-A、HPO-N、TPI-A和HPI的紫外-可见吸光度均降低,而TPI-N则相反.并且HPO-A、HPO-N、TPI-A和TPI-N中的O-H、C=C和苯环的含量降低,而C-O的含量升高,还生成了C=O和C-Cl.     

广东省主要土类的三卤甲烷生成潜能(THMFP)

通过振荡浸出实验,测定了广东省几种主要土类的三卤甲烷生成潜能(THMFP),比较了土壤浸提液中溶解态(可过滤态)有机物与悬浮态(不可过滤态)有机物在形成三卤甲烷(THMs)中的作用,并对影响土壤THMFP的各种因素进行讨论结果表明:①各主要土类表层土中,未过滤浸提液的整体THMFP(b-THMFP)含量范围为:0.7～36.8μg/g土,中值为10.6μg/g土;过滤浸提液的THMFP(指可溶性有机物的THMFP,即d-THMFP)含量范围为:0.5～21.2μg/g土,中值为3.9μg/g土;其中,19号石灰土的b-THMFP和d-THMFP最高,20号紫色土的b-THMFP最低,5号赤红壤的d-THMFP最低.②总体上,悬浮态有机物对THMs生成量有较大的正贡献.③影响土壤THMFP的因素主要是有机质含量、各种氧化物含量、土壤发生层次、植被等.     

Modeling trihalomethane formation for Jabal Amman water supply in Jordan

A mathematical model that expresses Total trihalomethane (TTHM) concentration in terms of initial chlorine concentration, total organic carbon, bromide ion concentration, contact time, and pH is developed for Zai water treatment plant which supplies water to Jabal Amman. The developed mathematical model is for constant temperature of 20°C. To adjust model calculated TTHM concentrations for temperatures other than 20°C, another mathematical model that expresses TTHM growth rate as function of temperature is also developed. To test the ability of the two developed models in predicting TTHM concentrations throughout water supplies, a sampling program that aimed at measuring TTHM concentrations in addition to the predictors in the two developed mathematical models namely; chlorine concentration, bromide ion concentration, total organic carbon, temperature and pH throughout Jabal Amman water supply was conducted. The two developed mathematical models and WaterCad, which was used to determine water age, were used to predict TTHM concentrations throughout Jabal Amman water supply. Predicted TTHM concentrations were compared to actual TTHM concentrations measured during the sampling program. Results showed that there is good agreement between measured and, calculated TTHM concentrations, which means that the method presented in this paper, can be used to obtain good estimates of TTHM concentrations throughout networks.     

人工地下水回灌过程中溶解性有机物的去除及变化

在实验室通过模拟土壤柱研究了人工地下水回灌过程中溶解性有机物的去除及其三卤甲烷生成势和三卤甲烷生成活性的变化.利用XAD树脂将回灌水中的溶解性有机物分为3个部分：疏水性有机酸、过渡亲水性有机酸和亲水性有机物.疏水性有机酸的三卤甲烷生成活性高于过渡亲水性有机酸和亲水性有机物.土壤含水层处理（SAT）对亲水性有机物的去除率为68.51%,对疏水性有机酸和过渡亲水性有机酸的去除率分别为58.64%和41.86%.经SAT系统处理后,溶解性有机物及各有机组分的三卤甲烷生成势减少,而三卤甲烷生成活性升高.疏水性有机酸是生成三卤甲烷的主要有机组分.亲水性有机物在SAT系统进水中的三卤甲烷生成活性较低,但由于含量高,三卤甲烷生成势也较大.而过渡亲水性有机酸由于含量和三卤甲烷生成活性较低,三卤甲烷生成势也较低.     

Trihalomethane Formation Potential and Concentration Changes During Water Treatment at Mumbai (India)

The treated water at the outlet oftreatment plants and representative servicereservoirs of Mumbai city have been evaluatedfor trihalomethane formation potential in1995–1996. Chloroform, dichlorobromomethane,chlorodibromomethane and bromoform have beenmonitored during monsoon, winter and summer.The levels of chloroform are found above theregulated WHO guideline value of 200 g L^-1 in final water during postmonsoon atGhatkopar (226 g L^-1), Malbar (210.3 g L^-1) and Tulsi (231.26 g L^-1).     

Reduction of DOM fractions and their trihalomethane formation potential in surface river water by in-line coagulation with ceramic membrane filtration

This research was aimed at investigating the reduction of DOM fractions and their trihalomethane formation potential （THMFP） by in-line coagulation with 0.1 μm ceramic membrane filtration. The combination of ceramic membrane filtration with a coagulation process is an alternative technology which can be applied to enhance conventional coagulation processes in the field of water treatment and drinking water production. The Ping River water （high turbidity water） was selected as the raw surface water because it is currently the main raw water source for water supply production in the urban and rural areas of Chiang Mai Province. From the investigation, the results showed that the highest percent reductions of DOC, UV-254, and THMFP （47.6%, 71.0%, and 67.4%, respectively） were achieved from in-line coagulation with ceramic membrane filtration at polyaluminum chloride dosage 40 mg/L. Resin adsorption techniques were employed to characterize the DOM in raw surface water and filtered water. The results showed that the use of a ceramic membrane with in-line coagulation was able to most efficiently reduce the hydrophobic fraction （HPOA） （68.5%）, which was then followed by the hydrophilic fraction （HPIA） （49.3%）. The greater mass DOC reduction of these two fractions provided the highest THMFP reductions （55.1% and 37.2%, respectively）. Furthermore, the in-line coagulation with ceramic membrane filtration was able to reduce the hydrophobic （HPOB） fraction which is characterized by high reactivity toward THM formation. The percent reduction of mass DOC and THMFP of HPOB by in-line coagulation with ceramic membrane filtration was 45.9% and 48.0%, respectively.     

氨氮及H2O2对溴酸盐和消毒副产物控制的影响

本研究以南方某含溴水源为原水,利用饮用水常规工艺及臭氧-活性炭深度处理中试连续实验,评价臭氧氧化过程中溴酸盐生成情况,并考察了氨氮、过氧化氢(H_2O_2)对溴酸盐控制效果及对三卤甲烷生成势(THMFP)的去除影响.结果表明,在不同水质条件下,臭氧消耗量为1.0 mg·L~(-1)以上时,溴酸盐的生成量超过标准(10.00μg·L~(-1)).利用氨氮和H_2O_2投加均能有效控制溴酸盐生成量,且随投加量增大,溴酸盐生成量逐渐降低,氨氮投加0.10~0.30 mg·L~(-1)或m(H_2O_2)/m(O3)(质量比)为0.2~1.0时,能够将溴酸盐控制在标准以内.当氨氮-H_2O_2联合控制溴酸盐时,溴酸盐生成量随m(H_2O_2)/m(O3)先升高后降低.在利用氨氮和H_2O_2投加进行溴酸盐控制过程中,氨氮对THMFP的去除效率影响并不显著,而投加H_2O_2使得THMFP去除效能有所降低.