聚合硫酸铁(PFS)混凝腐殖酸(HA)的过程中典型操作因素的影响研究

针对聚合硫酸铁（PFS）混凝-沉淀去除腐殖酸（HA）水样的过程,通过测定典型操作因素（PFS投加量、原水pH和搅拌方式）下微絮体的zeta电位、上清液的浊度、UV254、pH值及电导率和絮体沉降体积变化,探讨了这些因素对该过程的影响.结果表明：在原水pH=6.00时,PFS混凝HA的主要机制为电中和作用,搅拌方式对PFS的最佳投加范围没有明显的影响,但单一搅拌方式下HA的去除效果更好;在原水pH=8.00时,吸附络合-卷扫絮凝成为主要的混凝机制,复合搅拌方式下PFS的最佳投加量范围大于单一搅拌方式,且前者的HA去除效果更好.整体而言,几种混凝条件下PFS最佳投药量对应的微絮体zeta电位均在-12.00mV左右;原水pH=6.00时PFS混凝-沉淀去除HA的效果比原水pH=8.00时的好,且前者形成的PFS-HA沉淀絮体体积较小,但单一搅拌方式下絮体结构的重组过程并不是影响絮体体积的主要因素.复合搅拌方式中开始阶段的高强度搅拌有助于PFS组分在HA水样中的分散而有利于其电中和作用的发挥,但对PFS的水解过程影响不大.     

Cu2+在混凝中对富里酸氯化消毒副产物的影响

混凝实验采用硫酸铝作为混凝剂,以富里酸（FA）为目标物,考察Cu²⁺对浊度、溶解性有机碳（DOC）去除效果和氯化消毒副产物生成势（DBPsFP）的影响,并采用三维荧光光谱（3DEEM）和超滤膜分级对混凝出水进行表征.结果表明,Cu²⁺可以通过络合反应提高混凝过程对FA中亲水性组分和芳香结构DBPs前驱体的去除效果.在pH> 7时,可以使二氯乙酸生成势（DCAAFP）和三氯甲烷生成势（TCMFP）明显降低.Cu²⁺-混凝的作用更倾向于影响FA中分子量级分处于10~30kDa的物质,提高其对DOC和DBPs生成势的去除效果.     

强化混凝对二级处理出水中溶解性有机物特性的影响

以沈阳市B污水处理厂二级处理出水为研究对象,采用FeCl3.6H2O作为混凝剂,研究了强化混凝对二级处理出水中溶解性有机物(DOM)的卤代活性和荧光特性的影响.按照DOM在XAD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).结果表明,强化混凝(混凝剂投加量为80mg.L-1,pH=5.00)对DOC的去除率为55.3%.强化混凝对HPO-A的去除率最高,而对HPI的去除率最低.强化混凝后,HPO-N的三卤甲烷生成活性(STHMFP)上升,而其他4种DOM组分的STHMFP下降.强化混凝能够有效去除类富里酸荧光物质和具有高环数和高聚合度的稠环类芳香性荧光物质.强化混凝对DOM组分的去除率和DOM组分的荧光强度下降率的相关性不显著.     

Natural organic matter(NOM) removal from surface water by coagulation

IntroductionNaturalorganicmatter(NOM)inriversandlakesisacomplexmixtureofmoleculeswithvaryingmolecularweightandchemicalnatureandoriginatesfromavarietyofsources(degradationofterrestrialandaquaticorganisms,biologicalactivityinthewaterbody,humaninputsetc.).NO…     

Effect of bioflocculants on the coagulation activity of alum for removal of trihalomethane precursors from low turbid water

Reactivity of chlorine towards hydrophobic groups present in natural organic matter(NOM)provokes the formation of carcinogenic disinfection byproducts such as trihalomethanes in chlorinated water. The present study aimed to investigate the variations in coagulant activity of alum using two different bioflocculants(coagulant aid) namely, Moringa oleifera and Cyamopsis tetragonoloba for the removal of hydrophobic fractions of NOM and subsequent chlorine consumption by treated water. Effect of dual coagulants on trihalomethane surrogate parameters such as total organic carbon, dissolved organic carbon, UV absorbing materials and prominent hydrophobic species such as phenolic groups along with aromatic chromophores, polyhydroxy aromatic moiety have also been studied. The concept of differential spectroscopy and absorbance slope index has been employed to understand the combined effects of alum-bioflocculants on the reactivity of NOM with chlorine. Our result shows that the combination of alum and C. tetragonoloba is more efficient for reducing trihalomethane surrogates from chlorinated water as compared to M. oleifera. C. tetragonoloba elicited synchronized effects of sweep coagulation and particle bridging-adsorption which eventually facilitated efficient removal of hydrophobic fractions of NOM. The variation in the mechanistic approach of bioflocculants was due to the presence of cationic charge on M. oleifera and adhesive property of C. tetragonoloba.     

Removal natural organic matter in typical south-China source water during enhanced coagulation of a with IPF-PACl

Systematic investigation on enhancing removal of natural organic matter （NOM） using inorganic polymer flocculant （IPF）, polyaluminum chloride（PACI） and polyacrylamide（PAM） was performed in a typical south-China source water. Enhanced coagulation and applying polymer flocculant-aid were compared through jar tests and pilot tests. Raw water and settled water were characterized and fractionated by resin adsorption. The results show that DOC composes major part of TOC. The DOC distribution keeps relatively stable all around the year with typical high amounts of the hydrophilic matter around 50%. The distribution between HoB, HoA and HoN varies and undergoes fluctuation with the year round. During the summer season, the HoN becomes gradually the major part in hydrophobic parts. PACI with the species being tailor-made shows little pH effect during coagulation. The enhanced coagulation dosage for PACI could be 4.5 mg/L for the typical source water. The highest TOC removal achieved 31%. To be economically, 3 mg/L dose is the optimum dosage. Although hydrophilic fractions of NOM of both treatment strategies are removed about 30%, NOM causing UV254 absorbance were well removed（about 90%）. Hydrophobic bases and acids fractions are much more removed under enhanced conditions. The hydrophilic fraction could be better removed using PAM, the polymer coagulant aid.     

Removal of dispersant-stabilized carbon nanotubes by regular coagulants

Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes (CNTs) to aquatic organisms and human beings, which has been rarely documented. This study investigated the removal of dispersant-stabilized CNT suspensions by poly aluminum chloride (PACl) and KAl(SO₄)₂. 12H₂O (alum), with a focus on the effects of dispersant type, coagulant type and dosage. PACl performed better than alum in the removal of tannic acid-, humic acid-, and sodium dodecyl benzenesulfonate-stabilized CNTs, but worse for polyethylene glycol octylphenyl ether (TX100)-stabilized CNTs. Neither coagulant could effectively precipitate cetyltrimethyl ammonium bromide-stabilized CNTs. The removal by PACl first increased up to a plateau and then decreased with the continued increase of coagulant dosage. However, the removal rates leveled off but did not decrease after achieving their highest level with the continued addition of alum. The coagulation and flocculation of the CNT suspensions by PACl could be regulated mainly by the mechanism of adsorption charge neutralization, whereas the coagulation by alum mainly involved electrical double-layer compression.     

强化絮凝法去除水中DBP先质研究

采用强化絮凝的方法，实验研究和探明了混合反应强度，浊度，ＰＨ值等因素对去除水中ＤＢＰ先质的影响规律，进一步揭示了强化絮凝条件下除浊与除ＤＢＰ先质的相互关系，求得了不同水质条件下的最佳ＰＨ值和最佳投药量。     

Disinfection byproduct precursor removal by enhanced coagulation and their distribution in chemical fractions

Raw water from the Songhua River was treated by four types of coagulants, ferric chloride(FeCl3), aluminum sulfate(Al2(SO4)3),polyaluminum chloride(PACl) and composite polyaluminum(HPAC), in order to remove dissolved organic matter(DOM). Considering the disinfection byproduct(DBP) precursor treatability, DOM was divided into five chemical fractions based on resin adsorption.Trihalomethane formation potential(THMFP) and haloacetic acid formation potential(HAAFP) were measured for each fraction. The results showed that hydrophobic acids(HoA), hydrophilic matter(HiM) and hydrophobic neutral(HoN) were the dominant fractions.Although both HoN and HoA were the main THM precursors, the contribution for THMFP changed after coagulation. Additionally,HoA and HiM were the main HAA precursors, while the contribution of HoN to HAAFP significantly increased after coagulation.HoM was more easily removed than HiM, no matter which coagulant was used, especially under enhanced coagulation conditions.DOC removal was highest for enhanced coagulation using FeCl3 while DBPFP was lowest using PACl. This could indicate that not all DOC fractions contained the precursors of DBPs. Reduction of THMFP and HAAFP by PACl under enhanced coagulation could reach51% and 59% respectively.     

Formation of regulated and unregulated disinfection byproducts during chlorination and chloramination: Roles of dissolved organic matter type, bromide, and iodide

Algal blooms and wastewater effluents can introduce algal organic matter (AOM) and effluent organic matter (EfOM) into surface waters, respectively. In this study, the impact of bromide and iodide on the formation of halogenated disinfection byproducts (DBPs) during chlorination and chloramination from various types of dissolved organic matter (DOM, e.g., natural organic matter (NOM), AOM, and EfOM) were investigated based on the data collected from literature. In general, higher formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was observed in NOM than AOM and EfOM, indicating high reactivities of phenolic moieties with both chlorine and monochloramine. The formation of haloacetaldehydes (HALs), haloacetonitriles (HANs) and haloacetamides (HAMs) was much lower than THMs and HAAs. Increasing initial bromide concentrations increased the formation of THMs, HAAs, HANs, and HAMs, but not HALs. Bromine substitution factor (BSF) values of DBPs formed in chlorination decreased as specific ultraviolet absorbance (SUVA) increased. AOM favored the formation of iodinated THMs (I-THMs) during chloramination using preformed chloramines and chlorination-chloramination processes. Increasing prechlorination time can reduce the I-THM concentrations because of the conversion of iodide to iodate, but this increased the formation of chlorinated and brominated DBPs. In an analogous way, iodine substitution factor (ISF) values of I-THMs formed in chloramination decreased as SUVA values of DOM increased. Compared to chlorination, the formation of noniodinated DBPs is low in chloramination.     

氯化钙对聚合氯化铝混凝去除腐植酸的影响作用研究

研究了ＣａＣｌ２对ＰＡＣ混凝去除腐植酸的影响作用，发现ＣａＣｌ２可以改善混凝效果和沉淀性能。探讨了ｐＨ值、投加量、温度等因素的影响，对药剂费用进行了经济分析，为今后的实际应用提供了基本数据。     

Two-dimensional correlation spectroscopic analysis on the interaction between humic acids and aluminum coagulant

In this study, two-dimensional correlation spectroscopy integrated with synchronous fluorescence and infrared absorption spectroscopy was employed to investigate the interaction between humic acids and aluminum coagulant at slightly acidic and neutral p H. Higher fluorescence quenching was produced for fulvic-like and humic-like fractions at p H 5. At p H 5, the humic-like fractions originating from the carboxylic acid, carboxyl and polysaccharide compounds were bound to aluminum first, followed by the fulvic-like fractions originating from the carboxyl and polysaccharide compounds. This finding also demonstrated that the activated functional groups of HA were involved in forming the Al-HA complex, which was accompanied by the removal of other groups by co-precipitation.Meanwhile, at p H 7, almost no fluorescence quenching occurred, and surface complexation was observed to occur, in which the activated functional groups were absorbed on the amorphous Al(OH)3. Two-dimensional FT-IR correlation spectroscopy indicated the sequence of HA structural change during coagulation with aluminum, with IR bands affected in the order of COOH COO-NH deformation of amide Ⅱ aliphatic hydroxyl C\OH at p H 5, and COO-aliphatic hydroxyl C\OH at p H 7. This study provides a promising pathway for analysis and insight into the priority of functional groups in the interaction between organic matters and metal coagulants.     

Formation and speciation of disinfection byproducts during chlor(am)ination of aquarium seawater

The chemistry associated with the disinfection of aquarium seawater is more complicated than that of freshwater, therefore limited information is available on the formation and speciation of disinfection byproducts(DBPs) in marine aquaria. In this study, the effects of organic precursors, bromide(Br-) and pre-ozonation on the formation and speciation of several typical classes of DBPs, including trihalomethanes(THM4), haloacetic acids(HAAs),iodinated trihalomethanes(I-THMs), and haloacetamides(HAc Ams), were investigated during the chlorination/chloramination of aquarium seawater. Results indicate that with an increase in dissolved organic carbon concentration from 4.5 to 9.4 mg/L, the concentrations of THM4 and HAAs increased by 3.2–7.8 times under chlorination and by 1.1–2.3 times under chloramination. An increase in Br-concentration from 3 to 68 mg/L generally enhanced the formation of THM4, I-THMs and HAc Ams and increased the bromine substitution factors of all studied DBPs as well, whereas it impacted insignificantly on the yield of HAAs. Pre-ozonation with 1 mg/L O3 dose substantially reduced the formation of all studied DBPs in the subsequent chlorination and I-THMs in the subsequent chloramination. Because chloramination produces much lower amounts of DBPs than chlorination, it tends to be more suitable for disinfection of aquarium seawater.     

臭氧-混凝耦合工艺污水深度处理特性及其机制

针对传统混凝工艺对溶解性有机物去除效果有限的问题,本文利用臭氧-混凝耦合工艺对污水处理厂二级出水进行深度处理.与相同混凝剂投量下的预臭氧-混凝工艺和传统混凝工艺相比,该耦合工艺处理效果明显优于预臭氧-混凝工艺和传统混凝工艺的处理效果.在两种pH条件下耦合工艺对溶解性有机污染物的去除率最大,分别为37.96%和39.66%.为了进一步明确该耦合工艺去除溶解性有机物的机制,测定了两种pH和有无混凝剂Al Cl3·6H2O存在时对臭氧衰减的影响,结果表明较高的pH和有混凝剂存在时都能够加快臭氧的分解速度.同时,选择羟基自由基(·OH)的指示剂对氯苯甲酸(p-CBA)间接计算了·OH的暴露量,结果表明耦合工艺中存在涉及·OH产生的高级氧化机制,而混凝剂可以提高臭氧化工艺中·OH的产量.当混凝剂与臭氧接触后,铝系混凝剂及其水解产物将作为催化剂促进臭氧分解为氧化能力更强的·OH,强化臭氧化效果,提高溶解性有机物的去除效率.     

Characteristics of molecular weight distribution of dissolved organic matter in bromide-containing water and disinfection by-product formation properties during treatment processes

The characteristics of dissolved organic matter (DOM) and bromide ion concentration have a significant influence on the formation of disinfection by-products (DBPs). In order to identify the main DBP precursors, DOM was divided into five fractions based on molecular weight (MW), trihalomethane formation potential and haloacetic acid formation potential were determined for fractions, and the change in contents of different fractions and total DBPs during treatment processes (pre-chlorination, coagulation, sand filtration, disinfection) were studied. Moreover, the relationship between bromide concentration and DBP generation characteristics in processes was also analyzed. The results showed that the main DBP precursors were the fraction with MW < 1 kDa and fraction with MW 3−10 kDa, and the DBP''s generation ability of lower molecular weight DOM (< 10 kDa) was higher than that of higher molecular weight DOM. During different processes, pre-chlorination and disinfection had limited effect on removing organics but could alter the MW distribution, and coagulation and filtration could effectively remove organics with higher MW. For DBPs, trihalomethanes (THMs) were mainly generated in pre-chlorination and disinfection, while haloacetic acids (HAAs) were mostly generated during pre-chlorination; coagulation and sand filtration had little effect on THMs but resulted in a slight removal of HAAs. In addition, the results of ANOVA tests suggested that molecular sizes and treatment processes have significant influence on DBP formation. With increasing bromide concentration, the brominated DBPs significantly increased, but the bromine incorporation factor in the processes was basically consistent at each concentration.     

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of pH and fluoride at different molar ratios of fluoride to Al (R_F:Al) on the removal of cadmium (Cd²⁺) and phosphate by Al coagulation. Fluoride at R_F:Al ≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R_F:Al of 10:1 whereas at lowered R_F:Al (i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at pH 7 and 8 and that of phosphate at pH 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R_F:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)₃ precipitates, i.e., the formation of Al(OH)_nF_m. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower pH. Al–F complexes at high R_F:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R_F:Al shows little effect on Al coagulation behavior towards Cd^2 + and phosphate, and the spent defluoridation adsorbent, i.e., aluminum (Al) hydro(oxide) with adsorbed fluoride at R_F:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.     

不同聚合铝对水中有机物的去除研究

强化混凝是去除水中消毒副产物的最佳方法之一。文章针对强化混凝技术,从去除水中有机物的角度出发,对不同聚合铝的处理效果进行了研究。结果表明,酸性条件、加大投药量有利于水中TOC及UV254的去除,且酸性条件更为有利。在pH=6.3,工业PAC投药量为1.5×10-4mo(l有效铝)时去除效果最佳,水中总有机碳(TOC)及紫外吸光度(UV25)4的去除率分别可达到46%及57%,实验室制备的聚合铝碱化度越高越有利于水中有机物的去除。     

典型北方高碱度微污染水体强化混凝的示范研究

以高碱度、受有机物污染的典型北方水体为例,探索适宜的强化混凝技术.在水质调查的基础上,提出适合水质特征的强化混凝目标.研究了高碱度水体强化混凝技术方法.研究表明,可以通过3条技术途径提高水体中有机物的去除效率.其一在混凝前优化pH,促进絮凝剂水解形成中聚体,AlCl3在pH 6左右,FeCl3在pH 5左右时,有机物去除率可以提高一倍左右;其二是强化沉淀软化;其三是絮凝剂优化.结合我国实际情况,通过对传统絮凝剂进行改性,研制出了适合我国北方水质特征的高效絮凝剂,能较传统絮凝剂将有机物去除率提高30%以上.     

饮用水消毒副产物分析及相关研究进展

饮用水消毒副产物（DBPs）是消毒剂和一些天然有机物（NOM）反应生成的化合物,主要包括三卤甲烷（THMs）、卤代G@（HAAs）、卤代乙腈（HANs）和致诱变化舍物（MX）4类。本文针对氯、氯胺、二氧化氯、臭氧4种主要消毒方式产生的消毒副产物,讨论了有关分析技术的发展过程,从DBPs的前处理技术、分析技术等角度,介绍了DBPs研究领域近期所取得的进展,并展望了今后研究的发展方向。     

Comparison of three-dimensional fluorescence analysis methods for predicting formation of trihalomethanes and haloacetic acids

This work investigated the application of several fluorescence excitation-emission matrix analysis methods as natural organic matter (NOM) indicators for use in predicting the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). Waters from four different sources (two rivers and two lakes) were subjected to jar testing followed by 24 hr disinfection by-product formation tests using chlorine. NOM was quantified using three common measures: dissolved organic carbon, ultraviolet absorbance at 254 nm, and specific ultraviolet absorbance as well as by principal component analysis, peak picking, and parallel factor analysis of fluorescence spectra. Based on multi-linear modeling of THMs and HAAs, principle component (PC) scores resulted in the lowest mean squared prediction error of cross-folded test sets (THMs: 43.7 (μg/L)², HAAs: 233.3 (μg/L)²). Inclusion of principle components representative of protein-like material significantly decreased prediction error for both THMs and HAAs. Parallel factor analysis did not identify a protein-like component and resulted in prediction errors similar to traditional NOM surrogates as well as fluorescence peak picking. These results support the value of fluorescence excitation-emission matrix-principal component analysis as a suitable NOM indicator in predicting the formation of THMs and HAAs for the water sources studied.