臭氧对有机物混凝的影响

采用PDA(Photometric Disperse Analysis)和有机物表观分子量分级、有机物化学极性分级技术从絮体形成过程、絮体表现、有机物分子水平变化等方面研究了臭氧预氧化对混凝过程的影响;并对比了不同混凝剂在预臭氧条件下的混凝过程和效率.结果表明:臭氧预氧化对混凝过程有复杂的影响,其剂量和水体有机物特征决定了其对混凝的整体影响效果.有机物分级显示,臭氧化对有机物结构有重要影响,导致有机物极性、亲水性组分含量大幅提高(36.7%),小分子量组分(<10×10³)大幅增高(100%左右);但总的DOC去除率不高(3.28%).对PACl而言,在中、低剂量(O₃/TOC<0.7)下,臭氧对絮体形成过程影响较小,但对絮体沉降性和浊度去除已经有阻碍作用.在中、高剂量下(O₃/TOC>0.7),对絮体形成有显著滞后,浊度、有机物去除效率下降.AlCl₃对臭氧化作用反应敏感,臭氧化在试验剂量条件下,对絮体形成和浊度、有机物去除都有明显的阻碍作用.     

混凝去除垃圾渗滤液中DOM的实验研究

选取氯化铁(FeCl3.6H2O)为混凝剂,以经0.45μm膜和1nm膜分子切割的垃圾渗滤液为研究对象,通过混凝剂投加量和混凝pH值实验,研究了垃圾渗滤液中DOM的去除情况,并比较了两种不同分子量水平的渗滤液中DOM的混凝去除特点。研究表明,pH值是影响渗滤液DOM去除的主要因素,氯化铁在pH=5、投加量为4g/L的条件下混凝效果最佳。混凝pH值对大分子量渗滤液中DOC去除的影响较大;而两种分子量水平的渗滤液UV254的去除差异不大。     

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.     

Comparison of different combined treatment processes to address the source water with high concentration of natural organic matter during snowmelt period

The source water in one forest region of the Northeast China had very high natural organic matter(NOM) concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was compared to address the high concentration of NOM and the mechanisms were also analyzed. Conventional treatment can hardly remove dissolved organic carbon(DOC) in the source water. KMn O4pre-oxidization could improve the DOC removal to 22.0%. Post activated carbon adsorption improved the DOC removal of conventional treatment to 28.8%. The non-sufficient NOM removal could be attributed to the dominance of large molecular weight organic matters in raw water, which cannot be adsorbed by the micropore upon activated carbon. O3+ activated carbon treatment are another available technology for eliminating the color and UV254 in water. However, its performance of DOC removal was only 36.4%, which could not satisfy the requirement for organic matter. The limited ozone dosage is not sufficient to mineralize the high concentration of NOM. Magnetic ion-exchange resin combined with conventional treatment could remove 96.2%of color, 96.0% of UV254 and 87.1% of DOC, enabling effluents to meet the drinking water quality standard. The high removal efficiency could be explained by the negative charge on the surface of NOM which benefits the static adsorption of NOM on the anion exchange resin. The results indicated that magnetic ion-exchange resin combined with conventional treatment is the best available technology to remove high concentration of NOM.     

铁盐和铝盐混凝对水中天然有机物的去除特性研究

以三氯化铁和硫酸铝为研究对象,探讨了2种混凝剂对水中天然有机物的去除效果及特点.结果表明,低投量下,硫酸铝对天然有机物的去除效果要好于三氯化铁,混凝剂投量高于15mg/L时,三氯化铁的效果较好.如混凝剂投量为10mg/L时,硫酸铝和三氯化铁处理水的TOC分别为4.19mg/L和9mg/L;当混凝剂投量为20mg/L时, TOC分别降至2.44mg/L和1.69mg/L.三氯化铁混凝后水的pH值降低幅度高于硫酸铝,形成的水解产物所带正电荷密度升高,水中有机物的质子化程度高,有利于对有机物的吸附去除.通过对UV254出和SUVA的考察可知,三氯化铁对共轭结构及不饱和有机物的去除能力要高于硫酸铝.2种混凝剂对水中不同性质有机物的去除效果不同,三氯化铁对亲水性有机物去除效果较好,对小分子量有机物去除高于硫酸铝,如混凝剂投量为20mg/L时,三氯化铁和硫酸铝对相对分子质量区间小于10 000的有机物去除率分别为16.4%和6.1%,而硫酸铝对大分子量有机物去除效率较高.     

UV/H2 O2法对印染废水生化出水中不同种类有机物的去除效果

采用UV/H2O2高级氧化法对印染废水生化出水的处理进行研究,探讨了不同反应时间、H2O2投加量、反应初始pH值等因素对UV254,ADMI7.6、DOC和COD去除效果的影响.结果表明,以UV254、ADMI7.6、DOC和COD的去除率为筛选依据,确定出最佳参数组合为:反应初始pH值为原水pH 7.4～8.1,H2O2投加量为4.5 mmol.L-1,紫外光照射时间为50 min,在最佳处理条件下,UV254、ADMI7.6、DOC和COD的去除率分别达到77%、94%、40%和69%.通过XAD-8/XAD-4吸附树脂联用技术将印染废水生化出水中溶解性有机物分为疏水酸、非酸疏水物质、弱疏水物质及亲水物质4类有机物,研究了UV/H2O2氧化工艺对生化出水中各种有机物及色度的去除效果.实验结果表明,对于该印染废水的生化出水,疏水性物质是引起色度的主要物质,所占比例以ADMI7.6表征时为92%,其中以非酸疏水物质的贡献最大,达到53%.UV/H2O2高级氧化法处理此水样中的弱疏水性有机物、疏水酸和非酸疏水物质均有较好的处理效果,对亲水性有机物的处理效果较差.实验表明,相对分子质量>10 000的大分子有机物对DOC和ADMI7.6的去除贡献较大,对UV254的去除贡献接近一半.     

Preferential binding between intracellular organic matters and Al13 polymer to enhance coagulation performance

Coagulation is the best available method for removing intracellular organic matter (IOM), which is released from algae cells and is an important precursor to disinfection by-products in drinking water treatment. To gain insight into the best strategy to optimize IOM removal, the coagulation performance of two Al salts, i.e., aluminum chloride (AlCl₃) and polyaluminum chloride (PACl, containing 81.2% Al₁₃), was investigated to illuminate the effect of Al species distribution on IOM removal. PACl showed better removal efficiency than AlCl₃ with regard to the removal of turbidity and dissolved organic carbon (DOC), owing to the higher charge neutralization effect and greater stability of pre-formed Al₁₃ species. High pressure size exclusion chromatography analysis indicated that the superiority of PACl in DOC removal could be ascribed to the higher binding affinity between Al₁₃ polymer and the low and medium molecular weight (MW) fractions of IOM. The results of differential log-transformed absorbance at 254 and 350?nm indicated more significant formation of complexes between AlCl₃ and IOM, which benefits the removal of tryptophan-like proteins thereafter. Additionally, PACl showed more significant superiority compared to AlCl₃ in the removal of < 5?kDa and hydrophilic fractions, which are widely viewed as the most difficult to remove by coagulation. This study provides insight into the interactions between Al species and IOM, and advances the optimization of coagulation for the removal of IOM in eutrophic water.     

污水厂二级出水中难凝聚有机物的臭氧化特性

以城市污水处理厂二级出水为原水,研究臭氧化处理对水中难凝聚有机物的去除效果.结果表明单独混凝对水中有机物的去除率较低,混凝过程中未被去除的有机物属于难凝聚有机物,加入臭氧进行氧化,随着臭氧投加量的增加,二级出水色度和UV254去除率逐渐增大,而DOC去除率变化较小.当臭氧投加量(以O3/DOC计)增加至1.5 mg·mg-1时,色度、UV254和DOC的去除率分别为45%、34%和20%,说明臭氧易于与不饱和结构有机物反应,而直接氧化的矿化能力较弱.为进一步明确二级出水有机物种类和含量的变化,测定了混凝和不同臭氧投加量下有机物的相对分子质量和三维荧光光谱.结果表明混凝对有机物含量的影响很小,而臭氧能够优先氧化分解难凝聚有机物中的大分子物质,明显减弱腐殖质类物质的荧光峰强度,但不改变荧光峰位置.同时采用光电子能谱分析有机物结构的变化规律,结果表明混凝能够去除含羧基类官能团有机物,而臭氧则易于与含苯环类难凝聚有机物反应,随着臭氧投加量的增大,脂肪类饱和有机物含量有所升高.     

城市景观水体混凝除藻过程对氮元素协同去除特性初探

以城市景观水体净化为目标,考察混凝除藻同时去除氮元素的特性和影响因素. 结果发现,水体内较高的DOC(溶解性有机质)含量会阻碍藻浊度的去除. 聚合氯化铝(PACl)以及PACl与硫酸铝(Alum)的复合剂(PACl+Alum)对藻浊度的去除效果均相对单独使用PACl或Alum较好,其中PACl+Alum对其他物质(如氮、DOC等)的去除效果也相对单独使用PACl或Alum更佳;在同样的最佳投药量时,低pH条件能获得更好的藻浊度去除率;对氮元素去除的进一步研究发现,DON(溶解性有机氮)的去除特征和过程与TN(总氮)非常一致,表明该水体TN的去除主体上是通过DON的去除实现的;低pH条件同样有利于氮和DOC的去除;但DOC与DON去除的不同步性,说明DOC中的DON成分和性质是非均一性的,是未来可进一步深入研究的重要方向.      

磁性离子交换树脂对原水中有机物去除效能的研究

采用磁性离子交换树脂(MIEX)预处理原水中有机物的中试试验结果表明,MIEX技术可有效地去除原水中的有机物,对UV254,DOC和CODMn的去除率分别稳定在82%、66%和50%,MIEX预处理可以有效强化混凝沉淀对有机物、藻细胞和浊度的去除.与常规工艺相比,在混凝剂聚合氯化铝投加量降低56%时,该工艺对UV254和CODMn的去除率分别为90%和71%,对藻细胞数和浊度的去除率分别为99%和95%.对溶解性有机物分级和分子量分布的测定表明,MIEX预处理主要去除混凝沉淀无法有效去除的小分子区间的亲水性和疏水性有机物,可以有效控制消毒副产物的产生,MIEX预处理与混凝沉淀联用工艺出水的三卤甲烷生成势(THMFP)和卤乙酸生成势(HAAFP)比原水降低了88%和87%.     

不同氧化剂降低膜污染效果的研究

采用不同的氧化剂预处理黄浦江原水后进行微滤膜(MF)膜过滤试验,考察预氧化对有机物的去除作用,及其对MF膜过滤特性的影响.结果表明,3种不同氧化剂对有机物的去除效果存在较大差别.臭氧投量在0.5~3.0mg/L范围内,臭氧对DOC和UV254的去除率最高分别为10%和71%;而氯和高锰酸钾对有机物的去除效果则较差.臭氧可将大分子有机物转变成小分子有机物,将大部分疏水性有机物氧化成亲水性有机物.这种有机物组成结构的改变对膜过滤特性产生影响,明显降低了膜污染,膜污染下降率最高可达到22.7%.氯和高锰酸钾的氧化性相对较弱,仅能去除少部分疏水性有机物,对膜污染有较小减缓作用,膜污染下降率最高分别为9%和8.5%.     

MIEX预处理技术对长江原水中有机物的去除效能

利用烧杯试验研究了磁性离子交换树脂（magnetic ion exchange resin,MIEX）预处理对长江原水中有机物的去除效能,以总溶解有机碳(DOC)、254 nm紫外吸收值(UV254)、有机物相对分子质量分布、有机物分级、紫外扫描以及消毒副产物生成量等指标进行表征.结果表明,长江水源水中的有机物主要为小分子亲水性有机物,其含量占有机物总量的50%以上;MIEX预处理可以有效降低水中有机物的含量,投加量为10 mL/L、接触时间为15 min时,DOC的去除率超过35%,相对分子质量和分级的测定结果表明,小分子亲水性部分有机物的去除导致了DOC去除效果的改善;从紫外扫描结果可看出,MIEX预处理对在190～250 nm波长时有强吸收的有机物去除效果非常明显,但对在高于250 nm波长处有吸收的有机物去除效果与混凝阶段的效果相近.     

粉末活性炭预沉积去除藻类有机物及其对膜污染的影响

以东海原甲藻分泌的藻类有机物（AOM）为研究对象,研究粉末活性炭预沉积和预吸附两种膜前预处理手段对海水中AOM的去除作用,对比分析AOM直接超滤、预沉积和预吸附后再超滤时膜通量、膜阻力分布、膜表面亲疏水性和粗糙度的变化,探讨粉末活性炭孔隙结构、沉积量对AOM去除效果及超滤膜污染的影响.结果表明,活性炭预沉积和预吸附能够提高超滤膜对含AOM海水中DOC和UV₂₅₄的去除率,预沉积对AOM的去除作用优于预吸附,介孔活性炭较微孔活性炭的预沉积效果更好,当介孔活性炭PAC2的沉积量为0.4g/L时,DOC和UV₂₅₄的去除率较直接超滤分别提高了25.1%和33.6%.紫外吸收比指数（URI）分析表明,活性炭预沉积和预吸附对有机物的去除作用具有选择性,AOM中芳香族物质较脂肪族羧基类物质更易被除去.粉末活性炭预沉积下AOM超滤时的滤饼层污染阻力（R_c）和膜孔堵塞阻力（R_p）较直接超滤分别降低了39.6%和81.2%,活性炭在超滤膜表面形成的滤饼层结构将AOM与超滤膜进行了隔离,能够减缓膜污染速率,对于控制膜的不可逆污染亦具有重要作用.     

混凝和活性炭吸附去除微污染水源水中DON的研究

溶解性有机氮(dissolved organic nitrogen,DON)作为饮用水中新兴氮消毒副产物(nitrogenous disinfection by-products,N-DBPs)的前体物逐渐受到国内外学者的关注.为探讨混凝和活性炭吸附对微污染水源水中DON的去除机制,首先测定原水中DON、溶解性有机炭(dissolved organic carbon,DOC)、NH4+-N、UV254、pH和溶解氧(dissolved oxygen,DO)等指标和DON、DOC分子量分布;接着通过混凝和活性炭吸附试验来考察原水中DON、DOC和UV254变化,并应用三维荧光光谱对原水中DON变化进行表征.结果表明,微污染水源水中DON、DOC和UV254分别为1.28 mg.L-1、8.56 mg.L-1和0.16 cm-1,DOC与DON比值(DOC/DON)为6.69 mg.mg-1,SUVA为1.87 m-1.(mg.L-1)-1;小分子量(<6 000)DON占较高比例约为68%,大分子量(>20 000)DON占的比例为22%;当混凝剂投加量为10 mg.L-1,DON的去除率大约为20%,DOC和UV254去除率约26%、70%;当活性炭投加量为1.0 g,DON、DOC和UV254的去除率大约为60%、35%、100%;混凝和活性炭吸附组合试验时,对DON、DOC的去除率大约为82%和64%;三维荧光光谱证实,原水中DON变化与3个主要峰有关,分别代表物质为色氨酸类蛋白质、芳香族类蛋白质和富里酸类物质.     

臭氧/活性炭协同作用去除二级出水中DON

为探讨臭氧氧化和活性炭吸附对城市污水厂二级出水中溶解性有机氮(DON)的去除机制,首先测定二级出水DON、溶解性有机炭(DOC)、UV254、pH值等指标.接着通过臭氧氧化试验和活性炭吸附试验来考察二级出水中DON、DOC和UV254变化,以及DON分子量分布和DON亲疏水性变化,并应用三维荧光光谱对二级出水中DON变化进行表征.结果表明,当臭氧投加量为8mg/L,DON的去除率大约为33.9%,DOC和UV254去除率约21.2%、66.7%;当活性炭投加量为2.0g/L,DON、DOC和UV254的去除率大约为43.4%、27.6%、92.2%;臭氧氧化和活性炭吸附组合试验时,对DON的去除率大约为83.3%和81.5%;臭氧氧化提高小分子量( 20kDa)的DON所占比例;活性炭吸附降低小分子量( 20kDa)DON所占比例为;臭氧氧化和活性炭吸附都提高亲水性DON所占比例,而降低疏水性和过渡性DON所占比例;三维荧光光谱证实,二级出水中DON变化与3个主要峰有关,分别代表物质为色氨酸类蛋白质、芳香族类蛋白质和富里酸类物质.     

粉炭强化循环造粒流化床去除天然有机物的研究

强化天然有机物去除是饮用水处理工艺的重要目标.循环造粒流化床作为一种新型高效固液分离技术具有处理负荷高、水质适应性强的特点,将其与粉末活性炭（PAC）联用,探究对水库水中有机物的强化去除效果.研究发现当聚合氯化铝（PACl）与PAC同时投加,且PACl、聚丙烯酰胺（PAM）及PAC投加量分别为24mg/L、1.2mg/L、30mg/L时,流化床系统对进水浊度、UV₂₅₄、COD_Mn、DOC去除率分别为96.5%、72.0%、71.7%、61.0%.对进出水中的有机物进行三维荧光分析,发现流化床系统中结团造粒作用下出水的类富里酸和类腐殖酸的FI分别比进水降低了40.1%和43.0%;加入30mg/L PAC后,出水的类富里酸和类腐殖酸的的FI分别比原水降低了54.0%和55.3%.水库水中的有机物分子量主要在 < 1kDa和10~30kDa两个区间,分别占总有机物含量的37.1%和39.1%.循环造粒流化床系统中结团造粒作用主要去除10~30kDa区间的有机物,PAC吸附作用对 < 1kDa的有机物有很好的去除.     

Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting

High performance size exclusion chromatography (HPSEC) is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter (DOM), but by applying peak fitting to the chromatogram, this technique can also be used as a tool to model and predict DOM removal. Six low specific UV absorbance (SUVA) source waters were treated using coagulation with alum and both the source and treated water samples were analysed using HPSEC. By comparing the molecular weight profiles of the source and treated waters, it was established that several DOM components were not effectively removed by alum coagulation even after high dosage alum treatment. A peak-fitting technique was applied based on the concept of linking the character (molecular weight profile) of the recalcitrant organics in the treated water with those of the source water. This was then applied to predict DOM treatability by determining the areas of the peaks which were assigned to removable organics from the source water molecular weight profile after peak fitting, and this technique quantified the removable and non-removable organics. The prediction was compared with the actual dissolved organic carbon (DOC) removal determined from jar testing and showed good agreement, with variance between 2% and 10%. This confirmed that this prediction approach, which was originally developed for high SUVA waters, can also be applied successfully to predict DOC removal in low SUVA waters.     

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.     

Changes in different organic matter fractions during conventional treatment and advanced treatment

XAD-8 resin isolation of organic matter in water was used to divide organic matter into the hydrophobic and hydrophilic fractions. A pilot plant was used to investigate the change in both fractions during conventional and advanced treatment processes. The treatment of hydrophobic organics (HPO), rather than hydrophilic organicas (HPI), should carry greater emphasis due to HPO’s higher trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP). The removal of hydrophobic matter and its transmission into hydrophilic matter reduced ultimate DBP yield during the disinfection process. The results showed that sand filtration, ozonation, and biological activated carbon (BAC) filtration had distinct influences on the removal of both organic fractions. Additionally, the combination of processes changed the organic fraction proportions present during treatment. The use of ozonation and BAC maximized organic matter removal e ciency, especially for the hydrophobic fraction. In sum, the combination of pre-ozonation, conventional treatment, and O3-BAC removed 48% of dissolved organic carbon (DOC), 60% of HPO, 30% of HPI, 63% of THMFP, and 85% of HAAFP. The use of conventional treatment and O3-BAC without pre-ozonation had a comparable performance, removing 51% of DOC, 56% of HPO, 45% of HPI, 61% of THMFP, and 72% of HAAFP. The e ectiveness of this analysis method indicated that resin isolation and fractionation should be standardized as an applicable test to help assess water treatment process e ciency.     

混凝沉淀-UF工艺去除二级出水中ARGs效能研究

为了研究混凝沉淀-UF工艺对城市污水处理厂二级出水中ARGs（抗生素抗性基因）去除的影响,以PACl（聚合氯化铝）和PFS（聚合硫酸铁）作为混凝剂,采用qPCR（实时荧光定量聚合酶链式反应）和EEM（三维荧光光谱）等分析混凝沉淀-UF工艺对ARGs的削减及其影响因素.结果表明:① PACl、PFS投加量（分别以Al、Fe计,下同）分别为0.85、0.50 mmol/L时,与直接UF工艺相比,混凝沉淀-UF工艺对水中各类ARGs的去除量高2~3个数量级,其中PACl-UF工艺的效果更好,去除量为2.51~3.52个数量级;对水中DOC（溶解性有机碳）、富里酸类及溶解性微生物代谢产物的去除效果更好,DOC去除率由18%升至36%.②直接UF、PACl-UF、PFS-UF 3种工艺膜进、出水的线性拟合结果显示,ARGs浓度与ρ（DOC）、16S rDNA浓度均呈显著正相关.研究显示,混凝沉淀-UF工艺可以有效去除二级出水中的ARGs,且有机物、16S rDNA的去除有助于ARGs的削减.