可生物降解有机物在水厂净水工艺中的变化

以上海市两座不同水源的典型水厂为研究对象,分析了可生物降解有机物(BOM)和总有机物(以DOC表征)在水厂常规净水工艺中的变化规律.结果表明,水厂常规工艺对AOC、BDOC与DOC的去除能力均不高,且受水温影响明显,两水厂出水均为生物不稳定性饮用水;DOC主要在沉淀单元被去除,BDOC在沉淀、砂滤单元都有去除,AOC则主要在砂滤单元被去除;加氯可造成DOC(或BDOC)向AOC的转化,使出厂水AOC浓度增加,要确保出厂水的生物稳定性,必须同步削减水中BOM与总有机物的浓度.     

臭氧-生物活性炭与单独活性炭工艺处理效果比较

为有效去除水中有机物,明确是否应在活性炭前投加臭氧,比较了臭氧-生物活性炭（O3-BAC）和单独活性炭（GAC）过滤对CODMn、UV254和TOC的去除效果以及两套系统对提高水质生物稳定性的作用.研究发现,O3-BAC对CODMn、UV254和TOC的平均去除率比GAC分别高10.3%、11.1%、7.1%,对AOC的去除率＞80%,出水AOC浓度为25.9～46.4μg乙酸碳/L,属生物稳定性水质;单独GAC柱对AOC的去除率在40%左右,出水AOC浓度为85.8～117.6μg乙酸碳/L,有时不能满足水质生物稳定性的要求.可见在活性炭前投加臭氧,可以强化活性炭对有机物的去除作用,延长活性炭的使用周期,增强活性炭滤池的生物降解能力.     

超滤/臭氧氧化工艺对再生水中AOC的去除效果

如何控制微生物生长、保障水质生物稳定性,是再生水输配与利用过程中关注的重要问题。可同化有机碳(AOC)是评价水质生物稳定性的重要指标。对北京市某再生水厂超滤/臭氧氧化处理过程中AOC浓度及其分子质量分布特性的变化进行了研究,结果表明:二级出水中的AOC主要为分子质量>10 ku的有机物,超滤对二级出水中有机物的去除效果良好,对AOC的去除率达到73%。臭氧氧化可提高有机物的可生化性,导致AOC浓度升高了48%。在二级出水和超滤出水中,AOC物质以分子质量>10 ku的有机物为主,分别占79%和59%;经臭氧处理后,小分子质量(<1 ku)有机物对AOC的贡献明显上升,所占比例达到74%,同时大分子质量(>10 ku)和中等分子质量(1～10 ku)有机物所占的比例分别下降到22%和3%。     

颗粒活性炭吸附去除黄浦江原水中有机物的研究

采用超滤膜法分析了黄浦江原水和水厂常规工艺处理出水中有机物的分子质量（MW）分布以及颗粒活性炭（GAC）在不同吸附阶段吸附去除不同分子质量有机物的性能.试验结果表明,黄浦江原水及常规工艺出水中的溶解性有机物（DOC）以小分子为主,并主要集中在MW为10～30 ku和MW＜1 ku的区间;活性炭吸附出水中的溶解性有机物仍然主要集中在小分子区间;吸附初期的活性炭对有机物的去除能力较强,其中对CODMn的去除率＞83%,对UV254的去除率＞90%;随着通水倍数的增大则活性炭的吸附能力逐渐下降,当通水倍数达到6 590.9时,对CODMn和UV254的去除率都只有25%左右;活性炭吸附的各个阶段对小分子有机物的去除率均较高,而对大分子有机物的去除率则较低,从吸附初期到吸附后期,对小分子有机物的去除率高出对大分子有机物的去除率,其百分比从10%增大到30%.     

活性炭滤池中颗粒物数量和粒径分布的研究

结合水厂水处理工艺及活性炭深度处理装置,探讨了生物活性炭滤池出水中颗粒物数量的变化及粒径分布规律。结果表明,在过滤周期内活性炭滤池出水颗粒物数量与浊度会出现相似的变化规律,二者之间相关性较好,但活性炭滤池出水浊度的变化滞后于颗粒物数量的变化。生物活性炭滤池过滤初期,滤后水中大于2μm的颗粒物数量可达到111个／mL,50min后数量降至50个／mL以下。生物活性炭滤池出水中大于2μm的颗粒物主要由粒径为2～7μm的颗粒物组成。     

生物强化滤池在低温低浊水处理中的应用

在低温低浊条件下,通过对生物强化炭砂滤池(BCSFR)与普通炭砂滤池(CSFR)进行对比实验,研究有机物及消毒副产物的去除效果及机制。结果表明,在原水温度4~10°C,浊度为2~6NTU条件下,BCSFR对高锰酸盐指数(PI)、TOC和UV254的平均去除率分别达到48.28%、31.80%和29.32%。此外,可生物同化有机碳(AOC)和可生物降解有机碳(BDOC)的去除率分别为50.83%和51.16%。由于微生物降解与活性炭吸附的协同作用,BCSFR能够比普通CSFR更有效去除有机物,因此有可能成为一种适合处理寒冷地区低温低浊水的安全饮用水保障技术。     

O3／BAC工艺中溴酸盐的控制

通过试验考察了活性炭、陶粒以及挂膜陶粒对溴酸盐的去除效果,分析了微生物对溴酸盐的降解作用。结果表明,在滤池以及生物活性炭滤池内成熟的微生物膜对溴酸盐有降解能力,溴酸盐去除量与水力接触时间的关系为9．16μg（L·h）。在活性炭（GAC）吸附以及微生物降解协同作用下,可以在不增加运行成本的基础上稳定、有效地控制溴酸盐。     

珠江源水中THMFP的分子质量分布及其特征研究

以珠江广州段水源水为研究对象，采用超滤分离方法将其中的有机物分成分子质量不同的几种形态，考察了各分子质量组分在DOC、UV、THMFP等方面的差异。结果表明：①分子质量在3～10ku间的有机物是珠江广州段源水中最主要的THMs前驱物；②分子质量最小（〈1ku）的组分，尽管SUVA值最低，THMs生成能力（THMFP／DOC）却最强；③经超滤分离有机物量的损失很少，但紫外吸收明显减弱，THMs生成量也随之减少。     

从DOC、AOC的变化分析二氧化氯消毒工艺

考察了二氧化氯（CIO2）及其组合消毒工艺中溶解性有机物（DOC）浓度和可同化有机碳（AOC）浓度的变化规律。结果表明,以DOC表征的有机物浓度在消毒反应前后变化不大;CIO2的强氧化能力体现在将高分子有机物氧化成中、小分子有机物方面,氧化产物以草酸类物质为主,这导致了AOC浓度的升高,降低了出水的生物稳定性;增加CIO2的投量（〉4mg／L）或与氯胺组合消毒能有效降低出水的AOC浓度,消毒反应24h后出水的AOC浓度均比进水的（59μg/L）低。     

生物除锰滤池对砷(Ⅲ)的去除效果研究

砷是对人体有毒害作用的典型元素,且在水源水中普遍存在.为此人工配制了含As（Ⅲ）为0.05～0.25 mg/L、Mn2＋为0.5～3.0 mg/L的原水,并通过已培养成熟的生物除锰滤池进行过滤,分别考察了滤速为3、5、7 m/h时滤池对As（Ⅲ）及Mn2＋的去除效果.结果表明,在开始阶段由于受原水中As（Ⅲ）的影响,滤池的除锰能力有所下降,出水As（Ⅲ）也不能达标;经过15 d左右的运行培养后,滤池表现出了良好的除锰和除砷能力,出水As（Ⅲ）、Mn2＋浓度分别为0.02mg/L和0.05 mg/L左右.经过对不同取样口的水样进行检测,发现滤池的除砷能力集中在厚度为0～800 mm的滤层.     

Reducing the concentration of assimilable organic carbon (AOC) in treated drinking water

This study focuses on reducing the concentration of assimilable organic carbon (AOC) in treated drinking water. Experiments were conducted to evaluate the efficiency of AOC removal by biological activated carbon filters (BACF) in a pilot-scale system. The measured values of AOC in treated drinking water were approximately 59.0 ± 8.6 μg acetate-C/L. The results show that BACFs reduce the total concentration of AOC. The concentration of AOC primarily indicates microbial growth in a water supply network, and the amount of AOC in the water is significantly reduced after BACF treatment. After BACF treatment, the removal of AOC was approximately 58% after 40 min of empty-bed contact time. An AOC empirical equation was established by determining the relationship between water quality parameters, such as total organic carbon, dissolved organic carbon, UV₂₅₄, ammonia nitrogen, and total phosphorous.     

两种碳基材料对二级出水中有机物的去除特性

针对活性炭与活性焦两种碳基吸附材料,分别开展静态吸附与动态过滤实验,考察了两者对城镇再生水厂二级出水中有机物的去除效果。结果表明:活性焦介孔及大孔丰富,对应孔体积为0.436 cm³/g,为活性炭的1.6倍;准二级动力学模型更适用于两种材料对COD的吸附动力学拟合,活性焦动力学吸附速率常数k₂为活性炭的2倍;水温为22℃时,活性焦与活性炭对COD的Langmuir饱和吸附量分别为230.38、94.14 mg/g。在近4个月的连续运行中,活性焦滤柱对有机物的去除效果全程优于活性炭滤柱,尽管两滤柱在由单纯吸附向生物吸附降解转化的过程中对有机物的去除率有所降低,但对COD的去除率仍可分别稳定在28.43%和22.26%。活性焦颗粒与活性炭颗粒表面ATP含量最高分别为7032.94、5753.52 ng/g。此外,活性焦滤柱对1~10 ku有机物组分,以及腐殖酸类物质、溶解性微生物代谢产物等不同荧光特性有机物均有较好的去除效果。与活性炭相比,活性焦对再生水厂二级出水中有机物的去除效果更优。     

Advanced treatment of the reverse osmosis concentrate produced during reclamation of municipal wastewater

The work investigated the treatment of the concentrate produced from the reverse osmosis treatment of an MBR effluent. Two conventional chemical processes, coagulation and activated carbon adsorption, and three advanced oxidation processes (electrochemical treatment, photocatalysis and sonolysis) were applied. Coagulation with alum gave dissolved organic carbon (DOC) removals up to 42%, while FeCl(3) achieved higher removals (52%) at lower molar doses. Adsorption with granular activated carbon showed the highest DOC removals up to 91.3% for 5 g/L. The adsorption isotherm was linear with a non-adsorbable organic fraction of around 1.2 mg/L DOC. The three oxidation methods employed, electrolytic oxidation over a boron-doped diamond electrode, UVA/TiO2 photocatalysis and sonolysis at 80 kHz, showed similar behavior: during the first few minutes of treatment there was a moderate removal of DOC followed by further oxidation at a very slow rate. Electrolytic oxidation was capable of removing up to 36% at 17.8A after 30 min of treatment, sonolysis removed up to 34% at 135W after 60 min, while photocatalysis was capable of removing up to 50% at 60 min.     

活性炭吸附用于城市污水地下回灌技术的研究

通过静态吸附试验比较与Ｃｒｉｔｔｅｎｄｅｎ计算模型分析,选择ＧＨ－１６型粒状活性炭对北京高碑店污水处理厂二级出水进行深度处理试验。结果表明：ＧＨ－１６型活性炭的净化效果存在阈值,约２５％的ＤＯＣ不能被吸附,不被吸附的主要是分子量〉３０００ｕ的有机物。对以ＵＶ２５４表征的有机物去除效果最好,分子量〈１０００ｕ的弱极性有机物易被微孔吸附且吸附容量,对以ＡＯＸ表征的极性有机物去除效果较差。二级出水经活性     

炭龄对活性炭工艺去除南水北调水中有机物的影响

基于北方某水厂中试基地,采用新炭、2.5~3.5年炭、4.5~5.5年炭等不同炭龄的活性炭滤柱,进行为期1年的连续运行,对比研究炭龄对南水北调水源水中有机物去除效果的影响。结果表明,长期运行稳定的活性炭滤柱,主要通过生物作用去除水中的有机物;2.5~3.5年和4.5~5.5年炭龄滤柱对有机物的去除效果差异较小,但二者对三氯甲烷的去除效果优于生物膜不稳定的新炭滤柱;通过高通量测序解析发现,鞘氨醇单胞菌、DSSF69等是优势功能菌,炭龄长的生物多样性更丰富,生物膜系统更稳定。此外,活性炭滤柱对有机物的去除效果与进水有机物的污染程度相关,当进水溶解性有机物浓度较低时,活性炭滤柱会出现吸附物质逆扩散的现象,所以当水质较好时,活性炭滤池的有机物去除效果会减弱。     

不同深度的水处理工艺对比试验研究

采用中试装置,研究了常规处理工艺分别与活性炭工艺、超滤组合进行深度处理,结果表明:臭氧活性炭工艺对有机物的去除效果要好于超滤,出水CODMn、UV254、DOC等指标均优于超滤工艺;超滤工艺对浊度、颗粒物和微生物方面的去除效果要优于活性炭工艺,其原因在于不同的去除机理。     

活性炭的选型及炭滤池的运行维护

重点介绍了桐乡市自来水公司果园桥水厂活性炭滤池的炭选型、填充及运行维护情况。通过对不同活性炭滤池的运行情况进行跟踪分析,摸索出了活性炭滤池的运行维护管理经验,可为类似工程的设计和运行管理提供借鉴。     

Characterization of natural organic matter adsorption in granular activated carbon adsorbers

The removal of natural organic matter (NOM) from lake water was studied in two pilot-scale adsorbers containing granular activated carbon (GAC) with different physical properties. To study the adsorption behavior of individual NOM fractions as a function of time and adsorber depth, NOM was fractionated by size exclusion chromatography (SEC) into biopolymers, humics, building blocks, and low molecular weight (LMW) organics, and NOM fractions were quantified by both ultraviolet and organic carbon detectors. High molecular weight biopolymers were not retained in the two adsorbers. In contrast, humic substances, building blocks and LMW organics were initially well and irreversibly removed, and their effluent concentrations increased gradually in the outlet of the adsorbers until a pseudo-steady state concentration was reached. Poor removal of biopolymers was likely a result of their comparatively large size that prevented access to the internal pore structure of the GACs. In both GAC adsorbers, adsorbability of the remaining NOM fractions, compared on the basis of partition coefficients, increased with decreasing molecular size, suggesting that increasingly larger portions of the internal GAC surface area could be accessed as the size of NOM decreased. Overall DOC uptake at pseudo-steady state differed between the two tested GACs (18.9 and 28.6 g-C/kg GAC), and the percent difference in DOC uptake closely matched the percent difference in the volume of pores with widths in the 1-50 nm range that was measured for the two fresh GACs. Despite the differences in NOM uptake capacity, individual NOM fractions were removed in similar proportions by the two GACs.     

Membrane bioreactor process for removing biodegradable organic matter from water

This research investigated a membrane bioreactor (MBR) process for removing biodegradable organic matter (BOM) and trihalomethane (THM) precursors from pre-ozonated water. Bench-scale and mini-pilot-scale MBR experiments were conducted using powdered activated carbon (PAC) and acclimated biomass. Dissolved organic carbon (DOC) was removed through a combination of adsorption and biodegradation mechanisms, and the initial DOC removals depended on carbon dose, while steady-state removals were in the 20-60 percent range under various operating conditions. Both assimilable organic carbon (AOC) and total aldehydes were mostly removed to near detection limits and were not affected by PAC dosage. The AOC(NOX) removals were significantly higher than AOC(P17) or total AOC removals probably because the MBR microbial consortium was closer in characteristics to Aquaspirillum NOX than to Pseudomonas fluorescens (P17). The DOC was used instead of biodegradable organic carbon (BDOC) as a parameter for evaluating disinfection byproduct formation and bacterial regrowth potentials because BDOC assays did not yield consistent and conclusive results due to analytical difficulties. The removals of THM precursors were high when PAC was added; however, steady-state removals were a function of operating conditions and PAC dosage. Addition of PAC enhanced DOC removals and membrane permeate fluxes. Furthermore, pre-ozonation reduced membrane fouling and enhanced membrane permeate flux.     

Natural versus wastewater derived dissolved organic carbon: implications for the environmental fate of organic micropollutants

The interaction of organic micropollutants with dissolved organic carbon (DOC) can influence their transport, degradation and bioavailability. While this has been well established for natural organic carbon, very little is known regarding the influence of DOC on the fate of micropollutants during wastewater treatment and water recycling. Dissolved organic carbon-water partition coefficients (K_DOC) for wastewater derived and reference DOC were measured for a range of micropollutants using a depletion method with polydimethylsiloxane disks. For micropollutants with an octanol-water partition coefficient (log K_OW) greater than 4 there was a significant difference in K_DOC between reference and wastewater derived DOC, with partitioning to wastewater derived DOC over 1000 times lower for the most hydrophobic micropollutants. The interaction of nonylphenol with wastewater derived DOC from different stages of a wastewater and advanced water treatment train was studied, but little difference in K_DOC was observed. Organic carbon characterisation revealed that reference and wastewater derived DOC had very different properties due to their different origins. Consequently, the reduced sorption capacity of wastewater derived DOC may be related to their microbial origin which led to reduced aromaticity and lower molecular weight. This study suggests that for hydrophobic micropollutants (log K_OW > 4) a higher concentration of freely dissolved and thus bioavailable micropollutants is expected in the presence of wastewater derived DOC than predicted using K_DOC values quantified using reference DOC. The implication is that naturally derived DOC may not be an appropriate surrogate for wastewater derived DOC as a matrix for assessing the fate of micropollutants in engineered systems.