混凝和粉末炭去除黄浦江水中DOM的效果

研究表明,混凝去降分子量〉４０００ｕ的溶解性有机场（ＤＯＭ）效果较好,而对分子量〈４０００ｕ的去除效果较差。粉末活性炭去除低分子量的ＤＯＭ效果较好,去除大分子量的ＤＯＭ效果较差。当粉末活性炭投加量较大时,ＤＯＭ分子量的大小对吸附效果的影响减少。黄浦江水中分子量〉４０００ｕ的一部分有机物难以被粉末活性炭吸附去除。     

活性炭自硫脲溶液吸附金的氧化还原机理探讨

采用Ｘ射线衍射、元素分析及显微技术等方法，研究了活性炭自溶液中吸附金硫脲络合物的机理。研究发现，溶液中络合离子被活性炭表面的≥Ｃ－ＯＨ和≥Ｃ－Ｈ官能团还原为零价金Ａｕ（０）而吸附；提出了氧化还原吸附机理可能的步骤，并用Ｎｅｒｎｓｔ公式证明该氧化还原吸附过程为自发过程。     

珠江水中有机物分子量分布及其去除研究

采用超滤膜分级方法考察了常规混凝、高锰酸钾和粉末活性炭预处理等工艺对珠江水中各级分子量有机物的去除效果。结果表明,珠江水中有机物以分子量小于1kDa的小分子有机物为主,各级分子量有机物TOC和UV254具有良好的相关性。常规混凝工艺主要去除大分子有机物,且去除率随分子量的减小而降低。高锰酸钾预处理能够全面提高各级分子量有机物的去除效果;粉末活性炭主要吸附中小分子有机物,对各级分子量有机物的去除效果与常规混凝成互补。     

GAC,UF,RO去除饮用水中氯仿,四氯化碳性能的试验研究

研究了粒状活性炭（ＧＡＣ）,超滤（ＵＦ）和反渗透（ＲＯ）对自来水中氯仿和四氯化碳的去除性能,探讨了ＧＡＣ对氯仿和四氯化碳去除的物理吸附和微生物降解机理。试验发现ＵＦ膜对氯仿和四氯化碳的快速吸附与脱附现象,并讨论了ＲＯ膜对不同浓度氯仿、四氯化碳的去除效果和作用机理。     

GAC,UF,RO去除饮用水中氯仿,四氯化碳性能的试验研究

研究了粒状活性炭（ＧＡＣ）,超滤（ＵＦ）和反渗透（ＲＯ）对自来水中氯仿和四氯化碳的去除性能,探讨了ＧＡＣ对氯仿和四氯化碳去除的物理吸附和微生物降解机理。试验发现ＵＦ膜对氯仿和四氯化碳的快速吸附与脱附现象,并讨论了ＲＯ膜对不同浓度氯仿、四氯化碳的去除效果和作用机理。     

炭砂滤池去除硝基苯等微污染有机物的研究

采用炭砂滤池处理受硝基苯等有机物污染的松花江原水,在保证水厂原运行参数不变的条件下,通过50d的跟踪生产运行,考察了炭砂滤池对浊度和CODMn的去除效果,同时通过活性炭对硝基苯等7种有机物的静态吸附试验,分析了活性炭去除各种有机物的难易程度。结果表明,当进水浊度为2.4～5.3NTU、CODMn为2.34～4.36mg/L时,出水浊度始终保持在0.6～1.0NTU、CODMn为1.72～3.54mg/L,保证了炭砂滤池优质的出水水质。由不同吸附时间下活性炭对有机物的吸附率可知,在7h之前,活性炭对硝基苯的吸附率最低,这说明硝基苯较其他6种有机物的处理难度大,但只要保证一定的吸附时间,硝基苯也可被有效去除。     

生物活性炭性能对水质处理效果对比试验

活性炭滤料重要的评价指标是碘吸附值和亚甲蓝吸附值,活性炭采购价格又与碘吸附值和亚甲蓝吸附值的大小呈正相关关系.碘吸附值和亚甲蓝吸附值的大小又可能会影响出水水质.我们选取运行10年的生物活性炭池和运行1年的优选低碘吸附值和亚甲基蓝吸附值活性炭池经过近一年的跟踪试验发现:两个炭池出水平均浊度相当,没有受到活性炭滤料吸附值的影响;运行10年的生物活性炭池出水pH偏低且更稳定,优选活性炭池出水pH更接近进水pH,数据波动性也较大;对CODMn、UV254、消毒副产物前体物等有机物的去除效果优选活性炭会比旧炭更好一点,但旧炭对这些有机物也还有一定的处理能力.两种活性炭池出水水质总体情况均优于进水水质.     

臭氧化-生物活性炭深度净化饮用水试验研究

通过色－质联机方法对Ｇ厂地表水源及常规处理出水进行了分析和介,说明该厂地表水源已受到的严重的有机污染,采用常规给水处理流程无法去除其中的有毒、有害有机物。臭氧接触氧化－生物活性炭吸附降解－木鱼石过滤流程的动态小试结果表明,该流程能够控制和消除水中微量有机物的污染,可提供安全的优质饮用水。     

A2N工艺中有机物分子量分布及变化

本文利用超滤-纳滤膜法对改进A2N工艺中污水有机物分子量分布及变化进行测定试验研究。试验表明:原水中有机物近70%为颗粒性,且剩余溶解性有机物(DOC)在0.45μm³00分子量区间上呈现W型分布,其中在>10w、1w300分子量区间上呈现W型分布,其中在>10w、1w⁵k、<1k的有机物分别占36.76%、8.36%、45.18%;经工艺处理,颗粒性有机物去除98.58%,其中80.42%在预缺氧池被吸附去除,总DOC去除80.49%,且出水在0.45μm5k、<1k的有机物分别占36.76%、8.36%、45.18%;经工艺处理,颗粒性有机物去除98.58%,其中80.42%在预缺氧池被吸附去除,总DOC去除80.49%,且出水在0.45μm³00区间上分布平缓,各区间出水TOC浓度明显减少,均小于1mg/L。由此可知,反硝化碳源不仅来源于溶解性小分子有机物,其中颗粒性大分子有机物也是主要贡献者,且厌氧处理是颗粒性有机物向溶解性转化的有效方法。     

基于有机物分子质量分布的饮用水处理工艺选择

为应对市内运河排洪造成的出水有机物超标问题,建立了臭氧／活性炭中试装置,采用滤膜法测试了运河水、现有水厂各工艺段及臭氧／活性炭出水中有机物的分子质量分布,在此基础上对现有水处理工艺进行了评价。结果表明,由于原水受到工业污染,其大分子有机物含量较高,并且亲水性强而易被氧化,造成混凝沉淀的去除效果不好,而运河水中的溶解性小分子有机物含量较高,也不易被混凝沉淀去除,采用臭氧／活性炭深度处理工艺是一个很好的选择。臭氧和活性炭联用提高对有机物去除效果的原因在于,臭氧能有效地氧化大分子有机物为小分子有机物,有利于活性炭的吸附、降解去除。     

颗粒活性炭吸附对预臭氧后微污染原水水质影响研究

在不同的预臭氧浓度条件下处理微污染原水,考察了颗粒活性灰（GAC）吸附对处理后水样水质的影响.选择化学需氧量（CODMn）、溶解性有机碳（DOC）、生物可降解溶解性有机碳（BDOC）、UV254和氨氮（NH;-N）含量及有机物分子量分布作为考察吸附效果的检测指标.结果表明,在静态吸附时间达到5天时,颗粒活性炭吸附曲线开始趋于平缓,吸附时间超过5天之后吸附趋于饱和;预臭氧含量为2.5 mg/L时,颗粒活性炭对有机物的吸附效果最佳,对CODMn、DOC、BDOC的去除率分别为53.2％,63.2％和36.2％;在不同预臭氧处理条件下,颗粒活性炭对NH;-N的吸附效果并未表现出较大的差异,吸附去除率约为5％;颗粒活性炭优先吸附水中分子量＞ 10kDa的有机物,其次为分子量＜1 kDa的有机物.     

Adsorption of natural organic matter oxidized with ClO2 on granular activated carbon

The paper describes the influence of the oxidation of natural organic matter (NOM) molecules with chlorine dioxide (ClO2) on granulated activated carbon (GAC) adsorption. In order to determinate the influence of ClO2 dosage on the NOM adsorption on GAC two parallel pilot scale experiments were performed. The raw water was treated respectively with 0.2 and 0.4 mg ClO2 L(-1) followed by the adsorption on GAC filters. Experiments were total organic carbon (TOC) measurements and size exclusion chromatography (SEC) controlled. The molecular weight distribution of NOM in the filtration bed outlet demonstrates that the low molecular weight molecules are less retained than the higher molecular weight components of NOM. It is shown that low molecular weight NOM causes less ClO2 demand. The oxidation of NOM molecules and very high capacity of GAC filter bed for NOM components can be used to control high ClO2 demand.     

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.     

Removal of THM precursors by GAC: Ankara case study

The effectiveness of granular activated carbon (GAC) adsorption for the removal of natural organic matter and trihalomethanes from Ivedik Water Treatment Plant of Ankara City is investigated. Freundlich Isotherm constants K and n were determined as 17.61 and 1.66, respectively. Bench-scale GAC columns were run with empty bed contact times (EBCT) varying from 0.40 to 2.67 min to evaluate adsorption performance. 50% exhaustion values were used for comparison. The treated volumes of water increased with EBCT, showing a linear increase in GAC service life. Correspondingly, the carbon usage rate decreased. The capacities calculated by the isotherm equation and achieved by columns were also compared. The column capacities were within 43-65% of the isotherm capacities at complete breakthrough. However, they were only within 8-17% of the isotherm capacities at 50% breakthrough.     

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%.     

Comparison of NOM removal and microbial properties in up-flow/down-flow BAC filter

The removal of natural organic matter (NOM) in term of COD_Mn by up-flow biologically activated carbon filter (UBACF) and down-flow biologically activated carbon filter (DBACF) was investigated in a pilot-scale test. The impacts of the molecular weight distribution of NOM on its degradation by the UBACF and DBACF were evaluated. The relationship between biodegradation and the microbial properties in the UBACF and DBACF were approached as well. The feed water of the UBACF and DBACF were pumped from the effluent of the rapid sand filtration (RSF) of Chengnan Drinking Water Treatment Plant (CDWTP), Huaian, Jiangsu Province, China. When the adsorption was the dominant mechanism of NOM removal at the initial stage of operation, the COD_Mn removal efficiency by the UBACF was lower than the DBACF. However, with the microbes gradually accumulated and biofilm formed, the removal of COD_Mn by the UBACF increased correspondingly to 25.3%, at the steady-state operation and was approximately 10% higher than that by the DBACF. Heterotrophy plate count (HPC) in the finished water of the UBACF was observed 30% higher than that of the DBACF. The UBACF effluent had higher concentration of detached bacteria whereas the DBACF harbored more attached biomass. The highest attached biomass concentration of the UBACF was found in the middle of the GAC bed. On the contrary, the highest attached biomass concentration of the DBACF was found on the top of the GAC bed. Furthermore, a total of 9479 reads by pyrosequencing was obtained from samples of the UBACF and DBACF effluents. The UBACF effluent had a more diverse microbial community and more even distribution of species than the DBACF effluent did. Alphaproteobacteria and Betaproteobacteria were the dominant groups in the finished water of the UBACF and DBACF. The higher organic matter removal by the UBACF was attributed to the presence of its higher biologically activity.     

MTBE adsorption on alternative adsorbents and packed bed adsorber performance

Widespread use of the fuel additive methyl tertiary-butyl ether (MTBE) has led to frequent MTBE detections in North American and European drinking water sources. The overall objective of this research was to evaluate the effectiveness of a silicalite zeolite, a carbonaceous resin, and a coconut-shell-based granular activated carbon (GAC) for the removal of MTBE from water. Isotherm and short bed adsorber tests were conducted in ultrapure water and river water to obtain parameters describing MTBE adsorption equilibria and kinetics and to quantify the effect of natural organic matter (NOM) on MTBE adsorption. Both the silicalite zeolite and the carbonaceous resin exhibited larger MTBE adsorption uptakes than the tested GAC. Surface diffusion coefficients describing intraparticle MTBE mass transfer rates were largest for the GAC and smallest for the carbonaceous resin. Pilot tests were conducted to verify MTBE breakthrough curve predictions obtained with the homogeneous surface diffusion model and to evaluate the effect of NOM preloading on packed bed adsorber performance. Results showed that GAC was the most cost-competitive adsorbent when considering adsorbent usage rate only; however, the useful life of an adsorber containing silicalite zeolite was predicted to be approximately 5-6 times longer than that of an equally sized adsorber containing GAC. Pilot column results also showed that NOM preloading did not impair the MTBE removal efficiency of the silicalite zeolite. Thus, it may be possible to regenerate spent silicalite with less energy-intensive methods than those required to regenerate GAC.     

Adsorption and desorption of trace organic contaminants from granular activated carbon adsorbers after intermittent loading and throughout backwash cycles

A granular activated carbon (GAC) adsorption simulation methodology using the observed trace organic contaminant mid-point breakthrough and the pore diffusion model is presented, validated, and used to model adsorption and concentration gradient driven desorption. Trace organic contaminant adsorption was well-simulated by this approach; however, desorption from GAC adsorbers was found to occur at lower concentrations than predicted by either pore or surface diffusion model calculations. The observed concentration profiles during desorption yielded a lower peak concentration and more elongated attenuation of contaminants after intermittent loading conditions than predicted by the models. Hindered back diffusion caused by irreversibly adsorbed dissolved organic matter on the GAC surface is hypothesized to be responsible for slowing the desorption kinetics. In addition, laboratory test results indicate a negligible impact of simulated backwashing the GAC media on trace organic contaminant breakthrough.     

Anaerobic dechlorination using a fluidized-bed GAC reactor

A simulated high-strength industrial wastewater containing acetate, phenol, and orthochlorophenol (2-CP) was treated using an anaerobic fluidized-bed granular activated carbon (GAC) reactor. Although carbon replacement was initiated to maintain the effluent quality from the reactor and to minimize the inhibitory effects of 2-CP, the latter phase of this study demonstrated that carbon replacement was not necessary. A large pulse input of organic feed was introduced to investigate the resilience of the reactor to severe and sudden increases in influent organic loading. With appropriate pH adjustment, the reactor stabilized within less than two days. A mathematical model was developed to investigate the interaction between the adsorption and biodegradation of compounds in the reactor during the large pulse input. The model confirmed that the GAC was instrumental in controlling the buildup of 2-CP in the reactor.     

Adsorption of dissolved natural organic matter by modified activated carbons

Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA(254)) were employed to characterize the DOMs before and after adsorption. Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA(254) results showed no specific selectivity in the removal of different DOM components as a result of carbon modification. The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1--3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs.