负载型FeOOH催化臭氧氧化对HAAsFP的控制效果

考察了在连续流体系中,滤后水经负载型羟基氧化铁(FeOOH)催化臭氧氧化后5种卤乙酸的生成势(HAAsFP)。结果发现,经负载型FeOOH催化臭氧氧化后,滤后水的HAAsFP比单独臭氧氧化后的降低了33.1%,对TOC较高的去除率及.OH对卤代活性位较高的破坏能力,可能是连续流体系中催化臭氧氧化进一步控制HAAsFP的主要原因。同时还考察了Br-浓度、O3投量及停留时间对连续流体系中催化臭氧氧化控制滤后水中HAAsFP的影响。结果表明,在不同的反应条件下,FeOOH催化臭氧氧化都表现出明显控制HAAsFP的优势。Br-浓度的增加提高了溴代HAAs的比例,当[Br-]=1 mg/L时,FeOOH催化臭氧氧化降低滤后水中HAAsFP的优势相对更明显。增大臭氧投量和延长接触氧化的停留时间都能使FeOOH催化臭氧氧化滤后水中的HAAsFP值进一步降低。     

FeOOH催化臭氧氧化滤后水的醛、酮副产物生成情况

在连续流条件下采用羟基氧化铁催化臭氧氧化(FeOOH/O3)工艺处理滤后水,考察了小分子醛、酮副产物的生成情况。结果表明,FeOOH/O3明显提高了对DOC和SUVA的去除率,而醛、酮副产物的产量比单独臭氧氧化的增加了12.23%。经催化氧化后,出水中醛、酮产量的顺序为:甲醛乙醛乙二醛甲基乙二醛丙酮。在不同的反应条件下,随着O3投量的升高和接触氧化时间的延长,催化氧化出水的醛、酮总量均是先升高后降低,但都高于单独臭氧氧化的生成量。FeOOH/O3明显增加醛、酮总量的趋势表明,其能够进一步提高滤后水的可生化性。     

臭氧化阶段溴类物质生成及其对溴代副产物的影响

通过小试考察了含溴水在臭氧氧化阶段溴类物质的生成规律及Br-的分配情况,以及Br-初始浓度、臭氧投加量、pH值和氨氮含量对溴酸盐和其他溴类物质生成的影响,并针对溴代三卤甲烷生成势(THMFP-Br)、溴代卤乙酸生成势(HAAFP-Br),进一步分析了Br-分配对溴代消毒副产物生成的影响。结果表明,初始溴离子浓度较臭氧投加量对各类溴代副产物的生成量影响大。降低pH值可获得较好的控制BrO-3和降低消毒副产物生成势及其溴代程度的效果,但同时也造成臭氧氧化阶段有机溴化物生成量的增加。氨氮可使THMFP、HAAFP有一定程度的降低。     

藻细胞及胞外分泌物对三卤甲烷生成势的影响

以处于对数生长期后期的悦目颤藻为研究对象,研究藻细胞及其胞外分泌物(EOM)对三卤甲烷生成势(THMFP)的贡献,以及臭氧预氧化中臭氧投量及预氧化时间对THMFP的影响.研究表明EOM是原水中主要的THM前体物;藻细胞和EOM形成的三卤甲烷主要是三氯甲烷和一溴二氯甲烷.对含藻细胞水样的臭氧预氧化研究表明随着臭氧投量的增加,含藻细胞水样的三氯甲烷生成势和THMFP持续增加;随着预氧化时间的延长,THMFP几乎呈线性增加;臭氧预氧化会破坏藻细胞,使得胞内物质释放出来,这部分物质中的一部分是THM的前体物.对含EOM水样的臭氧预氧化研究表明随着臭氧投量的增加和预氧化时间的延长,臭氧氧化EOM使其不饱和键减少,生成的总卤代产物浓度减小;低投量的臭氧预氧化可以强化混凝去除EOM中的THM前体物,在试验条件下0.486 mg/L的臭氧作用5 min可强化混凝去除EOM中THMFP,去除率比单纯混凝高9.8%;随着预氧化时间的延长,含EOM水沉后水三氯甲烷生成势和THMFP略有升高,说明延长预氧化时间会引起含EOM水沉后水三卤甲烷前体物浓度的增加.由此,低投量短时间的臭氧预氧化可以强化混凝去除EOM的THMFP;并且在实际水处理中,应该在去除藻细胞之后再进行臭氧氧化处理,这样可防止臭氧氧化使藻细胞内物质释放而增加THM前体物浓度.     

ZnOOH催化臭氧氧化去除水中痕量卡马西平

采用连续流试验,研究了羟基化锌(ZnOOH)催化臭氧氧化和单独臭氧氧化去除水中痕量卡马西平(CBZ)的效果,并探讨了臭氧投加量、pH值、催化剂投加量及使用次数等因素对催化性能的影响。结果表明,ZnOOH对水中的CBZ有较强的催化活性,相同试验条件下,催化臭氧氧化出水中的CBZ浓度比单独臭氧氧化的低48.5%,且对CBZ的去除效果随催化剂投加量的增加而提高。本试验条件下,催化剂的最佳投加量为100 mg/L;催化剂在偏碱性条件下对目标物的去除效果更佳;催化剂使用了5次,其催化效果基本没有变化,没有发现锌离子溶出。     

CeO_2/Al_2O_3/O_3对滤后水中HAAsFP的控制作用

考察了负载型CeO2催化氧化(CeO2/Al2O3/O3)在连续流体系中对滤后水中卤乙酸生成势(HAAsFP)的影响。结果表明,主要以Ce(Ⅳ)的"表面络合作用"为催化机理的CeO2/Al2O3/O3,在连续流动态体系中也表现出了明显控制HAAsFP的效能,催化氧化后滤后水的HAAs-FP比单独臭氧氧化后的低了45.3%。"络合催化"作用下表现出来的高DOC去除率和卤代活性位破坏能力可能是CeO2/Al2O3/O3明显控制HAAsFP的主要原因。同时还考察了在不同反应条件下,连续流催化氧化滤后水后HAAsFP的变化规律。结果表明,在不同反应条件([O3]0=0.7~5.0 mg/L,[Br-]=0~3 mg/L,停留时间为3.3~9.8 min)下,CeO2/Al2O3/O3都能表现出明显控制HAAsFP的优势。实际生产建议采用O3/DOC≈1的中等臭氧投量和较长的接触停留时间。     

不同水源下臭氧/生物活性炭运行参数的优化

近年来,臭氧/生物活性炭工艺在国内得到广泛应用,在控制饮用水中消毒副产物的生成方面起到了重要作用。研究与生产实践表明,臭氧/生物活性炭运行参数的优化对其净水效能的发挥至关重要。针对江苏J水厂采用的H和X两个水质差异较大的水源,建立了中试装置,开展了以控制消毒副产物为目标的臭氧/生物活性炭运行参数优化研究。结果表明:随着臭氧投加量的增加,系统对H与X水源中三卤甲烷生成势(THMFP)的去除率先上升后逐渐平稳,对卤乙酸生成势(HAAFP)的去除率呈现先增加后降低的趋势;随着炭床停留时间的延长,生物活性炭工艺对THMFP、HAAFP的去除率均呈先上升后平稳的趋势。综合考虑THMFP和HAAFP的去除效能,优化后的臭氧/生物活性炭工艺运行参数如下:针对H水源,臭氧投加量为0. 5 mg/L,炭床停留时间为12 min;针对X水源,臭氧投加量为2. 0 mg/L,炭床停留时间为12 min。     

催化臭氧氧化工艺深度处理市政污水厂生化出水

以山东省某污水厂快滤池出水为催化臭氧氧化工艺进水,考察了臭氧投加量、臭氧浓度、接触反应时间等因素对催化臭氧氧化去除COD的影响,并从反应动力学和臭氧利用率两方面与相同工艺条件下的单独臭氧氧化技术进行了对比。结果表明,在一定范围内,增加臭氧投加量、提高臭氧浓度、延长反应接触时间都可以有效提高COD去除率;与单独臭氧氧化工艺相比,催化臭氧氧化具有更高的反应速率和臭氧利用率以及更低的单位质量COD消耗臭氧量,在处理市政污水中有着广阔的应用前景。     

臭氧/高锰酸盐复合预氧化控制氯化消毒副产物前质

研究了高锰酸盐与臭氧单独或复合预氧化对消毒副产物前质--三卤甲烷生成势（THMFP）和卤乙酸生成势（HAAFP）的去除效果.试验结果表明,高锰酸盐单独预氧化对消毒副产物前质的去除率可达20%以上,而臭氧预氧化的去除率仅约为10%.复合氧化比单一氧化更能有效去除消毒副产物前质,但受投加方式的影响,在试验务件下,以两种氧化剂同时投加的效果为最佳.复合氧化去除消毒副产物前质的机理包括：高锰酸盐与臭氧的协同氧化作用、锰的中间态产物对臭氧的催化作用以及高锰酸盐的强化混凝作用.     

二氧化铈催化分解水中臭氧的性能研究

通过静态试验,初步探讨了CeO2催化分解水中臭氧的机理,并考察了温度、H2O2、SO24-以及不同CeO2投量对CeO2催化分解臭氧的影响。结果表明,相对于羟基氧化铁催化分解臭氧以及单独分解臭氧而言,当以CeO2为催化剂时,在反应开始后的1 m in内,由于臭氧与CeO2-X发生氧化还原反应,臭氧分解速率非常快;CeO2抑制了O3+H2O2体系以及高温(35℃)下臭氧的分解,投加SO24-后,这种抑制作用逐渐消除;增加CeO2投量只加快了反应初期臭氧的分解,之后臭氧浓度仍较稳定。     

Transformation of dissolved organic matter during ozonation: effects on trihalomethane formation potential

Transformation of dissolved organic matter (DOM) during ozonation results in a higher reduction in trihalomethane formation potential (THMFP) relative to dissolved organic carbon (DOC). This study was conducted to determine the effect of DOM transformation after ozonation on THM formation and to elucidate the difference in THMFP and DOC removal. Changes in DOC, THMFP, reactivities of the hydrophilic and hydrophobic DOC, and phenolic-OH were determined to explain the difference in THMFP and DOC removal after ozonation. Higher reduction in THMFP (24-46%) relative to DOC (10-16%) was obtained and was attributed to the following: transformation of DOM from a more reactive hydrophobic DOC (microg THM produced per mg organic carbon) to a less reactive hydrophilic DOC and to the decrease in the reactivities of both the hydrophobic and hydrophilic DOC after ozonation. The results also showed decrease in phenolic-OH indicating the oxidation of some reactive sites like resorcinol or meta-dihydroxy benzene ring structures, which are prone to chlorine substitution, consequently decreasing the reactivity of the organic carbon to form THM. These changes in DOM led to a significant decrease in THMFP with no remarkable removal in DOC.     

Comparative study of ozonation and synthetic goethite-catalyzed ozonation of individual NOM fractions isolated and fractionated from a filtered river water

This study comparatively investigated ozonation and synthetic goethite-catalyzed ozonation of individual natural organic matter (NOM) fractions in terms of ozone consumption, dissolved organic carbon (DOC) and UV-absorbance reduction, molecular weight (MW) distribution, and formation of low-MW oxidation by-products. Hydrophobic acid and neutral (HOA and HON) and hydrophilic acid and base (HIA and HIB) were four major NOM fractions isolated from a filtered river water; so ozonation and catalytic ozonation were carried out on these fractions. Results indicate that in comparison to ozonation alone, catalytic ozonation can enhance ozone consumption, UV(254) and DOC reduction, fragmentation of fraction components with MW>3000Da, and formation of oxalic acid for these fractions under normal reaction conditions commonly adopted in water treatment plants. In addition, catalytic ozonation can enhance aldehydes formation and increase the percentage of easy biodegradable organic carbon compared with ozonation alone for HIA and HIB, but exert much less effect on these items for HOA and HON.     

Effect of pH on MnOx/GAC catalyzed ozonation for degradation of nitrobenzene

The effect of pH on MnO(x)/GAC heterogeneous catalytic ozonation was investigated. Nitrobenzene was used as a model refractory organic pollutant. It was found that in MnO(x)/GAC catalytic ozonation, the degradation efficiency of nitrobenzene was higher under low pH conditions (pH 2.74-3.52) than that under high pH conditions (pH 6.72-9.61). This result was different from the case of ozonation alone, in which higher pH had positive effect on the degradation of nitrobenzene due to the formation of hydroxyl radical. In the presence of MnO(x)/GAC catalyst, ozone decomposition was accelerated, and higher pH condition favored ozone decomposition. It was assumed that hydroxyl radicals might not be the dominating active species in the catalytic oxidation, for the presence of t-butanol did not have any influence on MnO(x)/GAC heterogeneous catalytic ozonation. Adsorption of organic micropollutants on MnO(x)/GAC catalyst was an important step and would have direct influence on the effectiveness of catalytic oxidation. It was assumed that the organic pollutants might be further decomposed on the surface of catalyst.     

蜂窝陶瓷催化臭氧氧化处理饮用水中试

在北京市某净水厂进行了臭氧催化氧化处理滤后水的中试，对各种操作条件下蜂窝陶瓷催化臭氧氧化／颗粒活性炭过滤工艺的净水效果进行了考察。结果表明，与臭氧单独氧化相比，臭氧催化氧化反应器中有较高的溶解性臭氧浓度，对天然有机物（NOM）及总有机物（TOC）的去除效果较好，三氯甲烷生成潜能（CHCl3FP）较低。臭氧催化氧化的后续活性炭滤柱上的生物量较多，出水TOC、UV254及CHCl3FP值也均低于臭氧单独氧化的后续活性炭滤柱出水。     

Iron type catalysts for the ozonation of oxalic acid in water

Two iron catalysts (Fe(III) and Fe2O3/Al2O3) have been used in the ozonation of oxalic acid in water at pH 2.5. Percentage removals of oxalic acid were 1.8%, 7% and 30% corresponding to the non-catalytic, homogeneous (Fe(III)) and heterogeneous (Fe2O3/Al2O3) catalytic ozonations, respectively. Catalytic oxalic acid ozonation leads in all cases to total mineralization. The mechanism of ozonation likely develops through formation of iron-oxalate complexes that further react with ozone without the participation of hydroxyl radicals. Because of the stringent acidic conditions, some metal leaching has been observed and quantified in the heterogeneous process. In the homogeneous catalysis, the kinetics was found to be first order with respect to ozone and oxalic acid while for the heterogeneous catalysis, the kinetic order depends on the concentration of ozone in the gas fed. Thus, at ozone concentrations lower than 30 mg L(-1), the heterogeneous ozonation is between first and zero order with respect to both ozone and oxalic acid while at higher ozone gas concentrations, the kinetics was found to be first and zero order with respect to oxalic acid and ozone, respectively. This kinetics is supported through an Eley-Rideal mechanism that involves a surface reaction between non-adsorbed ozone and adsorbed oxalic acid. Apparent activation energies of the homogeneous and heterogeneous catalytic ozonations were found to be 18.2 and 13.6 kcal mol(-1), respectively.     

Photocatalytic oxidation and ozonation of catechol over carbon-black-modified nano-TiO2 thin films supported on Al sheet

The photocatalytic activity of the carbon-black-modified nano-TiO2) (CB-TiO2) thin films was 1.5 times higher than that of TiO2 thin films in degrading Reactive Brilliant Red X-3B. Photocatalytic oxidation and ozonation of catechol over CB-TiO2 thin films supported on Al sheet was investigated. The experiments showed that ozone concentrations had an important effect on TOC removal. The combined photocatalysis with UV irradiation and ozonation (TiO2/UV/O3) process considerably increased TOC removal rate compared to combined photocatalysis with UV irradiation and oxygen oxidation (TiO2/UV/O2) process, ozonation alone (O3) process, combined ozonation and UV irradiation (UV/O3) process. The complete mineralization of catechol followed pseudo-zero-order kinetics dependent upon ozone (oxygen) concentration and indicated catechol concentration did not affect the kinetics during UV/O3 and TiO2/UV/O3 (O2) processes. The kinetic study showed that the rate constants in the complete mineralization of catechol with TiO2/UV/O3 are 1.32-1.80 times higher than that of UV/O3 with the same concentration of ozone. The rate constants are 2.56-5.36 times higher than the maximal rate constants of TiO2/UV/O2 and 4.68-9.8 times higher than the maximal rate constants of TiO2/UV.     

固定化生物活性炭强化饮用水深度处理

为比较固定化生物炭工艺与普通活性炭工艺的净水效果,以南方某水厂的滤后水为原水进行了试验。结果表明,固定化生物炭工艺对TOC的去除率稳定在40% ~50%,可以提高氨氮去除率30%;对三卤甲烷生成势(THMFP)的去除率比普通活性炭工艺提高了11% ~39%;对臭氧氧化副产物(甲醛)具有长期的去除效果。     

MnOx/GAC多相催化臭氧氧化降解有机物机理探讨

通过考察羟基自由基抑制剂——叔丁醇对MnOx／GAC多相催化臭氧氧化过程的影响，探讨了其对有机物的降解是否遵循羟基自由基反应机理。试验结果表明，叔丁醇的存在并未降低MnOx／GAC多相催化臭氧氧化对贿基苯的降解效率，由此可推断羟基自由基并非是MnOx／GAC多相催化臭氧氧化反应中的主导活性氧化物种。此外，MnOx／GAC多相催化臭氧氧化降解硝基苯的效果也未受重碳酸盐的影响。因此，MnOx／GAC多相催化臭氧氧化工艺可能比遵循羟基自由基反应机理的其他高级氧化法具有更广泛的适用性。     

活性炭催化臭氧氧化水中有机污染物的研究进展

介绍了活性炭作为催化剂催化臭氧氧化去除水中有机污染物的研究现状,对影响活性炭催化活性的关键因素、活性炭在反应前后表面性质的变化以及这种变化对其催化活性的影响进行了总结和分析,并阐述了活性炭催化臭氧氧化降解有机物的反应机理,最后对活性炭催化臭氧氧化的发展趋势进行了展望。