O_3/H_2O_2工艺去除饮用水中2-MIB的效能与机制

以2-甲基异莰醇(MIB)为嗅味物质的代表物,采用过氧化氢/臭氧氧化(O3/H2O2)工艺去除水中嗅味物质,考察了O3/H2O2工艺对水中2-MIB的去除效能与主导作用机制。研究表明,投加H2O2显著提高了单独O3氧化对2-MIB的去除效能,H2O2与O3最佳物质的量比为0.3∶1,且2-MIB去除效果随pH值的升高而升高。叔丁醇对2-MIB的去除表现出显著的抑制作用,在O3氧化2-MIB过程中,除O3分子氧化2-MIB外,O3在水中自分解产生的强氧化性的羟基自由基(HO.)也具有协同氧化作用。不同浓度的天然有机物(NOM)对2-MIB去除效果的影响不同,较低浓度的NOM促进了2-MIB的去除,但随着其浓度的升高,2-MIB去除率明显降低。O3/H2O2工艺对水中2-MIB表现出良好的去除效果,是强化去除水中2-MIB等致臭微量有机物的重要工艺。     

O3／H2O2艺去除饮用水中2-MIB的效能与机制

以2-甲基异莰醇（MIB）为嗅味物质的代表物,采用过氧化氢／臭氧氧化（O3／H2O2）工艺去除水中嗅味物质,考察了O3／H2O2工艺对水中2一MIB的去除效能与主导作用机制。研究表明,投加H2O2显著提高了单独0,氧化对2-MIB的去除效能,H2O2与O3最佳物质的量比为0．3：1,且2-MIB去除效果随pH值的升高而升高。叔丁醇对2-MIB的去除表现出显著的抑制作用,在O3氧化2-MIB过程中,除O3分子氧化2-MIB外,O3在水中自分解产生的强氧化性的羟基自由基（HO·）也具有协同氧化作用。不同浓度的天然有机物（NOM）对2-MIB去除效果的影响不同,较低浓度的NOM促进了2-MIB的去除,但随着其浓度的升高,2-MIB去除率明显降低。O3／H2O2工艺对水中2-MIB表现出良好的去除效果,是强化去除水中2-MIB等致臭微量有机物的重要工艺。     

2-MIB在某深度处理水厂中的去除规律研究

针对南方某湖泊水源净水厂4月—9月易发原水致嗅物质2-MIB超标问题,进行了2-MIB去除规律的生产性试验。结果表明,预臭氧工艺对2-MIB的平均去除率可达68.6%,不采用其他预处理工艺时,混凝沉淀和砂滤对2-MIB没有去除效果。使用预臭氧和混凝前加氯方式联合预处理时,混凝沉淀会抵消预臭氧对2-MIB的去除效果,后续砂滤单元对2-MIB的去除率为15%~35%,尽管缩短了砂滤池的反冲洗周期,但对2-MIB的去除率提高不超过5%。后臭氧/生物活性炭工艺对2-MIB的去除率随着臭氧投加量的增加而增大。当水厂负荷不超过80%、原水中2-MIB的浓度不超过911 ng/L时,通过预臭氧、前加氯、常规处理与后臭氧/生物活性炭单元的有机结合,可控制出厂水中2-MIB浓度低于10 ng/L。     

ZnO/O3工艺降解水中微量有机物的研究

以实验室制备的粉末氧化锌(ZnO)为催化剂,考察了ZnO/O3工艺去除水中有机物的效能.采用总有机碳(TOC)指标反映水中有机污染物的含量.结果表明:臭氧投量为1 mg/L、ZnO投量为300 mg/L时,反应60 min后ZnO-O3工艺对TOC的去除率为46%,比单独臭氧化提高了1倍;反应温度明显影响该工艺对有机物的降解效果,在水温为5,10,20和25 ℃时,TOC的去除率分别为17.5%,31.5%,45.9%和51.3%.臭氧浓度和催化剂投量的增加,可以提高TOC的氧化降解效率.     

臭氧氧化去除饮用水消毒副产物二氯乙酸

采用臭氧氧化技术降解饮用水中的消毒副产物二氯乙酸(DCAA),考察了DCAA初始浓度、臭氧投量、pH、叔丁醇和不同水质等对DCAA去除效果的影响。结果表明,臭氧对DCAA的氧化去除效果较好,当DCAA初始浓度为100μg/L、pH值为6.88、臭氧投量为1.96 mg/L、反应时间为25 m in时,对DCAA的去除率为32.4%;在相同的试验条件下,臭氧对DCAA的去除率随DCAA初始浓度的增大而降低、随臭氧投量和溶液pH的增大而升高。叔丁醇(.OH抑制剂)的加入显著抑制了臭氧对DCAA的氧化去除效果,表明臭氧氧化DCAA的过程主要遵循羟基自由基反应机理。另外发现,臭氧对给水厂滤后水和松花江原水中DCAA的去除率比超纯水中的分别降低了7.06%和19.58%,由此推测实际水体中的有机物和重碳酸盐会抑制臭氧对DCAA的氧化降解。     

去除D江异嗅的饮用水处理工艺选择研究

为去除C市D江饮用水中的异嗅,研究了强化混凝/KMnO4预氧化、强化混凝/粉末活性炭吸附和臭氧/活性炭工艺对水中异嗅和CODMn的去除特性.结果表明,臭氧氧化是去除异嗅的关键工艺.强化混凝/高锰酸钾预氧化及强化混凝/活性炭吸附工艺对异嗅和CODMn均有一定的去除作用,需要根据水中致嗅物质的组成和有机物特性进行选择.但当硫醇硫醚类致嗅物质与土嗅素和2-MIB并存时,强化混凝组合工艺无法完全去除水中的嗅味.当进水嗅阈值<35、CODMn<8 mg/L时,臭氧/活性炭深度处理工艺可以完全去除D江水中的嗅味,并且对CODMn也有很好的去除效果,但在水质再恶化时需联合使用强化预处理等工艺方能达标.     

臭氧化对臭氧耦合ASBR/SBR工艺硝化、反硝化的影响

针对臭氧耦合ASBR/SBR污泥减量化工艺,研究了臭氧氧化对硝化和反硝化能力的影响。结果表明,在臭氧投加量为0.074gO3/gSS左右的条件下,系统进水的COD平均值由氧化前的659mg/L增加到氧化后的713mg/L,碳源量提高了8.2%。进水氨氮由34.3mg/L增加到39.9mg/L,出水氨氮由1.7mg/L升高至1.9mg/L,硝化能力基本未受到影响。SBR段的出水NO3--N平均值由5.85mg/L下降为2.2mg/L,表明系统的反硝化能力增强。投加臭氧前后,系统进水TN平均值分别为49.1mg/L和52.9mg/L,出水TN平均值分别为10.9和13.4mg/L,对TN的平均去除率分别为77.7%和74.6%。可见,臭氧氧化未对SBR段的硝化和反硝化效果产生明显影响。     

臭氧预氧化强化混凝处理引黄水库水的中试研究

针对引黄水库水的特点,采用臭氧预氧化强化常规工艺处理引黄水库水。中试研究结果表明:臭氧预氧化能够降低常规工艺出水浊度,改善对有机物的去除效果,同时提高常规工艺对氨氮和藻类的去除率。适宜的臭氧投加量为1～2mg/L,当臭氧投加量为1mg/L时,臭氧预氧化后,滤后水浊度、CODMn、UV254、氨氮和叶绿素a的去除率,与常规工艺相比分别提高了2.7,2.5,7.8,5.2和4.8个百分点。     

臭氧+Flopac~(TM)工艺去除化工废水中难降解有机物

如何经济、有效地去除难降解有机物是当前水处理领域的难题之一。针对臭氧+FlopacTM工艺对化工废水难降解有机物的去除效果开展中试研究,并应用于具体工程实例。中试结果表明,增加臭氧投加量可有效提高化工废水的可生化性,当臭氧投加量由35 mg/L增加到75mg/L时,出水B/C值由0. 13提高到0. 17,对COD的去除率由27%提高到38%,出水COD浓度稳定在60 mg/L以下。实际工程运行数据表明,臭氧+Flopac~(TM)工艺可有效去除化工废水中的难降解有机物,出水水质稳定,臭氧投加量为65 mg/L、Flopac~(TM)平均滤速为6. 7 m/h时,COD去除率达到44%。     

O_3-BEAC-UV/Cl工艺去除低温水中氨氮的研究

为解决低温水中氨氮难去除的问题,将新菌种——哈尔滨不动细菌HITLi 7~T(占总菌量的80%)和专利菌种、菌剂构建低温除氨氮的优势菌群,形成生物增强活性炭工艺(BEAC),并前置臭氧(O_3)氧化,后置紫外/氯耦合(UV/Cl),构成O_3-BEAC-UV/Cl新工艺,并在4种工况下运行,确定该工艺的最佳运行条件,分析其对消毒副产物的控制情况。结果表明,投加O_3可以提高水中可生物降解有机物(BDOC)的量,提高BEAC工艺对氨氮的去除率。当臭氧投加量为1~2mg/L,氯氮比为3~4,紫外光强为15 m W/cm~2时,O_3-BEAC-UV/Cl工艺可在0~1℃条件下将原水中1~2 mg/L的氨氮去除至0.2~0.3 mg/L,且消毒副产物生成量极低,满足《生活饮用水卫生标准》(GB 5749—2006)的要求。     

Adsorptive ozonation of 2-methylisoborneol in natural water with preventing bromate formation

This paper presents an application of our newly developed adsorptive ozonation process using a high silica zeolite adsorbent (USY) for drinking water treatment. First, the adsorption of 2-methylisoborneol (2-MIB) on USY in a river water/pure water mixture was clarified by a batch-type adsorption experiment. The results showed that 2-MIB was adsorbed on USY; however, almost all of the adsorbed 2-MIB was desorbed over time. The desorption rate was increased with the ratio of river water to pure water, indicating that compounds dissolved in the river water, such as natural organic matter (NOM), prevent the adsorption of 2-MIB on USY. Second, the ability of the river water to consume ozone was confirmed in an experiment using a USY-packed column reactor. The ozone consumption was obviously increased by the presence of USY, indicating that USY-adsorbing compounds dissolved in the river water (probably small size NOM) consumed the ozone. However, the rapid ozone consumption was occurred by 6-8 s in the retention times when 3.14-4.38 mgL(-1) of water dissolved ozone was fed, this rapid ozone consumption lasted no more than these times. This result revealed that the rapid consumption of ozone by the adsorptive compounds in our process could be avoided within a certain retention time (6-8 s; especially for the river water used in this study) when enough concentration of ozone (3.14 mgL(-1) or more; same above) was supplied. We therefore performed a trial in which 2-MIB dissolved in river water was continuously decomposed using a USY-packed column with various ozone concentrations. In the process, the adsorptive compound dissolved in the river water adsorbed and reacted with ozone in the parts of the apparatus upstream of the column, while the adsorption and decomposition of 2-MIB took place in the parts of the apparatus downstream of the column. This resulted in a sufficient 2-MIB decomposition with minimizing bromate ion formation.     

原水硬度对臭氧和高锰酸钾预氧化除藻效果的影响

为掌握原水硬度对除藻效果的影响,以绿藻为研究对象,在原水钙硬度为50~300mg/L的环境下进行了臭氧和高锰酸钾的混凝除藻实验。混凝实验结果显示,不同的钙离子浓度均能显著提高臭氧和高锰酸钾的混凝除藻效果。当钙离子浓度较低时,臭氧预氧化—混凝除藻效果优于高锰酸钾预氧化—混凝;但当钙硬度> 90 mg/L时,高锰酸钾预氧化—混凝除藻效果则优于臭氧预氧化—混凝。水厂原水的3组平行实验数据也证明在高硬度环境下高锰酸钾预氧化—混凝除藻效果优于臭氧预氧化—混凝。     

UV-based advanced oxidation processes for the treatment of odour compounds: Efficiency and by-product formation

The occurrence of the taste and odour compounds geosmin and 2-methyl isoborneol (2-MIB) affects the organoleptic quality of raw waters from drinking water reservoirs worldwide. UV-based oxidation processes for the removal of these substances are an alternative to adsorption and biological processes, since they additionally provide disinfection of the raw water. We could show that the concentration of geosmin and 2-MIB could be reduced by VUV irradiation and the combination of UV irradiation with ozone and hydrogen peroxide in pure water and water from a drinking water reservoir. The figure of merit EE/O is an appropriate tool to compare the AOPs and showed that VUV and UV/O₃ yielded the lowest treatment costs for the odour compounds in pure and raw water, respectively. Additionally, VUV irradiation with addition of ozone, generated by the VUV lamp, was evaluated. The generation of ozone and the irradiation were performed in a single reactor system using the same low-pressure mercury lamp, thereby reducing the energy consumption of the treatment process. The formation of the undesired by-products nitrite and bromate was investigated. The combination of VUV irradiation with ozone produced by a VUV lamp avoided the formation of relevant concentrations of the by-products. The internal generation of ozone is capable to produce ozone concentrations sufficient to reduce EE/O below 1 kWh m⁻³ and without the risk of the formation of nitrite or bromate above the maximum contaminant level.     

Correlation of musty odor and 2-MIB in two drinking water treatment plants in South Taiwan

Possible odor groups and intensity, and seasonal effects were elucidated in two representative water treatment plants (WTPs), Feng-Shen and Gun-Shi, in southern Taiwan. The flavor profile analysis (FPA) was employed to determine the odor groups for the source water, while a chemical analysis, solid-phase microextraction (SPME) coupled with a gas chromatograph and mass spectrometric detector (GC/MSD), was used to concentrate and subsequently analyze the corresponding water samples. FPA results show that fishy and musty odors were the two major odor groups in the source water. Results of chemical analysis showed that 2-methyl-isoborneol (2-MIB) was present in the source water. The correlation between 2-MIB concentration and the FPA intensity of musty odor was compared with the dose-response curve generated in the laboratory by the FPA panelists. The experimental data from the two water treatment plants follow the calibration curve closely, indicating that the musty odor of the two source waters were most likely contributed from 2-MIB. In addition, there is good correlation between logarithmic 2-MIB concentration and water temperature, substantiating the importance of seasonal effect. Although approximately 40-50% of 2-MIB removal was found in the treatment trains for the two WTPs, only an approximately 0.3 FPA intensity scale of reduction was expected.     

饮用水中二甲基异莰醇的应急处理技术研究

针对郑州市S水厂原水二甲基异莰醇(2-MIB)季节性升高问题,采用在原水中投加粉末活性炭(PAC)或二氧化氯(ClO2)的应急处理技术。结果表明,在原水泵站投加PAC可以有效控制水体的臭味;与单层石英砂滤层相比,石英砂加活性炭滤层对2-MIB的去除率可增加56%;为防止活性炭吸附效率降低,应避免PAC与ClO2同时使用。     

Field analysis of PSA O2–ozone production process for water recycling

The use of an oxygen generator based on pressure swing adsorption technology (PSA) has been investigated as an alternative method for supplying oxygen for onsite ozone production. During the investigation period of 1040 h, the oxygen purity from the PSA process fluctuated within a range of 90.5–93 O₂% (v/v). Using the working ratio of 2.8 mol of O₂ to 1 m³ of raw water, the PSA process in series with a corona discharge ozone generator yielded an oxidation–reduction potential of ca. 200 mV and a concentration of 22.8 mg/L dissolved oxygen. The average efficiency of the raw water treatment was as follows: 47% chemical oxygen demand removal, 78% biological oxygen demand removal, 36% sulphide removal and 34% colour removal. The operating cost of the PSA O₂ generation was reduced 3 times compared with the cost of high‐pressure oxygen cylinders.     

Optimization of Coagulation and Ozonation Processes for Disinfection by–Products Formation Potential Reduction

Optimization of coagulation and ozonation processes for removal of disinfection by–products (DBP) formation potential in raw water was conducted by a pilot scale system. Proper poly–aluminum–chloride–sulfates (PACS), pre–ozone and post–ozone dosages are required for improving the removal performance of DBP formation potential to guarantee the safety of drinking water. Considering the treatment performances and economic costs, the optimum PACS, pre–ozone and post–ozone dosages for treating raw water with high organic concentration should be around 8.9 mg/L Al₂O₃, 0.5 and 2.5 mg/L, respectively. The combined drinking water treatment system of pre–ozonation, coagulation/sedimentation, sand filtration, post–ozonation, granular activated carbon filtration and disinfection is a promising process to reduce DBP formation potential from raw water in southern China. Under the optimum conditions, this combined system removed total trihalomethanes and haloacetic acids formation potential 50.16 and 69.10%, respectively.     

Ozone-biological activated carbon as a pretreatment process for reverse osmosis brine treatment and recovery

Ozonation was used in this study to improve biodegradability of RO brine from water reclamation facilities. An ozone dosage ranging from 3 to 10 mg O₃/L and contact times of 10 and 20 min in batch studies were found to increase the biodegradability (BOD₅/TOC ratio) of the RO brine by 1.8-3.5 times. At the same time, total organic carbon (TOC) removal was in the range of 5.3-24.5%. The lab-scale ozone-biological activated carbon (BAC) at an ozone dosage of 6.0 mg O₃/L with 20-min contact time was able to achieve 3 times higher TOC removal compared to using BAC alone. Further processing with Capacitive Deionization (CDI) process was able to generate a product water with better water quality than the RO feed water, i.e., with more than 80% ions removal and a lower TOC concentration. The ozone-BAC pretreatment has the potential of reducing fouling in the CDI process.