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富营养化水体大量繁殖的藻类分泌的嗅味物质长期以来一直是饮用水行业关注的主要问题[1-2]. 水体中嗅味物质的浓度通常在ng·L−1范围内,但通常因其嗅味阈值极低,嗅味物质直接影响饮用水的感官,以及公众对饮用水的信心和接受程度[3-4]. 土臭素(geosmin, GSM)和2-甲基异茨醇(2-methylisobornel, 2-MIB)是引发水体异嗅的主要物质,与大多数饮用水中土、霉味事件有关[5-6]. 我国生活饮用水卫生标准(GB 5749—2022)已经将GSM和2-MIB列入到出厂水和管网水需要检测的项目,并规定其含量不能超过10 ng·L−1[7].
目前传统处理工艺通常很难彻底去除在水体中赋存浓度极低的嗅味物质. 虽然基于颗粒活性炭和粉末活性炭等少数技术可以去除嗅味物质[8-9],但面临嗅味物质浓度升高而引起的去除效率低、达标困难和高成本等问题[10]. 随着对优质饮用水需求的不断增加,越来越多研究致力于发展更有效的嗅味物质替代处理工艺. 近年来,基于羟基自由基(hydroxyl radicals, ·OH)的高级氧化技术(advanced oxidation processes, AOPs),因具有选择性低和反应速度快等优点[11],成为了去除嗅味物质优先选择的技术[12]. 在众多AOPs中,紫外线(ultraviolet light, UV)和双氧水(H2O2)通过生成·OH去除嗅味物质,且具有工艺灵活便捷和无副产品等优势而受到广泛关注,但该方法也存在H2O2利用率低和残留等问题[13]. 近来研究表明,向UV/H2O2体系中加入低浓度O3可有效增加系统中的稳态自由基浓度,其与O3作用可促进水中有机物的降解[14-16]. 同时,UV/H2O2与生物活性炭(biological activated carbon, BAC)工艺联用(UV/H2O2-BAC)则可有效解决H2O2残留问题[17]. 目前基于UV/H2O2-BAC发展的嗅味物质去除工艺主要基于实验室小试装置或现场小规模试验进行,尽管能取得满意的去除效果,但其应用于大流量水的工艺条件少有优化,效果少有验证[18].
针对当前UV/H2O2-BAC工艺去除嗅味物质存在的难点,本研究利用增设的AOP中试装置,探究了UV/H2O2-BAC和UV/H2O2/O3-BAC两种耦合工艺对山东省某饮用水处理厂的砂滤池出水中GSM和2-MIB的去除效果,并考察了H2O2投加量、O3投加量、紫外线剂量及BAC对降解效率的影响,以期为发展绿色高效的嗅味物质去除技术提供数据和技术支撑.
中试紫外高级氧化耦合生物活性炭工艺去除典型嗅味物质
Pilot test of removing typical odors by the coupled UV advanced oxidation and biological activated carbon processes
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摘要: 利用增设的紫外高级氧化中试装置,研究了紫外/过氧化氢(UV/H2O2)和紫外/过氧化氢/臭氧(UV/H2O2/O3)与生物活性炭(BAC)耦合工艺对低温下大流量饮用水中较高含量土臭素(GSM)和2-甲基异莰醇(2-MIB)的去除效果. 重点考察了H2O2投加量、O3投加量、紫外线剂量及BAC对嗅味物质去除的影响,并分析了UV/H2O2过程中GSM和2-MIB的降解产物情况. 结果显示,相比UV/H2O2-BAC耦合工艺,UV/H2O2/O3-BAC耦合工艺对GSM(28.5—34.1 ng·L−1)和2-MIB(83.2—94.1 ng·L−1)具有更显著的去除效果,去除率分别可达90.1%和86.0%. 提高H2O2投加量、O3投加量和紫外线剂量促进了紫外高级氧化工艺段对GSM和2-MIB的去除,但H2O2投加量不可过高. 通过对降解产物进行分析,提出了UV/H2O2降解GSM和2-MIB的过程,其降解主要由羟基自由基引起,主要反应包括脱甲基、脱水、加成、环开裂等方式. 本研究可为发展绿色高效的嗅味物质去除技术提供技术指导和支撑.
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关键词:
- 土臭素 /
- 2-甲基异莰醇 /
- 紫外/过氧化氢 /
- 紫外/过氧化氢/臭氧 /
- 生物活性炭.
Abstract: Using a pilot-scale UV advanced oxidation plant, this study aimed to investigate the efficacy of UV/H2O2 and UV/H2O2/O3 coupled with biological activated carbon (BAC) processes in removing high levels of geosmin (GSM) and 2-methylisoborneol (2-MIB) from drinking water. The effects of H2O2 dosage, O3 dosage, UV dose, and BAC on odour removal were investigated in detail, along with the degradation products of GSM and 2-MIB during the UV/H2O2 process. Results showed that the UV/H2O2/O3-BAC coupling process exhibited higher removal rates on GSM (28.5—34.1 ng·L−1) and 2-MIB (83.2—94.1 ng·L−1), with removal rates up to 90.1% and 86.0%, respectively, compared to the UV/H2O2-BAC coupling process. Increasing the H2O2, O3, and UV doses promoted the removal of GSM and 2-MIB in the UV advanced oxidation process unit; however, the H2O2 dosage should not be excessively high. Based on the degradation products, a proposed degradation process and mechanism of GSM and 2-MIB by UV/H2O2 suggested that hydroxyl radicals, including demethylation, dehydration, addition, and ring-opening, caused immediate reactions. This study provides fundamental data and technical support for developing green and efficient odour removal technologies.-
Key words:
- GSM /
- 2-MIB /
- UV/H2O2 /
- UV/H2O2/O3 /
- BAC
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表 1 砂滤池的出水水质和嗅味物质浓度
Table 1. The quality and odors concentration of sand filter effluent
pH 温度/℃
Temperature溶解氧/(mg·L−1)
Dissolved oxygenTOC/
(mg·L−1)GSM浓度/(ng·L−1)
GSM concentration2-MIB浓度/(ng·L−1)
2-MIB concentration7.6—8.2 5.5—6.8 11.7—13.5 3.3—4.2 28.5—34.1 83.2—94.1 表 2 UV/H2O2-BAC和UV/H2O2/O3-BAC工艺的进出水TOC浓度
Table 2. TOC concentration of inlet and outlet water of UV/H2O2-BAC and UV/H2O2/O3-BAC
中试工艺
Pilot test process中试进水/(mg·L−1)
Pilot test influentAOP出水/(mg·L−1)
AOP effluentBAC出水/(mg·L−1)
BAC effluentUV+BAC 3.4±0.1 3.1±0.1 2.6±0.2 UV/H2O2+BAC 3.6±0.1 3.4±0.1 2.5±0.1 UV/O3+BAC 3.2±0.2 3.0±0.1 2.2±0.2 UV/H2O2/O3+BAC 3.3±0.2 3.1±0.3 1.0±0.2 表 3 UV/H2O2降解GSM的中间产物及其保留时间和质谱特征
Table 3. Retention time (tR) and mass spectral characteristics (M, m/z) of GMS degradation products in UV/H2O2
检出物质
Detected substancestR/min 分子量/Da
Molecular weight定性离子(m/z)
Qualitative ions结构式
StructureGSM 14.37 182.30 112, 125 Trans-1,10-dimethyl-trans-9-decalinol 13.34 182.30 126, 112, 43 4a-Methyl-4,4a,5,6,7,8-hexahydro-2(3H)-naphthalenone 12.44 164.24 164, 122, 107 2-Ethyl-2-hexenal 11.96 126.20 126, 97, 55 (1,2-Dimethylcyclopentyl)-methanol 11.83 128.21 97, 55 Cyclohexanone 8.14 5.27 112, 98, 55 Octanoic acid 7.98 144.21 101, 73, 60 Pentanal 7.48 86.13 58, 44, 29 表 4 UV/H2O2降解2-MIB的产物及其保留时间和质谱特征
Table 4. Retention time (tR) and mass spectral characteristics (M, m/z) of 2-MIB degradation products in UV/H2O2
检测物质
Detection of substancestR/min 分子量/Da
Molecular weight定性离子(m/z)
Qualitative ions结构式
Structure2-MIB 10.38 168.28 135, 95, 107 (2,2,3-Trimethyl-cyclopent-3-enyl)-acetaldehyde 11.34 152.23 108, 95, 93 (4Z)-4-chloro-6-ethoxy-2,6-dimethylhepta-2,4-diene 10.81 202.72 124, 109 2,3,4,5-Tetramethyl-2-cyclopentenone 8.77 138.21 138, 123, 95 2,6-Dimethyl-2,4-heptadiene 8.09 124.22 112, 69, 55 D-camphor 7.80 152.23 95, 81, 69 Bornane-2,5-dione 7.48 166.22 108, 93 -
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