微气泡O3/H2O2深度处理某树脂厂二级出水效果与机制

Efficiency and mechanism of microbubble O3/H2O2 advanced treatment of secondary effluent from a resin factory

    摘要
  • 摘要: 针对传统生物降解对树脂废水中苯系物、聚乙烯醇等大分子有机物降解效果不好、达不到排放标准的问题，构建微气泡O3/H2O2体系，对某树脂厂二级出水进行深度处理。对比了微气泡O3曝气与普通O3曝气的化学需氧量（COD）降解效果，考察了进气O3浓度、H2O2浓度、初始pH对微气泡O3/H2O2体系降解COD效果的影响，通过总有机碳验证体系的矿化效果，通过电子顺磁共振谱仪（EPR）检测微气泡O3/H2O2体系中的活性物质，最后通过气相色谱质谱联用仪（GC-MS）分析降解前后废水中主要有机物的种类，并对微气泡O3/H2O2体系降解COD的机制与路径进行分析。结果表明：1）微气泡O3/H2O2体系中微气泡粒径主要分布在10~50 μm，平均粒径为32.82 μm；与普通O3曝气方式进行对比，微气泡O3体系对COD降解率更高，说明微气泡可以延长O3气泡上升时间，增加O3气泡比表面积，提高O3传质系数和利用率。2）微气泡O3/H2O2体系降解COD，当O3浓度为60 mg/L、H2O2浓度为29.37 mmol/L、pH为7时，反应60 min后，微气泡O3/H2O2体系对树脂厂二级出水的COD降解率为89.53%，处理后出水COD为15.05 mg/L，可达到GB 31572—2015《合成树脂工业污染物排放标准》。3）EPR试验表明，H2O2可以促进微气泡O3体系产生更多的超氧自由基（\cdot\mathrmO_2^- ）和羟基自由基（·OH），从而提高体系的氧化能力和对COD的降解效果。根据GC-MS结果推断O3/H2O2体系降解COD的可能路径，即树脂厂二级出水以长链烷烃和环烷烃类为主的大分子物质在O3的作用下断链、开环，在·OH等自由基的作用下矿化或降解为以小分子有机酸为主的小分子物质。

     

    Abstract: Aiming at the problem that traditional biodegradation can not degrade the chemical oxygen demand (COD) of benzene series, polyvinyl alcohol and other macromolecular organic compounds in resin wastewater, and can not meet the discharge standard, a microbubble O3/H2O2 system was constructed to treat the secondary effluent of a resin factory deeply. The COD degradation effects of microbubble O3 aeration and ordinary O3 aeration were compared, and the effects of inlet O3 concentration, H2O2 concentration and initial pH on COD degradation efficiency of microbubble O3/H2O2 system were investigated. The mineralization effect of the system was verified by total organic carbon (TOC), and the active substances in microbubble O3/H2O2 were detected by electron paramagnetic resonance spectrometer (EPR). Finally, the types of main organic substances in wastewater before and after degradation were analyzed by GC-MS, and the mechanism and path of COD degradation by microbubble O3/H2O2 system were analyzed. The results showed that: (1) In the microbubble O3/H2O2 system, the particle size of microbubbles was mainly distributed in the range of 10-50 μm, with an average particle size of 32.82 μm. Compared with ordinary aeration, microbubble O3 system had a higher degradation rate of COD, which indicated that microbubbles could prolong the rising time of O3 bubbles, increase the specific surface area of O3 bubbles, and improve the mass transfer coefficient and utilization rate of O3. (2) The analysis of influencing factors of COD degradation by microbubble O3/H2O2 system showed that when O3 concentration was 60 mg/L, H2O2 concentration was 29.37 mmol/L, and pH was 7 after 60 minutes of reaction, the COD degradation rate of secondary effluent of the resin factory by microbubble O3/H2O2 system was 89.53%, and the treated effluent COD was 15.05 mg/L, meeting the requirements of Emission Standard of Pollutants for Synthetic Resin Industry (GB 31572-2015). (3) The EPR test showed that H2O2 could promote the microbubble O3 system to produce more superoxide radicals (\cdot\mathrmO_2^- ) and hydroxyl radicals (·OH), thus improving the oxidation capacity of the system and the degradation effect of COD. According to the results of GC-MS, the possible degradation path was inferred. Macromolecules in the secondary effluent from the resin factory, mainly composed of long-chain alkanes and cycloalkanes, underwent chain-breaking and ring-opening by O3, and were mineralized or degraded into micromolecule substances, mainly small-molecule organic acids, under the action of ·OH and other free radicals

     

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