O_3-BAC工艺臭氧优化和有机物分子质量分布研究

Research on ozone optimization and molecular weight distribution of organic matters in O_3/ BAC process

为了确定3种工艺:混凝-沉淀-砂滤-后臭氧-生物活性炭滤池(工艺Ⅰ)、预臭氧-混凝-沉淀-砂滤-生物活性炭滤池(工艺Ⅱ)和预臭氧-混凝-沉淀-砂滤-后臭氧-生物活性炭滤池(工艺Ⅲ)中臭氧的最优投加量和投加方式,采用动态实验进行了不同工况下有机物的去除效果研究,并从臭氧利用率的角度对3种工艺进行比较。同时,为了明晰工艺Ⅲ中各个单元对有机物的去除机制,研究了各处理阶段的有机物分子质量分布情况。结果表明,工艺Ⅲ在最佳工况下出水水质最优,但单位臭氧利用率较低,单位臭氧去除CODMn、TOC分别为0.92 mg/L和0.55 mg/L。该工艺中预臭氧可显著降低有机物分子质量水平,混凝沉淀砂滤主要去除分子质量>3 k Da的有机物,后臭氧则将大分子有机物进一步氧化为分子质量<3k Da的有机物,后者通过生物活性炭滤池得到有效地去除。因此,通过臭氧和生物活性炭的联用,能够有效去除有机物,是一种适宜的饮用水深度处理工艺。

Continuous-flow experiments were conducted to optimize the ozone dosage and the method of application by investigating the removal rate of organic pollutants in three processes： coagulation-sedimentation-sand filtration-ozone biological activated carbon（ BAC） filter process（ process Ⅰ）,pre-ozonation-coagulation-sedimentation-sand filtration-BAC process（ process Ⅱ）,and pre-ozonation-coagulation-sedimentation-sand filtration-O3-BAC process（ process Ⅲ）. The ozone utilization rate was used to compare these processes. Additionally,the organic molecular weight distribution during a variety of stages in process Ⅲ was studied to propose a mechanism of organic matter removal. The results showed that the effluent quality of process Ⅲ was the best under optimized conditions,but had the lowest utilization rate of ozone; the ratios of removed CODMnand TOC to the applied ozone were 0. 92 mg / L and 0. 55 mg / L,respectively. In process Ⅲ,the organic molecular weight was significantly reduced by pre-ozonation; coagulation,sedimentation,and sand filtration were mainly aimed at organic matter with molecular weight of over 3 k Da,while the high-molecular-weight organic matter could be degraded by the postozonation treatment to organic matter with molecular weight of less than 3 k Da,which could then be removed effectively in the BAC. Hence,the combination of ozone and BAC is an appropriate process for the advanced treatment of drinking water.