A Study On The Mechanism Of The Removal Of Organic Matters By Ozone And Biological Activated Carbon

In this paper, experimental investigations were conducted to treat the effluent from the secondary sedimentation tank of Xi'an Beishiqiao Wastewater Purification Center by Ozone and Biological Activated Carbon(O₃—BAC ),Ozone and Granular Activated Carbon(O₃—GAC) and Ozone and Biological Ceramic Filter (O₃—BCF).The removal efficiencies of pollutants were compared. The course of degradation of organic pollutants and mechanism of the removal of organic pollutants were emphasized in this paper, as well as the characteristics of ozonation of organic pollutants.O₃—BAC process could remove organic matters and other pollutants efficiently. The average removal of TOC, color, turbidity, and UV254 were 30%, 74%, 77% and 62%.Comparing the bioactivity of BAC and BCF, a new way to quantify adsorption and biodegradation capacities on Biological Activated carbon in the course of degradation of organic pollutants was set up. The removal of organic matters by O₃—BAC is a synergic effect of ozonation, adsorption and biodegradation. It was proved that biodegradation should be prevailing mechanism of the removal of organic matters. After ozonation, in the course of degradation of DOC, 65% of reduction of DOC was due to biodegradation and 35% was due to adsorption.The principal function of ozonation is to change molecule structure and character of organic matters in raw water besides removing a small part of pollutants directly. It was found organic matters with larger molecules were broken into smaller molecules, and biochemical degradability of organic matters in raw water was improved. Most of the organic matters in raw water were those with aromatic, carboxyl groups and hydrocarbon chains. After ozonation, the amount of biodegradable matters such as lipid, carboxyl and aliphatic substances were increased. The effects of ozonation on adsorption were also studied, which suggested that the residual ozone in the treated water can improve the micropore structure of activated carbon. Viewing the separate proportion of DOC removal by adsorption and biodegradation, ozonation went against improving the adsorption capacities on Biological Activated Carbon, but did improve the biodegradation capacities.