Study on Control of Trihalomethane Formation Potential in Ozonation-Biofiltration Process

It has attracted more and more attentions in recent years that how to control the harm caused by Trihalomethanes (THMs) (a group of very important chlorination by-products) in drinking water. In the experiment removal of total trihalomethane formation potential (THMFP) and four species of THMFP with ozonation and biofiltration were studied. The results showed that the removal of chloroform formation potential after ozonation increased from 12% to 27% when the ozone dosage was increased from 2mg/L to 4mg/L, but the removal of bromoform formation potential was only 3 ~ -38%, and higher ozone dosage would obviously stimulate formation of bromoform.. On the other hand, a continuous operation from May to December showed that when the Empty Bed Contact Time (EBCT) was set at 15 min, the removal of chloroform formation potential after BAC filtration was 19 ~ 30%, but compared with which its removal ability for brominated THMFP was lower and even decreased with the increase in the degree of bromination, especially when brominated THMFP of BAC influent was very high, there appeared to be formation of dibromochloromethane formation potential and bromoform formation potential in BAC filter. The experimental results suggested that in “ozone-BAC” process the removal of total THMFP was closely associated with composition of total THMFP, and was greatly influenced by the proportation of brominated THMFP.