|Title||Effect of pre-ozonation on organics removal by in-line direct filtration|
|Publication Type||Journal Article|
|Year of Publication||1993|
|Authors||Tobiason JE, Edzwald JK, Reckhow DA, Switzenbaum M.S.|
|Journal||Water, Science & Technology|
|Keywords||2-methylisoborneol, assimilable organic carbon, direct filtration, disinfection by-products, dissolved organic carbon, pre-ozonation|
A pilot-scale study of the effects of pre-ozonation on the performance of in-line direct filtration was carried out. Performance measures included filtered water turbidity, unit filter run volumes, and organics in filtered waters: DOC, UV254, AOC and DBPs. Continuous operation of four dual media GAC/sand filters with and without pre-ozonation and chlorinated backwash and a dual media anthracite/sand filter were compared to full-scale performance. Pre-ozonation frequently results in longer filter runs, causes a twofold increase in raw water AOC and has little effect on raw water DOC. GAC/sand filters consistently reduced the AOC in the ozone train to levels below that of the full-scale plant and also provided 25 % lower DOC levels as compared to anthracite/sand filters. The effect of ozone and filtration on chlorinated DBPs followed overall DOC removal while DBPs created by ozonation followed AOC removal trends.