Research On Treatment Of Polluted Raw Water By Multi-media Prosess And O₃-BAC

The performance of ammonia and organic pollutants removal by a pilot-scale multi-media process（made with multi-media tank and biological filter） or a pilot-scale O₃-BAC process was stuied. The main research contents and conclusions are listed as following:1) Multi-media tank and biological filter in combination process can effectively remove ammonia nitrogen, organic matter, turbidity, iron and manganese in the polluted water. The multi-media process can efficiently remove ammonia, organic matters and turbidity in polluted raw water. During the experience（Has been included in the debugging period）, the average removal rate of ammonia, organic matters, CODMn, UV254, TOC and turbidity are 91.19%, 31.20%, 23.97%, 14.39% and 83.18%, respectively. Among them, during the low temperature period, the average removal rate of ammonia can still keep at a high level, which is 95.32%. And the removal rate of CODMn has a slightly decreasing in compared with the normal temperature period. Stop running the reactor（<1d） in low temperature has no effect on ammonia removal. The removal rate of ammonia can reach to 95.10% in 48 hours, after stop running the reactor for 15 days. The multi-media process has high removal ability to ammonia and its limited ammonia loading is 31.5 g/m3·h.2) The difference of hydraulic retention time and gas water ratio can affect the removal efficiency of ammonia nitrogen would be different in different hydraulic retention time and gas water multi-media tank. Condition of air/water ratio at 1:1, when the HRT of the multi-media tank are 36 min, 30 min and 26 min, respectively, their corresponding average removal rate of ammonia are 84.02%, 83.36% and 81.31%, respectively. Condition of HRT is 45 min, when the HRT of the multimedia tank are 36 min, 30 min and 26 min, respectively, their corresponding average removal rate of ammonia are 84.02%, 83.36% and 81.31%, respectively. When the multi-media tank operated under different air/water ratio, such as 1.5:1, 1:1 and 0.5:1, the removal rate of ammonia are 83.27%, 83.65% and 74.94%, respectively. The most optimal operation for ammonia removal is HRT at 36 min and air/water ratio at 1:1. And this experience indicated that aeration has great effect on the transformation of N, the removal rate of ammonia was decreased from 84.05% to 18.21%, for nitrogen was form 45.75% to 24.66%, and for nitrate nitrogen was from 71.12% to 12.30%.3) The removal rate of ammonia nitrogen was decreased during the low temperature than aliquot of the multi-media tank, and average removal rate was 55.70%. The biological filter still has great ammonia removal ability with an average removal rate of 89.62% even in low temperature period, and turbidity removal is mianly happened inside, its average effluent turbidity is 0.27 NTU, and average removal rate at 77.48%.4) The contribution rate of multi-media tank and biological filter in the removal of pollutants was discussed. Combining multi-media preocess with biological filter, these two complementary process, can efficiently removal the pollutants in raw water and ensure the effluent quality.5) O₃-BAC has great performance on organic matters removal, and certain removal effect on ammonia, effluent ammonia nitrogen range was 0.02mg/L-0.29mg/L, but it is not so idea in remove turbidity.6) The ozone dosing method will affect the removal efficiency of organic matter will be affected by theto a certain extent. We set the total ozone dosage of O₃-BAC process for 2 mg/L, and allocated this dosage amount into three ozone columns by 4 different proportion, i.e. 2+0+0, 1.5+0.5+0, 1+1+0, 1+0.5+0.5. Its corresponding average removal rate of CODMn, UV254 and TOC are 39.04%, 36.95%, 28.77%, 28.08% and 52.44%, 51.06%, 41.04%, 42.68% and 27.60%, 26.62%, 25.58%, 25.86%, respectively. And the above data proved that pollutants removal associated with the ozone concentration of single-column one-time dosing, high ozone concentration environment may more conducive to the oxidative decomposition of organic matters. So the most optimal removal effect of organic matters is 2+0+0 dosing proportion.