Study On The Pilot-Scale Bio-filter System For Treatment Of Micro-polluted Source Water

The effect of Bio-filter System which uses carbonation sludge carrier removing pollutants from micro-polluted source water was studied. Research results were as follows.It is appropriate to adopt ammonia nitrogen removal rate 60% as a basic mark to judge mature biofilm. After the biofilm formation, Bio-filter had a high rate on removing CODMn, NH₄⁺-N and turbidity. The maximum removal rate of CODMn, NH₄⁺-N and turbidity were 41.70%, 79.89% and 84.11%.When the Empty bed contact time (EBCT) was 12 min, the gas to water ratio (G/W) was 1.0, the temperature was 20.2℃～26.5℃, pH was 6.8～7.9 and the system was operated steadily, the removal effect of pollutants by Bio-filter System which uses carbonation sludge carrier were as follows: the average removal rate of CODMn, UV254, NH₄⁺-N, NO2--N, turbidity and chroma were 46.19%, 32.34%, 80.48%, 83.26%, 87.69% and 73.56% respectively.Under the same condition, CODMn, NH₄⁺-N turbidity and chroma were used as the evaluation objects by the use of performance evaluation index of Bio-filter. It can be conclued that the performance of Bio-filter System using carbonation sludge carrier was best. Influence of EBCT, G/W, water temperature, organic volumatric loading, NH₄⁺-N volume loading on Bio-filter system performance were analyzed. When the CODMn was less than 6mg/L,the NH₄⁺-N volume loading was less than 2mg/L, EBCT was 12 min and G/W was 1.0, the Bio-filter could have a better effect. By use of orthogonal, the result showed that the degree of each factor were G/W, EBCT and volumatric loading on the CODMn removal. The degree of each factor were EBCT, G/W and volumatric loading on the NH₄⁺-N removal.The relation between operation characteristics and filter height of the Bio-filter was studied. The removal of CODMn turbidity and chroma were mainly occurred in 0-40cm. The removal of UV254 was mainly occurred in 0-60cm. The removal of NH₄⁺-N was mainly occurred in 20-60cm. Thus the Bio-filter height of 100cm used can make effluent meet the requirement.When EBCT was 12 min, G/W was 1.0 and the temperature was 20.2℃～26.5℃, the average removal rate of iron and manganese were 81.53% and 79.17%. When the G/W was 1.0-1.5, the Bio-filter system had a better removal rate on iron and manganese at the same time. The temperature influenced on manganese removal significantly. Iron and manganese removal were mainly occurred in 0-40cm and 20-80cm. The Fe and Mn removal mechanism were mainly chemical oxidation and biological effect respectively.