Study on the Treatment of Compound Micro-Polluted Groundwater by Contact Oxidation Process under Different Filtration Rates

Abstract

The compound micro-polluted groundwater was treated by three-stage contact oxidation filters with total 1.5m ceramic layer. The filtration rates, in accordance with the time sequence, were respectively 1m/h, 1.5m/h, 2m/h, 3m/h and 4m/h. The result indicated that, in the condition of sufficient dissolved oxygen, the effluent concentration of iron, manganese, ammonia nitrogen and CODMn can met the National Drinking Water Standards. Under the range of filtration rates the average effluent concentration was respectively that 0.073 mg/L, 0.278 mg/L, 0.229 mg/L, 0.172 mg/L and 0.199mg/L for iron; 0.150 mg/L, 0.180 mg/L, 0.110 mg/L, 0.150 mg/L and 0.359 mg/L for ammonia nitrogen. The average concentration of manganese was 1.828mg/L with dropping aeration only, compare with that 0.323mg/L with strengthening aeration under filtration rate 1m/h. And the manganese concentration was 0.061mg/L, 0.062 mg/L, 0.084 mg/L and 0.071 mg/L, respectively under the range of filtration rates of 1.5-4m/h by strengthening aeration. Because of the biological system in filter layer no perfect, humic acid and low temperature, the average removal rate of CODMn was only 16.10% under the 1m/h filtration rate. Then when the rates were up to 1.5m/h-3m/h, effect of CODMn removal increased and the water treated met the Standard with the maturity of filter layer. But under the rate 4m/h CODMn concentration of effluent was exceed the Standard. Meanwhile, in the range of 1m/h-3m/h, consumption of dissolved oxygen respectively were 19.26mg/L, 14.73mg/L, 13.99mg/L and 13.99mg/L.