Research On Aerated Biological Activated Carbon Filter Combined With Sand Filter For Advanced Water Treatment

Biological activated carbon filter was easy to plug and compact, and in the southern humid area it can easily lead to microbial leakage when using the upflow carbon filter as terminal unit. Adding one sand filter at the front-end and rear-end of biological activated carbon filter respectively, to form a aerated biological activated carbon filter combined sand filter can solve these problems. Pilot test of the craft was conducted to conclude the results:(1) For the carbon filter, the optimal filtration rate was 14m/h, and combined air and water rinse for 10 min(air flush strength was 8 L /(m2 ? s), water flush intensity was 10 L /(m2 ? s)) every 30 days. Pre-sand filter backwash style was air impact(10 L /(m2 ? s)) for 3 min, combined air and water wash(water flush intensity was 5 L/(m2?s), air rushed strength was 10 L/(m2?s)) lasted 8 min, single water flush( 8 L/(m2?s)) for 3min and backwash cycle was 24 h. The apposite backwash for rear sand filter was combined gas and water rinse sustained 10 min(water flush intensity was 10 L /(m2 ? s), air flush strength was 5 L /(m2 ? s)), every 36 h. When the gas-water ratio of carbon filter was choosen to be 0.3, the removal rate of CODMn and ammonia nitrogen reached the maximum, the removal rate were 32.64%, 83.48% respectively.(2) Removal rate of CODMn with carbon filter was approximately 26.83%. Comparing with the mid-aeration biological activated carbon filter, the new combined process demonstrated some advantages that head loss of activated carbon filter and organics removal sustained stably, and backwash cycle was longer. For the change of water quality during the torrential rain, the new craft presented a strong ability to deal with it, CODMn, ammonia, nitrite, and turbidity of effluent measuring up drinking water standards.(3) Combined chlorine disinfection and ozone disinfection, adding 1.0 mg / L of ozone in the carbon filter outlet; dosing chlorine in the rear sand filter outlet, to keep the residual chlorine in the effluent at 1.5 mg/L. The disinfection had good effect, and the biodegradability of organic carbon concentration of effluent kept low.