Study On The Water Purification Process Of Water-Dropping Aeration Biological Contact Oxidation And Ultrafiltration

The traditional water treatment process isn't suitable for the situation of raw water polluted. New processes are needed imminently. A process of Water-dropping Aeration Biological Contact Oxidation (WABCO)and Ultrafiltration (WABCOU)was studied in the paper. With a pilot-scale test, the characteristics of biofilm forming in the Three-step Water-dropping Biological Contact Oxidation(TWABCO)were studied during the cold period. Some factors of the influence on the efficiency of the TWABCO, such as HTR and pollutants loading , were discussed. Also , the laws of removal rate of pollutants in different reactors of TWABCO and different height of padding in each factor were investigated. The biomass of two padding and the efficiency of filtration by sand and ceramic-ball were compared. At last , it was showed that the removal efficiency of pollutants by Ultrafiltration and the operation characteristics of Ultrafiltration. The main conclusion showed as follow:(1) During the cold period , it took about 30 to 40 days to make the biofilm mature in the TWABCO.(2) The removal rates of main pollutants by the TWABCO increased with the increasing of HRT and it was more obvious when HRT was lower than 1.6 hours. As the HRT of the TWABCO was 1.6 hours, the removal rates of turbidity, ammonia nitrogen, CODMn, algae, UV254(ultraviolet absorbency at the wavelength of 254nm ) by TWABCO were as flow separately: 52%,35.9%,19.8%,71.0% and 5.9%.(3) The biomass on elasticity-padding was more than the ones on compounding-padding in the TWABCO.(4) The removal rates of turbidity, ammonia nitrogen, CODMn, algae, UV254 by Ultrafiltration were as flow separately: 95.5%,13.9%,16.3%,84.2% and 6.9%.(5) Ultratration was operated with dead-end style ; the concentrate was discharged every 40minutes lasting for 1 minute, and the membrane was back washed by penetrate every 2 hours lasting for 2 to 3 minutes with the flux of 1,800 LPH( litre per hour ). Under these condition , it could slower the membrane fouling.(6)The membrane was washed by NaOH(0.5%) adding NaClO(10mg Cl/L) mixed solution lasting for 40minutes,the specific penetrate flux recovered to 80% of the initial one.(7)As the average temperature of raw water was 7.6℃and the HRT of TWABCO was 1.6 hours, the removal rates of turbidity, ammonia nitrogen, CODMn, algae, UV254 by WABCOU were as flow separately: 99.1%,44.0%,35.3%,97.9% and 6.9%.