Combined System of Powdered Activated Carbon Reflux and Ultrafiltration for Treatment of Micro-polluted Raw Water

Sludge water containing powdered activated carbon( PAC) from sedimentation tank was refluxed to mixing tank to enhance the removal of ammonia nitrogen and organics. The powdered activated carbon reflux was combined with ultrafiltration,and the membrane fouling was investigated. The results showed that when the dosage of PAC was increased,the biomass and biological activity in the sludge containing PAC were increased,and the removal rates of ammonia nitrogen and organics were increased,too. The removal rates of 36. 9%,52. 7% and 61. 5% for ammonia nitrogen,of 20%,35% and 50%for CODMnand of 30%,40% and 45% for UV254 were achieved by the stable system when the dosages of PAC were 0 mg / L,100 mg / L and 200 mg / L,respectively. The removal effect of disinfection by-product precursors by the combined system was significantly better than that by the conventional process. The turbidity of settled water stabilized at around 2. 5 NTU,the turbidity of the effluent of ultrafiltration stabilized at 0. 1 NTU or less. At the flux of 30 L /( m2·h),PVC membrane could operate stably almost without irreversible pollution,but when the dosage of PAC was excessive,transmembrane pressure was increased.