| Along with the society and economy rapidly development, better drinking water quality is demanded. However, traditional drinking water treatment process could not guarantee the treatment effect to meet the stricter drinking water standard for serious water pollution. In recent years, for its strong ability to intercept particulate matter, colloid, bacteria, etc., ultrafiltration, the core of third generation water treatment process, develop rapidly in the water treatment industry. But the separated ultrafiltration had tow serious questions: membrane fouling and the limited ability of remove organics, common solutions included optimization of ultrafiltration membrane combined process, optimization of operating parameters ultrafiltration equipment, carry out integrated PAC-UF process, etc. This article mainly aims at optimizing coagulation/short time sedimentation-UF combination process operation parameters and integrated PAC-UF process operating parameters. By changing membrane flux, filtration time, backwash time, sludge discharge cycle and sludge discharge mode five kinds of operation parameters, water quality and membrane fouling were taken into investigation to find an optimal. On this basis, integrated PAC-UF combination process was built. Through optimizing PAC dosing amount, adding way and residence time these three kinds of operation parameters, and observing the effluent water quality and membrane pollution situation, the optimal operation condition was put forward to further improve the water purification ability and effective membrane fouling control. Finally, complete and feasible technical guide would be proposed for upgrading water plants along the Beijiang River.Firstly, the research had been conducted to optimize the operation parameters of coagulation/ short time sedimentation-UF combination process. The result shows that different membrane flux, filtration time, backwash time, sludge discharge cycle and sludge discharge mode have little influence on water quality but have significant influence on membrane fouling. The ultrafiltration treated water had an quality that turbidity is under 0.15 NTU, metal ions removal rate is above 95%, ultrafiltration removal rate of TOC is 8~12%, ultrafiltration removal rate of UV254 is between 0~8%, almost has no ability to intercept, the removal rate of CODMn is 20~30%. Membrane flux was 40 L/(m2.h), filtration time was 90 min, backwash time was 60 s, sludge discharge cycle was 24 h, when sludge discharge model was half discharge mode, membrane fouling slowed down obviously,but the organics removal capacity remains to be improved.Then, the research had been conducted to optimize operating parameter towards the integrated PAC-UF combination process. The result shows that no matter of PAC dosing amount, adding way, residence time, the removal efficiency of turbidity and Fe had no obvious effect, removal rate was always over 99%. And different operating parameters had significant influence on the removal of organic matter and the disinfection by-products(THMFP). While the PAC dosing quantity was 15 mg/L the maximum adsorption capacity was to be played, the removal of TOC, UV254, CODMn, THMFP reached 28.2%, 41.7%, 41.7% and 63.5%. Intermittent dosing to remove organic matter, disinfection by-products generated potential effect is obviously better than that of the continuous dosing. the removal of TOC, UV254, CODMn, THMFP reached 13.5%, 33.7%, 6.0% and 51.7%. When sludge discharge cycle was 24 h, the ability to remove organic matters was continued during the running late. PAC dosing quantity influence on membrane fouling was not significantly, with the increase of PAC dosing quantity, TMP growth rate increased slightly. In single sludge discharge cycle, continuous dosing compared with the intermittent dosing, TMP grew quickly. while sludge discharge cycle was 12 h and 24 h, TMP growth differed not too much with each other and membrane fouling grew slowly. Eventually the PAC dosing quantity was determined at 15 mg/L, using intermittent high concentrations dosing, sludge discharge cycle 24 h, the effluent water quality was excellent and membrane pollution was relatively slow.PAC-UF combined process run long time under the best conditions, the effluent water quality was excellent and stable, and did not cause damage to the ultrafiltration membrane, by the water cleaning and chemical cleaning TMP restored to its original level. |
