A Study On The Experiments Of UF For Water Purification

In order to discover the removal of micro-pollutant in the water source by UF membrane process and offer referential information to the development of integrative drinking water treatment equipments. This paper mainly studied the characteristics of ultrafiltration for the tap water, water of Xiang river and crude humic acid by means of hydrophilic modified PAN hollow fiber ultrafiltration membrane filters and analyzed the removal effect contrasted UF itself with adding turbidity and coagulation pretreatment UF. UF experiments for turbidity and commercial humic acid were also carried out to examine the flux decline causing by membrane fouling . The principle of UF flux decline was preliminarily discussed.The results show that UF is efficient for the removal of bacteria and turbidity with the 99% removal of bacteria achieved and residual turbidity within 0.05NTU in the treated water; There is no obvious removal of PH, Fe, Mn, Rigidity and normal removal as for organic substance in the water by UF. While, adding turbidity or aluminum coagulation pretreatment enhances the UF removal of organic substance. The bigger the NTU is ,the higher the removal by UF is. At PH=7 the mechanism of coagulation is adsorption or bridging of organic substance on the amorphous solid-phase [Al(OH)₃]_n, while, at PH=5,the mechanism is charge-neutralization. In terms of the removal of organic substance(COD_Mn,UV₂₅₄) ,the effect of coagulation pretreatment-UF under PH=7 turns out to be much better than that under the condition of PH=5 because that the flocculating constituent at PH=7 is easily reject with looser in shape and bigger in size than those at PH=5,the ability of reject enhances especially for the 73% removal of UV254 (HA),66% removal of UV₂₅₄(water of Xiang river) . Results indicates pretreatment-UF can reject THMs more efficiently offering better safeguards to drinking water; The decline of the membrane flux is mainly attributed to the cake layer formation, but he HA cake layer leads to much worse membrane flux decline than turbidity cake layer does. If UF is just reject turbidity, the filter cake form slowly and the fouling by membrane pore blocking also is poor, but ,for the removal of macromolecular organic substance ,the permeate flux decline is resulted mainly by membrane pore blocking in the beginning, while in the final period mainly by cake formation. In the case of exclusion of organic substance, the presence of turbidity improve the permeate flux in the earlier filtering stage, but the...