| It was studied that the treatment of surface water in low temperature and low turbidity with ultrafiltration. The removal effect of each index was studied on the condition of different inlet water quality. In low temperature and low turbidity water, different concentarion of powder activated carbon, polyacry lamide(PAM) flocculants(such as ferric chloride , polymeric aluminium, polymeric aluminium chloride and so on) were applied in combination. It was analyzed that the effect factor of stabilize operation of ultrafiltration when the chemical backwashing and air backwashing was taken.The conclusion was showed that:1 .When raw water is in low temperature and low turbidity,the outlet water of secondary filter is taken as inlet water of UF and chlorhydric acid backwashing is also taken,pH=3~4 , soaking 3~5 minutes in every 24 perid. Standard ratio of water flux is stabilized. When the outlet water of first filter is taken as inlet water of UF, the acid backwashing is taken every 16 perid, pH= 11 ~ 12, soaking 3~5 minutes. The chlorhydric acid backwashing is taken every 8~12h, pH=3~4, soaking 3~5 minutes.It is showed that fluctuation of standard ratio of water flux but can be kept stabilize relatively.2. When raw water is in low temperature and low turbidity, inlet water tuibility is 1 ~2 NTU. The powdered activated carbon and ferric chloride is added. Standard ratio of water flux can resume as original value by general backwashing method. General backwashing water can flush large amount of black floe which showed that combination application of powdered activated carbon and ferric chloride can form effective filtra layer in the surface of membrane. So it can prevent the pollution of UF. It has not effect on standard ratio of water flux by filtra period.3. When raw water is in low temperature and low turbidity,anionic PAM is added by 0.02 ppm. Standard ratio of water flux can stable basically just only rise feebly. Genera backwashing can flush tiny floc.Adding non-ionic PAM by 0.02 ppm, standard ratio of water flux can stable basically and large amount of broken floe is flushed by general backwashing. |
