Effect of floc characteristics on nanofiltration membrane fouling
絮体性质对纳滤膜污染的影响

Flocs formed by coagulation process will also affect the performance of membrane filtration. Floc characteristics of coagulants-conventional Al salt (AlCl3) and polyaluminum chloride (PAC) under different dosages were investigated by using a laser diffraction instrument. The results showed that membrane flux decline was deteriorated less than 0.20 mmol/L dosages. With the dosages increasing, membrane flux decline decreased significantly. The flux decline (J/J0) with only humic acid (HA) was 0.65. Adding 0.50 mmol/L AlCl3 and PAC coagulants, the flux declined 0.78 and 0.75, respectively. Cake resistance was more obviously affected by floc size. The bigger floc size is, the better permeability of cake is. The mechanism of nanofiltration membrane fouling was mainly pore blocking by fouling model analysis.