Influence of Si Fe mol ratio on coagulation behavior of Si Fe complex coagulant and its influence mechanism

Key words:  Si Fe mol ratio  limit ratio  influence mechanism  complex coagulant  water from Yellow River

Abstract:

Poly silicic ferric (PSF) coagulant with various Si Fe mol ratios (n(Si)/n(Fe)) was prepared by copolymerization. The influence of Si Fe mol ratio on both coagulation efficiency and influence mechanism of PSF was investigated. The coagulation efficiency using PSF as coagulant in treating water from Yellow River in comparison with that using Polyaluminium chloride (PAC) as coagulant was studied. The results show that the removal of turbidity and CODMn for water from Yellow River reduces by 3.2％ and 3.8％ when n(Si)/n(Fe) varies from 0.5 to 1, the removal of turbidity and CODMn increases when n(Si)/n(Fe) varies from 1 to 3. The relative amount of Si or Fe in PSF has a limit ratio. PSF can give the optimum complex action of Si and Fe only at the optimum n(Si)/n(Fe) ratio range which is near the limit of n(Si)/n(Fe) ratio. PSF has lower optimum dose in treating water from Yellow River than PAC, giving more CODMn removal of 5％-19％ or so than PAC at given dose range.