聚硅酸铁混凝剂絮凝与破碎的定量研究

以水玻璃、硫酸亚铁及氯酸钠为原料,应用共聚工艺制备聚硅酸铁(PSF)混凝剂,采用搅拌实验和颗粒计数法对比研究PSF与复合铝铁(PFA)的混凝性能,絮凝阶段残余粒子分布及紊流剪切力对絮体的影响.结果表明,高投药量时PSF去除高锰酸盐指数的性能优于PFA.PSF处理地表水时不宜采用过高或过低的絮凝速度,絮凝速度与絮凝时间应紧密配合才能提高混凝性能,即提高絮凝速度则需要减少絮凝时间.增加紊流剪切力时,PSF絮体的破碎程度远远小于PFA,被打碎的PSF絮体其再结合能力大于PFA.在数量级上,PSF的絮凝系数KA为10-2～10-3,破碎系数KB为10-7～10-8.对于粒径＜2 μm的颗粒,PSF的KA比PFA大4个数量级,KB与PFA相近,而其余粒径范围PSF的KA比PFA大近2个数量级,KB比PFA小近10多倍.

Investigation on Flocculation and Destruction of Poly-silicic-ferric (PSF) Coagulant

An inorganic polymer, poly-silicic-ferric (PSF) coagulant was prepared using water glass, FeSO4 x 7H2O and NaClO3 by copolymerization. A comparison of coagulation performance, distribution of residual flocs in finished water and influence of turbulent shear force on the flocs between PSF and polyferric aluminum (PFA) was explored by jar tests and particle counter approach. The results indicate that PSF has superior removal of COD at higher dose to PFA. Flocculating speed should not be much higher or lower when using PSF as coagulant in treating surface water, and excellent coagulation efficiency can be obtained by the close cooperation of flocculation speed with flocculation time, that is, higher flocculation speed should be consistent with shorter flocculation time. The PFA flocs are much easier destructed than PSF flocs when increasing the turbulent shear force, and the destructed PSF flocs tend to be more easily re-coupled than PFA flocs. From the order magnitude, the flocculation coefficient KA of PSF is from 10(-2) to 10(-3), in comparison with the destruction coefficient KB from 10(-7) to 10(-8). For particles whose size is smaller than 2 microm, KA of PSF is 4 order magnitude more than that of PFA, and KB of PSF is almost the same to that of PFA; while for the other particles, KA of PSF is 2 order magnitude more than that of PFA, and KB of PSF is almost ten times smaller than that of PFA.