聚合氯化铝（PACl）混凝絮体的破碎与恢复

通过烧杯实验以及在线粒度监测考察了聚合氯化铝（PACl）混凝所生成絮体的破碎以及随后絮体的恢复情况.结果发现,絮体的破碎以及恢复情况因混凝区域的不同而呈现不同的规律.在稳定区,絮体的强度较大,不易破碎,且破碎后的絮体可进一步增长,其恢复因子高达259%;在电中和混凝区,絮体的强度最小,易于破碎,但破碎后可完全恢复;在再稳区和卷扫混凝区,絮体的强度较大,不易破碎,但破碎后不能完全恢复,其中后者的恢复因子仅为18.6％.再搅拌强度越大,对絮体的破碎及恢复程度的影响越大.对于卷扫混凝,经再搅拌破碎后而得到部分恢复的絮体,相对于未经再搅拌的絮体而言,其絮体层与水体间界面的沉降高度及平均沉降速率均较低,且在絮凝沉降区和区域沉降区,该絮体界面的瞬时沉降速率在同一絮体浓度下均较低,但在压缩沉降区,二者的瞬时沉降速率相同.

Breakage and Regrowth of Flocs Coagulation with Polyaluminum Chloride (PACl)

The conventional jar test and the monitoring technique of floc size in line were employed to investigate the breakage and regrowth of the flocs formed by PACl. It was found that the breakage and regrowth of flocs varied with coagulation zones. The flocs formed in stabilization zone were of high strength and difficult to break, and could regrow better after broken, with the recovery factor of up to 259%. The flocs formed in charge neutralization zone were of the lowest strength and prone to break, but could reform completely after broken. The flocs formed in restabilization and sweep coagulation zones were also of high strength and difficult to break, but significantly irreversible after broken. The recovery factor of the broken flocs in sweep coagulation zone was only 18.6%. The effects of remixing on the breakage and regrowth of flocs increased with remixing intensity. In sweep coagulation zone, the settling height and mean settling velocity of the interface between flocs blanket and water were lower for the broken and partly reforming flocs than for those unbroken; Moreover, in flocculation settling and zone settling zones, the instantaneous settling velocity of the interface at the same flocs concentration was also lower for the broken flocs than for those unbroken, but in compression settling zone, the instantaneous settling velocity was the same whether the flocs were broken or not.