Analysis of post-coagulation properties of flocs in terms of coagulant choice

The knowledge of properties of floes produced in coagulation may enable one to reduce effects of their breakage in a treatment system. This is particularly important in treatment of water contaminated mainly with natural organic matter; produced floes are fragile and susceptible to rupture. The purpose of the research was to determine the influence of a coagulant type on postcoagulation suspension strength. The results show that floes produced based on prehydrolyzed coagulants are more resistant to breakage than those produced by a hydrolyzing coagulant. Strength of post-coagulation suspension increased with the increase of polynuclear Al species (Al_b species).