Does polyaluminum chloride coagulate with hydrolyzed coagulants?

Coagulation with hydrolyzing coagulants has been studied thoroughly, but the coagulation behavior of pre-hydrolyzed coagulants such as polyaluminum chloride (PACl), especially the coagulation mechanisms at various coagulant dosages and pH values of raw water, has not been systemically investigated and not been well understood , .

How is polyaluminium silicate chloride coagulant synthesized?

Polyaluminium silicate chloride (PASiC) coagulant was synthesized by co-polymerization technique using aluminium salt and polysilicic acid at different OH/Al and Al/Si molar ratios. A synthetic turbid sample was used to investigate the coagulation efficiency of the prepared coagulant.

What is the optimum turbidity for coagulation / flocculation of polyelectrolyte?

Ferric chloride (2.5% FeCl 3) combined with the polyelectrolyte, on the other hand, required 0.1 g while the optimum turbidity is almost the same. As for calcium chloride (2.5% CaCl 2) it was found to be the least effective. The coagulation/flocculation process was found to be dependent on both pH and the agitation speed.

How to optimize coagulation-flocculation process?

Efficiency of coagulation–flocculation process depends on process parameters. Optimization of significant parameters such as initial pH, coagulant and flocculant dosage, settling time, mixing parameters and the effective temperature for coagulation–flocculation performance is crucial.

What is the optimal coagulation mechanism at final pH 7.0?

The optimal mechanism at final pH < 7.0 is charge neutralization. Satisfactory coagulation efficiency could be obtained with either charge neutralization coagulation or sweep coagulation at the final pH values from 7.0 to 10.0. The coagulation process of PACl and the formation of PACl precipitates have the same optimal pH value.

How PACL coagulation zones are compared with alum?

The coagulation zones at various PACl dosages and solution pH values were developed and compared with those of alum. It is found that the optimal mechanism under acidic condition is charge neutralization, while alkaline condition will facilitate the coagulation of PACl.