Is polyaluminium chloride better than polyelectrolyte – alum-based coagulation?

At the Barekese Water Treatment Plant in Ghana, an alternative, the polyelectrolyte – polyaluminium chloride (PAC) is also used in coagulation but limited information is available on the operating conditions required to achieve better performance than alum-based coagulation.

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.

What is poly aluminum chloride (PAC)?

Consist of monomeric Al, polymeric Al, and aluminum hydroxide (Al (OH) 3), poly aluminum chloride (PAC) is widely used for particulate matter destabilizing during coagulation in water treatment plants . In contrast to Al salts, more attention was appealed by PAC, which was more effective and lower costing.

What is the optimal pH range for Pac coagulation?

The optimal pH range for PAC coagulation performance was 7.5 to 8.0. The coagulation process in conventional water treatment could be enhanced and the ensuing water pH decline reduced appreciably by applying the right dosage of polyaluminium chloride and appropriate process conditions of pH, fluid mixing speed matrix and residence time.

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 , .

What is the basicity of PACL powder?

Commercial PACl powder (Nanning Chemical Engineering Co. Ltd., Nanning, China), with a basicity (OH/Al) of 1.35 and Al 2 O 3 content of 30% (mass fraction), was dispersed into deionized water to prepare a concentrated stock solution (2 mol·L − 1 Al).