Why is polyaluminum chloride a good coagulant for water treatment?

Polyaluminum chloride (PAC) is highly effective coagulant for water treatment over conventional coagulants because of low dosage requirement, shorter flocculation time, smaller amount of sludge, high efficiency and low aluminum residual in treated water .

What is high-purity poly-aluminum chloride (PACL)?

Poly-aluminum chloride (PACl) is one of the common coagulants for water and wastewater treatment. A new Chinese national standard of PACl has been implemented, where the concentration of insoluble substances, iron and heavy metals is to be controlled strictly, then researches on the preparation of high–purity PACl are needed.

Which coagulants are used for water treatment?

Aluminum sulfate, ferric chloride, ferric sulfate and polyaluminum chloride are inorganic based chemicals which can be used for water treatment . Aluminum based coagulants have higher color and turbidity removal efficiencies, in comparison with ferric based coagulants .

What is the coagulation time for aluminum sulfate and aluminum chloride coagulants?

However, for aluminum sulfate and aluminum chloride coagulants the coagulation time and settling time were reached to 15 and 35 min, respectively. The results revealed that the residual aluminum concentration in the treated water was very small for synthesized PAC coagulant which was <0.2 mg L −1.

Why are pre-polymerized coagulants better?

The superior performance of pre-polymerized coagulants is attributed to their wider working pH range, a lower sensitivity to low water temperature, lower doses required to achieve the equivalent treatment efficiency, and lower residual metal-ion concentrations .

Does high-purity PACL remove turbidity?

Samples taken from the Huangpu River were used to evaluate the coagulation performance of high-purity PACl in comparison with conventional PACl. The results demonstrate that for the whole dose range studied, high-purity PACls removed more turbidity than conventional PACl.