What is the difference between Alum and polyaluminium coagulants?

For water treatment applications, instead of Alum, now there are several alternative aluminium-based coagulants. Polyaluminium coagulants (PACl) consume considerably less alkalinity than Alum. Compared to Alum, PACl works effectively over a broader pH range (5.0 to 8.0).

What is the basicity of a polyaluminium coagulant?

Basicity is a quantitative measure of how many hydroxyl ions are included in the structure of a polyaluminium coagulant. The higher the basicity of a coagulant, the lower the impact it will have on dosed water pH. For example, a polyaluminium structure like (Al2 (OH)5Cl) has basicity of 83.3%.

Does polyaluminium chloride coagulant remove turbidity from surface water?

The effect of different basicity of polyaluminium chloride (PAC) coagulant to remove turbidity from surface water was evaluated by laboratory experiments and in two different working WTPs of various capacities.

What is polyaluminium chloride used for?

Among the aforementioned products, polyaluminium chloride has become one of the most effective coagulant agents in water and wastewater treatment facilities with various applications, including removal of colloids and suspended particles, organic matter, metal ions, phosphates, toxic metals and color.

Is there an alternative preparation procedure for polyaluminium chloride (PAC)?

An alternative preparation procedure for polyaluminium chloride (PAC), a common inorganic coagulant, is presented in this paper.

How should coagulation pH be matched to raw water alkalinity?

PACl basicity should be matched to raw water alkalinity, so that coagulation pH is as close as possible to the pH of minimum solubility of the coagulant. The solids separation process used for treatment was also found to be important for coagulant selection.