Is polyaluminium chloride a coagulant?

Water Supply (2022) 22 (3): 2793–2802. Polyaluminium chloride (PAC) with different basicity is used as a coagulant in most drinking water treatment plants (WTP). The aluminium concentration in PAC and its hydrolysis mechanism varied with the basicity of PAC.

How are polyaluminum coagulants selected?

Selection of polyaluminum (PAXs) coagulants is examined for different raw water types and solid-liquid separation processes. PAXs were tested with various basicities and sulfated versus non-sulfated. Four widely different water supplies were studied in terms of alkalinity, turbidity, and concentration and nature of natural organic matter (NOM).

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.

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.

How does a coagulant work in a water treatment plant?

In water treatment plants (WTP), the coagulant plays a significant role in neutralising these particles' electrostatic repulsive forces. The coagulant's metal ion attracts these negatively charged particles and coagulates with them to form small-sized floc.

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.