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.

Why are aluminium based polymers used in water treatment?

These shortfalls in the use of alum have led to the synthesis of improved, aluminium-based polymers, which have been used extensively, over the few last decades, for treating water due to their high efficiency at lower dosages, and wider pH and temperature application ranges (Sahu & Chaudhari 2013).

What are the disadvantages of alum coagulant?

Water Practice and Technology 1 October 2021; 16 (4): 1215–1223. doi: Alum, the predominant coagulant in conventional drinking water treatment schemes, has various disadvantages including the production of large volumes of sludge, lowering water pH (requiring pH adjustment using lime), limited coagulation pH range of 6.5 to 8.0, etc.

What are coagulants used for in water coagulation?

In coagulation, coagulants are used to neutralize and destabilize charges on suspended and colloidal particles in the raw water (Sahu & Chaudhari 2013). In coagulation, these particles and any pathogens attached to them are removed, enhancing the water's quality (Miller et al. 2008).

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.

Is polyaluminium chloride better than alum?

Application of polyaluminium chloride under the recommended process conditions produces relatively better quality treated water than alum application. Freshwater is finite and required for human and ecosystem survival.