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.

What is Longwater® polyaluminium chloride (PAC/PACL)?

CAS No.:1327-41-9 EINECS No.:215-477-2 Chemical Formula: [AL2 (OH)nCL6-n] Longwater® Polyaluminium Chloride (PAC/PACL) as a kind of high effective inorganic compound polymer coagulant or flocculant. Longwater® All the polyaluminium chloride is manufactured by National Standard and almost equal to ANSI/AWWA Standard, JIS Standard, NSF Standard.

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.

What is Pac based water treatment?

PAC is the polymer adopted by the Ghana Water Company Limited (GWCL) and the Barekese Water Treatment Plant management in Ghana. However, limited information is available on the optimal dosage and operating conditions for PAC-based water treatment.

What is the turbidity of a PAC flocculated water?

The average PAC dose, since its introduction in December 2016, was 33.2 mg/l, with minimum and maximum dosages of 14.1 and 43.8 mg/l. Since PAC's introduction, the turbidity of the flocculated water has remained fairly stable, within the range 3.5 to 6.1 NTU. When alum was in use, the range was 2.0 to 6.4 NTU (Figure 4).

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.