Do poly aluminum chloride and poly ferric sulfate affect was digestion?

Poly aluminum chloride (PAC) and poly ferric sulfate (PFS) are widely used in wastewater treatment and sludge dewatering, resulting in their amounts being accumulated substantially in waste activated sludge (WAS). Till now, however, little information about their influence on WAS digestion is available.

What is polyferric sulphate coagulant?

Keywords: coagulation, polyferric sulphate, inorganic polymeric coagulant, prepolymerised coagulant. 1 Introduction The process of coagulation is widely used in the wastewater treatment facilities especially for the destabilisation of colloids suspensions and for the removal of suspended solids along with the removal of phosphate ions.

What is the chemical formula for PFS?

It consists of medium and high molecular weight polymeric chains and it can be described with the chemical formula [Fe2 (OH)n (SO4) (6-n)/2]m. In this paper, the role of some parameters including temperature, types of chemical reagents etc in the preparation stages of PFS were investigated.

Why are PFS coagulants better than ferric sulphate?

Therefore, as the PFS coagulants consist mainly of polymeric species, they exhibit better coagulation behaviour. It is worth noting that for a 90% removal efficiency, only 20 mg/l of PFS are required, whereas the respective dosage of ferric sulphate in this case is much higher, i.e. 30 mg/l.

Is PFS sludge a coagulant?

There are some studies reported that Fe-based flocculants are more effective coagulant for the removal of phytoplankton, turbidity, DOC, TSS, color, COD, and oil from wastewaters, so, it would be reasonable that sludge particle size of PFS sludge was larger than PAC sludge ( Wang et al., 2002 ).

Is PFS a good coagulant?

Furthermore, it has been reported by several researchers that PFS exhibits a superior efficiency in the removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), turbidity and colour, than the conventional coagulants based on iron , , .