The influence of different doses of aluminium sulphate and polyaluminium chlorides when cleaning a thin and a thick sewage on the residual turbidity, concentrations of TOC, ortho-P, non-ortho-P, SS, and alkalinity and sludge volume produced was studied.Both the alkalinity consumed and the amount of ortho-phosphate precipitated decreased with increasing basicity of the coagulant. At low coagulant doses no or little alkalinity was consumed. When the coagulants were added above a threshold concentration the alkalinity consumed as well as the amount of sludge produced increased strongly with the dose used.When the thick water was cleaned to a constant phosphorus concentration the type of coagulant giving lowest sludge volume depended on the amount of phosphorus removed. At high removal rates the lowest basicity coagulants gave the lowest sludge volume. When the residual P concentration was 1.5 mg/1 the coagulant with OH/A1 of 1.1 gave the lowest sludge volume.When waters were cleaned to a constant turbidity the sludge volume decreased somewhat with increasing basicity of the coagulant.
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- Influence of the Basicity of Polyaluminium Chlorides When Cleaning Municipal Wastewater
- Springer Berlin Heidelberg