Polyaluminum sulfate with reduced chloride content

Abstract

Methods are described for manufacturing ultra-low chloride, polyaluminum sulfate (PAS) coagulants useful for removing suspended colloidal matter and organic carbon in potable water, industrial process water and wastewater. A method of preparing a PAS solution includes forming a basic solution of sodium carbonate and sodium aluminate, adding an aqueous solution of aluminum sulfate and the basic solution to water to form a mixture having a pH between about 5 to 7, allowing precipitates of aluminum hydroxide to form in the mixture, and adding an additional aqueous solution of aluminum sulfate in an amount sufficient to dissolve the precipitates of the aluminum hydroxide and to form the PAS solution. The PAS solution has reduced corrosivity compared to other aluminum-based coagulants, and is particularly suitable for drinking water applications. The simplified methods used to produce the PAS coagulant provide a high quality product that is less expensive to produce than current methods.

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