Water Science & Technology Vol 53 No 12 pp 169–175 © IWA Publishing 2006 doi:10.2166/wst.2006.419

Phosphorus removal using novel crystallisation technology

K. Wood^*, G. Wood^*, D. Prokop^** and F. Lewyille^***

A soy protein manufacturing facility was faced with the challenge of reducing its effluent phosphorus (P) content from 20–50 mg L^-1 down to <2 mg L^-1 total P without increasing soluble salt levels to comply with discharge and receiving water requirements. A number of biological and chemical P removal technologies previously evaluated either failed to achieve the new standards or would have produced prohibitive amounts of residual sludge and unacceptably high effluent salt concentrations. Lime precipitation, utilising a novel crystallisation technology, was demonstrated through on-site pilot testing to meet the process objectives. It is capable of achieving the required P removal at pH 10 while not increasing soluble salts and producing rapid settling and filterable particles. Also, minimal carbonate removal was observed with residual solids generation being only 40% of a complete lime softening reaction. This paper describes the technical evaluation that led to the full-scale treatment system that was put into operation in late 2005.

Keywords: Chemical treatment; crystallisation; food industry wastewater; phosphorus removal

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