Recovery & re-use of sewage phosphate as a fertilizing soil amendment

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Waterloo Biofilter is a company based in Rockwood, Ontario that manufactures technologies for sewage treatment, specifically in off-sewer developments (www.waterloo-biofilter.com). The core technology is an absorbent trickle filter for remediation of septic tank effluent to 'sand filter quality' effluent. The Biofilter removes organic and nitrogenous contaminants, but phosphorus is only removed with add-on technologies, such as dosing of liquid aluminate. This approach is expensive, and constant re-supply of caustic chemical, plugging and freezing of pipes, etc., makes it impractical for use at small facilities and houses. The Company has developed a low-cost phosphorus removal system using Fe generated by a proprietary electrochemical process (EC-PTM), to sequester phosphate in a variety of P-removal filter matrices. The iron-rich EC-P effluent (preferably pretreated to secondary quality) will pass through a 'P-recovery medium' such as vitreous silicate fiber, the present focus for P-recovery medium, as it is already used as a textural soil amendment. Iron-phosphate minerals precipitate in the matrix, and the availability of the P sequestered in the minerals is unknown. Researchers at the University of Guelph will collaborate with Waterloo Biofilter research staff to investigate the re-use of the saturated matrix in soil as a fertilizing soil amendment.