Beneficial Use of Water Treatment Residuals in Land Application

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Metro Vancouver

Excess application of phosphorus to soils can result in high available phosphorus levels that can negatively impact local water quality.  Water treatment residuals are capable of binding available phosphorus in soil and soil amendments to reduce environmental risks; however, land application of this material is not a common regional management practice.  SYLVIS investigated the potential for using water treatment residuals for phosphorus mitigation in a British Columbia (BC) regional context.

Water treatment residuals are the soil-like byproduct of drinking water treatment which often contain compounds that are able to bind to phosphorus.  Water treatment residuals can be beneficially managed in accordance with BC’s Code of Practice for Soil Amendments.  Metro Vancouver generates a large amount of this material every year and currently disposes of this material in a landfill. 

Metro Vancouver sought beneficial use options for its water treatment residuals that capitalized on this material’s inherent beneficial properties, including phosphorus binding potential.  To pursue these options, Metro Vancouver retained SYLVIS to investigate phosphorus-mitigation potential for using these residuals as a soil amendment in local agricultural soils and as a co-amendment with Metro Vancouver biosolids.  SYLVIS conducted a review of the scientific literature followed by a bench-scale examination of phosphorus binding by water treatment residuals in several types of soil and in combination with biosolids. 

The results of SYLVIS trial showed dramatic reductions in mobile phosphorus with the use of water treatment residuals and the suitability of the material as an amendment.   SYLVIS’s work paves the way for larger-scale demonstrations using water treatment residuals generated in the region to address local phosphorus hot spots, reduce the risks of phosphorus pollution, and provide beneficial use options.  The project demonstrates SYLVIS’s innovative approach to using residuals to provide solutions to environmental challenges.