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What are biosolids?

Animal and human wastes are a part of the natural cycle of life. These materials are a valuable resource for enriching and rejuvenating soils and they should not be wasted. The land application, or recycling, of these wastes is a practice that has been used all over the world since ancient times. More recently, this practice has evolved into the sophisticated programs seen in modern urban societies.

Sewage biosolids are a by-product of municipal wastewater treatment processes. After entering a treatment plant, wastewater goes through a sophisticated process to settle out the solids.

The solids, or sludge, then undergo further treatment or digestion. In the digestion phase, the sludge is stabilized with odours being significantly reduced and pathogens destroyed.

After the digestion phase, the sludge is referred to as biosolids. The biosolids are transferred to a storage facility until conditions permit them to be spread on land.

Each year, approximately 120,000 dry tonnes of treated sewage sludge, or biosolids, are applied to agricultural land in Ontario. About 80 per cent of Ontario municipalities participate in some form of this practice. Durham Region’s Biosolids Management Program applies between 1,000 and 5,000 dry tones annually, depending on weather conditions and land availability.
It is estimated that the average household produces approximately 1.2 m3 of biosolids per year. We all have some responsibility in the generation and management of this material.