Biosolids are the end-product of wastewater treatment processes that begin when you flush your toilet or send dishwater down the drain.

After you flush, your wastewater joins wastewater from many other sources to begin a journey through kilometres of underground piping. Eventually, this wastewater reaches its destination: a wastewater treatment plant (WWTP).

At the WWTP, the solids are separated from the wastewater. These solids, which consist mainly of organic matter, are then treated and dewatered. At the end of the process, the solids (also known as sewage sludge) become biosolids. There are three main components in biosolids: water, organic matter, and silt/sand. Percentages of trace elements in biosolids from the Annacis Island WWTP:

Element	Percentage
Nitrogen	4.32%
Iron	3.86%
Phosphorous	2.88%
Aluminium	1.56%
Magnesium	0.54%
Copper	0.11%
Potassium	0.15%
Zinc	0.10%
Sodium	0.09%
Manganese	0.04%
other trace Elements	less than 0.03%

(values obtained from the mean concentrations for samples collected in 2005 based on dry weight.)

The biosolids produced in Metro Vancouver plants are rich in nutrients and organic matter. Today, they are being used to:
· Rehabilitate land where mining or other activities have removed soil and vegetation,
· Fertilize lands to improve vegetative production,
· Create soil for landscaping purposes.

Biosolids benefit the environment in two significant ways:
1. Nutrient resources are recovered when biosolids are recycled;
2. Unproductive land is improved when biosolids are used to add essential plant nutrients and organic matter.

Metro Vancouver is finding more ways to recycle this valuable resource.