The goal of wastewater treatment is to protect and maintain healthy rivers and oceans. If pollutants in wastewater are not removed, they flow directly into our waterways. This can threaten public health, fisheries, wildlife habitat, recreation opportunities and ultimately, our quality of life.

Two of the important components of wastewater addressed through treatment are:

Total Suspended Solids (TSS)

Total suspended solids refers to particles of matter – both large and small – that can be present in wastewater. These particles carry bacteria that can make wastewater harder to disinfect and can use up oxygen in the water as they break down. Solids can also sink, blanketing the bottom of rivers and oceans and destroying habitat for aquatic and marine life.

Biochemical Oxygen Demand (BOD)

When organic materials— both solid and dissolved—break down in wastewater, they use up oxygen. Biochemical oxygen demand measures the amount of oxygen consumed by these materials in water as they biodegrade. If the biological oxygen demand is high and too much oxygen is being consumed, it can cause problems for fish and other aquatic life that also need to use the oxygen in the water.

The amount of total suspended solids and biochemical oxygen demand removed from wastewater is used to gauge the effectiveness of wastewater treatment plants. Wastewater is regularly monitored to comply with provincial standards.