Wastewater Treatment Centre

How the WWTC treats wastewater

• Primary treatment

  Primary treatment involves mainly mechanical processes such as headworks and primary sedimentation that removes up to 60 percent of suspended solids from wastewater. Larger materials such as rags, sticks, plastics, stones, and other non-flushable items are removed from the wastewater system and sent to the landfill.

• Secondary treatment

  The secondary treatment involves biological processes that can remove up to 90 percent of BOD and total suspended solids (TSS). This process is completed in an extended aeration tank to promote flocculation of the microbes to promote sedimentation for sludge development in the secondary clarifiers prior to the discharge of wastewater into the Fraser River.

• Tertiary treatment

  Tertiary treatment was added in the 1996-1997 expansion upgrade to the WWTC with the addition of the trickling filter system. The trickling filters are plastic media blocks that serve as a support structure on which naturally occurring microorganisms can grow and absorb the dissolved organic material present in the wastewater. This addition to the wastewater treatment process allows for an increased treatment level for BOD and TSS in wastewater. 

• Treated wastewater discharge

  Once the wastewater has been treated through the WWTC treatment process, the treated wastewater is discharged by gravity into the Fraser River via a diffuser outfall pipe.

• Biochemical oxygen demand (BOD)

  Biochemical oxygen demand is the measure of the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic conditions. 

• Total suspended solids (TSS)

  Total suspended solids (TSS) means the total suspended matter that floats on the surface of, or is suspended in water, wastewater, or other liquids.

• Why are BOD and TSS in wastewater a concern?

  High levels of BOD and TSS entering the wastewater treatment plan can adversely affect the treatment process and cause severe harm to wildlife and aquatic life in the receiving environment. 

• Biosolids

  Biosolids are the organic material resulting from the treatment of domestic sewage by a Wastewater Treatment facility. Biosolids are rich in nutrients that may be beneficially used to improve soil conditions and provide nutrients and essential organic matter for various land applications.

  Biosolids are an organic product of wastewater treatment process. The WWTC currently produces approximately 3,000 Wet Tonnes of Class B Biosolids per year. In British Columbi, biosolids are regulated under the Organic Matter Recycling Regulation (OMRR) for the production of high-quality biosolids and subsequent land applications. The City works with several local property owners each year for the land application of the biosolids for non-agricultural property uses in the region.