Where is Vancouver’s wastewater going?

By Steph Baker

In the Greater Vancouver area, everything that’s flushed down our kitchen sinks, toilets and drains ends up at the Iona Wastewater Treatment Plant, where the sewage is treated and discharged into the Salish Sea.

 Yes – the ocean. Is the water being pumped out clean? Well, not quite. But it could be.

T he plant, built in the early ‘60s, is a primary treatment facility; it uses the most basic and oldest treatment technology, invented over one hundred years ago.

The Federal Government has mandated that all wastewater treatment facilities be a minimum of ‘secondary treatment’ level by 2030. This is the next step up from primary, but it’s still not the best; it falls behind many other countries who have far more advanced treatment technologies. Higher levels of treatment are commonly called ‘tertiary’ treatments, and are able to remove 99.9% of contaminants from the water. This is, undoubtedly, the only condition we should be releasing treated sewage water into the Salish Sea.



The Iona Wastewater Treatment Plant pipe. The jetty is a popular cycling and walking route used by the public, an out-and-back pathway that sits on top of the discharge pipe. Upon reaching the end of the jetty, the treated effluent is discharged a further 3km out to sea.


“Tertiary treatment is the best option for metro Vancouver communities because it will prevent the largest quantity of harmful toxins like nitrogen, ammonia, metals and microplastics from polluting the Salish Sea.

— Georgia Strait Alliance


The Iona plant is in the early stages of redevelopment to secondary treatment. Microplastics, pathogens, antibiotics, and more can escape past secondary treatment. With a growing urban population and the resulting influx of toxic substances being flushed down household and commercial drains, the upgrades must be of the highest standard to handle the future of urban wastewater. The Salish Sea deserves tertiary treatment.

Nonprofit associations the Georgia Strait Alliance and Obabika are working to highlight awareness of the issue and encourage community feedback. We have a pivotal window to influence the Metro Vancouver representatives to make the new facility tertiary level. Metro Vancouver’s Wastewater Committee is currently accepting community feedback before moving forwards with preliminary planning. The alliances have created an online feedback tool for you to take action now.

TAKE ACTION NOW

Wildlife
Sitting at the mouth of the Fraser River and alongside the Salish Sea, the treatment plant is an ecologically sensitive area for wildlife. The Fraser River is British Columbia’s most important salmon-bearing habitat, which is seeing record declines in salmon returns. The Fraser Estuary is one of the most important corridors for migratory birds in North America. The Salish Sea is home to the critically endangered Southern Resident Killer Whales, which are being found with some of the highest amounts of toxic chemicals in their fat deposits.

Raising our voice works
The Lions Gate Wastewater Treatment Facility on the North Shore was initially proposed for an upgrade to secondary treatment level, yet local advocates saw an opportunity to push for tertiary treatment. In July 2019, Metro Vancouver approved tertiary treatment for the plant. The city of Victoria is infamously in the midst of building its first ever wastewater treatment facility; it has, until now, never treated its outflowing sewage. The plant being built will use tertiary treatment.

Primary Treatment

How it works
When wastewater enters the facility, it filters through a screen that removes any larger objects such as sticks, sanitary items, shoes, guns – you name it, it’s probably been found in pre-treatment. After the larger items have been removed, the water goes through a grit chamber, which removes smaller pieces such as sand, gravel and glass. It’s now time for primary treatment. The water passes through a sedimentation tank which works to remove the grease, fat and solids. Through controlling the speed of the moving water, ‘sludge’ settles at the bottom of the tank and ‘scum’ at the top. Sounds disgusting - it is. But, the removed sludge (or biosolids) are mostly used efficiently, often as fertilizer for soils and plants. This is the last stage of primary treatment, and the water is discharged into the ocean or river.

Effectiveness


Primary treatment only removes 50 to 60 per cent of the total suspended solids (TSS) and 30 to 50 per cent of the biochemical oxygen demand (BOD). BOD is the measure of oxygen demand used by the organic matter that’s still in the water. The higher the BOD, the greater the degree of pollution in the water and lesser oxygen for aquatic life. Pathogens, antibiotics, metals, nitrates, phosphates, microplastics and high levels of BOD can all escape primary treatment.

Secondary Treatment

How It Works


Secondary treatment uses bacteria to digest the remaining pollutants. One of the most popular methods used is a trickling filter. After the water has left the sedimentation tank in the primary treatment stage, the water is pumped through a series of plastic filters or rocks, where bacteria cling to the filters and consume the organic matter as it passes through. Another popular method is the ‘activated sludge’ method. It uses beneficial bacteria to digest the bad bacteria in the water, and dissolved oxygen is pumped in to keep the good bacteria growing. The water then hits another settling tank where the biological sludge (the byproduct from the bacteria digestion) is separated from the cleaner water, which is then discharged.

Effectiveness


Secondary treatment plants remove about 95 per cent of the organic materials in wastewater after primary treatment. Since the activated sludge method was created in 1913, what goes down our drains has evolved from just, you know what.
Pathogens, antibiotics, metals and microplastics can still escape secondary treatment. The majority of these microplastics are microfibres shed from our clothes through laundry wastewater. A 2018 study at a Vancouver secondary WWTP highlights that around 30 billion particles of microplastics were released into the aquatic environment annually, from just one plant. This number will only increase with a growing population.

Tertiary Treatment

How It Works
Types of tertiary treatments vary depending on what the discharged water will be used for. The resulting water can be reused for industry, crop irrigation and even drinking water. UV disinfection is a popular method for water discharge close to swimming areas, and Reverse Osmosis and Ozone treatments are popular for reusable drinking water. The latter treatment methods are energy intensive, yet they have been proven to remove 99.9% of bacteria in water.

Effectiveness
The main function of tertiary treatment is to remove all remaining pollutants in the water, with emphasis on phosphates, nitrates and pharmaceuticals. Some facilities reuse the captured phosphates and nitrates for reuse as fertilizer in fields.
Ultrafiltration methods have been found to remove 99.4% of microplastics from treated water, and Reverse Osmosis has been able to remove 83-99% of pharmaceuticals.

Sources

What Happens When I Flush? Metro Vancouverhttp://www.metrovancouver.org/services/liquid-waste/LiquidWastePublications/WhenIFlushBrochure.pdf 
Metro approves tertiary treatment for North Vancouver sewage plant, North Shore News https://www.nsnews.com/news/metro-approves-tertiary-treatment-for-north-vancouver-sewage-plant-1.23952118 
How Wastewater Treatment Works: The Basics, U.S. Environmental Protection Agency https://www3.epa.gov/npdes/pubs/bastre.pdf 
Iona Island Wastewater Treatment Plant Project, Metro Vancouver http://www.metrovancouver.org/services/liquid-waste/projects-initiatives/iona-island-wwtp-project/Pages/default.aspx