Blackwater System – Vancouver Convention Centre West, Trailblazers since 2010!
- Kalpna Solanki, BSc, MBA, CPHI(C)
There are new stories every day on climate change, climate emergency, and the importance of water conservation. Yet, there are only a handful of systems in BC/Yukon that have sophisticated systems in place that treat wastewater as a resource, and truly cut down on the use of potable water for uses such as flushing toilets and watering gardens.
The Vancouver Convention Centre West has 4,339m2 (466,500 ft2) of function space – that’s a lot of toilets and sinks. Add to that, there are a number of restaurants within the complex as well – that’s even more toilets and sinks.
As the world’s first double LEED® Platinum certified convention centre, the facility is committed to being as ‘green’ as possible and has its own unique Blackwater Treatment Plant that is run by Bruce Caister (EOCP Certified Operator, WT III, WD I, WWT IV) and Saeed Bahreini. Wastewater from the convention centre and restaurants is collected in an equalization tank with a volume of 75,708L (20,000 gallons). To keep hydrogen sulphide under control, an aeration system that pumps in air at a rate of 311L/min (11 ft3/min) has been installed, and the tank is also dosed with hydrogen peroxide. For additional odour control, carbon filters have also been installed. There is also a safeguard in place: if the equalization tank gets filled, a lift station can discharge wastewater to the city’s sewer system
The wastewater then goes through two bioreactors in series, and then through membrane filters. The resulting effluent is treated with sodium hypochlorite and stored in three tanks that in combination hold 100,000L. The system can treat up to 250m3 of wastewater per day, the effluent looks very clear and odourless coming out of the sampling tap, and has a chlorine residual of 0.5 ppm.
The system not only saves potable water – up to 37,355 meters3/year – but importantly also demonstrates that a building even as large and complex as the Vancouver Convention Centre, can treat its wastewater for reuse. The treated effluent is used for flushing 150 toilets and also for irrigation of the roof garden that is 24,281m2 (6 acres) in size and covers almost the entire convention centre.
In addition, although not currently in use, the facility also has a reverse osmosis system in place for desalinating ocean water.
It has never made sense to use drinking water to flush toilets, and with increasing pressures to reduce, reuse, and recycle, we hope more facilities will implement systems that are more ‘green’.