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Q&A: Making more out of sewage

Sewage treatment is the million-dollar question for Vancouver’s municipal politicians and environmentalists. One approach already in use in the False…

By Kevin Sauve , in Environment , on November 13, 2008

Sewage treatment is the million-dollar question for Vancouver’s municipal politicians and environmentalists. One approach already in use in the False Creek area of the city is called Integrated Resource Recovery and involves capturing resources from liquid waste.

What is “waste”?

Water, heat, nutrients, and biofuels; did you know that you can find all of these valuable resources in both your litter and your latrine? Landfills and Sewage outfalls constitute two of the largest economic and pollution problems on the planet. In 2006 alone, Canadians dumped over one trillion liters of liquid waste into lakes, rivers and oceans, and piled up more 27,250,000 tonnes of solid waste.

What is integrated resource recovery?

IRR uses modern technology to capture resources from waste. Raw sewage primarily consists of heat and water, and organic matter has energy potential. Using IRR, both liquid and solid organic waste can be processed to produce both biofuels (that can be used in place of fossil fuels) and electricity.

How does it work?

Raw sewage is treated at the neighborhood level in plants that would be smaller than houses and similar to mini pump stations. Heat from sewage would be captured and used to heat household air and water. Treated water is then disinfected and recharged into the ground. Using “digesters” the remaining wet organic waste, which comes from the sludge of treated sewage, along with solid wet waste from landfills, can be converted into methane rich biofuels that can be used to fuel vehicles. Dry waste, can be converted into gas in “gasifiers” which can then be used to generate electricity and heat. Minerals contained in the residual material can be sent to refining facilities to recover metals.

What are the benefits?

A full scale IRR model has the potential to completely eliminate solid waste from landfills and to turn the effluent from sewage into little more than H2O. It also significantly reduces the amount of greenhouse gases produced through the incineration of garbage, the burning of fossil fuels, and the treatment of sewage. And the big bonus, resources recovered from sewage can be sold, putting our waste to work.

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