By Maura Forrest
June 5, 2014
It’s time to stop literally flushing energy down the toilet.
That is the message of a growing industry of “sewage miners” —companies transforming sewage into electricity, fuel and even biodegradable plastic.
According to them, cutting greenhouse gas emissions is only one reason to invest in sewage mining. Wastewater treatment is an enormous financial burden for many cities, and one that is growing as more people flock to urban centres. Generating revenue from the process is an attractive way to offset costs.
The secret to creating value from waste lies with the unwanted residue of the wastewater treatment process—a leftover sludge that can contain toxins and disease-causing microorganisms.
In many treatment plants, that solid waste is passed through an anaerobic digester to remove hazardous ingredients. The process produces biogas, which was traditionally treated as a waste product and burned off. But these days, the true potential of that biogas has made it a commodity.
Back in 2010, San Antonio, Texas, became the first North American city to invest in commercial-scale biogas production from sewage. The biogas was sold to a nearby gas pipeline as a renewable substitute for natural gas.
Elsewhere, biogas is used to produce electricity to power operations at wastewater treatment plants, thereby reducing energy costs.
And even the sludge itself has proved useful. Jerusalem-based Applied CleanTech has recently created its own Sewage Recycling System, which harvests cellulose fibres from solid waste to form a product it calls Recyllose. Recyllose can be used as an alternative fuel, a heat source, and even as a bioplastic—a biodegradable material that can be used instead of traditional petroleum-based plastics.
In February 2014, the Canadian Sewage Mining Corporation signed a distribution alliance with Applied CleanTech, and agreed to install at least five Sewage Recycling Systems in Canada within the next five years.
Elsewhere in Canada, biogas from sewage has been slow to take off.
A 2013 report found that capturing the biogas produced by wastewater treatment plants in Canada could reduce greenhouse gas emissions by an amount “equivalent to taking 560,000 cars off the road.” The report also found that “digester construction projects would result in 1,000 direct and 3,000 indirect jobs.”
There are some projects underway. A wastewater treatment plant in Hamilton, ON, began capturing biogas in 2006 and using it to heat and power the plant. And in Richmond, BC, the Lulu Island Wastewater Treatment Plant sells refined biogas to FortisBC, which sells it to customers as renewable natural gas.
But these are just the early days for what could be our only energy source that is not only renewable, but becoming more abundant every year.