Using Wastewater to Create Energy

By Laura Nichol
October 2012

Researchers are helping rural communities reduce the cost of wastewater treatment while creating a sustainable source of energy.

Wood chips collected from the harvesting process

Traditional wastewater systems for rural communities can cost millions of dollars to maintain and upgrade. Dealing with these costs can be a major financial challenge. Now, five Alberta communities are turning a costly problem into a community asset.

Working with researchers at Natural Resources Canada (NRCan), the municipalities of Whitecourt, Camrose County, Beaverlodge, Edmonton and County of Grande Prairie are experimenting with using treated municipal wastewater and biosolidsto irrigate and fertilize woody crops. The system reduces wastewater management costs and provides communities with the added benefit of biomass production every two to four years, or timber harvests every 15 to 20 years.

Creating Bioenergy

The Whitecourt wastewater irrigation site in summer 2011 before its second harvest of biomass

Short rotation woody plant crops such as poplar and willow grow quickly, making them a good source of biomass. But plantations have not been widely established in Alberta’s semi-arid regions because they require substantial amounts of water.

The system developed by researchers at NRCan’s Canadian Wood Fibre Centre (CWFC) utilizes municipal wastewater to meet the water needs of these crops.

Researchers found that these trees thrive on treated wastewater and its associated nutrients. Overall, crop yields were increased by an average of over 30 percent when irrigated with treated wastewater, compared to no irrigation. Willow and poplar plantations incorporating these systems utilize approximately 5 million litres of wastewater per hectare every year. Since 2006, over 120,000 willow and poplar cuttings have been planted on 8 hectares across the five municipalities.

The biomass will be harvested to meet community energy needs. Camrose County is planning to use the willow biomass from their site to supplement the heating requirements of local municipal buildings. Beaverlodge will use the wood in a planned municipal heating system. These projects will help to reduce municipal expenditure on fossil fuels and their associated greenhouse gas emissions.

Reducing Waste Costs for Rural Communities

Wood chips being blown into a wagon during the harvesting of willow crops at the Whitecourt wastewater irrigation site

Wastewater systems in smaller rural communities tend to be lagoon systems, made up of a series of holding ponds. Untreated municipal wastewater is sent to these ponds where natural microbiological processes break down nutrients. Eventually, the treated water is released back to surface water bodies like lakes and streams.

By continually utilizing the water from the holding ponds, the need for additional waste removal or system upgrades to increase holding capacity is diminished.

Martin Blank, a wood fibre and bioremediation technician with the CWFC, highlights the advantages of this system. “The maintenance is quite low and waste removal and potential system upgrade costs are significantly reduced,” says Martin. “Not only are municipalities solving a waste management problem, they are creating a valuable biomass commodity. The system is a great fit for many smaller rural communities.”

CWFC continues to monitor the environmental impacts and crop response to wastewater application. This includes growth, groundwater testing, soil testing, and foliage and plant tissue analysis.

Supporting Sustainable Community Development

The lagoon at the Beaverlodge wastewater irrigation site; the irrigation pump is submerged beneath the float platform

The CWFC research sites and project collaborators were recently brought together to form the Alberta Rural Organic Waste-to-Energy Network (AROWEN). The purpose of the network is to share information and best practices, and to help other interested communities develop and manage similar plantations.

CWFC researchers will support the ongoing work of AROWEN by providing technical expertise, gathering data and monitoring crop response and environmental effects.

For more information on research conducted by the CWFC, visit NRCan’s “Canadian Wood Fibre Centre” web page.

To read about related articles, see Renewable Energy.

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