Sustainable algal wastewater treatment in the Canadian context with energy and phosphorus recovery

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Conventional wastewater treatment is an energy intensive process. In North America, approximately 320 kWh of electricity are utilized to treat 1000 cubic metres of wastewater (Menendez, 2010). For a city the size of Winnipeg, it costs wastewater treatment plants about $7,900 per day for electricity alone (Smyrski, 2013). In addition, there are a number of environmental concerns that are associated with wastewater treatment. First, a key component of wastewater treatment is the conversion of organic carbon into CO2 (a potent greenhouse gas). Second, there has been a steady increase in the quantity of dissolved nutrients (like nitrogen and phosphorus) that need to be removed from wastewater. These nutrients are disrupting the natural ecology of our lakes and rivers. Therefore, there is an urgent need for the development of sustainable and cost-effective technologies that reduce the energy requirements and greenhouse gas emissions associated with water treatment, while continuing to meet, or surpass, the stringent regulations that ensure the safety of the treated wastewater that is discharged back into our public waterways. Algae hold great promise in this regard. Algae use sunlight as an energy source and remove CO2 from the air, producing oxygen in return. Algae also have a demonstrated capacity for the removal of nutrients from wastewater. Therefore, the use of algae for the treatment of wastewater has the potential to provide great environmental and practical sustainability. However, there are a number of hurdles that must be overcome before algae can be made truly economically feasible. First, they must be adapted to grow in relatively cold temperatures, which is particularly relevant in northern regions like Canada. Second, there needs to be a cost effective way to provide sufficient light for algae growth. Finally, methods must be developed for efficient harvesting of the algae, which can subsequently be digested to produce fuel. Our research aims to develop sustainable algal wastewater treatment processes that remove nutrients at low temperatures, recover energy through the production of biogas (by digesting harvested algae), and recover the phosphorus from harvested algae so that it can be recycled as a natural fertilizer. This technology will lead to reduced cost, reduced carbon footprint and greenhouse gas emissions, and will therefore provide direct economic and environmental benefits for all of Canada. In addition, this technology can be exported to other cold climate areas throughout the world to raise the international recognition of our research in this important field of study.