Organic waste to energy project using proven GWE RAPTOR system provides green power and fertiliser

An organic waste-to-energy project in a Canadian city is using a proven technology from Global Water Engineering (GWE) to produce green power and bio fertiliser. GWE, represented in Australia by CST Wastewater Solutions, has been a world leader in anaerobic digestion of industrial effluents and green energy solutions for more than 35 years.

About the size of Canberra, the Sunshine Coast or Newcastle, the city of London in Ontario, Canada with a population of about 366,000, is set to demonstrate benefits achievable worldwide by converting more than 65,000 tons of mixed organic waste a year into environmentally harmonious green energy and dry fertiliser.

The privately owned Harvest Power Mustang Generation Limited plant will process more than 15 different waste streams into biogas to generate electricity as well as dry bio fertilisers. Incorporating a GWE RAPTOR system, the 4.5-hectare plant converts waste such as grocery store rejects, kitchen and market waste, food processing residues, leachate, manure, and slaughterhouse residues into enough biogas to generate 2.85 MW of electricity and 8.7 tons a day of dry bio fertiliser.

CST Wastewater Solutions Managing Director, Mr Michael Bambridge explains that these green energy initiatives are readily adaptable to a host of Australian cities.

Biogas replaces fossil fuels typically used to heat factory process plant such as boilers or to generate electricity. The London, Ontario plant’s biogas production of more than 27,000 Nm³ a day @ 62.5 per cent methane is equivalent to 20,000kg a day of fuel oil, or 7,300 tons of fossil fuel a year, worth nearly $US 6 million a year with clear environmental benefits.

According to President and CEO of Global Water Engineering, Mr Jean Pierre Ombregt, industrial waste water plants equipped with similar RAPTOR technology have already doubled their annual production of green energy, so Harvest Power’s targets are eminently realistic and easily expanded on a global scale. 

GWE’s RAPTOR (Rapid Transformation of Organic Residues) is a powerful liquid-state anaerobic digestion process that consists of enhanced pre-treatment followed by multi-step biological fermentation. In the Harvest Power application, it is integrated into a process that begins with waste reception and storage, depackaging and conditioning, and the removal of contamination such as plastics, metals, and glass. It then undergoes thermophilic acidification, anaerobic digestion by the RAPTOR process, post digestion, aerobic treatment of the liquid part of the digestate, sludge conditioning and drying. This is followed by biogas sweetening (removal of hydrogen sulfide), drying and then use in combined heat and power (CHP) systems and engine generator sets of 2.85 MWe feeding back into the local electricity grid.

The RAPTOR process consumes about 76 per cent of the potentially environmentally harmful COD (chemical oxygen demand) content of the waste, which comprises content of natural origin that can be broken down into biogas by anaerobic bacteria. While the biogas is conditioned and utilised to produce energy, solids and liquid residuals provide valuable fertiliser products. The odour-free, rapid throughput design also attracted the strong community backing essential to its success.

Jean-Pierre Ombregt says the type of anaerobic technologies being employed at the Harvest Power site can pay for themselves in a year or two through savings in fossil fuel, while also protecting the environment from groundwater and air pollution. He adds that waste product/green energy technologies such as those from GWE score over solar and wind power by delivering better results in terms of base load and cost-efficiency. 

These plants can be replicated anywhere there is a community, factory or process with one or more digestible solid waste streams. Breweries, fruit, food waste, agro industries, and energy crops including corn can easily use this technology to generate energy, opening the door to environmental and production efficiency gains globally.

GWE has been involved in more than 300 water, waste water and green energy projects in 70 countries in regions including Africa, North and South America, Australia, China, Europe (including Eastern Europe), Russia and South-East Asia.