Self-Powered Sewage Plant Developed in CA
Original Source: http://www.sustainablelifemedia.com
Author: Thomas Miner
Original Publication Date: August 2, 2010
August 2, 2010 – Engineers at Stanford University have developed a self-powered sewage treatment process that also reduces greenhouse gas emissions by utilizing existing rocket-thruster technology and harvesting many of the greenhouse gases that escape into the atmosphere at a traditional plant.
Using microbes to break down sewage produces nitrous oxide and methane, which contribute to climate change. Now a team at Stanford University in California hopes to increase production of these gases so the methane can be used as fuel and the nitrous oxide can be used to facilitate the generation of heat and electricity.
Reducing the oxygen supply to the bacteria increases production of these substances, which are very potent greenhouse gases. Instead of being allowed to escape into the atmosphere, the methane could power the treatment plant while the nitrous oxide could be broken down into nitrogen and oxygen to release energy in a process also used by rocket thrusters.
The reaction, triggered by heat and a catalyst, also produces enough energy to heat an engine to almost 3,000° Farenheit so it can become self-sustaining and used to generate electricity using, for example, a Stirling cycle engine.
To control the gas production from the sewage treatment, the team needs to encourage different bacteria to grow. Traditional methods use costly and energy-intensive aeration to supply oxygen to aerobic species of microbes that produce nitrogen from ammonia.
Reducing the oxygen will instead favour anaerobic species that release more nitrous oxide but leave more organic matter for microbes that produce methane. This could increase methane production by two or three times and also reduce costs, as aeration accounts for up to half of sewage plants’ operating expenses.
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