New Sewage Treatment Method Doubles Renewable Gas Output, Cuts Costs
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Researchers at Washington State University (WSU) have developed a pretreatment method for sewage sludge that doubled the production of renewable natural gas and cut disposal costs by nearly half. The process converts up to 80% of sludge into a valuable product and could help reduce the significant greenhouse gas emissions and energy demands of wastewater treatment. The team is now working with an industrial partner to scale up the technology.
Facts First
- A new pretreatment method doubled renewable natural gas production from sewage sludge compared to current practices.
- The process reduced the cost to treat sewage from $494 to $253 per ton of dry solids.
- The method converts up to 80% of sludge into a valuable product, resulting in 99% pure methane.
- The technology could address wastewater treatment's environmental impact, which accounts for 3-4% of U.S. electricity demand and contributes 21 million metric tons of greenhouse gases annually.
- The research team has patented a key bacterial strain and is working with an industrial partner to scale up the project.
What Happened
A Washington State University (WSU) research team has tested a new pretreatment method for sewage sludge that significantly boosts the production of renewable natural gas. The method involves treating sludge at high temperature and pressure with added oxygen before the standard anaerobic digestion process. This pretreatment step, where small amounts of oxygen act as a catalyst, resulted in 200% more renewable natural gas compared to current practices. The process also reduced the cost to treat sewage from $494 to $253 per ton of dry solids. The researchers used a newly discovered and isolated bacterial strain to upgrade the biogas, converting carbon dioxide with hydrogen into methane, and verified the resulting gas was 99% pure methane.
Why this Matters to You
This development could lead to more efficient and less costly wastewater treatment, which accounts for between 3% and 4% of the total electricity demand in the United States. If scaled, the technology may help utilities lower operational costs, which could potentially influence municipal fees. The increased production of renewable natural gas—a fuel that can be used for electricity generation, home heating, or transportation—could contribute to a cleaner energy mix and help reduce the approximately 21 million metric tons of greenhouse gases wastewater treatment contributes annually.
What's Next
The WSU team has patented the bacterial strain with help from WSU’s Office of Innovation and Entrepreneurship. The researchers are currently working with an industrial partner to develop a larger scale project, which could move the technology from a pilot study toward practical application at wastewater facilities.