Washington State University Pilot Study Increases Renewable Natural Gas Yield by 200 Percent Using Advanced Pretreatment

A WSU pilot study reveals a new pretreatment method that increases renewable natural gas production from sewage by 200% while halving costs.

By: AXL Media

Published: Apr 21, 2026, 9:53 AM EDT

Source: Information for this report was sourced from EurekAlert!

Transforming Wastewater Treatment into Energy Production

The management of municipal sewage sludge has long been a costly and energy-intensive challenge for small communities and major cities alike. However, a pilot study conducted at Washington State University (WSU) and reported in the Chemical Engineering Journal suggests a major shift in how this waste is handled. By refining the treatment of sewage sludge, researchers have successfully produced 200% more renewable natural gas compared to existing methods. Professor Birgitte Ahring of WSU’s Bioproducts, Sciences, and Engineering Laboratory stated that the technology converts up to 80% of sludge into valuable energy, effectively turning wastewater facilities into local power hubs.

Overcoming the Inefficiencies of Anaerobic Digestion

Currently, about half of the 15,000 wastewater treatment plants in the United States utilize anaerobic digestion to break down waste, but the process is often hindered by complex molecules that microbes cannot easily digest. This results in a biogas mixture of carbon dioxide and methane that has limited utility, leaving behind biosolids that typically end up in landfills. The WSU team addressed this by introducing a pretreatment step involving high temperature and pressure. By adding a small amount of oxygen as a catalyst, the researchers were able to break down long polymer chains in the sludge, making the material significantly more accessible for subsequent biological processing.

A Novel Bacterial Strain for Pipeline Quality Gas

One of the most significant breakthroughs in the study is the discovery of a specialized bacterial strain that upgrades biogas into pure renewable natural gas. After the pretreatment and initial digestion, this "workhorse" microbe converts carbon dioxide and hydrogen into methane with 99% purity. Unlike other biological systems that require expensive organic additives or constant maintenance, this strain thrives on a simple regimen of water and vitamins. This direct production of pipeline-quality gas eliminates the need for complex secondary purification steps, addressing a primary limitation of existing sludge-to-energy systems.