April 12 — New research out of North Carolina has discovered exactly why landfills produce methane.

North Carolina State University researchers said they have identified a species of microbe — Methanosarcina bakeri — that “appears to be the key” to allow production of the gas.

“Landfills receive a wide variety of solid waste, and that waste generally starts out with a fairly low pH level,” said Francis de los Reyes, an associate professor of civil engineering and co-author of a paper describing the research.

“The low pH level makes it difficult for most methanogens — methane-producing organisms — to survive. We started this project in hopes of better understanding the mechanism that raises the pH level in landfills, fostering the growth of methanogens,” de los Reyes said.

Researches discovered that the microbe M. bakeri survives in at low pH levels, consumes acids and produces methane. This increases pH levels and makes an area “more amenable for other methanogens,” the school said.

Moisture leaching through a landfill then spreads the high pH levels, allowing other parts of the disposal site to continue the process, research shows.

“The research community can use our findings to explore ways of accelerating the methane-generation process,” de los Reyes said, “creating methane more quickly for power generation and making additional room in the landfill for waste disposal.”

The findings are explained in a paper, “Effect of Spatial Differences in Microbial Activity, pH, and Substrate Levels on Methanogenesis Initiation in Refuse,” that´s being published in the April issue of “Allied and Environmental Microbiology.”

The paper was co-authored by Bryan Staley, who is president and CEO of the Environmental Research and Education Foundation, de los Reyes, and Morton Barlaz, a professor and department head of civil, construction and environmental engineering at N.C. State. Research funding was provided by Waste Management Inc. and the foundation. Staley worked on the project while he was a doctoral student at the university.