B.C. Company Aims to Speed up Biogas Production

by Andrew Snook (Canadian Biomass) While the Province of B.C. has expressed desire to expand its renewable gas production capacity, one roadblock to its production has always been the time it takes to convert organic waste into biogas. However, Vancouver-based Vertogen Technologies aims to solve this issue with its proprietary Renewable Natural Gas (RNG) Accelerator, designed to reduce processing times for anaerobic digesters by upwards of 90 per cent through a high-rate pretreatment process that speeds up RNG production from wastewater sludge and organic waste.

This technology got the attention of NorthX Climate Tech (NorthX), which recently announced an investment of $500,000 in non-dilutive investments into Vertogen Technologies. The funding will support Vertogen’s expansion of its pilot testing and deploying its RNG Accelerator at a wastewater treatment plant in British Columbia within the next eight months. NorthX stated that this technology would drop standard production times from more than 20 days to less than two days.

Typical anaerobic digestion involves four different groups of bacteria. The first group decomposes large solids into smaller solids; the second group takes those small solids and organic material and converts it into volatile fatty acids; and a third group breaks down the volatile fatty acids into acetic acid, not unlike vinegar.

“What’s advantageous is the last group of bacteria are anaerobic. That means they can’t survive with oxygen, but they love acetic acid which they can easily transport though the cell membrane and then convert it into biogas, consisting of carbon dioxide and methane as a renewable natural gas,” explains Dr. Troy Vassos, CEO of Vertogen and the creator of the technology.

These four groups of bacteria are all present in a conventional digester which is optimized for the methane gas producers, under conditions that are sub-optimal for the other three. As a consequence, it can take 20 days or more to produce methane gas and about 60 per cent of the original solids going to waste.

“That’s generally the best that can be done under those conditions,” Vassos says. “In the past 10 to 15, years, people have been looking at trying to optimize renewable gas production, make it work faster and better. Multiple attempts to speed up and optimize the process have failed to yield phenomenal results.”

That is until Vertogen’s technology, which began its journey in a lab about 25 years ago when Vassos came across a phenomenon that resulted in extremely high yields of acetic acid that shouldn’t have existed under the observed conditions.

“We took a look at it, and through research, determined that we could accelerate the process by separately optimizing the growing conditions for the first three groups of bacteria, causing them to rapidly convert the waste organic matter into large amounts of acetic acid over 24 to 48 hours, and then feed the acetic acid to the methanogens, which convert the acetic acid to methane gas within hours” Vassos explains.

This both dramatically reduces the amount of time it takes to generate methane gas from organic matter and we can easily adapt the process to an existing conventionally designed anaerobic digester,” Vassos says. “Essentially, we take the organic matter that the big reactor normally takes, and convert most of it into acetic acid, and then send the acetic acid enhanced feedstock to the digester to continue the digestion process while the methane producing bacteria immediately convert the acetic acid into methane gas.”

The current pilot testing being done with the funding from NorthX involves establishing optimal operating conditions for different sources of waste organic matter for application at a commercial scale.

The ability to speed up the process for municipal wastes and convert them into renewable energy has the potential to generate significant economic benefits to municipalities while finding more optimal ways to dispose of their waste.

“What we’re doing, essentially, reduces the capital cost for anaerobic digestion and increases the amount of organic waste and the amount of energy that can be generated, which means the production of renewable natural gas can be much more economical than it has been historically. Secondly, we can take existing infrastructure that has already been paid for, and we’re talking hundreds of millions of dollars in a treatment plant, and being able to make it work 10 times better than it did before; take 10 times more waste; and delay any expansion of anaerobic digestion facilities, probably for just about forever,” Vassos says. “From a practical standpoint of the lifespan of a digester, it has great potential for being very disruptive as a technology.”

“Producing renewable gas from waste has huge potential but has long been constrained by slow, costly processes,” says Dr. Troy Vassos, CEO of Vertogen. “By dramatically reducing processing time, our technology helps make renewable gas production faster and more efficient, while lowering waste and disposal costs.