A type of bacteria is being used as a chemical-free method of removing impurities and upgrading biogas, according to Denmark-based Biogasclean during a recent gasworld webinar.
The company, part of the CycleØ pan-European biomethane platform, says its systems are today operating in more than 370 facilities across over 40 countries.
Using thiobacillus bacteria within trickle-bed reactors, the technology removes more than 99% of hydrogen sulphide – an impurity in fuel gases – from biogas streams through a fully biological, self-regulating process.
It produces elemental sulphur and sulphate without the need for chemical additives, fitting with strict gas grid requirements on oxygen content and emissions. The process is called biological desulphurisation.
What is a trickle-bed reactor?
A trickle-bed reactor is a type of chemical reactor that uses the downward movement of a liquid and the downward or upward movement of gas over a packed bed of solid catalyst particles.
In biogas upgrading, the liquid, typically containing nutrients and bacteria, trickles over the packing material. The bacteria attach to the surface of the packing material, forming a biofilm.
Scheme of a trickle bed reactor ©Daniele Pugliesi
This biofilm aids a reaction called biological methanation, which converts CO2 and hydrogen into methane. This increases the amount of methane in biogas from 50% to 60% to at least 98%. The upgraded biogas, with its high methane content and lower CO2 content, can be used as a fuel source.
Thomas Bucha, Sales Director at Biogasclean, said the company is “backed by deep engineering know-how, global experience and decarbonisation-focused capital” through parent firm CycleØ and private equity backer Ara Partners.
Biogasclean’s systems are integrated with modular biogas upgrading units supplied by CycleØ group company FNX and are increasingly tailored to North American markets, where more than 60% of equipment is now locally sourced.
Dr Brian Jensen, R&D specialist at Biogasclean, said the company’s patented quick sludge removal system simplifies maintenance by allowing packed media to be cleaned using recirculated process water. He added that recent developments include a low-oxygen output option to help customers meet gas injection standards.
The company has worked with clients such as Seaboard Energy, which faced seasonal variations in waste flow and hydrogen sulphide levels. Biogasclean designed a flexible biological desulphurisation system capable of handling flow rates ranging from 20% to 100% of capacity, according to US Sales Manager Wyatt Bishop.
Biogasclean will next exhibit at Biogas Americas in Denver, Colorado, later this month. The company has said it continues to evolve its technology while maintaining support agreements for long-term system performance.
