Biological conversion of coal gas to methane.

Biological conversion of low-Btu coal synthesis gas to higher Btu methane was demonstrated using both pure co-cultures and/or adapted-mixed anaerobic bacteria. Peptostreptococcus productus metabolized coal gas to mainly acetate and CO. The co-cultures containing methanogens converted these products to methane. In mixed culture studies, CH and small amounts of acetate were produced. Reactor studies using stirred-tank and immobilized cell reactors exhibited excellent potential to convert CO, CO and H to methane at higher gas flow rates. Gas retention times ranging from 0.7 to 2 hours and high agitation were required for 90 percent CO conversion in these systems. This paper also illustrates the potential of biological methanation and demonstrates the need for good mass transfer in converting gas phase substrates. [ABSTRACT FROM AUTHOR]