Enhancement of biodiesel, hydrogen and methane generation from molasses by Cunninghamella echinulata and anaerobic bacteria through sequential three-stage fermentation

Abstract

Biodiesel was produced by direct esterification of Cunninghamella echinulata dry mass using sugarcane molasses as substrate in the first stage of fermentation. GC/MS results for fatty acid methyl esters revealed abundant low degree unsaturated long chain fatty acids and saturated long chain fatty acids that are similar to plant oils. In the second stage, the spent medium of C. echinulata culture was used as the fermentation medium for hydrogen production by Clostridium acetobutylicum ATCC 824. The maximum total H2 yield was 1450ml H2/l after 48h fermentation. In the third stage, the spent medium of Clostridium containing volatile organic acids was used for methane production by methanogenic bacteria. The highest cumulative methane yield was 1690mll-1 spent medium obtained after 48h. The gross energy content of biodesel, H2 and methane generated through three successive stages fermentation from 84g molasses was 3928kJmol-1. The results presented in this study suggest a possibility of interlinking biodiesel production technology by fungi with hydrogen production by C. acetobutylicum and methane production by methanogenic bacteria to exploit the residual sugars and organic acids in the spent medium and therefore increase the economic feasibility of the bioenergy production from molasses. acetobutylicum spent medium was used for methane production through methanogensis