Dark fermentation of crude glycerol by locally isolated microorganisms to hydrogen

Abstract

The need for sustainable management of the waste along with the availability of crude glycerol (CG) has generated interest on glycerol-based cultures. To date, CG is used as cheap substrate in fermentation in replace of glucose or other types of substrates. In this study, raw CG is used as a sole substrate for the locally isolated microorganisms from biodiesel sludge to produce bio-hydrogen via dark-fermentation. Prior to the isolation of potential microbes, preliminary test was done to ensure that hydrogen is among the gases produced during the fermentation. This preliminary test was conducted using the wastewater. Mixed-microbes including the potential microbes were expected to be in the wastewater and help in the bioconversion of both pure and crude glycerol to hydrogen. The experiment using pure commercial glycerol was also conducted to compare the performance and conversion of the hydrogen. The gas was collected in a sampling bag. Analysis of the gas was done using GC-TCD with argon as carrier gas. Isolation and screening of potential hydrogen producer has successfully isolated 10 potential microorganisms. Screening was based on their ability to produce gas globules in the agar. Findings on the gas analysis showed that the microorganisms produced only hydrogen and carbon dioxide. No traces of methane was observed from the GC analysis indicating that no methanogenic microbes in the mixedcultures, and no foam was produced during the dark-fermentation using crude glycerol as carbon source. In contrast, foam is formed in the fermentation of pure commercial glycerol. From the findings, it can be concluded that the isolated microbes has the potential to produce hydrogen from the raw crude glycerol.