Abstract:
The effects of bacterial stress enrichment combined with different feed to inoculum (F/I) ratios on the bio-hydrogen yield from potato peel and cabbage waste were studied in various volatile solid (VS) concentrations using batch anaerobic digesters under mesophilic conditions in three stages. From results of the preliminary study, it was concluded that inoculum treated with heat shock at 95°C had the longest lag time of 48 hours, but it was most successful at suppressing the methanogens giving the least methane production out of all the 4 pre-treatment methods employed. Heat shock at 35°C produced most amount of hydrogen which was 158 times more than the control reactor. Heat shock at 35 and 95°C and aeration for 24 hours were selected to proceed to the next phase of experimentation which was to study the effects of feed to inoculum ratio at VS concentrations ranging from 0.35 to 0.76. In the repeated batch experimentation, 95P20 gave the highest specific biogas yield of 87.74 ml H2 per gram of VS added followed by aCP20 which stood at 61.57 ml H2/gVS added and 35P20 which yielded 56.86 ml H2/gVS added. Chemical characterization revealed the high removal efficiencies in terms of volatile solids, chemical oxygen demand and total organic carbon for the above mentioned reactors. This study concluded that hydrogen production is feasible from mixed microflora if the suitable method of microbial enrichment is paired with the appropriate F/I ratio since different microbes give different response to the pre-treatment method and organic loading in the fermentative digester.
