Abstract
Repeated batch cultivation is known as most attractive method in improving hydrogen productivity, due to the facts that this approach could minimize the reuse of the cell and the inoculum preparation. In addition, with the combination of attach growth system during the fermentation processes to produce biohydrogen, the density of cells will be increased and the cell washout could be avoided. Therefore, this study aimed to examine the effectiveness of repeated batch cultivation for enrichment of anaerobic mixed culture onto granular activated carbon (GAC) and investigate the effect of molasses concentration during immobilization of mixed culture onto the GAC. The molasses concentration using 50 %, 40 %, 30 %, 20 % and 10 % of diluted molasses were used as feedstock in the fermentation process. The maximum hydrogen production of 60 ml was obtained at 30 % of molasses concentration with 831 ppm of hydrogen concentration. Thus, the kinetic parameter obtained from the batch profiling based on modified Gompertz equation are, Hm= 58 ml for the maximum hydrogen production and Rm= 2.02 ml/h representing the hydrogen production rate.
Highlights
Nowadays, the utilization of fossil fuels was rapidly increase as energy supply especially in transportation and electricity
The characterization of seed sludge as inoculum to immobilized on granular activated carbon (GAC), and molasses as feedstock were listed as follow: Table 2
The hydrogen collected was increased from 19 ml to 21.3 ml when the molasses concentration is increase from 10% to 20% and 30%
Summary
The utilization of fossil fuels was rapidly increase as energy supply especially in transportation and electricity. About 75% of the increasing CO2 concentration in the atmosphere contributes from burning of fossil fuels. Burning fossil fuels resources could increase four times the present value of the CO2 concentration in the atmosphere which of about 350 to 1500 ppmv (parts per million by volume) [1]. There is a need to replace the fossil fuels with a new renewable energy sources such as hydrogen. Hydrogen has high energy yield which is 122 kJ/g compared with other fuels [3]. There are few types of processes, which are light-dependent processes (e.g. photo-fermentation) and lightindependent processes (e.g. dark fermentation) [4]. Dark fermentation is more attractive due to the ability of anaerobic microorganism to produce hydrogen gas
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