Production of bioethanol from potatoes wastes as an alternative fuel

Production of ethanol from biomass is one way to reduce both the consumption of crude oil and environmental pollution. The current research focused to produce the bioethanol from crop wastes. The study carried out in Agricultural Engineering Department and Agric. Botany Department at faculty of Agriculture, Kafrelsheikh University. The main objective in this part of the current study is producing the bioethanol from potato wastes to applicable in the engine of the farm machine. The experiment was carried out in aerobic batch digester and bioreactor after potato tubers wastes pretreatment with Bacillus subtilis (E34) as amylolytic bacteria for 7 days. The bioreactor system consists of three main units. The first unit was ethanol reactor which represents the main unit of the fermentation process and the second is the agitating unit required to enhance the fermentation process and to increase the efficiency of ethanol production for all treatments. Third unit is the collector tank; it is consisted of the 8 liters capacity tank with input and output valves. The output valve used to measure the pH values for different ethanol production. The 10 liters of water that was feeding in solution of potatoes wastes was heated to 30°C. Bioethanol fermentation was conducted in reactor. The yeast Saccharomyces cerevisae was used for fermentation process in dried form. The inoculum was used at 50 g from dried Saccharomyces cerevisae were used to inoculate 3 l from the pretreated potato wastes. The pH of the medium was adjusted to 4.5. All experiments were incubated at 30°C under different stirring speeds (30, 120 and 200 min-1) in the reactor for 7 days. The values of the percentage of bioethanol production increased and reached to the maximum values after 18 hour of elapsed time for 30 min-1, 120 min-1 and 200 min-1 agitation rotational speeds. The maximum values of bioethanol production percentage were 37.8%, 44.45% and 68.68% after 18 hour elapsed time for 30, 120, 200 min-1 respectively. On the other hand, the increase of agitation speed from 30 to 200 min-1 tends to increase the percentage of bioethanol production. The energy requirement of volume bioethanol production increased due to increase of the agitation speed from 30 min-1 to 200 min-1. The highest value of energy requirement was 5.9 Wh at 200 min-1 after 24 hours for bioethanol production. The lowest energy requirement for agitation was 8.7 Wh at 30 min-1 after 2 hours. Bioethanol production increased and reached to 70.9% at 18 hour of duration time for bioreactor compared to 65% bioethanol percent after 18 days for batch reactor.