Research on anaerobic digestion of pig hair after alkali pretreatment and biodegradation by Bacillus spp.

• Main Authors: Ting-Hsuan Yu, 于庭萱
• Other Authors: 蘇忠楨
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/k6x2y5

碩士 === 國立臺灣大學 === 動物科學技術學研究所 === 107 === Pig hair is one of slaughter wastes which contains high contents of keratins. The structure of keratins is recalcitrant made them hard to be biodegraded. But some chemical agents and keratinase are capable of destructing keratins to become soluble proteins. Besides, anaerobic digestion of organic matters in the slaughterhouse wastes can recover renewable energy, e.g. biogas, from the treatment process. The objective of this study was to evaluate the feasibility of biogas production from anaerobic digestion of alkali and microbial pretreated pig hair. A combination of hydrolysis with low concentration alkali solution and biodegradation by Bacillus licheniformis 11594 strain was performed as the pretreatment process. Those treated pig hairs with obvious hair appearance were used as the substrate for all time course experiments. Pig manure sludge was used as the sole inoculum for all time course experiments of anaerobic digestion. For the first batch, gas production of pretreated dried pig hair, which was pretreated with alkaline or the biodegradation, was compared with control group which no pig hair was add. For the second batch, addition of pig hair and its hydrolysate were compared with the control group. For the third batch, anaerobic digestion of pig hair and hydrolysate for promoting the methane production under different degradation time periods was investigated. Results of pig hair pretreatment experiments showed that the alkali pretreated pig hair increased the efficiency of microbial degradation by Bacillus spp. with prolonged cultivation time. Results of anaerobic digestion showed that the total gas production of alkali pretreated pig hair group and untreated pig hair group in a 30-d time period was 1310 and 1443 mL, respectively. Gas production of the group with pig hair addition increased significantly comparing to that of the control group (237 mL). However, the methane production in the alkali pretreated group was significantly lower than that of the untreated group. Among the hydrolysate addition groups under different degradation time period, the shorter cultivation time (a 4-d time period) group and the better its performance. Gas production of other groups (8- and 16-d time period) also much higher than that of the control group. Moreover, there was no significant difference between the 16-d time period pretreated group and the control in methane production. For the experiments of both pig hair and its hydrolysate addition, the control group carried out better gas production, but there was no significant difference on gas production between the control and any treatment groups. Because there were some easily biodegradable organic matters carried into anaerobic digester when inoculated with pig sludge. They might affect utilization of tough bio-degraded keratin and gas production during anaerobic digestion of pig hair. In conclusion, addition of dried pig hair in anaerobic digesters increased gas and methane production, but pretreatment of pig hair did not affect the efficiency of gas production. When the pig hair hydrolysate was used as the substrate, the group of a 4-d biodegradation pretreatment achieved best results. Besides, easily decomposed organic matters content was an important factor of anaerobic digestion.