Research Of Methane Production From Restaurant Wastewater And Corncob And Utilization By Black Soldier Fly Wuhan Strain

As the serious shortage situation of the fossil energy and the increasingly pollution of environment, converting organic wastes into energy materials play a very important role in our life. Restaurant wastewater is the main component in restaurant wastes, as a source of pollution threatening the urban living environment and our healthy. Corncob is one of several kinds of organic wastes that have not been fully used embodied much energy matter. The resource utilization of these organic wastes can alleviate the energy shortage. At present, anaerobic fermentation is one of the main technologies for biological treatment of organic wastes for energy production. Meanwhile, using insects to convert organic waste for biomass accumulation for the production of energy material also becomes a highlight of scientific research in this century. Anaerobic fermentation and black soldier fly wuhan strain(Hermetia illucens) conversion were applied for renewable energy production from restaurant wastewater and corncob in this study, it could achieve the goal of utilization of organic wastes and obtain additional energy, develop new areas of utilization of the biological energy, provide reference for the sustainable development of biomass.Composition and acidification characteristics of different sources of restaurant wastewater were investigated and it was found that the higher the temperature, the faster the acidification. In order to improve the pH value and relieve the inhibition of acidification during anaerobic fermentation, different proportions of aerobic activated sludge inoculated in restaurant wastewater for improving pH value were discussed. Then, research on the influence of the aeration treatment on the basis of the aerobic activated sludge treatment on restaurant wastewater was applied. The results showed that the pH value of restaurant wastewater quickly grew to about 6.5 after the combination treatment of aeration and aerobic activated sludge. Then different ratios of anaerobic activated sludge were inoculated in restaurant wastewater for methane production. Meanwhile, different alkali pretreatment of restaurant wastewater for anaerobic fermentation was applied. The results showed that the most methane production group with the average methane rate 1.70±0.1L/d was pretreated by 30% KOH before anaerobic fermentation. Explore the acidification characteristics of restaurant wastewater and study the methane production from high concentration of acetic acid of restaurant wastewater, can provide the basis for the pretreatment of corncob by restaurant wastewater which can be used as acid pretreatment material.In order to study the energy production potential of corncob, this research used different proportions of corncob and pig manure for anaerobic fermentation for methane production, 3:2 ratio of corncob and pig manure at dry weight was analyzed as the best methane-producing group, it found that 86.70 L biogas was produced from 400 g corncob after 29 days of anaerobic fermentation, the accumulation biogas production rate was 220.71mL/gVSadded, the accumulation methane production rate was 139.37mL/gVSadded; Black soldier fly wuhan strain was utilized for conversion on biogas residue, it produced 14.35 g of black soldier fly wuhan strain dry larva after 8 days, extracted 3.34 g grease and prepared 3.17 g biodiesel, biodiesel extraction yield was about 94.91%, meanwhile, about 2.05% of the lignin was degraded. Corncob not only can produce methane by anaerobic fermentation, but also can prepare biodiesel by black soldier fly wuhan strain conversion, and the process of black soldier fly wuhan strain conversion has the potential of biodegrading fibers.For further research of the process of energy production from corncob by black soldier fly wuhan strain, this study respectively used acetic acid and KOH, cellulose and yeast pretreated corncob. Supernatant was respectively utilized for methane production by anaerobic fermentation. After comparison of different groups on biogas and methane production potential, it was found that 8% acetic acid pretreatment group and 2% KOH pretreatment group were better than others on gas production after 13 days anaerobic fermentation in 800 ml working volume, they produced biogas and methane respectively 6.46 L and 3.03 L, 6.14 L and 3.06 L. In addition, it was found that high concentration of KOH pretreatment could inhibit the gas production of supernatant; Corncob residue was converted for 10 days by black soldier fly wuhan strain, it was found that 4% acetic acid treatment group and 4% KOH treatment group respectively produced about 0.26g/50 and 0.44g/50 larvae grease which were more than others, the oil extraction rate reached 23.01% and 24.04%, respectively. Cellulose, hemicellulose and lignin were largely degraded in the whole process, which indicated that energy production from corncob by the biological combined treatment of anaerobic fermentation and black soldier fly wuhan strain conversion is feasible.According to the acidification characteristic of restaurant wastewater, restaurant wastewater was used as acid additives pretreated corncob for the study of methane production and fat accumulation in black soldier fly wuhan strain. After orthogonal experiment of restaurant wastewater pretreated corncob, it was found that soaking temperature of 75℃, soaking time of 5h and soaking concentration of 60g/L were the optimum pretreatment conditions. About 15.04L/(Lsupernatant) of biogas with 6.44 L/(Lsupernatant) of methane was produced from supernatant by anaerobic fermentation after 4L restaurant wastewater soaked 240 g corncob under optimum pretreatment conditions, about 1.33 g grease was extracted from 200 black soldier fly wuhan strain after the conversion on corncob residue. Degradation rate of cellulose, hemicellulose and lignin of corncob were respectively about 27.34%, 45.14% and 29.33% during the whole process. Based on the characteristics of restaurant wastewater, this study used restaurant wastewater soaked corncob for methane production by anaerobic fermentation and black soldier fly wuhan strain converted corncob residue for fat accumulation. It can provide reference for production of energy by combining technologies of anaerobic fermentation and black soldier fly wuhan strain conversion.