| China has a large population of rural people, and energy shortage is a serious problem in rural China.The development of biogas technology is not only an effective way for renewable energy using, but also can improve the ecological environment in rural areas. It has significant benefits in energy, economy, ecology and environment. By exploiting the effects of temperature and ratio of mixing raw material on biogas production, discussing the trend of pH value in the whole process of anaerobic fermentation, giving an integrate study of temperature, ratio of material, pH value, the optimal proportion under different temperatures and materials is obtained and a theoretical basis for the raw material selection will be provided.A simulation experiment under 10℃～40℃and the mixture ratio of 3:1, 2:1, 1:1, 1:2 were conducted in a self-manufactured anaerobic fermentation reactor.Chicken dung, pig manure, cow dung with corn straw were chosen as fermentation materials. To approach the effect of anaerobic fermentation by mixed fermentation in different ratios and temperature and the change trend of liquid pH value in the whole course of reaction were discussed. In conclusion, the optimal ratio and the maximum gas production of mixed materials under different temperatures through the SPSS regression were analysed. The result showed that:1. View from the ratio of raw materials under 10℃～40℃, in the group of chicken dung with corn straw, the maximum cumulative gas production occurred at the ratio of 3:1, 1:2, 3:1 under 10℃, 15℃, 40℃and in the other temperature it occurred at the ratio of 2:1; in the group of pig manure with corn straw , the maximum cumulative gas production occurred at the ratio of 3:1 under 15℃and in the other temperature it occurred at the ratio of 2:1; in the group of cow dung with corn straw, the maximum cumulative gas production occurred at the ratio of 1:1, 3:1, 1:2, 1:2, 1:1, 1:2, 3:1 according to the order of temperature.2. View from the cumulative gas production of 3 mixture materials, the ratio of 2:1 was the best and it obtained the maximum gas production 16865mL under 35℃and the ratio of 2:1, 1:1 obtained the minimum gas production 310 mL under 10℃in the group of chicken dung with corn straw;the ratio of 2:1 was the best and it obtained the maximum gas production 15177mL under 35℃and the ratio of 3:1 obtained the minimum gas production 205 mL under 10℃in the group of pig manure with corn straw; the ratio of 1:2 was the best and it obtained the maximum gas production 12973mL under 35℃and the ratio of 2:1 obtained the minimum gas production 280mL under 10℃in the group of cow dung with corn straw.3. The pH value of the 3 mixture materials was generally low in the early of fermentation, and then it increased with the gas production rate increase, it decreased when the pH reached the maximum value, and showed dynamic changes in pH value throughout the whole fermentation process. The change range was smaller of pH value under 10℃～20℃, and along with response advance that the pH value of 3 mixture materials was increased until the end of the fermentation under 20℃, the pH value's change tendency was basically similar with gas production rate under 25℃～40℃.4. The experimentation results were analyzed by SPSS software showed that: Under 10℃when the ratio of pig manure with corn straw is 2.11:1, the maximum cumulative biogas production is expected to reach 261mL, when the ratio of cow dung with corn straw is 3.28:1, the maximum cumulative biogas production is expected to reach 313 mL. Under 15℃when the ratio of pig manure with corn straw is 1.35:1, the maximum cumulative biogas production is expected to reach 1440 mL. Under 20℃when the ratio of chicken dung with corn straw is 2.23:1, the maximum cumulative biogas production is expected to reach 3277mL, when the ratio of pig manure with corn straw is 1.79:1, the maximum cumulative biogas production is expected to reach 6272mL. Under 25℃when the ratio of chicken dung with corn straw is 1.87:1, the maximum cumulative biogas production is expected to reach 10254mL, when the ratio of pig manure with corn straw is 1.68:1, the maximum cumulative biogas production is expected to reach 11000 mL. Under 30℃when the ratio of chicken dung with corn straw is 1.86:1, the maximum cumulative biogas production is expected to reach 12084mL, when the ratio of pig manure with corn straw is 1.89:1, the maximum cumulative biogas production is expected to reach11864mL, when the ratio of cow dung with corn straw is 2.82:1, the maximum cumulative biogas production is expected to reach 9895mL. Under 35℃when the ratio of chicken dung with corn straw is 1.81:1, the maximum cumulative biogas production is expected to reach 17000mL, when the ratio of pig manure with corn straw is 1.86:1, the maximum cumulative biogas production is expected to reach 15246 mL. Under 40℃when the ratio of chicken dung with corn straw is 1.467:1, the maximum cumulative biogas production is expected to reach 15095mL, when the ratio of pig manure with corn straw is 1.47:1, the maximum cumulative biogas production is expected to reach 15513mL. |
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