Studies On Potato Lees Of Methane Fermentation

Biogas anaerobic fermentation is effected by many factors,the most important factors are temperature,inoculum size,pH,carbon and nitrogen ratio.The right temperature is conducive to microbial growth and reproduction, and a certain amount of inoculum is to ensure that the premise of fermentation, the appropriate pH is favor to the growth of microorganisms, too acid or too alkaline will prevent microbial growth even to death. The trial studies on the three potato (sweet potato, cassava, potato) lees of microorganisms and conditions, the main research method, content, results and significance are as follows:1. Through routine testing and analysis, the physical and chemical indicators of the three potato distiller's grains were determined, and found the protein and fiber content is more higher, protein content of potato (37.8413%)>cassava (32.1415%)>sweet potato (27.5721%); cellulose content of sweet potato (28.5020%)>cassava (24.6956%) >Potato (18.9092%);total sugar content of sweet potato (9.8078%)>cassava(7.0764%) > Potato (5.0623%); to understand the results of the nutritional content of the fermentation substrate, so as to make the premise for preparing fermentation.2. By measured sweet potato grains' change of gas production rate (gas production per gram of dry matter), to found the influence in different condition. It was found that at pH 7.0, inoculum 30%, temperature 30℃,35℃,40℃,45℃condition, temperature 45℃for sweet potato lees of gas production rate is the highest at 74.1856mL/g. At the conditions of pH 7.0, temperature 45℃, inoculum size were 20%,30%,40%,50%, the inoculation of 50% on sweet potato lees' gas production rate is the highest at 124.1447mL/g. At the temperature is 45℃, inoculation is 40%, pH conditions were 6.0-9.5, pH 8.0 for sweet potato lees of gas production rate is the highest at 173.0364mL/g.3. Methane content was analyzed by the guide Tianjin GC2010 gas chromatography, in the process of sweet potato lees fermentation, the highest amount of methane are 45℃,50% inoculum,pH7.5and the average percentage is 60.6724%,66.3670%,72.2646% respectively. 4. At the sweet potato distiller's lees anaerobic fermentation, the fixed fermentation time is 40d, using temperature, inoculum size and pH factors as L9 (34) orthogonal test, the best conditions of the total gas production rate, COD (Chemical oxygen demand) reduction rate and methane percent component is:A3B2C2, the temperature is 45℃, the inoculation is 40%, pH is 8.0, fermentation time is 40d.Though the validation test, the total gas production rate, COD reduction rates and methane percent components are 205.2675mL/g, 59.82%and 67.7459%.5. Analyzed the sweet potato, cassava, potato lees of the gas production rate, pH, NH4+-N (Amino nitrogen) and VFA (Total volatile fatty acids). Analysis shows that: at the optimum temperature, optimum inoculation, the best pH; the best pH for sweet potato lees of gas production rate is the highest at 173.0364mL/g; the pH in the latter period maintenaned at 7.5; NH4+-N is between 800mg/L-1000mg/L; VFA is between 400mg/L-1200mg/L; the best pH for cassava distiller's lees of gas production rate is the highest at 190.5353mL/g; the pH in the latter period maintenaned at 7.0; NH4+-N is between 400mg/L-1000m/L; VFA is between 100mg/L-1000mg/L;the best pH for Potato distiller's lees of gas production rate is the highest at 169.2110mL/g;the pH in the latter period maintenaned at 7.5; NH4+-N is between 1100mg/L-1700mg/L; VFA is between 300mg/L-1200mg/L.6. Compared the total methane production of three potato at the optimum temperature, optimum inoculation, the best pH, the result is that:at the best pH,sweet potato lees is the highest at 4905.4583mL; the best inoculation, Cassava lees is the highest at 4316.1928 mL; at the best pH, potato lees is the highest at 4922.8880mL.7. When in mid-temperature fermentation of sweet potato lees,microorganisms were cultured by serial dilutions of culture medium,using MPN method to counts,the results was checked by three largest contingent tables. The growth and reproduction of oxygen acid bacteria,aerobic bacteria,anaerobic bacteria,anaerobic ammonification acid bacteria and anaerobic bacteria is the fastest at 45℃.