半连续补料沼气发酵过程中主要微生物生理群的消长及其对产甲烷效率的影响

每隔11天以青草和猪粪(9:1)连续补料四次,每次补料后主要微生物生理群的消长趋势基本一致。随着补料次数的增加,纤维分解细菌、产酸细菌、氨化细菌的最高菌数略有下降趋势,其菌数对数由第一次补料后的5.3、8.6、7.7到第四次补料后则为4.6、6.28、6.28。而产甲烷细菌则比较稳定,甚菌数对数均为6.0。半连续补料能维持较长时间的较高日产气效率。日产气效率和纤维素、半纤维素降解率呈正相关,而纤维素、半纤维素的降解率又直接受纤维分解细菌的影响。每次补料后,纤维素降解率分别为38.51％、38.80％36.71％和31.96％,平均日产气效率分别为17.90、19.90、18.50和17.80m1/g·d。沼气中甲烷百分含量和日产甲炕效率的高低与产甲炕细菌菌数有关。每次补料后的平均甲烷百分含量为58.00％、52.30％、55.80％、60.00％,平均日产甲烷效率分别为10.97、10.54、10.88、10.68ml/g·d,比较稳定。

THE CROWTH GURVES OF PRINCIPAL MICROBIAL PHYSIOLOGICAL GROUPS AND THEIR EFFECTS ON METHANE PRODUCING RATE IN SEMI-SUCCESSIONAL ADDITION OF FERMENTING MATERIALS

With intervals of every 11 days, 4 times of semi-successional addition of green grasses and pig manure (9:1) to the fermentor as the fermenting materials for methane production were applied. After each addition of new materials, the growth curves of principal microbial physiological groups were in a similar tendency. In the later additions, the highest numbers of cellulose decomposing bacteria acid-producing bacteria and ammonifying bacteria gredually decreased, but the methane producing bacteria remained constant. In this semi-successional fermentation, a prolonged period of high rate daily gas production was maintained. The daily gas production rate was in positive relationship with cellulose and hemicellulose decomposition rates, which were directly in relation to the development of cellulose decomposing bacteria. Methane content of the gas produced and the methane producing rate were determined by the total number of methane producing bacteria developed. The methane production after each addition of fermenting material was in constant rate.