Effects of Acetic Acid Production on Dry Fermentation Systems with Corn Stalk

In order to solve the problems of fermentation failure and unstable operation caused by acetic acid accumulation in the dry anaerobic fermentation system,gas chromatography was used to determine the contents of acetic acid and CH4 during dry anaerobic fermentation with corn stalks. Correlations between contentes of TS,acetic acid and the dynamic tent of acetic acid production were studied by correlation analysis and regression analysis. The effect mechanism of content of acetic acid on CH4 production was also investigated. The results showed that content of acetic acid increased first and then decreased during the dry anaerobic fermentation. With content of TS increase from 20% to 30%,the duration of content of acetic acid increase extended from 5 to 15 days. Pearson correlation analysis indicates a significant negative correlation between contents of TS and acetic acid(R - 0. 979,P 0. 01). The equation,y =- 1 214. 8w(TS) + 668. 2,was obtained by unitary linearity regression analysis; the equation suggested that the production of acetic acid was clearly restrained by TS. During the dry anaerobic fermentation of corn stalks,content of acetic acid system was 160-451 mg/g. With the increase of content of acetic acid,the production of CH4(TVS) increased initially and then remained stable,then finally decreased.The maximum production was more than 120 m3/t with the content of acetic acid ranging from 212 to 312 mg/g,while the production of CH4 achieved 80-120 m3/t with the content of acetic acid ranging from 312 to 410 mg/g.