Influence of acetic acid on biohydrogen production

• Main Authors: Chia-shan Hsu, 許佳珊
• Other Authors: Kuo-shun Fan
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/05187670234873648481

碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程所 === 95 === During the anaerobic fermentation process, organic matter converted to hydrogen, acetic acid, propionic acid, butyric acid and alcohols by fermentative bacteria, but during reaction process had usually inhibition feedback of production. Recently, a lot of aimed at environmental factor and little information is available regarding the inhibitory of volatile fatty acids on hydrogen fermentation in the literature. Therefore, this study was conducted to investigate the influence of acetic acid that one of the main VFAs on the biohydrogen production. Because of acetic acid the same existed form were acetic acid and acetate ion in water. Both of role on the biohydrogen production also were this study point. In this study batch experiments were by using glucose and sludge after cultivate in continuous-flow stirred tank reactor when biogas rate on steady stage was used. Control condition is sodium acetate concentration range of 62.5 to 20000 mg/L and pH range of 4.5 to 6.5. Using full factorial experiment design to worked three different sodium acetate concentration range test: Test 1:62.5 - 500 mg/L; Test 2:2000 - 8000 mg/L and Test 3: 5000 - 20000 mg/L. Every test had one blank (didn’t add sodium acetate) for contrast. Then using inhibition model and Grompertz equation and multiple regression to analyze data. Results are reported sodium acetate concentration smaller than 5000 mg/L and pH greater than 5.5, hydrogen production increased about 10~20%. But sodium acetate concentration above 10000 mg/L and under pH 5.0, hydrogen production decreased more than 95% to blank. It showed low sodium acetate concentration and high pH conditions would raise hydrogen production. The effect of pH showed when above pH 5.5 hydrogen production increased about 10~30%. On the other hand, under pH 5.5 hydrogen production decreased about above 60%. Hydrogen production accompany with pH increased. The inhibition of acetic acid addition on hydrogen production was described well by a non-competitive and non-linear inhibition model. When acetic acid concentration is lower than 126 mg/L （C10, the acetic acid concentration at which bioactivity is reduced by 10%), bioactivity was only slightly inhibited and acetic acid concentration increase to 778 mg/L (C50) imposed a moderate inhibitory effect on bioactivity. When acetic acid concentration is greater than 5000 mg/L (C*), acetic acid will a strong inhibitory influence on bioactivity, showed decreased bioactivity accompany with increased acetic acid concentration and not direct correlate with pH changed. The inhibition effect of acetate ion addition to hydrogen production was showed that C10, C50, C* value is 171 to 1288 mg/L, 924 to 7505 mg/L and 3000 to 9000 mg/L with pH 4.5 up to 6.5, respectively. And obvious effect of acetate ion concentration inhibited bioactivity with lower pH. Both of pH and acetate ion concentration were effect hydrogen production of hydrogen producing bacteria.