| Summary: | 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.
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