| In this paper, the effects of different concentrations of depressants on anaerobic H2production were investigated and microbial community structure was also examined by using DGGE. Thus the favorable microbial communities for fermentative H2production by anaerobic sludge were obtained. The effects of benzoate concentration on CH4production and benzoate anaerobic degradation were analyzed with kinetic mode. The continuous experiments were conducted to explore how to enhance the activity of H2-producing acetogens in UASB reactor on the basis of the results of batch experiments. The analysis results for relative abundances of H2-producing acetogens using FISH approach along with the SMA determination demonstrated that the bacteria were enriched. The main conclusions are as follows:(1) The H2production ability by anaerobic sludge could be improved through repressing methanogenic activity with CHCl3and phenol pretreatment. Correspondingly, the favorable microbial community structures for H2production by anaerobic sludge were formed by controlling organic inhibitors concentration in appropriate level. The optimal concentration of CHCl3and phenol for H2production were0.050%and800mg COD-L-1, respectively.(2) With benzoate as the sole carbon source, the maximum CH4yield and specific CH4production rate were achieved at substrate concentration of1.Og-L-1and1.2g-L-1, respectively. The maximum benzoate concentration for CH4production was2.79g·L-1according to Han-Levenspiel model analysis. The benzoate degradation rate was found to be the first order within range of substrate concentration from0-2.Og·L-1.(3) The UASB reactors were operated at internal temperature of37±1℃, pH of6.8-7.2, and HRT of30h. The activity of hydrogen-producing acetogens could be effectively enhanced by adding sodium acetate in influent (COD:N:P=300:5:1) of UASB. Both SMA of anaerobic sludge and relative abundances of H2-producing acetogens through augmentation were improved significantly compared to control system. |
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