Research on the operation of butyric acid type fermentation and ethanol type fermentation of biological hydrogen production

On the base of the continuous flow test of mixed micro-flora, our research were the fermentation types and their H₂-Production capacity and the operation control of the biohydrogen production reactor. Also contrasted different ways to suppress the methanogenic activity. When the pH was between 6.57-;7.1, continuous stirred tank (CSTR) I got butyric acid type fermentation. The content of hydrogen in the biogas was 13%. When the pH was between 4.0-4.8, CSTR II got ethanol type fermentation. The content of hydrogen in the biogas was 49%. By the researches and analyses of the fermentation type in the biohydrogen production system, ethanol type fermentation bacteria have the largest H₂-Production capability, butyric acid type fermentation bacteria take the second place. When the influent COD was 5000 mg/L and the temperature was 35±l°C, the H₂-Yield corresponding were 19.4L/d and 1.8L/d. By adding B₂ES to CSTR I or controlling the hydraulic retention time (HRT) of CSTR II both could suppress the methanogenic activity.