Effect of Initial pH on Thermophilic Fermentative Hydrogen Production From Cassava Ethanol Wastewater

Abstract:

The effect of initial pH(4.0~10.0) on thermophilic fermentative hydrogen production from cassava ethanol wastewater was investigated in batch experiments.Results show maximum hydrogen product (383 mL) is obtained at initial pH 6.0 and the corresponding hydrogen yield is 70 mL·g-1.The total amount of VFA /ethanol and the proportion of acetic acid in the VFA increase with the increase of pH.The distribution of aqueous products is always dominated by butyrate.The heat-pretreatment at 90℃ for 1h cannot completely inhibit the activities of methanogenic bacteria and homoacetogenic bacteria.Hydrogen consumption at different degrees was observed at initial pH 6.0~10.0,and methane was detected at initial pH 9.0~10.0 during the fermentative process.The degradation of substrates in cassava ethanol wastewater and fermentative products further demonstrate that the hydrogen is generated from the production of butyrate,resulted from the carbohydrate degradation.

Key words:initial pH; cassava ethanol wastewater; fermentative hydrogen production