Fermentative production of hydrogen from cassava processing wastewater by Clostridium acetobutylicum

This work reports on the effect of initial substrate concentration on COD consumption, pH, and H2 production during cassava processing wastewater fermentation by Clostridium acetobutylicum ATCC 824. Five initial COD wastewater concentrations, namely 5.0, 7.5, 10.7, 15.0, and 30.0 g/L, were used. The results showed that higher substrate concentrations (30.0 and 15.0 COD/L) led to lower H2 yield as well as less efficient substrate conversion into H2. On the other hand, initial COD concentrations of 10.7, 7.5 and 5 g/L furnished 1.34, 1.2 and 2.41 mol H2/mol glucose, with efficiency of glucose conversion into H2 of 34, 30, and 60% (mol/mol), respectively. These results demonstrate that cassava processing wastewater, a highly polluting effluent, can be successfully employed as substrate for H2 production by C. acetobutylicum at lower COD concentrations.

► Five concentrations of cassava processing wastewater were used for H2 production.
► Higher substrate concentrations (30.0 and 15.0 gCOD/L) led to lower H2 yield.
► Lower cassava wastewater COD concentrations lead to higher H2 production.
► 2.41 mol H2/mol glucose was obtained using 5g COD/L of cassava wastewater.
► Cassava wastewater can be used to produce clean energy.