Continuous hydrogen production from cassava starch processing wastewater by two-stage thermophilic dark fermentation and microbial electrolysis

Abstract

Hydrogen production from cassava starch processing wastewater by two-stage thermophilic dark fermentation and microbial electrolysis was investigated. Single-chamber membrane-free microbial electrolysis cell with applied voltage of 0.6 V was optimum for hydrogen production with hydrogen yield of 245 ml H2 gCOD−1. Continuous microbial electrolysis reactor has a maximum hydrogen yield of 182 ml H2 gCOD−1 at HRT of 48 h with energy recovery efficiency of 217%. The continuous integrated two-stage dark fermentation and microbial electrolysis have hydrogen yield of 465 ml H2 gCOD−1 with 2 times hydrogen yield improving compared with a single stage and a maximum COD removal of 58% was achieved. Dominated bacteria at an anode of microbial electrolysis cell were exoelectrogens belong to Brevibacillus sp. Caloranaerobacter sp. and Geobacillus sp. Continuous two-stage thermophilic dark hydrogen fermentation and microbial electrolysis were efficient processes for hydrogen production from cassava starch processing wastewater.