Maximization of Energy Recovery from Starch Processing Wastewater by Thermophilic Dark Fermentation Coupled with Microbial fuel Cell Technology

Abstract

Utilization of organic wastewater for hydrogen production has dual advantages of clean energy generation and bioremediation, which is sustainable for a longer period. To maximize the energy recovery from starch rich wastewater, a two stage system comprising of thermophilic dark fermentation coupled with microbial fuel cell was employed. A single parameter optimization strategy was implemented for the operation of the batch system. The maximum cumulative hydrogen production obtained was 2.56 L L⁻¹ with a 48% reduction in COD under the optimal conditions of 35 g L⁻¹ initial substrate concentration (COD), temperature 60 °C, and pH 6.5. The H₂ yield and H₂ production rate were 6.8 mol H₂/kg COD_reduced and 731.3 mL L⁻¹ h⁻¹, respectively. The effect of the organic loading rate (OLR) on H₂ production rate was studied in a continuous stirred tank reactor (CSTR). A maximum hydrogen production rate of 913 mL L⁻¹ h⁻¹ was observed at an OLR of 5.6 g L⁻¹ h⁻¹. Effluent recycle played an important role in the improvement of H₂ production. A maximum H₂ production rate of 1224 mL L⁻¹ h⁻¹ was observed at a recycle ratio of 0.6. Power density of 4.2 W m⁻³ was observed with MFC using the dark fermentative spent media neutralized with carbonate buffer at an optimal pH of 7. A total COD reduction of 86% was observed.

Keywords:

• CSTR
• energy efficiency
• microbial fuel cell
• starch processing wastewater
• thermophilic dark fermentation

Acknowledgement

The authors wish to thank the financial support from MNRE, CSIR, UGC, and DBT, Govt. of India and IIT Kharagpur for the facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.