Enhancing biohydrogen production by optimization of waste potato concentration in dark and photo fermentation

Abstract

Hydrogen (H₂) production using biological dark and photo fermentation processes with carbohydrate rich wastes are environmentally friendly and inexpensive methods for organic waste treatment and cleaner fuel production. The current study aims for H₂ production using carbohydrate rich potato waste powder by dark and photo fermentation. The carbohydrate concentration from 1 to 5 g L^-1 was optimized during fermentation process for enhancing H₂ yield. Additionally, the effect of total volatile fatty acid (TVFA) concentration (1.53 and 3.06 g L^-1) on H₂ production was investigated in photo fermentation. In addition to acetic and propionic acids, trace amounts of lactic and butyric acids were detected in dark fermentative effluent (DFE). A maximum H₂ yield of 175 mL H₂ g^-1 carbohydrate (1.41 mol H₂ mol^-1 glucose) and 240 mL H₂ g^-1 carbohydrate (1.92 mol H₂ mol^-1 glucose) was obtained with carbohydrate concentration of 2 g L^-1 in dark and photo fermentation respectively. H₂ yield for DFE (TVFA 1.53 g L^-1) and synthetic DFE (TVFA 3.06 g L^-1) was 58.9 and 212.4 mL H₂ g^-1 TVFA respectively. The maximum H₂ production in dark and photo fermentation was 600 and 800 mL L^-1 respectively at carbohydrate concentration 5 g L^-1, indicating the photo fermentation process has higher efficiency than dark fermentation. Further an adjacent R² of more than 99% indicated a good fit of various models with experimental data.