Comparative study on Thermotoga maritima and Rhodobacter meghalophilus for hydrogen gas production using crude glycerol from Biodiesel plants

Abstract

Hydrogen gas is a clean fuel with high calorific value. The current study is focused on production of hydrogen gas using Rhodobacter meghalophilus and Thermatoga maritima through anaerobic fermentation. Crude glycerol, by-product from biodiesel plant is used as carbon substrate due to its rich organic composition. Batch experiments have been carried out to study the impact of the inoculum size (1, 2 and 4 mL/L) and crude glycerol (5,10 and 15 mL/L) on the bacterial growth and hydrogen production rates by both the organisms. Inoculum size of 2 mL/L and crude glycerol of 15 mL/L of crude glycerol in medium for fermentation by R. meghalophilus, is found to produce 160 mL/L of gas with hydrogen production rate at 1.163×10-8 m3/kg.s and substrate conversion efficiency of 43.28%. Anaerobic fermentation by T. maritima is found to produce 120 mL/L of gas with 2 mL/L of inoculum and 10 mL/L of crude glycerol with hydrogen production rate of 9.4×10-9 m3/kg.s and substrate conversion efficiency of 23.88%. GC analysis of gas produced by T. maritima and R. meghalophilus shows 25% (v/v) and 19% (v/v) of hydrogen respectively. Thus, R. meghalophilus is found to acclimatize faster and exhibit better hydrogen production rate while T.maritima produces higher yield of hydrogen.