Hydrogen Production in Incubated Anaerobic Mesophilic Mixed Culture by Oleic Acid (OA) for Different Periods

Abstract

Compared to carbon-based fossil energy sources such as coal and oil, hydrogen is considered an important and promising alternative energy carrier because it can reduce carbon dioxide emissions, and it can also produce energy. Wastewater from dairies, food and vegetable oil processing industries contain large amount of Long Chain fatty Acids (LCFAs). Oleic acid (OA), a group of LCFA can be used incubated in anaerobic mesophilic mixed culture for hydrogen production. With OA, wastewater was treated, and hydrogen was produced through the fermentation of glucose using incubated cultures at 37 °C and pH 5.0 for varying periods. Inhibitory effect of OA and its β-oxidation by-products on hydrogenotrophic methanogens in all the OA incubated cultures were also examined. Hydrogen production from glucose fermentation was studied using mixed anaerobic cultures incubated to 2000 mg/L Oleic acid (OA) for varying periods (0 to 25 days in 5 days consecutive increments) at 37 °C under low pH conditions (pH 5). Accumulation and production of Hydrogen was observed for all cultures incubated with OA. Inhibitation of methanogenic activity was found for OA and OA β-oxidation by-products, palmitic, myristic and lauric acids. OA and lauric acid suppressed methanogenic behaviour to the same degree on the basis of hydrogen yields. The average hydrogen yield detected over the duration of the study was 2.12 ± 0.44 mol H2 per mole glucose while maximum yield of 2.44 ± 0.12 mol H2 mole−1 glucose was observed in cultures where OA was predominant.