Utilization of lactic acid rich medium and cassava starch wastewater for biological hydrogen production

Abstract

H2 production from lactic acid rich medium and H2 production from cassava starch wastewater by isolated bacteria were investigated. The isolation of H2 producing bacteria from heat treated sludge was carried out. The H2 production from lactic acid rich medium which used 1.5 g/L sodium acetate, 1.5 g/L sodium lactate and 1 g/L sucrose as carbon sources. The effects of inoculums size of 10, 20, 30 and 40 % (v/v) and incubation temperature of 35, 45 and 55 °C using cassava starch wastewater as the substrate on H2 production by isolation strains were investigated. Results showed 6 isolated strains i.e. isolation code of MK01to MK06 indicated the H2 production capability when cultured in lactic acid rich medium. However, 3 isolated strains i.e. MK01, MK04, and MK06 were preferred to use as seed inoculums for further experiments depend on a high H2 production capacity obtained. Results indicated that the optimal condition of H2 production from cassava starch wastewater was 30% (v/v) inoculum size of MK06 under 35°C of incubation temperature. The maximum H2 production potential, H2 yield and H2 production rate of 4.20 L H2/L medium, 1.47 L H2/g substrate consumed, and 14.00 mL H2/L/h was obtained. Identification and characterization of MK06 were investigated using 16S rRNA gene sequence analysis followed by phylogenetic analysis. The 100% similarity of 16S rDNA compare with closely related species was indicated Klebsiella pneumoniae subsp. pneumoniae DSM 30104(T).