Isolation, Identification Of Biohydrogen Producing Bacteria And The Optimization Of Hydrogen Production Condition

Hydrogen is a clean energy, which can not only ease the energy crisis but also solve the environment pollution coming from fossil fuels. Therefore it has a wide range of applications. Anaerobic hydrogen production is a more potential method to obtain hydrogen energy for the reason that can use organic waste water and solid waste to produce hydrogen and the operation is relatively simple.In this paper,10 strains hydrogen producing bacteria were isolated by the methods of two overlapping air-culture dish and tablet coating method from the sewage treatment plant in Xi'an and Baoji Fufeng monosodium glutamate activated sludge plant. The strain WS-3 and the strain WJ-5 were high hydrogen production bacteria. The strain WS-3 was the highest hydrogen production bacteria from which can achieve 988 mL/L,the hydrogen production rate was 0.72molH2/mol glucose, the hydrogen production of the strain WJ-5 reached 905 mL/L, the hydrogen production rate was 0.66molH2/mol glucose.According to"Berger bacterial identification manual" (eighth edition), "General Methods for Identification of bacteria commonly used," the strain WS-3 and the strain WJ-5 was identified. The preliminary identification results are as follows:WS-3 belongs to Clostridium, WJ-5 belongs to Enterobacter.This experiment also studied the hydrogen production character of the stain WS-3, which included the biomass growth, hydrogen production, gas production, viable count, pH, sugar concentration changes. Cell growth, hydrogen production and gas production had a delay period, their values at this stage essentially unchanged, with the fermentation time increased, their value increases first and then stabilized until the hydrogen the end of fermentation. The important factors of influencing hydrogen fermentation conclude carbon and nitrogen sources, inoculum size, initial pH, fermentation temperature. These single factor experiment were studied. Then using the orthogonal design test method to determine the strain WS-3's optimum hydrogen production fermentative condition. The result showed that the optimum medium glucose concentration was 10g/L. The optimized nitrogen composition was 0.4% protein and 0.3% beef extract 0.2% yeast extract, L-cysteine concentration was 0.5 g/L. The optimum hydrogen production fermentative condition were that bacterium age 16h, the inoculation 10%, temperature 37℃, initial pH 7.0. After optimization, the bacteria's hydrogen production capacity was 1689 mL/L. The hydrogen production rate was 1.24molH2/mol glucose. It was increased by 70.9%than before (988 mL/L).The bacteria's average hydrogen production rate was 78.6mL/(L-h),It was increased by 86.3% than before (42.2 mL/(L·h)).The strain WS-3 was a strain with high yield potential of hydrogen and worthy of more in-depth study.This article also discussed the effort of the pretreatment methods of apple residue on the strain WS-3's hydrogen production. The effort of apple residue's concentration was aslo invested. The result showed that the best concentration of ammonia liquid was 0.75% and the best disposal time was 20 hours. Under the optimal pretreatment of ammonia liquid,the optimal concentration of apple residue was 20g/L. At this time, hydrogen production was 934 m L/L and the average hydrogen production rate was 57.0 mL/(L·h).