The Study On Hydrogen Production With Rice Straw And Apple Pomace By Anaerobic Fermentation

Fermentative hydrogen production resolves the organic wastes by biological technology to realize the aim of preparing bioenergy and reducing agriculture wastes. In this paper biological hydrogen was generated by anaerobic fermentation using cow dung and rice straw or apple pomace.Batch tests were carried out to analyze influences of several environmental factors on biohydrogen production from rice straw such as pre-treatment,initial pH value,temperature and substrate concentration.The experimental results showed that sulfuric acid（H₂SO₄） pretreatment had a significant role on hydrogen production in the fermentation of rice straw.The 1.8%H₂SO₄ heat pretreatment for thirty minutes （19.64ml/gTS） had remarkable effect on the hydrogen production,which was increased by 196 times as compared with the untreated rice straw（0.1ml/gTS）. Temperature was the key factor influencing on the hydrogen production through the anaerobic fermentation of rice straw.After orthogonal tests,the best hydrogen productivity of rice straw was 32.42ml/gTS under the conditions of initial pH8.5, T=37℃,ratio of cow dung and rice straw 0.44:1 and substrate concentration 57.89g/L, moreover,the hydrogen concentration was 67.93%and there was no methane detected.Comparison of the rice straw fermentation results,temperature also had a great influence on the hydrogen production in the fermentation of apple pomace.The fermentation conditions of producing hydrogen from apple pomace were studied by a serial of single factors and orthogonal design tests.The best hydrogen productivity of apple pomace was 35.21ml/gTS under the conditions of initial pH8.0,T=37℃and substrate concentration 34.32g/L,the hydrogen concentration was 61.19%and also there was no methane detected.Based on the results of batch tests,biohydrogen production from rice straw and apple pomace were carried out in a 5-liter stirred-tank reactor.The mechanism of bio-degradability of hydrogen-producing substrates and the pH value changes were discussed.The results showed volatile fatty acids（acetate,butyrate and propionate） and alcohols（ethanol and propanol） were both generated accompanied with hydrogen-producing process.They were the main by-products in the metabolism of hydrogen fermentation.The test results showed that fermentation process from rice straw and apple pomace were butyrate-style fermentation,which acetate and butyrate accounted for 87%and 71%of the total by-products,respectively.