Raw Material (cow Dung, Seaweed) Anaerobic Fermentation Hydrogen Production From The Study

Biological hydrogen was generated from cow dung compost and kelp by anaerobic fermentation. Batch tests were carried out to analyze influences of several environmental factors on biohydrogen production from different substrates such as pH value, chemical pre-treatment and substrate concentration. The experimental results showed that the optimal initial pH values of biohydrogen production form cow dung compost and kelp were 5.0, 6.5, and the optimal substrate concentrations are 70g/l, 50 g/l, respectively. Before the raw cow dung compost and kelp were degraded by microorganisms, first they were pretreated with 0.2% HC1 and 10% lactic acid by heating 30min, respectively. The maximum cumulative hydrogen yields and maximum hydrogen concentrations of cow dung compost, kelp under the optimal conditions were 19 mlH2/g-TVS, 84 mlH2/g-TVS and 38.6%, 32%, respectively. There was no significant methane observed in the biogas throughout the study. The maximum hydrogen production rates were 1.1ml H2/(gTVS·h), 1.0 ml H2/(gTVS·h) by calculating, respectively. Test results confirmed that pre-treatment is an effective method improving hydrogen production ability. For different substrate, appropriate pre-treatment can improve more or less hydrogen production ability. For example, the accumulative hydrogen yield increased obviously from 13.3 mlH2/g-TVS of original cow dung compost to 19 mlH2/g-TVS of HCl pretreatment cow dung compost; and that of pretreated kelp was 6.4 times as compared with that of raw kelp.Based on the results of batch tests, biohydrogen production from cow dung compost was carried out in a 5-liter stirred-tank reactor. The mechanism of bio-degradability of hydrogen-producing microorganism and oxidation-reduction potential (ORP) were discussed. The results showed VFAs (acetate, butyrate and propionate) and alcohol are generated accompanied with hydrogen-producing process. They are the main by-products in the metabolism of hydrogen fermentation. The test results show that fermentation process from cow dung compost is butyrate-style fermentation. The hydrogen production was accompanied with the formation of VFAs and alcohol while both of them were the main by-products in the metabolism of...