Study On Hydrogen Production From Cornstalk By Fermentation

Hydrogen is a clean renewable energy.In the process of burning it only produces water without carbon-based emissions that contribute to environmental pollution and climate change. Currently, with the more requirement to energy and the increasing price of petroleum,the problem of energy shortage and environmental pollution brings challenge to sustainable development of our nation economy.So,it is very significative to find some new substituted energy,develope the study of renewable energy for protecting the security of energy strategy and reducing the environmental pollution.In this process, micro-organisms degrade organic wastes to produce hydrogen.It reaches two aims: getting rid of wastes and protecting environment.So it must have a good future.Based on the results of the batch test, biohydrogen production has been carried out in a 5-litre mixed reactor from agricultural organic wastes(cornstalk) by natural anaerobic microorganisms,we got the significant study result.1. The method of enrichment, culture and the condition of acclimation was investigated with natural anaerobic microorganism bacterium from cow dung compost, the sucrose as substrate. The results showed that it was effective that the compost was boiled for 15 min and then aerated for 2 hours to harvest hydrogen bacteria, the hydrogen productivity was 141.86 ml/g,gas production began after only 10 hours; semi-continuous culture method was introduced, at time points of 12 hours after the bacterium was inoculated, fresh culture medium or sodium hydroxide were added to control the pH, the results showed that the hydrogen productivity of substrate was increased and activity of the bacterium was enhanced; the loading rate of volume 50 ±2g/(1.d) was optimal when acclimating microorganism, under the conditions, the reactor obtained a hydrogen yield of 150.93ml/(1.h),the maximum hydrogen productivity was 175.14ml/g,the hydrogen average concentration in the biogas reached 54.88%,the COD removal efficiency could reach 30%. 2. Biohydrogen production has been carried out in a 5-litre scale-up reactor from cornstalk by natural anaerobic microorganisms. In order to develop the biohydrogenproduction technology, the engineering technique parameters were researched in this thesis. The optimal operation condition and some controlling parameters can be determined as follows:T36± 1 °C, pH 5.2~5.4,speed of agitator 100~120r/min,initial concentration of cornstalk 10g/l,interval of feeding 8 ~ 9h.Under the optimal experimental conditions, the results showed that the scale-up reactor obtained a hydrogen yield of 103.45 ml/(l-h) continuously, the maximum hydrogen productivity of cornstalk was 108ml/g,the average hydrogen concentration in the biogas reached 45%. Experimental results of metabolites analysis demonstrated that there were acetate, butyrate, ethanol, H2, CO2 and the terminal-product. Methane was not be detected in the biogas. Because the butyrate concentration was the highest in all liquid phase-products at all times, it might be butyrate acid type fermentation that biohydrogen production in the 5-litre scale-up reactor.