Yanlin Zhang

The studies on the methane production with solid state fermentation by mixed the rice straw and swine manures

In this study, an anaerobic dry fermentation system was designed and erected to validate the feasibility and test the performance of dry fermentation by using the mixtures of rice straw and fresh pig manures under the near middle temperature. And during the course of fermentation the leachate was refluxed from the leachate tank to the fermentation tank in order to increase the performance of mass transfer. Some key parameters such as pH value, VFA value, start-up time, gas production and CH4 content were used to reflect the fermentation performance. Experimental results show that after 6 days CH4 content in biogas can be above than 45%, which means that the anaerobic dry fermentation is started up. In addition, the total amount of biogas produced is about 16.55 m3 from 6-day to 22-day, and the maximum volume gas production rate can be about 1.2 m3 biogas/(d·m3 fermentation tank). Furthermore the CH4 content in the biogas after the start-up time can be maintained at about 50%∼70%. These useful results imply that the anaerobic dry fermentation using rice straw and fresh pig manures is viable. On the other side, the germinating index (GI) for cabbage was also experimented to test whether or not the leachate and the fermentation residues can be used to act as fertilizer. Results show that the GI is higher than 70% after 25 days anaerobic fermentation which suggests that these residues can be adopted to act as fertilizer.

Impact factor on the pretreatment technology for anaerobic fermentation of rice straw

The pretreatment processing method has obvious influence to the degradation of straw when used as the raw material in anaerobic digestion. Rice straw was chosen as raw material in the research. The experiments was carried out on effects of the straw smashing size, the ratio of carbon to nitrogen, the pile of bubbles time and was designed on the basis of quadratic orthogonal regressive rotational combination principle with three factors and five levels. A quadratic equation for biogas yield was built. The optimal processing parameters which obtained according to the analysis of the data are as follows: the smashing size of rice straw is 4∼8 mm, C/N is 40, the pile of bubbles time is 8 d.