Research On Phase Separation Of Straw Two-Phase Anaerobic Fermentation

With the rapid development of modern agriculture, the crop straw processing problem is increasingly serious. As one of the most effective ways to cope with this problem, anaerobic fermentation biogas crop straw has received much attention at home and abroad. Compared with the traditional single-phase fermentation, two-phase anaerobic fermentation technology can not only realize acidogenic phase and methanogenic phase separation, but also improve the gas yield and organic load obviously, therefore, it has better application prospect. This paper conducts studies from the following aspects:the actual two-phase straw anaerobic fermentation system operation, the unsatisfying effect of acidogenic phase and methanogenic phase separation, and the low biological conversion rate and low quality methane problems arising from high acidogenic phase gas production,and low acidogenic phase gas production, The paper aims at finding controlling measures to reduce the acidogenic phase gas production, improve methanogenic phase gas production, realize acidogenic phase reactor open in the actual project operation, and eventually achieve the purpose that reduceing the project investment, and providing operations with convenience in coincides with the in and out of material at any time.1. Studying the effect of phase separation through the backflow fluid aeration treatment. The results show that there are not obvious differences between the backflow liquid aeration processing and non-aeration processing system in COD, SCOD, VFA, daily gas production yields, methane concentrations, accumulative gas production, and accumulative methane production After using the aeration treatment, pH value of backflow liquid is apparently higher than that before aeration and without aeration treatment. But the pH value does not significantly affect on the phase separation. The aeration treatment also has little effect on the degradation of rice stalks cellulose, hemi cellulose, and lignin. So the aeration treatment used in the backflow liquid can’t achieve the purpose of separation.2. Analyzing the influence of the pH regulation and aeration treatment on anaerobic fermentation biogas and methane production by experiments. Taking the glucose as its substrate, the experiments were conducted by adjusting the initial pH value of the fermentation liquid and the aeration. The results show that:the continuous aeration treatment can decrease the pH value of the reactor liquid materials, increase the liquid materials oxidation reduction potential and Prompt reactor isobutyric acid and isovaleric acid accumulation. Simultaneously, it also can reduce the reactor gas production and methane concentrations, the maximum cumulative gas production is up to six times the minimum cumulative gas production, and the maximum and minimum cumulative methane production is more than330times. From the comprehensive test results, this paper obtains that the initial pH, aeration interval time and oxygen are6.0,8h and5L, which have suppressing effects on anaerobic fermentation of gas production and methane production.3. In order to prove the effect of the former experiment, the experimental parameters were put into straw two-phase anaerobic system for verification. The initial pH of the two-phase system of acidogenic phase, aeration interval time and oxygen were respectively set to6.0,8h and5L. The results show that the aeration compartment time and initial pH regulation can restrain gas production and methanogenic bacteria methane production in the acidogenic phase, but the methanogenic phase gas production and methane production of aeration processing is not better than the methanogenic phase of not aeration processing. Aeration two-phase system of total gas production and methane production is only1/3and1/5of the not aeration treatment total gas production and methane production. This demostrates that although the the acidogenic phase gas production can be reduces by using of the aeration treatment, the straw hydrolysis speed are influenced and the hydrolysis product is consumed in acidogenic phase meanwhile. Therefore, the expected effect of two-phase separation can’t be reached through adjusting the initial pH of the two-phase system hydrolysis acidification and taking aeration treatment.