| A large amount of agricultural waste and livestock and poultry manure are produced every year in China.If it is not effectively treated,it will not only cause a great waste of biomass resources,but also cause serious pollution to the environment.Anaerobic fermentation uses biomass energy as raw material,biogas as output and it is an important model for realizing the recycling and environmental protection of agricultural waste and livestock manure.However,the fermentation process is complicated and difficult to control,and the single-phase fermentation process microbial activity is susceptible to impact load and environmental changes,which is not conducive to the smooth progress of fermentation.Two-phase anaerobic fermentation,separates the acid-producing phase and the methane-producing phase in the fermentation process,and completes the acid-producing and methane-producing in different anaerobic fermentation devices The pH value of fermentation has an important influence on the activity of microorganisms.The optimum pH range for acid-producing bacteria is 5.0-8.5,and the optimum pH range for methanogens is 6.5-7.5.According to the different pH values of acid-producing bacteria and methanogens,adjusting the pH value of the inoculum can effectively control the activity of microorganisms,achieve two-phase separation,and improve gas production efficiency.To determine the gas production efficiency and separation degree of two-phase fermentation of mixed raw materials with different inoculum pH values,experiments were carried out on single-phase fermentation of mixed raw materials,single-phase fermentation with different inoculum pH and two-phase fermentation with different inoculum pH respectively.The effect of gas production efficiency under different raw material ratios,the effect of different inoculum pH value on gas production efficiency and methanogen activity in single-phase fermentation,and the effect of different inoculum pH value on the separation degree of two phases and gas production efficiency during two-phase fermentation process(Comparison with single-phase fermentation)were determined..The research results of this paper are as follows:(1)The mixing ratio of different raw materials had an important influence on the fermentation process.Among the mixed raw materials,when the pig manure content was 80%,the gas production efficiency was the highest,which was 342 mL·g-1,which was 108.15%higher than the pure rice straw fermentation(164.71 mL·g-1).and 11.175%higher than the pig manure fermentation(308.39 mL·g-1)(2)Adjusting the pH of the inoculum had a greater influence on the activity of methanogens and gas production in the single-phase fermentation process.When the pH value of the inoculum was lower than 5,the activity of methanogens was seriously affected,and it was difficult to recover,and the gas production rate was low.When the pH value of the inoculum was adjusted to 3.5,the gas production efficiency was the worst,184 mL·g-1,which was lower than that of the control group(309 mL·g-1)68.15%.When the pH value of the inoculum was adjusted to 6,the gas production efficiency was 243 mL·g-1,which was lower than that of the control group 21.36%.(3)Adjusting the pH value of the inoculum for two-phase fermentation can effectively improve the gas production efficiency of raw materials(compared with the single).When the pig manure content were 0,33%,50%and 100%,and the inoculum pH were 4,4,4,and 5,respectively,the unit TS gas production reacheed the maximum,which increased by 98.14%,35.83%,13.4%and 20.20%,compared with single-phase fermentation.(4)Adjusting the pH of the inoculum can effectively suppress the gas generation of the acid-generating phase and promote the separation of the two phases.In the two-phase fermentation process,under different pig manure content,when the inoculum pH was less than 5,the cumulative gas production of each group of methane phase accounted for more than 95%.When the pH of the inoculum was 5,the cumulative gas production of the methane phase in each group accounted for 89%-95%of the total gas production,which was significantly higher than the control group 52%-84%... |
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