| Livestock wastewater is a kind of high concentration of organic wastewater, which will cause serious environmental pollution without proper treatment. Anaerobic biological treatment technology which can not only effectively deal with wastewater but also produce methane and recycle energy, is widely used to treat the high concentration of organic wastewater. By improving the acetic acid content of acidogenic phase and the methanogenic activity of methane-producing phase, the research aimed to increase biogas production and methane yield, at optimal operation conditions including temperature, hydraulic retention time(HRT) and pH in the independent design of automatic temperature control of two-phase anaerobic reactor. Through the analysis of gas production characteristics and the degradation pattern of organic content in the two-phase anaerobic reactor, the research which was supposed to provide a workable solution to the current shortage of energy resources increased gas production and improved the energy conservation and emissions reduction effect.Firstly, the research improved the operating condition of acid phase by batch trials, namely the temperature 33℃, the initial pH between 5.0-6.0, HRT 3d and stir. Then it studied the influence of carbon source with different C/N(ethanol, sodium acetate and glucose), different initial pH(4.5-8.24) and trace elements(Fe, Co, Ni) to acid producing effect and the type of fermentation. The results revealed that adding C/N of 70 ethanol and glucose can get good type of ethanol fermentation on the third day of acid phase, then the type of acid fermentation changed to propionic. When adding the glucose of C/N of 70, it got the highest content of VFAs, the largest acetic acid percentage and decent gas production, which were 88.58 mg/L, 69.18% and 198 mL, respectively. Initial pH 6.0 and adding 5mg/L Fe both had good effect on the accumulation of acetic. C/N of 70 ethanol matrix had obvious degradation of proteins and polysaccharides, 82% and 66%, respectively.Then the operating condition of methane-producing phase was improved by batch trials, namely the temperature 36℃, the initial pH 7.0, quiet place. Contrasted and researched the influence on the activity of methanogens by adding trace elements(Fe, Co, Ni) and carbon source(acetic acid and sodium acetate). The results showed that the addition of trace elements can improve the activity of methanogens. The best separate addition amount of Fe, Co, Ni, were 20mg/L, 15mg/L, 10mg/L, respectively. But Fe Co, Fe Ni, Co Ni combination has little influence on biogas yield and methane content, whose daily methane content was 20%-30%. Fe, Co, Ni added simultaneously can obviously promote gas production and methane production, methane content can reach 60% and the best removal efficiency of COD, SS, NH4+-N were achieved, which were 74.1%, 71% and 71%, respectively. After adding acetic acid, the removal efficiency of SS can reach 77.6%.At last, combined the best methods of acidification phase and methanation phase in the twophase anaerobic reactor, and compared with the control group, which showed that: Methane production and gas production had been experienced a rise- steady- drop- then steady- drop again process, gas production and methane percent of the experimental group were 1978 mL and 72%, respectively. Compared with the control group, it increased by 55.5% and 44%, respectively. pH and VFAs changed stably during the fermentation process, the removal efficiency of COD, NH4+-N, SS were 91.7%, 85% and 86.5%, respectively. Anaerobic granular sludge with medium particle size and well settling performance was helpful to preserve enough microbial biomass. |
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