| Summary: | 碩士 === 國立中興大學 === 農業機械工程學系 === 89 === ABSTRACT
This study compared the performances between thermophilic and mesophilic system treating poultry mortalities using a sequential bath system. This research also discussed the characteristics of leachbeds at room temperature. The change of room temperature in a year influenced the hydrolysis velocity and methane production rate of LBs. It can be divided into two stages using anaerobic sequential bath system to process poultry mortalities. The first stage was two-phased stage included one UASB and one LB, the UASB helped LB to enter the methane phase. The second stage was single phase stage only had LBs in the system, LBs can process dead chicken alone without connecting to UASB, even LB had new dead chicken in the 2nd cycle.
In the first stage, two systems used the same two-phase anaerobic sequential bath system, they liked two-phase anaerobic system, but something different. The systems in this study consisted of an UASB and several LBs, and they were closed system. The traditional two-phase anaerobic system was not closed system, it must have influent continuously, but the closed system were not. When the first cycle is over the liquid can be used again and well controlled. UASBs were kept at 55℃ and 35℃ incubators, where the LBs were kept at room temperature.
The hydrolysis of nitrogen-rich wastes was more completely in high temperature as 55℃. It came up with the problem of high free-ammonia concentration. So, in the process of the experiment we controlled the pH value of on high temperature UASB, thus we can have lower equilibrium of NH4+ and NH3 , then we compared the differences of UASBs in high temperature.
The result showed that UASB in thermophilic temperature is not as stable as mesophilic temperature, it needed longer time to adapt the leachate of LB and it was influenced by the high free-ammonia concentration.
When control the pH value, the COD and VFAs were lower than the other, we can have stable UASB in high temperature but in the first stage LBs connected to adjusted-UASB were not good.
Temperature influenced the hydrolysis of LBs, in the first cycle, LA55-3 and LB55-3 were started in the range of lower room temperature, and the temperature increased later, so the CODs of LBs had lowed down first and come up with high COD. When the room temperature was lower than 20℃ the hydrolysis and methane production rates were not good . Therefor if we can pay attention to the temperature、schedule of processing dead chickens and LR with the change of room temperature we can have good performances of LBs. UASBs were kept at uniform temperature so they won't have the problem of unstable temperature.
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