| It was an effective way to deal with livestock manure and manage the odor pollution which was composted in aerobic fermentation tank.The current research on fermentation tank was mainly embodied in the design of intelligent fermentation tank.During the operation of the fermentation tank,intermittent or continuous agitation and ventilation were usually carried out according to experience,which lacked scientific basis.In fermentation tanks with intermittent stirring and ventilation,aerobic compost often stopped fermenting because of insufficient oxygen content in reactors;compared with intermittent stirring and ventilation,continuous stirring and ventilation could keep the oxygen content in the fermentation tank sufficiently,but it need greater power consumption.Therefore,it was very imperative to develop a temperature and oxygen content monitoring system for aerobic composting fermentation tanks.This research was based on the monitoring requirements of temperature and oxygen content in aerobic composting fermentation tanks,and took the dynamic changes of temperature and oxygen content in each stage of aerobic composting fermentation process as research object.Firstly,the applicability of O2-A3 oxygen content sensor in aerobic composting environment was studied,and whether the sensor could be used to monitor oxygen content in the aerobic composting fermentation tanks was judged through One Way ANOVA;Secondly,the monitoring devices oxygen content and temperature for aerobic composting fermentation tanks were designed and built,which were used to monitor the dynamic changes of temperature and oxygen content in each stage of aerobic composting fermentation process;Finally,a stirring and ventilation strategy for aerobic composting fermentation tanks based on oxygen content was proposed,and on this basis,the development of the aerobic composting fermentation tank temperature and oxygen content monitoring system based on the AT89C52 single-chip computer was completed,and the monitoring system was simulated by Proteus,the design of the PCB board for the monitoring system was then completed through Altium Designer15,the results of the research were as follows:（1）The O2-A3 oxygen content sensor could be used to monitor the oxygen content in aerobic composting fermentation tanks.Based on the physical and chemical properties of pile environment in aerobic composting fermentation tanks,the applicability of the O2-A3 oxygen content sensor was tested.The test dates were analyzed by One Way ANOVA,it was found that the output signal of the sensor in a stack environment with a moisture content of 55%and a temperature of 20-70℃was not significantly different from that in the air（P>0.05）,which showed that the O2-A3 oxygen content sensor could be used to monitor the oxygen content in aerobic composting fermentation tanks.And on the basis of the sensor applicability test,the sensor calibration was completed,and the relationship between the sensor output signal（μA）and the oxygen content was:y=361.79x-5.6612,R2=0.9991.（2）Monitoring devices of oxygen content and temperature were built which could be applied in aerobic composting fermentation tanks.Based on the 8-channel signal collector which was purchased,an IV conversion amplifier module can amplify 110K times and a±15V power supply module for powering it were designed,and the IV conversion amplifier module could convert the O2-A3 oxygen content sensor output signal（μA）into a±15V voltage signal,which could collect 8 channels of oxygen content signal.The temperature monitoring device was designed mainly included NTC thermistor,NTC temperature control board and electric heating device.It could collect and control dual-channel temperature,which could be used to monitor the temperature of aerobic composting,and also could be used to control the environmental temperature of aerobic composting in a simulated fermentation test.（3）The dynamic changes of oxygen content in each stage of aerobic composting fermentation process were studied,and the stirring and ventilation strategy of aerobic composting fermentation tanks based on oxygen content was developed.In order to research the dynamic changes of temperature and oxygen content during aerobic composting,the aerobic composting tests of chicken manure and rice husk in 120L and 15L tanks were carried out.The study found that when temperature of the pile was higher than 25℃and the oxygen content was 8-17%,aerobic composting could quickly heat up;after stopped the stirring and oxygenation for 5 minutes,the oxygen content of the pile in aerobic composting heating stage and the early stage of high temperature stage was lower than 8%;after 30 minutes,the oxygen content of the pile in aerobic composting cooling and decomposing stage was still higher than 10%;during aerobic composting heating stage and the early stage of high temperature stage（1-4d）,the aerobic composting fermentation started to be inhibited when the oxygen content of the pile was less than 8%;and when the oxygen content was lower than 6%,the aerobic composting gradually stopped fermenting.Based on the dynamic changes of oxygen content in aerobic composting fermentation process and the growth curve of oxygen content at different depths in the fermentation tank during stirring and ventilation,the stirring and ventilation strategy was formulated:when the oxygen content at different depths in the fermentation tank was lower than 6%,the fermentation tank started to stir and ventilate;after stirring and ventilating until the oxygen content in the tank was higher than 17%,the monitoring system judged whether the temperature of the stack was higher than 60℃,if it was higher,continued stirring and ventilating for 20 minutes,if it was lower,stopped stirring and ventilating.Compared with intermittent and continuous stirring and ventilation,this stirring and ventilation strategy reduced the power consumption caused by excessive stirring and ventilation under the premise of ensuring sufficient oxygen content in the tank.（4）The monitoring system of temperature and oxygen content in the aerobic composting fermentation tank was developed.The hardware circuit of the monitoring system for aerobic composting fermentation tank was designed and completed based on the AT89C52 single-chip microcomputer;according to the formulated stirring and ventilation strategy,the MCU program code was written and completed by Keil.After simulating the monitoring system of the aerobic composting fermentation tank,the monitoring system could realize one-key switching between automatic monitoring and manual monitoring modes.In the automatic mode,the temperature and oxygen content in the fermentation tank could be automatically monitored by adjusting the temperature and oxygen content threshold;and in the manual mode,by setting the stirring and ventilation time and the stirring and ventilation frequency,the manual monitoring of temperature and oxygen content in the fermentation tank was realized.On this basis,the design and development of the PCB board was completed.This research proposed a new stirring ventilation strategy of aerobic composting fermentation tanks,a monitoring system of temperature and oxygen content for aerobic composting fermentation tank was developed based on this ventilation strategy,which had a certain reference value for improving the craft of aerobic composting fermentation tanks. |
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