According to the introduction of our previous articles, during the composting process, with the intensification of microbial activity in the material, when the heat released by the microorganisms decomposing the organic matter is greater than the heat consumption of the compost, the compost temperature will rise. Therefore, the temperature is the best parameter to judge the intensity of microbial activity.
Temperature changes can affect the growth of microorganisms. We generally believe that the degradation efficiency of high-temperature bacteria on the organic matter is higher than that of mesophilic bacteria. Today’s fast and high-temperature aerobic composting takes advantage of this feature. In the early stage of composting, the temperature of compost body is close to the ambient temperature, after 1~2 days of the action of mesophilic bacteria, the composting temperature can reach the ideal temperature of 50~60 °C for high-temperature bacteria. According to this temperature, the harmless process of composting can be completed after 5~6 days. Therefore, in the composting process, the temperature of the compost windrow should be controlled between 50 and 65 °C, but it is better at 55 to 60 °C, and should not exceed 65 °C. When the temperature exceeds 65 °C, the growth of microorganisms begins to be inhibited. Also, high temperatures can over-consume organic matter and reduce the quality of the compost product. To achieve the effect of killing pathogenic bacteria, for the device system (reactor system) and static ventilation windrow composting system, the time when the internal temperature of the stack is greater than 55 °C must be about 3 days. For the windrow pile composting system, the internal temperature of the stack is greater than 55°C for at least 15 days and at least 3 days during operation. For the bar-stack system, the time when the internal temperature of the windrow pile is greater than 55 °C is at least 15 days, and the composting windrow pile shall be turned over at least 5 times during the operation.
According to the drawn temperature change curve of conventional compost, the progress of the fermentation process can be judged. If the measured temperature deviates from the conventional temperature curve, it indicates that the activity of microorganisms is disturbed or hindered by certain factors, and the conventional influencing factors are mainly oxygen supply and garbage moisture content. Generally, in the first 3 to 5 days of composting, the main purpose of ventilation is to supply oxygen, make the biochemical reaction proceed smoothly, and achieve the purpose of increasing the temperature of the compost. When the compost temperature rises to 80~90℃, it will seriously affect the growth and reproduction of microorganisms. Therefore, it is necessary to increase the ventilation rate to take away the moisture and heat in the compost body, to reduce the compost temperature. In actual production, the automatic temperature control is often completed through the temperature-air supply feedback system. By installing the temperature feedback system in the stacked body, when the internal temperature of the stacked body exceeds 60 °C, the fan automatically starts to supply air to the stacked body, thereby The heat and water vapor in the windrow is discharged to lower the temperature of the pile. For the windrow pile-type compost without a ventilation system, regular compost turning is used to achieve ventilation and temperature control. If the operation is normal, but the compost temperature continues to drop, it can be determined that the compost has entered the cooling stage before the end.
Post time: Aug-01-2022