PROPERTIES OF ORGANIC MATTER IN ANAEROBIC FERMENTATION LEACHATE FROM A DOMESTIC WASTE INCINERATION POWER PLANT IN THE COLD REGION IN NORTHERN CHINA

The frozen garbage in the waste incineration plant of northern China is usually difficult to dehydrate in winter, which seriously affects the efficiency of waste incineration, and has become a bottleneck problem limiting the development of the waste incineration industry. This study focused on the changes of COD, TOC, NH₄⁺-N, TN and TP in the leachate during anaerobic fermentation of garbage waste under the fermentation temperature of 10 ℃, 20 ℃ and 30 ℃ in the waste storage pit of incineration plant for 10 days. The results showed that at 10 ℃, the concentrations of COD, TOC, TN and NH₄⁺-N in leachate all decreased rapidly within 4 days, and the TP concentration decreased to the minimum value on day 6th. Then the organic indexes gradually increased later and reached the maximum on day 10th. At 20 ℃ and 30 ℃, COD, TOC, NH₄⁺-N and TP concentration decreased gradually in first three days, then increased gradually in the 3rd to 7th day, and decreased gradually in the 7th to 10th day. It was found that the decrease of organic concentration in the leachate at the initial stage was mainly due to the moisture precipitation in the garbage. In the middle stage, macromolecular organic matter in the garbage was degraded into smaller molecular matter and transferred into leachate, and organic matter concentration in leachate increased. In the later stage, the utilization of C, N and P in leachate by microorganisms was the main reason for the decline of each parameter. In addition, when the fermentation temperature of garbage was higher than 20 ℃, and the fermentation time was longer than 3 to 4 days, the macromolecular fiber chain in the garbage was broken, and a large amount of organic matter was degraded and entered the leachate, leading to the decrease of garbage calorific value, affecting the garbage incineration effect. Finally, after comprehensive consideration of multiple factors, such as the change of organic matter in fermentation leachate, the calorific value of waste and the capacity of waste storage pits, it was confirmed that the garbage fermentation temperature and time in storage pit in cold areas should be controlled at 10 to 20 ℃ for 3 to 6 days. The research can provide reference for further research on influencing factors of frozen waste incineration efficiency in cold regions in China.