Experimental Study On Organic Fertilizer Production From Kitchen Waste By Hydrothermal Treatment

Due to the growing amount of MSW (municipal solid waste) and the relative lack of waste disposal capacity, how to deal with waste effectively has become a technical problem to be faced. After taking the kitchen waste classified from MSW into account, which contain lots of organic matter and nutrient, it is a good choice to extract organic fertilizer from kitchen waste. While hydrothermal is an effective method to make kitchen waste resource utilized. Therefore, it will have great importance to study hydrothermal characteristics of kitchen waste.This paper is mainly based on experimental research, analysis the characteristics and various fertilizer indicators of the solid-liquid phase samples after hydrothermal treatment. Meanwhile combined with the formation mechanism of humus, analysis the catalytic effect of inorganic weak acid, the migration of heavy metals and the effect of salt in kitchen waste, The main conclusions are as follows:After the hydrothermal treatment, the waste has a high degree of humification, and we found that a large part of organic matter is converted to humus, which accounts for more than2/5of the organic matter. While under the condition of205℃,50min, humification rate reaches1.31, reflecting the very high degree of humification, which is also verified in the infrared spectrum analysis process. This conclusion is similar with the hydrothermal treatment of raw waste. Under the same condition, the raw waste’s humus content reaches33.82%, humification rate reaches1.19.Adding0.01%sulfuric acid has some catalytic effect in promoting humus formation in hydrothermal processes. After adding acid, humus does not change significantly, but humification rate increases a lot. At the initial time of hydrothermal reaction with the same high temperature, inorganic weak acid catalysis exhibit more pronounced.Hydrothermal treatment can promotes the stability of heavy metals and reduces their potential mobility, which would be helpful for kitchen waste’s agricultural utilization. During hydrothermal treatment process, the percent of oxidizable and residual state of Cu and Pb increase significantly. The stability of As increases slightly. Due to Zn is easy to bond with small molecule humus, its residual state changes little. After hydrothermal, most of salt remain in hydrolysate, The concentration of salt in solid phase is very low and the proportion of NaCl transferred to hydrolysate are mostly greater than85%. Adding different concentrations of NaCl has little effect on humus formation. Under the high concentration of NaCl condition, humification rate is little lower than the condition without NaCl. Whatever, the effect of salt on hydrothermal is relative lower than compost.As what I have studied, Hydrothermal treatment is an effective agricultural technology to kitchen waste. Making the main components as an entry point to study the mechanism of hydro-thermal treatment of kitchen waste. In this study, we find that the total nutrients and organic matter’s content of the product after hydrothermal treatment are within the requirements of the national agricultural standards, in which the content of total nutrients is more than5%and organic matter’s content is between60%and70%. It shows that the organic matter is well preserved.