Research on the key influencing factors and operating parameters for the weight reduction of kitchen waste achieved by hydrothermal reaction

Using the hydrothermal carbonization process, the effect of varying temperatures (170 to 270 ℃), residence time (0 to 100 min), and solid-water ratios (1∶1, 1∶3, and 1∶9) on the weight reduction of hydrothermal reaction of kitchen waste was researched, and the operating parameters were optimized. The findings of this test revealed that as the temperature rose, the weight loss rate of kitchen waste increased, reaching a value of over 91%. The weight loss rate increased slightly as the residence time extended from 20 to 40 minutes and from 80 to 100 minutes. During the residence times of 0 to 100 minutes, the weight loss rate increased from 83.90% to 86.80%. A higher solid-water ratio would have a negative impact on the weight loss rate. The corresponding weight loss rates were 91.60% to 91.87%, 86.20% to 87.00% and 83.90% to 88.10% at solid-water ratios of 1∶9, 1∶3 and 1∶1, respectively. The solid-water ratio and the reaction temperature were the main factors affecting COD of the liquid products, which initially gradually decreased and leveled off as the reaction progressed before slightly increasing. This was demonstrated by the results of COD measurement of the liquid products. The higher heating value of hydrochar obtained in the test was 30.50 to 31.90 MJ/kg, which was greater than the national standard coal calorific value of 29.30 MJ/kg.