Impact of hydrothermal process on the nutrient ingredients of restaurant garbage

In order to recover the nutrient resource from restaurant garbage, a complete trial with 2 factors on 5 levels of experiments was carried out. The temperature and heating time are the main factors influencing on hydrothermal process (HP) by which improves the degradability and digestibility of the restaurant garbage favorably to make animal feeds or fertilizer. The results showed the variation of protein, saccharide, and oil in the garbage. It showed that protein dissolved and liquefied during hydrothermal process, which made organic nitrogen in solid phase transfer to liquid phase. After heating at 180 degrees C for 60 min, organic nitrogen in liquid phase began to transform into ammonia. It also showed that hydrothermal process could promote the dextrinization, dissolution of the starch and its hydrolysis to reducing sugar, due to that starch in the restaurant garbage decreases and reducing sugar increases. When the temperature reached 140 degrees C, the reducing sugar started to decrease due to chemical reactions. The cellulose was stable at 100--180cC. The floatable oil increased markedly in the hydrothermal process. The suitable condition for de-oil was observed at 160 degrees C heating for 80 min. Furthermore, the extraction of grease from the solid phase accords with first-order reaction dynamic model.