Impact of hydrothermal process on the liquid substances transformation of aquatic wastes

Taking aquatic product processing waste as the main experimental object, the effects of different hydrothermal process parameters such as temperature and time on the physical and chemical characteristics of aquatic product waste and the law of liquid substances transformation are investigated. The pH, SCOD (soluble chemical oxygen demand), VFA(volatile fatty acid) and the amount of floating oil in the liquid product during hydrothermal treatment process (HTL) were measured. The experimental results show that under the conditions of 165 degrees C and 80min, the mass concentration of organic carbon in HTL reaches the highest, with SCOD content of 97.677g/L; the treatment temperature has a great influence on VFA. In a certain temperature range, VFA increases with the increase of temperature. Under the working condition of 195 degrees C and 60min, the VFA concentration in HTL reaches the highest value of 17.48g/L, which is 37.3% higher than that in the control group. Under certain hydrothermal conditions, it can increase the amount of floating oil, reaching the highest content of 97.8ml/k at 180 degrees C for 40min. The control of the treatment time is more important than the treatment temperature, and it is better to control it within 60min. The results of this study further show that hydrothermal process can improve the efficiency of transferring solid matter to liquid. Macromolecular substances in raw materials are hydrolyzed into small soluble substances (such as fatty acids, amino acids), which provides more nutrients with high homogenization degree for liquid-phase biological treatment, and is more conducive to resource utilization.