Comprehensive utilization for hydrothermal conversion products of food waste

Abstract

Hydrothermal conversion technology is a promising technique for resource utilization. In this study, the influence of reaction conditions on the distribution of hydrothermal conversion products was investigated, and the resource utilization methods of all components of hydrothermal conversion products were discussed. The results showed that the highest bio-oil yield was obtained at 310 °C, which was 36.75 %. The higher heating value and energy recovery rate of bio-oil can reach 39.68 MJ/kg and 78.55 % respectively. And it had great potential as an alternative fuel. When wheat seeds cultured by aqueous were diluted 100 times at 310 °C with GI ≥ 80 %, the phytotoxicity disappears. At this time, the contents of total nitrogen, total phosphorus, and total potassium were 1234.80, 150.34, and 1640.36 mg/L respectively, and the heavy metal content was lower than the national standard for foliar fertilizer. The optimal conditions for biochar to adsorb methylene blue were adsorbent dose 2 g/L, 180 rpm, temperature 70 °C, and time 120 min; The gas phase yield increased with the increase of temperature (0.15–7.45 %). The yield at 310 °C was 2.76 %. The main component of the gas phase was CO2, accounting for 93.71–97.92 %. The innovation of this study was that food waste can be converted into bio-oil through high-temperature hydrothermal reaction, achieving energy recovery. The aqueous phase product of hydrothermal conversion was used as water-soluble liquid fertilizer, achieving resource utilization. At the same time, the reaction was carried out under high temperature and pressure, which can completely kill pathogens in food waste and has extremely high biological safety.