New model of nutrient utilization and salt regulation of anaerobic digestate from food waste

Anaerobic digestion (AD) treatment of food waste (FW) has become increasingly popular, in the meantime, it creates a challenge for effective management of its by-products. The study of biogas slurry (BS) treatment methods is an ongoing endeavor. In this study, we formulated the following scenarios for the treatment of BS: S1 as sewage treatment, S2 as a base rice fertilizer, and S3 as an additional rice fertilizer. The results of the material flow analysis and comprehensive evaluation showed that the nitrogen and phosphorus recovery of S2 reached 42.4 % and 14.9 %, respectively. Without causing soil salt accumulation, it shows the best economic efficiency and minimizes the environmental impact, which is the preferred feasible solution worth popularizing. Based on the predicted FW production in China in 2030, the adoption of S2 could replace the use of 155.2 kt of chemical fertilizers, irrigate about 689.6 kha of paddy fields, and save $2045.9 million in BS sewage treatment costs. Moreover, the rice produced is of superior quality and can bring an additional profit of $2177.1 million. In conclusion, this study offers a new idea for large-scale treatment of BS and provide scientific knowledge to improve the sustainable management of FW anaerobic digestate.