Thermal hydrolyzed food waste liquor as liquid organic fertilizer

Thermal hydrolysis (TH) is an efficient technology for foodwaste (FW) management. This study investigated the nutrients released fromFWunder various THtemperature (140, 160, 180, 200 and 220 degrees C) and evaluated the feasibility of the hydrolyzed liquor (HL) as liquid organic fertilizer. The phytotoxicity and biotoxicity of HL was analyzed using wheat seed and Pseudomonas putida. Results revealed that TH could effectively solubilize FW and release nutrients (N, P and K) and organic substances. The highest content of total nitrogen (TN, 1685 mgN/L) and phosphorus (TP, 235 mgP/L) in the HL was obtained under 180 degrees C. The K+ was 278-293 mg/L regardless of treatment temperature. Secondary nutrients (Ca and Mg) and micro metals (Fe, Cu, Zn, Al, Co and Mn) were all detected at relatively high level, while heavymetals (As and Cd) were generally lower than 0.5mg/L. Twenty types of free amino acid were identified and the maximum total concentration was 4965.13 mg/L. 2% HL displayed higher germination index (>80%) and enhanced root and shoot lengths. No biotoxicity was observed as confirmed by the bioassay. This study proposes a feasible method to solubilize food waste and produce liquid organic fertilizer. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Thermal hydrolysis is an efficient technology to release nutrients and organic substances from food waste for liquid organic fertilizer production. Results show that 180 degrees Celsius is the optimal temperature for releasing total nitrogen and phosphorus, and the hydrolyzed liquor has no biotoxicity to seedlings.