Semi-solid anaerobic co-digestion of source-separated fecal slag and food waste: focusing on methane production, ecological risk assessment, and quality evaluation as fertilizer

Yusuf, Hamza Hassan; Pan, Xiaofang; Cai, Guanjing; Cai, Jiasheng; Huang, Xuewei; Ye, Zhi-Long

Semi-solid anaerobic co-digestion of source-separated fecal slag and food waste: focusing on methane production, ecological risk assessment, and quality evaluation as fertilizer

2022

Toilet revolution is driven by the urgent need for solutions to improve sanitation and access to high-quality organic fertilizer for rural areas, which is tagged “resource recovery from human waste.” This study provides a possible solution via semi-solid anaerobic co-digestion (Aco-D) of source-separated fecal slag (SFS) and food waste (FW) (3:1). A comprehensive investigation of Aco-D at different inoculum/substrate ratios (ISR) was conducted. Results revealed that the reactor with ISR of 1:4 reached the highest methane yield (255.05 mL/gVS), which enhanced Methanosaetaceae, Methanomicrobiales, and Syntrophomonas. Additionally, the reactor with low feedstock (ISR of 1:2) showed higher removal efficiency of antibiotics (74.75%). The ecological risk of digestate decreased to an insignificant hazard quotient level, and the contents of nutrients and heavy metals were in line with the standard requirement for fertilizer. This study could serve as an alternative technology to support further research in SFS management and digestate utilization as fertilizer.

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