Dynamic interaction mechanism of environment, microorganisms, and functions in anaerobic digestion of food waste with magnetic powder supplement

Abstract

The reutilisation of food waste for the production of clean energy was promoted by supplementing magnet powder in anaerobic digestion (AD). This study found that adding 5% magnet powder optimally increased the amount of biogas produced by 61.9%, and the pH and volatile fatty acids (VFA) content had the greatest correlation with biogas production. A further metagenomics analysis in the early, middle, and late stages of the AD revealed that interaction between bacteria and archaea had highest explanation rate for pH and VFA changes rather than enzymes. Moreover, the 5% magnet powder increased the proportion of the CO₂ methanogenesis and decreased the acetate methanogenesis on day 15 of peak biogas production. And it was an innovative discovery that conversion of tetrahydromethanopterin S-methyltransferase to methane increased, which is an important common node of methanogenesis metabolic and may be the fundamental reason for the increase in biogas production caused by magnetic powder.

Keywords: Anaerobic digestion; Food waste; Magnet powder; Metagenomics; Methane metabolic pathway.