Electric field as extracellular enzyme activator promotes conversion of lignocellulose to humic acid in composting process

Abstract

To promote efficient conversion of lignocellulose to humus (HS) during composting, a novel bio-electrochemical technology was applied and explored the effect and mechanism of electrification on carbon conversion during different composting periods. The results showed that supplementary electric field played different roles during composting. In the early stage, organic matter mineralization was significantly accelerated under electric field application, that was embodied in a 29.8% increase of CO2 emission due to the enhanced metabolic activity of microorganisms. However, the electric field functioned as an extracellular enzyme activator during the later stage since the abundance of functional microorganisms related to lignocellulose degradation was increased by 1.5–2.8 fold that effectively promoted the conversion of lignocellulose to HS. The humic acid content of the compost products increased by 23.0–32.9% compared with control. This study elucidated how electric fields affect carbon conversion during composting, which provides a novel strategy for returning agricultural wastes to soil.