Effects of functional-membrane covering technique on nitrogen succession during aerobic composting: Metabolic pathways, functional enzymes, and functional genes

•Functional-membrane covering (FMC) increased O2 utilization and pile temperature.•FMC significantly affected functional enzymes and nitrogen metabolism (p < 0.05).•FMC down-regulated nitrification and denitrification gene abundances.•Coupling of functional genes affected the nitrogen succession process.•FMC increased NH3 emissions by 14%–73% and decreased N2O emissions by 16%–41%.