N-Methyl Pyrrolidone Manufacturing Wastewater as the Electron Donor for Denitrification

Wastewater generated from N-methylpyrrolidone (NMP) manufacture was used as electron donor for denitrification in tertiary treatment. The organic components of NMP wastewater were mainly NMP and monomethylamine (CH3NH2), and their biodegradation released ammonium that was nitrified to nitrate that also had to be denitrified. Bench-scale experiments documented that alternating denitrification and nitrification realized effective total-nitrogen removal. Ammonium released from NMP was nitrified in the aerobic reactor and then denitrified when actual NMP wastewater was used as the electron donor for endogenous and exogenous nitrate. Whereas TN and NMP removals occurred in the denitrification step, DOC and CH3NH2 removals occurred in the denitrification and nitrification stages. Genera Thauera and Paracoccus were important for NMP biodegradation and denitrification in the denitrification reactor; in the nitrification stage, Amaricoccus and Sphingobium played key roles for biodegrading intermediates of NMP, while Nitrospira was responsible for NH4+ oxidation to NO3–. These results document that an N-containing organic compound in an industrial wastewater can enable total-N removal in a tertiary-treatment scenario