Evaluation of N-methylpyrrolidone and its oxidative products toxicity utilizing the microtox assay

N-Methylpyrrolidone (NMP) is a cyclic nitrogen-containing organic chemical used to replace more volatile and toxic organic solvents in paint coating and cleaning applications. The Marine Corps Multi-Commodity Maintenance Center was concerned that the high NMP and organic levels in process water would upset treatment processes at the industrial Process Water Plant (IWP). The NMP contaminated process water was oxidized by a semicontinuous advanced oxidation reactor to reduce the organic concentration. The oxidative byproducts of NMP were identified by GC/MS and tested for their toxicity. A toxicity test, utilizing the Microtox toxicity assay, revealed that methylsuccinimide was the most toxic identifiable product of NMP oxidation. The toxicity of the process water was reduced as methylsuccinimide and was further oxidized to succinimide and other amine products. The results indicate that NMP contaminated process water should be oxidized past the N-methylsuccinimide compound prior to standard industrial process water treatment procedures, so as to reduce toxicity concerns associated with NMP contaminated process water.