title: Continuous treatment of the insensitive munitions compound N-methyl-p-nitro aniline (MNA) in an upflow anaerobic sludge blanket (UASB) bioreactor.
abstract: N-methyl-p-nitroaniline (MNA) is an ingredient of insensitive munitions (IM) compounds that serves as a plasticizer and helps reduce unwanted detonations. As its use becomes widespread, MNA waste streams will be generated, necessitating viable treatment options. We studied MNA biodegradation and its inhibition potential to a representative anaerobic microbial population in wastewater treatment, methanogens. Anaerobic biodegradation and toxicity assays were performed and an up-flow anaerobic sludge blanket reactor (UASB) was operated to test continuous degradation of MNA. MNA was transformed almost stoichiometrically to N-methyl-p-phenylenediamine (MPD). MPD was not mineralized; however, it was readily autoxidized and polymerized extensively upon aeration at pH = 9. In the UASB reactor, MNA was fully degraded up to a loading rate of 297.5 μM MNA d(-1). Regarding toxicity, MNA was very inhibitory to acetoclastic methanogens (IC50 = 103 μM) whereas MPD was much less toxic, causing only 13.9% inhibition at the highest concentration tested (1025 μM). The results taken as a whole indicate that anaerobic sludge can transform MNA to MPD continuously, and that the transformation decreases the cytotoxicity of the parent pollutant. MPD can be removed through extensive polymerization. These insights could help define efficient treatment options for waste streams polluted with MNA.
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA.
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Olivares
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA.
authors.forename: Junqin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA; Departamento de Procesos y Tecnología, División de Ciencias Naturales e Ingeniería, Universidad Autónoma Metropolitana - Unidad Cuajimalpa (UAM-C), Vasco de Quiroga 4871, Col. Santa Fe Cuajimalpa, Cuajimalpa de Morelos, C.P. 05300 México, D.F., Mexico.
authors.forename: Carlos D Silva
authors.initials: CD
authors.lastname: Luna
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA.
authors.forename: Jim A
authors.initials: JA
authors.lastname: Field
authors.affiliation: Department of Chemistry & Biochemistry, University of Arizona, P.O. Box 210041, Tucson, AZ 85721-0041, USA; Department of Soil, Water & Environmental Science, University of Arizona, P.O. Box 210038, Tucson, AZ 85721-0038, USA.
authors.forename: Leif
authors.initials: L
authors.lastname: Abrell
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721-0011, USA. Electronic address: rsierra@email.arizona.edu.
authors.forename: Reyes
authors.initials: R
authors.lastname: Sierra-Alvarez
mesh_terms: D000693:Anaerobiosis; D000814:Aniline Compounds / Q000032:analysis*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D000814:Aniline Compounds; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical; C554272:N-methyl-4-nitroaniline
keywords: Anaerobic; Biodegradation; Insensitive munitions; Microbial toxicity; N-methyl-p-nitroaniline; Nitroaromatic