AEROBIC BIODEGRADATION OF 2,4-DINITROTOLUENE, AMINONITROTOLUENE ISOMERS, AND 2,4-DIAMINOTOLUENE

2,4-Dinitrotoluene (DNT) is widely used in industry, including the man ufacture of propellants. 2,4-Diaminotoluene (DAT), 2-amino-4-nitrotolu ene (2A4NT), and 4-amino-2-nitrotoluene (4A2NT) are among the products that can result from biological treatment of DNT. The objective of th is study was to examine the biodegradability of these hazardous compou nds. Using an inoculum from a munitions wastewater treatment plant, en richment cultures were developed that readily consumed DAT, 4A2NT, 2A4 NT, and DNT when they were provided as sole organic substrates (84-100 mg 1(-1)) or when ethanol (600 mg 1(-1)) was added as a cosubstrate. Low effluent chemical oxygen demand (COD) levels suggested that the ar omatics were mineralized, rather than simply transformed to other poss ibly hazardous compounds. The addition of ether (142 mg 1(-1)) as a co substrate had no significant effect on the biodegradation of DAT and 4 A2NT, but did inhibit the consumption of DNT and 2A4NT. The presence o f ether in munitions wastewater may therefore present a challenge to e ffective biological treatment. When DNT was added to enrichment cultur es as sole substrate, nitrite was released stoichiometrically. However , when ethanol was also added, nitrite release was only 59% of the max imum, indicating that most of the DNT was reduced prior to ring cleava ge. When provided to enrichment cultures as the sole substrates, the o bserved yield coefficients for the aromatic compounds ranged from 0.10 to 0.28 mg of volatile suspended solids per mg COD.