Modeling the mineralization of trinitrotoluene and dinitrotoluenes in aerobic/anoxic biofilm

摘要

This study investigates the feasibility of using a single aerobic biofilm reactor, operated such that anoxic zones develop, to mineralize a mixed waste stream of 2,4-dinitrotoluene (24DNT), 2,6-dinitrotoluene (26DNT), and trinitrotoluene (TNT). In the anoxic zone of the biofilm, TNT is reduced to 2-amino-4,6-dinitrotoluene (2A46DNT) and 4-amino-2,6-dinitrotoluene (4A26DNT), and in the aerobic zone, 24DNT, 26DNT, 2A46DNT, and 4A26DNT are mineralized. In this research, a biofilm model was constructed to depict the simulataneous transformation of these nitroaromatic compounds in a fluidized bed biofilm reactor. Parameters for the reactor system and DNT degradation were determined from a fluidized bed biofilm reactor mineralizing 24DNT and 26DNT. TNT transformation parameters were taken from a kinetic analysis of anaerobic TNT reduction rates. Results from the model indicate that this system is capable of mineralizing 24DNT, 26DNT, and TNT simultaneously. However, in order for anoxic zones to devleop in a system with such low maximum growth rates, substrate flux must to be increased beyond the treatment capacity o f the system. As a result, effluent concentrations for 24DNT, 26DNT, and TNT are high because of the short retention time. These problems might be resolved by using a different reactor design.