Anaerobic fluidized-bed treatment of propellant wastewater

Treatment of propellant wastewater by anaerobic fluidized-bed bioreactors (FBRs) containing granular activated carbon has been shown to be effective in laboratory and field feasibility studies. These studies were conducted in 100 mm (4 in.) diameter columns (8 L volume) treating low volumes of water taken directly from a propellant-production operation. The contaminant of interest, dinitrotoluene, was converted anaerobically to diaminotoluene (DAT), with subsequent aerobic mineralization of the DAT in an activated-sludge process. A demonstration of this technology has been conducted at Radford, Virginia, Army Ammunition Plant, using a commercially available 500 mm (2O in.) diameter column (710 L volume) FBR modified for anaerobic operation. The FBR was followed in series by a rotating biological contactor to simulate anaerobic pretreatment at a point source, followed by aerobic treatment at the existing facilities. Significant differences in the composition of the wastewater stream were encountered between the feasibility study and demonstration. The concentrations of easily degraded solvents (ethanol and ether) were much lower during the demonstration than during the feasibility studies, The events encountered in scaling up the process from the laboratory to pilot scale are reported, and the results of the pilot-scale demonstration are compared with the laboratory-scale data.