Development of a process for treating red water by organic/inorganic separation and biodegradation

The final stage of TNT production involves the purification of TNT by selective conversion of the unsymmetrical isomers into water-soluble sulfonates by reaction of the crude TNT with an aqueous sulfite (sellite) solution. This treatment generates an intense, red-colored waste stream commonly referred to as red water,'' which has been listed as a hazardous waste by the EPA. Its composition is primarily soluble organic sulfonates and the sodium salts of sulfate, sulfite, nitrate and nitrite. Argonne National Laboratory (ANL) is developing a process for treating red water. This process couples the separation of the organic and inorganic constituents of red water, followed by treatment of the organics by biodegradation to nonhazardous products. Sludge formation in the biotreatment step is further minimized by conversion of the sodium-containing organics to their respective acidic forms during the organic/inorganic separation. The level of separation will be such that the inorganic residues can qualify as nonhazardous byproducts. Initial efforts have been directed towards performing proof-of-concept demonstrations of processes that can achieve these goals. Candidate technologies that are being examined for separating the organic constituents from actual red water samples are (1) flocculation, (2) foam fractionation, and (3) aqueous biphasic solvent extraction. 22 refs.