BACKGROUND: Environmental contamination by nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX), atrazine, and/or simazine (TRAS) generated as waste from military and agricultural activities is a serious worldwide problem. Microbiological treatment of these compounds is an attractive method because many explosives and herbicides are biodegradable and the process can be made cost-effective. We explored the feasibility of using cultures of Pseudomonas putida HK-6 for simultaneous degradation of TRAS with the aim of microbial application in wastewater treatment in bench-scale bioreactors. RESULTS: Experiments were conducted to study the effects of supplemental carbons, nitrogens, and Tween-80 on the degradation of Ps. putida HK-6 in media containing TRAS as target substrate(s). The most effective TRAS degradation was shown in the presence of molasses. Addition of nitrogen sources produced a delayed effect for the target substrate(s). Tween-80 enhanced the degradation of target substrate(s). Simultaneous degradation of these compounds proceeded to completion within the given period. CONCLUSIONS: Ps. putida HK-6 was capable of growth with TRAS, and the effects of supplements on TRAS degradation and simultaneous TRAS degradation were evaluated in bench-scale bioreactors. The results of this study have practical applications in the processes of industrial waste stream treatment where the disposal of TRAS may be problematic. (C) 2008 Society of Chemical Industry.