Acute toxicity evaluation of explosive wastewater by bacterial bioluminescence assays using a freshwater luminescent bacterium, Vibrio qinghaiensis sp. Nov.

The compositions of explosive wastewater generated from TNT (2,4,6-trinitrotoluene) purification stage were characterized by using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatograph (HPLC) and gas chromatograph/mass spectroscopy (GC/MS). The acute toxicity was evaluated by bacterium bioluminescence assay using a freshwater luminescent bacterium (Vibrio qinghaiensis sp. Nov.) and a marine luminescent bacterium (Photobacterium phosphoreum). The results showed that the wastewater's biodegradability was poor due to the high amount of chemical oxygen demand (COD). The main organic components were dinitrotoluene sulfonates (DNTS) with small amount of TNT, dinitrotoluene (DNT), mononitrotoluene (MNT) and other derivatives of nitrobenzene. It was highly toxic to luminescent bacteria P. phosphoreum and V. qinghaiensis sp. Nov. After reaction time of 15 min, the relative concentration of toxic pollutants (expressed as reciprocal of dilution ratio of wastewater) at 50% of luminescence inhibition ratio was 5.32×10(-4) for P. phosphoreu, while that was 4.34×10(-4) for V. qinghaiensis. V. qinghaiensis is more sensitive and suitable for evaluating the wastewater's acute toxicity than P. phosphoreum. After adsorption by resin, the acute toxicity can be greatly reduced, which is helpful for further treatment by biological methods.