Phyto-removal of trinitrotoluene from water with batch kinetic studies

A series of batch reactor studies were conducted to obtain kinetic data for optimizing phyto-treatment of water contaminated with trinitrotoluene (TNT). A plant screening study indicated that stonewort and parrotfeather were the most effective among the plants tested; parrotfeather being chosen for further testing because it is heartier and easier to cultivate than stonewort. Treatment was reproducible under similar conditions, and sequential formation and breakdown of aminodinitrotoluene (ADNT) and diaminonitrotoluene (DANT) were observed in the aqueous phase. TNT removal rates increased with increased plant density, and removal kinetics increased with increasing temperature up to 34° C. Michaelis–Menton kinetics applied to the phyto-removal of TNT. At concentrations less than 5.5 mg/l TNT, a pseudo-first-order approximation of the Michealis–Menton equation was used with acceptable deviation. Prior exposure to TNT did not appear to have a significant effect on phyto-transformation rates, suggesting that the mechanisms for removal were not induced. Small concentrations of ADNT were found in the plant material, however, TNT was not detected. The results indicated that optimized reactors for the phyto-treatment of contaminated wastewater and groundwater are feasible, increasing degradation rates and decreasing reactor volumes.