ALKALINE REMEDIATION FOR TNT-CONTAMINATED WATER IN BATCH AND CONTINUOUS-FLOW REACTORS

The objective of this study was to assess the effectiveness of alkaline hydrolysis as an alternative ex-situ technology for remediating groundwater contaminated with 2,4,6-trinitrotoluene (TNT). Both kinetics and treatability were investigated in a batch reactor and a continuous flow-stirred tank reactor (CFSTR). The batch system achieved pseudo first-order TNT transformation rates in the range of 3.0×10−5 to 1.3×10−2 min−1, with a strong dependence on the reaction pH (11 to 13) and initial TNT concentration (5 to 25 mg/L). In the CFSTR system with the initial TNT concentration of 1 mg/L, the highest 73% TNT removal (i.e., 1 mg/L influent TNT → 0.27 mg/L effluent TNT) was achieved with the hydraulic retention time of 2 days and the reaction pH of 11.9. The net OH− demand used only for TNT destruction in the CFSTR was found to be 1530, 610, and 210 M OH−/M TNTremoved at pH of 11.9, 11.5, and 11.0, respectively. Further study on the production of color-forming compounds during hydrolysis and their influence on the effectiveness of alkaline hydrolysis are under way.