Remediation of TNT-contaminated soils by anaerobic proteinaceous immobilisation

In this work a practical remediation technique for TNT-contaminated soils is demonstrated at the laboratory scale level. Addition of 2% proteinaceous material and 20% compost to a TNT-polluted soil (633 + 210 mg TNT kg(-1)) decreased free TNT with 87% and water leachable TNT with 67% after 3 weeks anaerobic incubation. Upon subsequent aerobic incubation, there was an increase in soil respiration, in the activity of both groups of nitrifiers and also in the activity of methane-oxidising bacteria compared to untreated TNT-contaminated soil. Italian ryegrass (% Lolium multiflorum var. % Bartolini) was succesfully grown after the treatment and developed an extensive root system within 28 days. After a subsequent anaerobic/aerobic phase and growth of Italian ryegrass comprising a total treatment time of 10 weeks, earthworms were capable of surviving and increasing weight in the remediated soil. The overall procedure of anaerobic immobilisation and subsequent growth of Italian ryegrass offers a low-cost method for practitioners to significantly improve the quality of TNT-contaminated soils.