Biodegradation of nitrilotriacetic acid and its metal complexes in river water

Abstract

In this work, we investigated the biodegradability of both the complexing agent (nitrilotriacetic acid, NTA) and its various metal complexes in an aquatic environment. A laboratory experiment was used to simulate the rates of biodegradation of NTA and NTA-metal (Ca, Pb, Zn, and Cu) complexes in river water. A first-order reaction was applied to describe the rates of biodegradation of NTA and NTA-metal complexes. NTA became completely degraded within 2 - 3 d after acclimation for 6 d and the rate coefficient (k) was 1.56 - 4.54 d(-1). Except Ca-NTA, all NTA-metal complexes degraded at a more smaller rate than NTA. The stabilities of these complexes are in the decreasing order Cu-NTA > Pb-NTA > Zn-NTA > Ca-NTA.