Evaluation of the potential of anoxic biodegradation of intracellular and dissolved microcystins in lake sediments.

The kinetics of the anoxic biodegradation of intracellular and dissolved microcystin (MCs) and the effects of soluble organic materials on the process were investigated via a series of well-controlled microcosm experiments. The potential for the removal of intracellular and dissolved MCs from lake sediment differed. The dissolved MCs could be degraded to below the detection limit at 20 °C within one to 3 days after a lag phase of 2-6 days under anoxic conditions. The levels of intracellular MCs were also significantly reduced in the sun-dried cyanobacterial samples but not rapidly reduced in fresh cyanobacterial samples until the cells were ruptured. The addition of soluble organic matter enhanced the anoxic biodegradation of MCs. These results indicate that the application of anoxic biodegradation via lake sediments is an effective method to remove dissolved and intracellular MCs and that this process exhibits significant bioremediation potential for the further treatment of cyanobacteria.