Phytoremediation of liquid radioactive waste using apu wood (Pistia Stratiotes) to reduce thorium contents

Thorium (Th) waste is an alpha-emitting radioactive waste that is harmful to the environment and living things so it is necessary to treat the waste effectively with phytoremediation. Phytoremediation is a plant ability to reduce pollutants presence in the environment. This research aim is examining apu wood plant ability to reduce Th contents from Th-contaminated waste. The UV-VIS spectrophotometer analysed Th level in apu wood plant and liquid waste while the Ludlum Model 1000 Scaler measured their radioactivity. The parameters for phytoremediation occurrence include the decreasing physical condition of the plants, the pH of the waste that is close to neutral, and the temperature that fluctuates with the ambient temperature. The results showed that the plant biomass of apu wood decreased after phytoremediation to 96.2 % with a remediation efficiency of 97.4 % from the initial concentration of Th liquid radioactive waste of 10 ppm. This is due to thorium absorption resulting in thorium accumulation in apu wood plants of 4,069.4 mg/kg. Apu wood was also able to reduce Th liquid waste radioactivity to 0.631 Bq/L from the initial radioactivity of 2.819 Bq/L. The radioactivity level is below the Klierens Level and it is safe to release the waste into the environment. (author)