Potential phytoremediation of coal fly ash leachate using Lemna minor: a free floating macrophyte

Coal fly ash, is a major waste material of thermal power industry. It is predominantly dumped in fly ash ponds that often results to the seeping of heavy metals present into the surrounding ground water. Fly ash leachate is thus a combination of heavy metals and organic matters. Finding a suitable plant species for phytoremediation is challenging as fly ash leachate is a heterogeneous mix of different heavy metals. Here we have selected Duck weed— Lemna minor (L. minor), a free-floating plant that is widely used for wastewater treatment. In the present study, we have grown L. minor in fly ash leachate for a period of 7 days with the objective that the plant could alleviate the harmful effects of fly ash leachate. The results show that, L. minor can effectively decrease the metal content in fly ash leachate. DNA damage was observed in the fronds of the plants, without any significant changes in the level of photosynthetic pigments and an increased growth rate of the plant was observed. Active participation of antioxidative enzyme system especially catalase activity played a pivotal role in protection of plant from oxidative stress. The accumulation of heavy metals within the plant tissue without any substantial damage to plant growth and physiological functions demonstrated the potential of L. minor to effectively remediate coal fly ash leachate contaminants. Graphical Abstract