Effect of Electrical Conductivity (ec) on Growth Performance of Duckweed at Dumpsite Leachate

Two batch experiments were conducted during the months of June-July (summer) and September-October (fall) to determine the effect of Electrical Conductivity (EC) on nutrient and COD removal & uptake efficiency and growth of duckweed (Lemna minor) at leachate with various EC levels (500-3,000 μS cm -1 ) under the natural climatic conditions of Islamabad, Pakistan. Maximum removal rates (mg m -2 day -1 ) of TKN (175.6±0.7), NH4-N (124±0.4), TP (92.4± 0.1), o-PO4 3-P (31.8 ± 1.2) and COD (3,660±9.1) were observed at 1,000 μS cm -1 EC of leachate during summer while; during the fall season, these removal rates were 182.9 ± 0.7, 117.3 ± 0.3, 91.1 ± 0.04, 76.9 ± 1.8 and 3,295 ± 6.1 mg m -2 day -1 respectively. The maximum growth rate of duckweed was 5.70±0.2 g m -2 day -1 during summer and 3.21±0.08 g m -2 day -1 during fall at 1,000 μS cm -1 EC of leachate. Out of the total removed, about 79.77% & 68.83% of N and 75.75% & 53.02% of P was absorbed by duckweed during summer and fall seasons respectively at 1,000 μS cm-1 EC. Seasonal variations during June to September have less significant effect on duckweed growth and its nutrient & COD removal efficiency from leachate. Results of the study show that duckweed can be used as potential aquatic macrophyte for duckweed based leachate treatment under natural climatic conditions.