Efficacy of an integrated system incorporated with Eichhornia crassipes in phytoremediation of calcium from inland saline water.

Abstract

In the present study, free floating plant Eichhornia crassipes was used for the phytoremediation of calcium from inland saline water by using water having salinity of 2.5, 5 and 7.5 ppt for one week each. Water samples were collected on 0th, 4th and 6th day and plant sample was at end of the experiment for calcium estimation and for other water quality parameters i.e., total hardness (TH), total alkalinity (TA), dissolved oxygen (DO), carbon dioxide (CO2), potassium (K) and pH on 0th and 6th day of the experiment. There was a significant difference in the calcium uptake (P<0.05) by the plants compared to the 0th day samples. The higher percentage removal of calcium was noted at 2.5 ppt salinity (47.7%) followed by 5 and 7.5 ppt salinity (36.04 and 23.13%) respectively. There was significant improvement in the water quality characteristics. In first cycle at 2.5 ppt salinity, the initial concentration of TH, TA, K and CO2 was 833.33, 166.66, 2.7 and 2.6 mg.L⁻¹ which decreased to 813.33, 144.66, 1.7 and 0 mg.L⁻¹ respectively, at the end of experiment. Similarly, there was a decrease in the concentration of pH noted from 8.5 to 8.2. An increase was obtained in the concentration of DO i.e., from 6.3 to 7.1 mg.L⁻¹. The trend of decreasing was observed for other cycles also. The used integrated system (sand filter + charcoal filter + coconut coir bed filter incorporated with E. crassipes) was efficient for calcium removal and higher percentage removal was obtained at 2.5 ppt salinity followed by 5 and 7.7 ppt. At 2.5 ppt, higher percentage removal was obtained in second cycle i.e. 47.7% compared to first and third cycle i.e. 45 and 46.22% respectively. Similar trend of percentage removal was obtained at 5 and 7.5 ppt i.e., 36.04 and 23.13% respectively than other two cycles. The overall results suggest that finding of this study will serve as a baseline for treatment of inland saline water to make it useful for various agricultural and aquaculture applications.