Estimation of chromium reduction potential of two wetland plants using pilot scale constructed wetlands

Abstract

Two parallel pilot scale sub-surface flow constructed wetlands (SSFCW) are designed and fabricated. The two natural wetland plants selected for the present study are Cyperus alopecuroides and Canna indica. These plant species are grown in constructed wetland tanks A (with Canna indica) and B (with Cyperus alopecuroides) for two months by supplying fresh tap water. After the plants are grown healthy, potassium dicromate solution of different concentrations is introduced into both the tanks in a constant rate flow of 25 ml/min in plug flow manner from inlet tanks. The hydraulic retention time (HRT) is maintained as five days. After 5 days the effluent is collected at the outlet and tested for chromium (VI). The experiment is continued for four months and chromium VI in the outlet waters is analysed. At the end of the experiment, plants are harvested and seperated into leaves, rhizomes and roots. They are seperately analysed for total chromium concentration. Bio-concentration Factor (BCF) and Translocation Factor (TF) are also estimated.