Chelate assisted phytoremediation of chromium from soil irrigated with municipal wastewater using <i>Calotropis procera</i>

Abstract

In this study, the efficiency of ethylenediamine tetraacetic acid (EDTA) and citric acid (CA) in the extraction of chromium (Cr) from soil irrigated with municipal wastewater using C. procera was investigated. The seeds of C. procera were planted in different pots containing 1kg of soil obtained from Lambun Sarki vegetable garden and irrigated with municipal wastewater. Five (5) ml of 0.1mmol EDTA and five (5) ml of 0.5mmol CA were added separately on the 10^th, 11^th and 12^th week. The control was setup the same way but without amendment. The plants were harvested after 13 weeks of planting and the average shoot heights of the plants were recorded. Cr contents in the roots and shoots of the plants in the control and chelate amended soils were analysed using microwave plasma atomic spectrophotometer (MP- AES). The results obtained showed that the individual application of EDTA and CA to the soil increased the average shoot heights of C. procera relative to the shoot height of control. The results obtained also showed that the application of EDTA and CA to the soil increased the accumulation of Cr in the plant tissues. Phytoextraction ability was assessed in terms of bioconcentration factor (BCF) and transfer factor (TF). The BCF values of C. procera for Cr increased with the application of EDTA and CA to the soil. The TF also increased with the application of EDTA and CA. The TF values showed that the removal of Cr by C. procera with EDTA and CA amendment was by phytoextraction.