A study of aquatic macrophyte for remediation of chromium and cadmium in wastewater effluents in Yenagoa Metropolis, Niger Delta

Abstract

Although aquatic macrophytes have been used individually for wastewater remediation, there is a dearth of studies comparing their efficiency level to determine the most effective for remediation of specific heavy metals. This study aimed to determine the most effective aquatic macrophyte amongst Eichhornia crassipes, Pistia stratiotes, Nymphaea nouchalli, Lemna minor and Ceratophyllum demersum for the remediation of Cr and Cd from wastewater effluents in Yenagoa Metropolis, Niger Delta. Wastewater samples from emulsion paint industries were collected from six locations (L1-L6) and analyzed for Cr and Cd concentration using Inductively Coupled Plasma Atomic Emission Spectroscopy. The wastewater samples were treated with these aquatic macrophytes and the concentration of Cr and Cd in the samples were assessed every two weeks for six weeks. Results showed that the mean Cr concentration (0.27mg/L) and Cd levels (0.080mg/L) in the wastewater samples were higher than the recommended WHO limits of 0.05 and 0.003mg/L respectively. The treated wastewater showed that Cr and Cd concentrations in the wastewater were reduced to minimum values by P. statiotes (0.003±0.001mg/L) and E. crassipes (0.000±0.000mg/L) respectively. The removal potentials of the macrophytes were in the order of P. stratiotes > E. crassipes > N. nouchalli > L. minor > C. demersum for Cr, and E. crassipes > P. stratiotes > N. nouchalli > C. demersum > L. minor for Cd. It was concluded that the most effective aquatic macrophyte for remediation of Cr was P. stratiotes (with 97% efficiency) and Cd was E. crassipes (87.5% efficiency). Therefore the macrophytes were considered good phytoremediators.