| Summary: | Industrial wastewater treatment by microalgae is an eco-friendly technology for improving the quality of wastewater. This study evaluated the removal of heavy metals (Cu, Fe, Ni, Pb, Cd and Zn) in wastewater collected from a metal rolling mill industry using Nostoc commune, Oscillatoria limosa and Chlorella vulgaris. Metals were determined using Atomic Absorption Spectroscopy (AAS). Other wastewater parameters determined using the standard procedure were pH, dissolved oxygen (DO), biological oxygen demand (BOD), Cl−, SO42−and NO3-. Data collected were analyzed for descriptive statistics. The results of the raw industrial wastewater were 8.50±0.07 mg/L for Cu, 3.51±0.80 mg/L for Fe, 0.16±0.01 mg/L for Ni, 1.31±0.11 mg/L for Cd and 2.48±1.00 mg/L for Pb. These values were above the permissible standards of the National Environmental Standards and Regulations Enforcement Agency (NESREA) for wastewater. After 45 days of treatment, removal efficiency for heavy metals by the microalgae ranged from 10% (Cu) to 90% (Pb). Despite the appreciable levels of metal removal in wastewater by the microalgae; the treated wastewater still exhibited metal values (except Zn) greater than the permissible limits of the NESREA. The effectiveness of the three microalgae for removing metals followed similar pattern. The present study showed the promising potentials of the three microalgae in wastewater treatment.
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