Bioremediation of Metal-Polluted Industrial Wastewater with Algal-Bacterial Consortia: A Sustainable Strategy

Abstract

Aquatic pollution is a burning issue nowadays due to urbanization and industrialization. Industrial wastewater (IWW) contains pollutants that pose a great risk to the environment and human beings and is a big challenge for industries. The remediation of IWW by microorganisms is an environmentally friendly technique. This study was carried out to evaluate the pollution of IWW and to use consortia of Bacillus pakistanensis, Lysinibacillus composti, and Cladophora glomerata for bioremediation. The IWW was obtained from the Hayatabad Industrial Estate and was evaluated for physicochemical parameters and metal concentration. A pot experiment was carried out for two weeks to assess the efficiency of the developed consortia. The IWW and tap water (control) were treated with three different consortia (Bacillus pakistanensis-Cladophora glomerata (CT1, E1), Lysinibacillus composti-Cladophora glomerata (CT2, E2), and Bacillus pakistanensis-Lysinibacillus composti-Cladophora glomerata (CT3, E3). The three pots (CT1, CT2, and CT3) serving as the control were provided with tap water, and the three experimental pots (E1, E2, and E3) were provided with IWW. After treatment, substantial reductions were obtained in the following parameters and percentages: colour 85.7%, electrical conductivity (EC) 40.8%, turbidity 69.6%, sulphide 78.5%, fluoride 38.8%, chloride 62.9%, biological oxygen demand (BOD) 66%, chemical oxygen demand (COD) 81.8%, total suspended solids (TSSs) 82.7%, total dissolved solids (TDSs) 24.6%, Ca hardness 37.2%, Mg hardness 50%, and total hardness 39%. The samples of water were also examined for metal concentrations using atomic absorption spectrophotometry. The selected species removed 98.2% of Mn, 94% of Cu, 97.7% of Cr, 91.6% of Cd, 92.8% of Co, 79.6% of Ag, 82.6% of Ni, 98% of Ca, 90% of Mg, and 82.1% of Pb. The BCF values showed by the consortia for Mn, Cu, Cr, Cd, Co, Ag, Ni, Ca, Mg, and Pb were 91.8, 67, 97.5, 83.3, 85.7, 48.1, 80.4, 84.3, 82.5, and 80.3%, respectively. The t-test analysis showed that the treatment with the selected species significantly decreased the metal concentrations in the IWW (p ≤ 0.05). Overall, the study concludes that metal concentration in the water was decreased significantly by the consortia of algae-bacteria.