Abstract
Five heavy metals tolerant bacteria were isolated from petroleum refinery effluent and identified as Pseudomonas aeruginosa, Staphylococcus aureus, E. coli, Proteus vulgaris and Klebsiella pneumoniae. Each isolate was inoculated into different concentrations of cadmium, chromium, nickel and zinc to determine its maximum tolerance for each heavy metal. All five isolates had low maximum tolerance concentration for cadmium (0.9 mg/L) when compared to chromium (5 mg/L), nickel (5 mg/L) and zinc (7 mg/L). Mixed culture consortium (MCC) remediated high percentage of cadmium (100%), chromium (33.4%), nickel (73.9%), and zinc (90.1%) from the petroleum refinery effluent than pure culture isolates. Among the pure culture isolates Pseudomonas aeruginosa (Cd (100%), Cr (23.1%), Ni (64.3%) & Zn (53.9%) yielded high values for the reduction of heavy metals in the refinery effluent when compared to Staphylococcus aureus, E.coli, Proteus vulgaris and Klebsiella pneumoniae. The isolated bacteria were effective for the remediation of heavy metals from petroleum refinery effluent.
Highlights
Industrial development results in the generation of industrial effluents and if untreated, results in water, sediments and soil pollution (Fakayode, 2005)
Biochemical characterization (Table 1) of Isolates A, B, C, D and E revealed them as Pseudomonas aeruginosa, Staphylococcus aureus, E.coli, Proteus vulgaris and Klebsiella pneumoniae
The Optical Density (OD) values recorded for Pseudomonas aeruginosa had Maximium Tolerance Concentration (MTC) of 0.9 mg/L for cadmium, 4 mg/L for chromium, 4 mg/L for nickel and 7 mg/L for zinc
Summary
Industrial development results in the generation of industrial effluents and if untreated, results in water, sediments and soil pollution (Fakayode, 2005). Industrial effluent is heavily loaded with different types of organic and inorganic pollutants, which are discharged into receiving water bodies (Jern, 2006). Conventional physicochemical techniques for metal remediation such as filtration, acid leaching, electrochemical processes or ion exchange are expensive and may not be very effective. Biological treatment is preferred over physicochemical for toxic pollutants as the former is cost effective, efficient and environmentally friendlier (Ojo 2006; Hamza et al, 2009). Studies have discovered the use of microorganisms, plants and enzymes extracted from other organisms for the remediation of pollutants in contaminated soil, water and ground water (Hamza et al, 2009; Usman et al, 2012)
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