APPLICATION OF MICROORGANISMS ISOLATED FROM FIBER CEMENT ROOFING SHEET WASTE AS A POTENTIAL HEAVY METAL REMOVAL AGENT
Author: BALOGUN, Catherine Ese
Abstract
Potential of heavy metal removal by indigenous microorganisms obtained from fiber cement roofing sheet waste was examined. The pH, electrical conductivity and metal concentrations were determined using pH meter, electrical conductivity meter and Atomic Absorption Spectrophotometer respectively. Enumeration and isolation of microorganisms were by pour plate method while identification was by standard microbiological protocol (Gram reaction, morphology and biochemical test). The ability of bacteria and fungi isolated to utilize the fiber cement waste as growth medium was tested. A total of fourteen (14) bacterial species and 7 fungal isolates were identified. Bacillus and Proteus species (bacteria), Rhizopus and Microsporium (fungi) were selected for the waste treatment tests based on their ability to grow on fiber cement waste medium. The Minimum Inhibitory Concentration (MIC) of the metals on the growth of bacterial and fungal isolates were subsequently determined. The MIC values for Bacillus, Proteus, Microsporium and Rhizopus species were 300mg/ml, 250mg/ml, 450mg/ml and 400mg/ml for Nickel; 250mg/ml, 350mg/ml, 450mg/ml and 400mg/ml for Chromium; 900mg/ml, 1000mg/ml, 700mg/ml and 750mg/ml for Cadmium respectively. The percentage reduction of Cadmium in treated samples with single isolates ranged from 5-33%; Chromium, 6- 49% and Nickel, 4-23%, percentage reduction in treatment with all bacteria was Cadmium 22- 56%; Chromium, 16-60% and Nickel, 5-37% while for all fungi the values were Cadmium 18- 50%; Chromium, 17-56% and Nickel, 4-28%. The treatment with consortium of the isolates had the higher efficiency in the heavy metal reduction. Percentage reduction of Cadmium, Chromium and Nickel by the consortium was 31-75%, 20-78% and 7-52% respectively. When compared to the untreated samples, biological treatment with the selected isolates significantly (t-test, p<0.01-p reduced the heavy metals to varying levels. The efficacy of the treatment was assessed by seed germination (beans and maize) in treated samples using germination index. Although analysis of variance (F 0.06-8.41, showed that the seeds germinated better in treated waste samples as indicated by one way ANOVA. Germination of the seeds improved and not significantly different from germination in untreated samples. It can therefore, be concluded that a biological treatment consortium comprising indigenous strain of Proteus Bacillus, Rhizopus and Microsporium species emerged from this study to be an effective, ecologically friendly and cost-effective treatment alternative since the consortium demonstrated a higher percentage of heavy-metal removal. This study demonstrates that microorganisms from fiber cement waste, soil without fiber and waste dumpsite have potential to be used as an alternative bioremedial tool for treating fiber cement waste containing contaminated with heavy metals.
Supervisor: DR. (MRS.) O.O. AKPOMIE
