Removal of Heavy Metal from Diesel-Polluted Water using Klebsiella Species Isolated from Diesel-Polluted Soil.
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Date
2014
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Department of Chemical Engineering,Obafemi Awolowo University.
Abstract
This project investigated the microorganisms indigenous to a diesel-oil-polluted soil sample, their potential use in bioremediation of heavy metals in diesel-oil-polluted water using ex situ technique and factors affecting bioremediation. This was with a view of reducing the hazards that arise due to heavy metal pollution.
A diesel-oil-polluted soil sample was collected from a mechanic workshop. A working sample was prepared in a conical flask by suspending 0.5 g of the diesel-oil-polluted soil sample in 50 ml of sterile distilled water (dilution of 10-2 w/v) in a 100 ml conical flask in which some glass chips were inserted. The flask was carefully agitated to obtain a uniform suspension. Dilutions of 10-4 and 10-6 were carried out in test tubes A and B. One milliliter of each dilution in tubes A and B was transferred into properly labelled petri dishes respectively. Culturing was done by making use of 20 ml molten sterile Eosin Methylene Blue agar and left to stand for the medium to set. They were incubated at 35 oC for 48 h. Colonial characteristics of the mixed culture obtained was observed. The differential colonies were isolated by sub-culturing into nutrient agar slants and labelled accordingly for use. The 18 h cultures were gram stained to study the morphological characteristics of the cultures and to ensure their purification. The ability of the isolates to grow on a heavy metal polluted medium was investigated. A digestion process was carried out and the sample was analyzed for Copper, Nickel, Chromium and Cadmium using atomic absorption spectrometry. Two hundred and fifty millilitres of bushnell-haas medium was distributed into each conical flask in which 10 ml of diesel-polluted water was added. Sterilization by autoclaving was done at 121 oC for 15 min. The medium was inoculated in a sterile environment with pure and mixed cultures of the Klebsiella species and labelled appropriately. They were incubated in a New Brunswick Gyratory shaker for 16 days. Samples were withdrawn at four days interval for analysis. Design-Expert 8.0.3.1 was used for the design, modelling and optimization using time and pH as the two variables.
The isolated organisms isolated and used for the bioremediation studies were Klebsiella edwardsii, Klebsiella oxytoca, Klebsiella pneumoniae and Pseudomonas cepacia. When Klebsiella edwardsii was used as bioremediating agent, concentration of Cu, Ni, Cr and Cd reduced by 87.28, 81.55, 98.30 and 92.59% respectively. Klebsiella oxytoca removed 85.55, 80.58, 98.56 and 96.29% of Cu, Ni, Cr and Cd respectively from the original sample. When the polluted water was treated with Klebsiella pneumoniae, percentage reduction in concentration of Cu, Ni, Cr and Cd were 89.59, 83.49, 98.49 and 88.88% respectively. In the mixed culture of Klebsiella edwardsii, Klebsiella oxytoca and Klebsiella pneumoniae, percentage reduction in values were 82.65, 83.49, 98.27 and 92.59% for Cu, Ni, Cr and Cd respectively. In the optimization studies, optimum pH and time for the bioremediation of the heavy metals of interest were 7.46 and 16 days respectively.
This study revealed that Klebsiella species is an efficient bioremediating agent for Cu, Ni, Cr and Cd. It also showed that pH and time have a significant effect on bioremediation of heavy metals.
Description
xvii, 103p
Keywords
Heavy Metals, Diesel Polluted Water, Klebsiella Species, Diesel Polluted Soil, Microorganisms
Citation
Abayomi, O.A.(2014).Removal of heavy metal from diesel-polluted water using klebsiella species Isolated from diesel-polluted soil.Obafemi Awolowo University.