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Title: Characterization and Determination of Fluoride Removal Efficiency and Antimicrobial Activities of Moringa stenopetala Seeds
Authors: Robel, Sahilu
Advisors: Dr. Seyoum Leta
Keywords: Moringa stenopetala
Crude water extract
Fluoride removal
Antibacterial activity and Minimum inhibitory concentration
Copyright: Mar-2010
Date Added: 6-May-2012
Publisher: Prof Yalemtsehay Mekonnen
Abstract: Abstract The seeds extract of Moringa is used as coagulant for drinking water clarification. It is known to be effective bioadsorbent for the removal of turbidity, chemical contaminants and microorganisms from water. Fluoride removal and antibacterial activities of the crude water extract (CWE) of the seeds of Moringa stenopetala were carried out in this study. The CWE was tested for the removal of fluoride from standard Sodium Fluoride (NaF) water samples by measuring the residual fluoride concentration before and after the treatment. Effect of dose, contact time, initial fluoride concentration and pH on its removal efficiency was evaluated. Its activity was also tested using ground water samples taken from Hawassa, Zeway and Alaba Woreda (Bendo Kebele). Antibacterial activity of the CWE tested against Escherichia coli, Pseudomonas aeruginosa, Shigella boydii, Staphylococcus aureus and Streptococcus pneumoniae. Fluoride removal from initial fluoride concentration of 10 mg/L at neutral pH, indicated that when the CWE dose increased from 0.5 to 4.0 g/L, fluoride removal efficiency increases from 48.8% to 83.7 % at the contact time of 90 min. Similarly, removal efficiency increases from 34.1% to 81.6 % as the contact time increased from 15 to 180 min for 2.0 g/L dose applied. At fixed 2 g/L dose of the CWE and pH of the solution; fluoride removal efficiency decreases from 93.1 % to 44.9 % as the initial concentration of fluoride increased from 5.0 mg/L to 20 mg/L. Controlling other factors constant; maximum 83.3 % and minimum 33.4 % of fluoride removal efficiencies were observed at pH of 3 and 12, respectively, at a 2.0 g/L dose of the CWE applied. These might indicate that efficiency of the CWE is affected by these factors in addition to dose and contact time. Fluoride removal efficiency of the CWE was less for the ground water samples compared to the standard NaF water samples. Growth Inhibition was observed for S. boydii, S. aureus and S. pneumoniae; however, E. coli and P. aeruginosa completely resist the antibacterial activity of the CWE. As the dose applied increased from 25 to 200 mg/ml; the mean inhibition zone was also increased from 16.8 to 26.4 mm against S. boydii, from 18.8 to 28.8 mm against S. aureus and from 20.2 to 27.8 mm against S. pneumoniae which might indicate growth inhibition was a function of the dose applied. viii The mean inhibition zones of 23.2, 24.8, 25.6 mm and 26.4, 28.2, 27.8 mm obtained against S. boydii, S. aureus and S. pneumoniae when 100 and 200 mg/ml doses of the CWE applied, respectively, indicated that the CWE was more effective than the 0.025 mg/ml dose of tetracycline having the mean inhibition zones of 21.4, 23.4 and 21.8 mm against S. boydii, S. aureus and S. pneumoniae, respectively. The mean inhibition zones of 16.8, 18.8, 20.2 mm and 19.2, 22.0, 22.6 mm obtained against S. boydii, S. aureus and S. pneumoniae when 25 and 50 mg/ml doses of the CWE applied, respectively, indicated that the CWE was less effective than the 0.025 mg/ml dose of tetracycline (except 50 mg/ml dose for S. pneumoniae) having the mean inhibition zones of 21.4, 23.4 and 21.8 mm against S. boydii, S. aureus and S. pneumoniae, respectively. The above result might indicate that the seeds of M. stenopetala can disinfect bacteria in addition to the physical removal from water. Minimum inhibitory concentration (MIC) of the CWE was higher against E. coli and P. aeruginosa compared to the rest, which may also support their resistance against the activity of the CWE. In conclusion, the CWE of the seeds of M. stenopetala has defluoridation capacity and antibacterial activity.
URI: http://hdl.handle.net/123456789/2623
Appears in:Thesis - Environmental Sciences

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