Production Of Acetic And Butyric Acid From Treated Leachate By Clostridium Butyricum Ncimb 7423 In Stirred Tank And Membrane Reactor
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Date
2016-08
Authors
Othman, Mohd Firdaus
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Abstract
Leachate is a contaminated liquid generated from landfill, imposing a devastating effect to the environment. This study focuses on bioconversion of treated leachate to acetic and butyric acid by Clostridium butyricum NCIMB 7423 which aims to solve the leachate treatment problem and at the same time produce value added product from the treatment. Leachate was taken from Pulau Burung Landfill Site (PBLS) and pretreated with limestone to remove volatile fatty acids (VFA). Two types of adjustments were carried out on leachate prior to fermentation namely altered leachate according to Biological Oxygen Demand (BOD) and altered leachate according to total carbohydrate. Stirred tank (STR) and membrane reactors were used in the fermentation of pretreated leachate by C. butyricum NCIMB 7423 of pH 6.5 and 37°C. Synthetic medium fermentation with the exact condition was carried out as a benchmark for leachate fermentation, and non-altered leachate fermentation as the control. Synthetic medium in STR fermentation showed productivity of acetic acid, butyric acid, CO2 and H2 of 0.46, 0.67, 8.24, 0.001 g/L/h respectively, with 91.3% of carbon recovery. For leachate STR fermentation, the productivity of non-altered leachate for acetic acid, butyric acid, CO2 and H2 were 0.00, 0.004, 0.39 and 0.0009 g/L/h respectively with 38.9% of carbon recovery. While the
productivity of altered leachate according to BOD for acetic acid, butyric acid, CO2 and H2 reached 0.09, 0.11, 1.94 and 0.0002 g/L/h respectively, and carbon recovery of 78.9%. The productivity of altered leachate according to the total carbohydrate for acetic acid, butyric acid, CO2 and H2 were 0.04, 0.03, 0.32 and 0.00005 g/L/h respectively with 24.9% of carbon recovery. Besides, synthetic medium membrane fermentation achieved productivity of acetic acid, butyric acid, CO2 and H2 at 0.02, 0.01, 3.39 and 0.0002 g/L/h respectively, with 65.6% of carbon recovery. Leachate fermentation in a membrane reactor achieved productivity of acetic acid, butyric acid, CO2 and H2 at 0.04, 0.08, 10.17, and 0.002 g/L/h respectively, with 72.0% of carbon recovery. Leachate fermentation in STR resulted in slightly lower productivity compared to similar fermentation using synthetic medium, whereas leachate fermentation in a membrane reactor showed relatively high production and carbon recovery compared to synthetic medium fermentation in membrane reactor. Leachate altered to BOD was selected as the best alteration for fermentation based on the carbon recovery.
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Bioconversion of treated leachate to acetic and butyric acid , to solve the leachate treatment problem.