| Abstract |
| A column reactor with biobarrier consisting of polyurethane-activated carbon (PU-AC) media with hollow silicon tubing coiled inside the media was operated to estimate the potential for treatment of nitrate-contaminated groundwater. The tubing was also evaluated for its potential to provide carbon sources such as glucose, methanol, ethanol, and acetic acid for denitrification process. Methanol was selected as the most effective carbon because the highest amount of methanol could be delivered with appropriate releasing rate. In a column experiment, the groundwater containing 60 mg/L of nitrate was flowed through the PU-AC biobarrier. Denitrification of NO3 - coupled to carbon supply throughout the silicon tubing was successfully observed, depending on the groundwater velocity and methanol concentration. For satisfying potable groundwater criteria of nitrate (10 mg/L), 0.033 cm/min of groundwater velocity with 3% of methanol content in silicon tubing was appropriate corresponding to negative ORP value of -240 mV during denitrification. To deduce the optimum operating condition of the column reactor, the groundwater velocity was further reduced to 0.018 cm/min and the carbon content (%) was changed from 2.0 to 3.5% in the silicon tubing, which resulting in 3.5% of the optimum value (approximately 83% of NO3-N removal). At this point, the ORP showed all negative values, indicating that ORP can be used as an indicator of denitrification in biobarrier in field. |
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| Key Words |
| Permeable Biobarrier, Denitrification, Nitrate, Groundwater, Silicon tubing |
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