Impact of Media Type and Various Operating Parameters
on Nitrification in Polishing Biological Aerated Filters |
Jeong Hyub Ha1, Say Kee Ong2†, and R. Surampalli3 |
1Department of Chemical Engineering, School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea 2Iowa State University, Department of Civil, Construction and Environmental Engineering, Ames IA 50011, USA 3US EPA, Kansas City, KS 66101, USA |
Corresponding Author:
Say Kee Ong ,Tel: +1-515-294-3927, Fax: +1-515-294-8216, Email: skong@iastate.edu |
Received: December 21, 2009; Accepted: April 26, 2010. |
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ABSTRACT |
Three biological aerated filters (BAFs) composed of a PVC pipe with a diameter of 75 mm were constructed and operated at a wastewater
temperature at 13°C. The media used for each BAF were: 5-mm gravel; 5-mm lava rock; 12.5-mm diameter by 15-mm long plastic
rings, all with a media depth of 1.7 m. The feedwater, which simulated the effluent of aerated lagoons, had influent soluble chemical
oxygen demand (sCOD) and ammonia concentrations of approximately 50 and 25 mg/L, respectively. For a hydraulic retention time
(HRT) of two hours without recirculation, ammonia percent removals were 98.5, 98.9, and 97.8%, for the gravel, lava rock, and plastic
rings, respectively. By increasing the effluent recirculation from 100 to 200% for an HRT of one hour, respective ammonia removals improved
from 90.1 to 96, 76.5 to 90, and 65.3 to 79.5% for gravel, lava rock, and plastic rings. Based on the ammonia and sCOD loadings
for different HRTs, the estimated maximum ammonia loading was approximately 0.6 kg NH3-N/m3-day for the three BAFs of different
media types. The zero-order biotransformation rates for the BAF with gravel were found to be higher than the lava rock and plastic ring
media. The results ultimately showed that BAF can be used as an add-on system to aerated lagoons or as a secondary treatment unit to
meet ammonia discharge limits. |
Keywords:
Nitrification | Biological aerated filter | Recirculation | National Pollution Discharge Elimination System |
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