Nitrification and denitrification in partially aerated biological aerated filter (BAF) with dual size sand media.
A 104-mm (4-inch) diameter pilot-scale biological aerated filter (BAF) with a media depth of 2.5 m (8.3 feet) was operated with an anaerobic, anoxic and oxic zone at a temperature of 23 degrees C. The medium for the anaerobic and anoxic zones was 10 mm diameter sand while the medium for the oxic zone was 5 mm diameter sand. The influent sCOD and total nitrogen concentrations in the feedwater were approximately 250 mg/L and 35 mg N/L, respectively. sCOD removal at optimum hydraulic retention time (HRT) of 3 h with recirculation rates of 100, 200 and 300% in the column was above 96%. Nitrification was found to be more than 96% for 3 h HRT at 200 and 300% recirculation. Total nitrogen removal was consistent at more than 80% for 4 and 6 h HRT at 300% recirculation. For 3 h HRT and 300% recirculation, total nitrogen removal was approximately 79%. The ammonia loading rates for maximum ammonia removed were 0.15 and 0.19 kg NH3-N/m3-day for 100 and 200% recirculation, respectively. The experimental results demonstrated that the BAF can be operated at an HRT of 3h with 200-300% recirculation rates with more than 96% removal of sCOD and ammonia and at least 75% removal of total nitrogen.
Ha
J H
JH
Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, Iowa 50011, USA. jhha@iastate.edu
Ong
S K
SK
D000641:Ammonia / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism; D005374:Filtration / Q000295:instrumentation / Q000379:methods*; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D012822:Silicon Dioxide / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000379:methods*
D009573:Nitrites; D012722:Sewage; D012822:Silicon Dioxide; D000641:Ammonia; D009584:Nitrogen