Combined organic carbon and complete nitrogen removal using anaerobic and aerobic upflow filters

Joseph C. Akunna, Claude Bizeau, René Moletta, Nicolas Bernet, Alain Héduit

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    Two laboratory upflow aerobic and anaerobic filters fed with synthetic wastewaters were used to study firstly the effects of aeration rate on the nitrification of anaerobically pre-treated effluents and secondly the effects of recycle-to-influent ratios on methane production rate, denitrification and nitrification performances of a combined aerobic and anaerobic wastewater treatment process. Nitrification of anaerobically pre-treated effluent was accompanied by aerobic post-treatment for residual COD removal. A comparison of nitrification performances using autotrophic medium and anaerobically pre-treated effluents (containing 1203 mg COD 1−1) with the same ammonia nitrogen concentration of about 300 mg NH4-N 1-1 showed that 3% of added ammonia nitrogen was assimilated by autotrophic nitrifiers during nitrification of the autotrophic medium while up to 30% was assimilated by both nitrifiers and heterotrophs during organic carbon removal and nitrification of anaerobically pre-treated effluent. Furthermore, it was suspected that significant nitrogen loss through denitrification occured in the aerobic filter especially at low aeration rates. In the study of the combined aerobic-anaerobic system, maximum ammonia nitrogen removal of 70% through denitrification was obtained at recycle-to-influent ratios of 4 and 5. COD removal efficiency in the anaerobic filter decreased from 77 to 60% for recycle-to-influent ratios of zero to 5. Overall COD removal efficiency of the entire system was constant at about 99% due to heterotrophic COD removal in the aerobic filter.
    Original languageEnglish
    Pages (from-to)297-306
    Number of pages10
    JournalWater Science and Technology
    Issue number12
    Publication statusPublished - Dec 1994


    • Anaerobic digestion
    • Denitrification
    • Nitrification
    • Methane
    • Nitrate
    • Ammonia
    • Anaerobic filter
    • Aerobic filter


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