Removal of Organics and Nitrogen from Municipal Landfill Leachate in Two-Stage SBR Reactors
D. Kulikowska*, E. Klimiuk
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Faculty of Environmental Sciences and Fisheries, University of Warmia and Mazury in Olsztyn,
Oczapowskiego St. 5, 10-957 Olsztyn Poland
Pol. J. Environ. Stud. 2004;13(4):389–396
The aim of this study was to investigate efficiency of ammonium nitrogen removal from municipal landfill leachate in activated sludge in two-stage SBR reactors. Treated leachate contains low concentrations of organic substances measured as chemical oxygen demand (COD) - 757 mg O2/dm3 and high concentrations of ammonium - 362 mgNNH4/dm3. Nitrification was studied in two parallel, aerated SBR reactors with two different hydraulic retention times (HRT), 3 and 2 days, respectively. We have found that 2 days HRT was sufficient to achieve complete nitrification. In the effluent ammonium, nitrite and nitrate nitrogen concentrations were 0.08 mgN NH4/dm3, 0.04 mgN NO2/dm3 and 320 mgN NO3 /dm3, respectively. The ammonium nitrogen removal rate was 20.2 mgN NH4 /dm3.h. The effluent from aerobic reactors (HRT 2 days) was fed to the anoxic SBR reactors. An external carbon source (methanol) was added to promote denitrification. In the anoxic reactor, at a methanol dosage 3.6 mg COD/mg N NO3 and HRT of 1 day complete denitrification was achieve with nitrate nitrogen residual concentrations of 0.9 mgNNO3/dm3. The maximum denitrification rate was 48.4 mgN NOx/dm3.h. The highest values of the yield methanol coefficient Y m/N-NOx were determined for dosages 3.6 mg COD/mg NNO3 and 5.4 mg COD/mg NNO3, the lowest for 1.8 mg COD/mg NNO3.