Anaerobic ammonium oxidation of ammonium-rich waste streams in fixed-bed reactors

摘要

The feasibility of anaerobic ammonium oxidation (Anammox) in fixed-bed reactors was evaluated on laboratory and pilot scales. Using synthetic wastewater, the specific nitrogen removal rate was increased from 0.05-0.1 kgNm~(-3)_(reactor)d~(-1) to 0.35-0.38 kgNm~(-3)_(reactor)d~(-1) within ayear (T= 22-27℃) in all applications. However, the anammox activity was seriously and repeatedly inhibited at prolonged high nitrite concentrations (e.g. six days at 30-50 gNO_2-Nm~(-3)) and recovery was always a lengthy process. But even at a moderate nitrite concentration (11 ± 10 gNO_2-Nm~(-3)), the observed specific growth rate was only 0.018 d~1 at 26.4 ± 0.8℃, which corresponds to approximately 0.025 d~(-1) at 30℃ (doubling time: 28 days). In a second experimental period for another 250 days, one of the laboratory reactors was fed with partially nitrified sludge liquors from a domestic wastewater treatment plant (WWTP). In this case, the specific elimination rate was as high as 3.5 kgNm~(-3)_(reactor)d~(-1)at 26-27℃. Independently of the feed, the average nitrogen elimination rate lay between 80-85% in all applications. An appropriate hydraulic design is essential to prevent clogging and local nitrite inhibition in fixed-bed reactors.