Anammox bacteria with attached-growth media for nitrogen removal in wastewater

In side-by-side tests with high nitrogen wastewaters (483–1096 mg N/L), it was shown that an attached-growth media system more effectively removed nitrogen than did a suspended-growth system. The attached-growth system better handled the high nitrogen loading concentrations as calculated by the specific annamox activities (SAA) of the two systems. Moreover, the attached-growth medium was able to retain the anammox culture within the system. Based on these results, attached-growth was chosen for additional investigation of the effect of acetate in short- and long-term studies. In a short-term experiment, acetate concentrations of 0.25 and 0.5 mM did not affect the anammox bacteria activity. However, in a long-term experiment, the addition of acetate at 0.25 mM decreased the ammonium oxidation rate. The results from this study suggest that attached-growth systems show more promise for use in the field than suspended-growth systems.