Removal of ammonium and organic carbon from leachate by the anammox process in a fixed bed bioreactor

One of the inevitable drawbacks of sanitary landfilling of municipal solid waste (MSW) is the production of leachate. This study aimed to assess the treatment of leachate for the purpose of removing ammonium and organic carbon using the anammox process. To grow autotrophic bacteria in the reactor, the carbon source was gradually decreased from 500 mg L-1 to less than 10 mg L-1. NH4 and nitrite concentrations from 5 and 6.6 to 300 and 396 mg L-1, respectively, were injected into the reactor and the removal was investigated. Finally, in order to assess carbon and nitrogen removal simultaneously, the concentrations of chemical oxygen demand, ammonia, and nitrite were increased to 250, 500, and 660 mg L-1, respectively. The highest efficiencies for ammonium and nitrite removal that were obtained were 76.69% and 91.12%, respectively, at the volumetric loading rate of 0.15 and 0.132 kg m(-3) d(-1) in the hydraulic retention time (HRT) of 24 h. As HRT decreased from 24 to 6 h and the loading rate increased, the highest efficiencies achieved for the removal of ammonia and NO2 were 95.19% and 80.56%, respectively. Eventually, ammonium removal efficiency did not exceed 22.28% while the removal efficiency for organic matters was 72.63%. Contrary to nitrite, ammonium removal is dependent on the appropriate performance of the anammox process.