Combining partial nitritation and heterotrophic denitritation for the treatment of landfill leachate previous to an anammox reactor

摘要

Landfill leachate can present extremely elevated concentrations of ammonium (up to 6,000mgnN-NHþn4 L21n) and a low biodegradable organic matter fraction. As an alternative to conventionalnsystems, this wastewater can be treated on a more sustainable way by a fully autotrophic partialnnitritation–anammox system. The operation of the first step of this system, the partial nitritation,nis critical since the elevated concentrations of ammonium and nitrite in the reactor can severelyninhibit ammonium oxidizing bacteria (AOB) activity. In this way, the inclusion of anoxic phasesnduring the feeding events to promote the denitrification via nitrite can be a good option fornupgrading the process performance and increasing the stability of the system. This paper dealsnwith the evaluation of an anoxic–aerobic step-feed strategy for the operation of a partialnnitritation SBR. Results of this study have revealed a decrease on the total nitrogen inside thenreactor of more than 200mg NL21nwithout prejudice on the partial nitritation process.nFurthermore, this study has also allowed detecting an AOB activity reduction at the end ofnaerobic phases due to bicarbonate limitation and/or free nitrous acid inhibition.