The effect of urban landfill leachate characteristics on the coexistence of anammox bacteria and heterotrophic denitrifiers

摘要

Heterotrophic denitrification coexists with the anammox process contributing to N removalnowing to the biodegradable organic matter supply from urban landfill leachate and the decay ofnmicroorganisms. Both biomasses consumed nitrite increasing the nitrite requirements of thensystem. The aim of this paper is the study of the causes which induce the system to decreasennitrogen removal efficiency. In this study, urban landfill leachate has been treated in annanammox Sequencing Batch Reactor (SBR) for 360 days. The anammox reactor treated onnaverage 0.24 kgNm23 d21 obtaining nitrogen removal efficiencies up to 89%. The resultsndemonstrated that i) a suitable influent nitrite to ammonium molar ratio is a crucial factor tonavoid troubles in the anammox reactor performance; ii) an excess of nitrite implied nitritenaccumulation in the reactor; iii) a lower nitrite supply than the necessary for the system couldnforce a loss of specific anammox activity due to nitrite competition with denitrifiers. Thesenresults pointed out the importance of the previous partial-nitritation process control in order tonobtain a correct influent nitrite to ammonium molar ratio for the anammox reactor. In addition,nsudden variation of the leachate characteristics must be avoided.