**3.9 Anaerobic ammonium oxidation (Anammox)**

It is an auto trophic nitrogen removal method which uses ammonium and nitrite as electron donor and acceptor respectively to attain nitrogen removal. Anammox is specially recommended for mature type of leachate, which has non-biodegradable COD and high concentration of nitrogen [72]. Anammox process overcomes the requirement of organic carbon for nitrification in activated sludge process, reduces the amount of energy required for aeration and there is less production of excess sludge and CO2 emission [73]. A continuous flow process having nitrification and anammox has been studied to treat mature type of landfill leachate. The efficiency for removal of TN and COD were found to be 94 and 62% respectively [74].
