Evaluation of Partial Nitritation/Anammox Process for Reduction of Pollutants from Sanitary Landfill Leachate

Abstract

A proposed combined process (partial nitritation process followed by anaerobic ammonia oxidation process (anammox)) was used to treat municipal landfill leachate with high amount of pollutants. This process remains under the considerable scope to increase the treatment ability of hazardous leachate. This proposed treatment will conserve surface water and ground water and save energy as well. Leachate used in this study was provided from a drainage system of a landfill in Borg El-Arab city, Egypt. The leachate produced from the studied landfill has a high concentration of ammonia that ranged from 115 mM to 160 mM. Batch laboratory experiments were performed using synthetic wastewater composed of ammonia and nitrite in the theoretical stoichiometric molar relationship ratio (1:1.32) to enrich anammox granules. This experiment was followed by using real sanitary landfill leachate produced from partial nitritation process (PN). Partial nitritation reactor was operated at constant hydraulic retention time (24 h), using three different leachate concentrations, namely, 5.9%, 25%, and 50%. The results showed that the partial nitritation process ranged from 30% to 50.8% over the study period due to the inhibition of nitrite-oxidizing bacteria by free ammonia and free nitrous acid. Ammonia reduction up to 85% has been achieved in the anammox reactor. Corresponding nitrite reduction was almost 99% in the anammox reactor. This study revealed that Broccadia species in the anammox reactor was demonstrated to be responsible for the anammox process.