Landfill-leachate treatment: Innovative autotrophic biological processes for the nitrogen removal

This study was carried out as an initial step towards development of Simultaneous partial Nitritation, Anammox and Denitrification (SNAD) process to treat old leandfill leachates, which are characterized by carbon and nitrogen compounds and by heavy metals. SNAD process supports simultaneous removal of carbon and nitrogen from effluents in one single reactor, and is was encouraged rather than pure autotrophic anammox process. Sequential batch studies confirmed that anaerobic ammonia removal is a sustainable process also in presence of organic matter (OM) but it is feasible for low C/N ratio. At high C/N ratios, denitrifers and DNRA organisms are highly competitive with anammox bacteria. Furthermore, in order to facilitate the start-up of SNAD process a nytrifing biomass well adapted to landfill leachate is necessary. The result of batch studies would be of great importance in developing a SNAD process in Sequential Batch Reactor (SBR) with flocs and granular biomass as a sustainable treatment for old landfill leachates. An overview is presented of novel biological autotrophic nitrogen removal technologies under anaerobic or oxygen limited conditions and a review of SNAD process.