Application of the SNAD process to Municipal Solid Waste leachate

Simultaneous partial Nitrification, Anammox and Denitrification (SNAD) process was validated to treat old landfill leachate in a 4 L sequencing batch reactor. The old landfill leachate used in our study was characterized through chemical and respirometric analysis. The characteristics were high soluble COD content (~80% of total COD) and low particulate COD. Further only 6 % of soluble COD was readily biodegradable while the largest part of organic matter was mainly refractory organics. Batch studies were conducted both on synthetic wastewater and leachate with nitrogen load rate of 0,25 kg m-3d-1 and organic load rate of 0,39 kg m-3d-1. In batch tests on synthetic wastewater, an ammonium and total nitrogen removal of 99% and 92% was observed, respectively. A high COD removal was observed (~ 50%). Good results were achieved when old landfill leachate was used as influent, reaching an ammonium and total nitrogen removal of 72% and 65%, respectively. A lower COD removal was observed (~ 20%) probably due to the presence of non-biodegradable or slowly biodegradable organic matter in the leachate. Monitored on-line parameters also showed that the SNAD process performed in a sequencing batch reactor (SBR) could be controlled and optimized through on-line measurement of the DO, pH and ORP values.