Partial nitrification coupled with denitrification and anammox to treat landfill leachate in a tower biofilter reactor (TBFR)

Abstract

This study investigated the performance of partial nitrification (PN), carbon oxidation, denitrification and anammox in a continuous tower biofilter reactor (TBFR) with large height-to-diameter ratio of 13 in treating actual landfill leachate. The nitrogen loading rate (NLR) and organic loading rate (OLR) varied from 0.44 to 1.31 kg-N/(m3·day) and 1.59 to 4.76 kg/(m3·day), respectively. The average removal rates of total nitrogen (TN) and chemical oxygen demand (COD) in the TBFR reached 87.47% and 88.45% at the maximum NLR and OLR of 1.31 kg-N/(m3·day) and 4.76 kg/(m3·day), respectively. Variation of water quality along the TBFR in different operating conditions indicated that approximately 45% - 60% of the influent NH4+-N was converted into NO2−-N, and nearly 55% - 70% of the influent COD was removed in the 0–40 cm zone, which provided suitable conditions for the subsequent anaerobic anammox and denitrification processes in the 40–160 cm zone. Overall, the TBFR with a large height-to-diameter ratio demonstrated an effective technology for the treatment of landfill leachate by creating distinct aerobic and anaerobic zones in a single reactor.