Carbon Source Selection for Deep-bed Partial Denitrification: Anammox (PdNA) Polishing Filters

Applying partial denitrification – anammox (PdNA) in polishing filters as a final treatment step would allow stringent nitrogen limits to be met while minimizing the use of external carbon for denitrification. This study showed the comparison of methanol versus glycerol for PdNA filter applications. Although both carbon sources resulted in good PdNA performance, glycerol showed slightly higher PdN efficiency, PdNA rate and PdNA contribution to overall total inorganic nitrogen removal. The selection of carbon source will mainly depend on carbon unit cost rather than performance difference. Moreover, this study showed stable and efficient PdNA over a 9-month test period. Effluent TIN levels of 2 mg N/L were reached when upstream aeration control was optimized. Lastly, maximum activity tests showed high anammox retention and about 1.5-3.5 times more anammox activity than needed to meet expected removal. These results are very encouraging and increase the confidence of this concept for full scale application.