Batch Operation of Biofilter - Free-water Surface Wetland Series for Enhancing Nitritation and Anammox

This study compared two series of ecologically engineered treatment systems for nitrogen removal by enhancing nitritation and anammox. Each treatment series had two biofilters followed by one free-water surface (FWS) wetland. The first series included biofilters packed with marble chips and demonstrated a development process in nitrogen removal through the first 26 cycles of weekly batch operation. The series then stabilized at an average ammonium removal rate of 19.2 g N/m(3).d and total nitrogen removal rate of 10.6 g N/m(3).d during the latest 22 cycles. The second series, which consisted of biofilters packed with pea pebbles, experienced decreasing nitrogen removal rates. Anammox and heterotrophic denitrification accounted for 77% and 23%, respectively, of the total nitrogen removal in the marble biofilters. Nitrogen removal rates in the FWS wetlands increased significantly with ammonium loading rates increasing up to approximately 30 g N/m(3).d. Ammonium and total nitrogen removal followed zero-order reaction kinetics. The marble biofilter-wetland series reached an ammonium removal rate of 30.3 g N/m(3).d and total nitrogen removal rate of 23.0 g N/m(3).d through the latest 22 cycles of batch operation at the average ammonium loading rate of 56.4 g N/m(3).d. Water Environ. Res., 83, 541 (2011).