Single stage biological nitrogen removal by nitritation and anaerobic ammonium oxidation in biofilm systems

Abstract

In full scale wastewater treatment plants with at times considerable deficits in the nitrogen balances, it could hitherto not be sufficiently explained which reactions are the cause of the nitrogen losses and which micro-organisms participate in the process. The single stage conversion of ammonium into gaseous end-products--which is henceforth referred to as deammonification--occurs particularly frequently in biofilm systems. In the meantime, one has succeeded to establish the deammonification processes in a continuous flow moving-bed pilot plant. In batch tests with the biofilm covered carriers, it was possible for the first time to examine the nitrogen conversion at the intact biofilm. Depending on the dissolved oxygen (DO) concentration, two autotrophic nitrogen converting reactions in the biofilm could be proven: one nitritation process under aerobic conditions and one anaerobic ammonium oxidation. With the anaerobic ammonium oxidation, ammonium as electron donor was converted with nitrite as electron acceptor. The end-product of this reaction was N2. Ammonium and nitrite did react in a stoichiometrical ratio of 1:1.37, a ratio which has in the very same dimension been described for the ANAMMOX-process (1:1.31 +/- 0.06). Via the oxygen concentration in the surrounding medium, it was possible to control the ratio of nitritation and anaerobic ammonium oxidation in the nitrogen conversion of the biofilm. Both processes were evenly balanced at a DO concentration of 0.7 mg/l, so that it was possible to achieve a direct, almost complete elimination of ammonium without addition of nitrite. One part of the provided ammonium did participate in the nitritation, the other in the anaerobic ammonium oxidation. Through the aerobic ammonium oxidation into nitrite within the outer oxygen supplied layers of the biofilm, the reaction partner was produced for the anaerobic ammonium oxidation within the inner layers of the biofilm.

Investigations of Nitrogen Removal Pathways in a Biological Packed Bed Reactor Using Elementary Mass Balances

“…For example, substantial nitrogen losses, ranging from 10 to 90%, were found in lab-scale rotating biological contactors (RBC) treating ammonium rich wastewater at low C/N ratios (Helmer and Kunst, 1998;Siegrist et al, 1998;Helmer et al 1999, Pynaert et al, 2002. In a pilot-scale moving bed biological reactor (MBBR), the observed nitrogen losses were exceeding 90% (Helmer et al 2001).…”

Characterization of an Autotrophic Nitrogen-Removing Biofilm from a Highly Loaded Lab-Scale Rotating Biological Contactor

“…More recently, a one-reactor combination of partial nitrification to NO 2 Ϫ and Anammox was proposed (completely autotrophic nitrogen removal over nitrite [CANON], equation 4), described mainly for suspended systems (41,44) but also modeled as a biofilm process (14) In parallel with the research on Sharon and Anammox, several reports of unexplained N losses in full-scale nitrifying biofilm reactors have been published (16,20,40). The process has been called aerobic/anoxic deammonification (18). Autotrophic N-removing biofilm reactors have been examined at the compositional and ecophysiological level (10,17,18) and have been subjected to mathematical modeling (25).…”

“…The process has been called aerobic/anoxic deammonification (18). Autotrophic N-removing biofilm reactors have been examined at the compositional and ecophysiological level (10,17,18) and have been subjected to mathematical modeling (25). A second type of planctomycete AnAOB (Candidatus Kuenenia stuttgartiensis [38]), only distantly (Ͻ91% sequence similarity) related to the original anaerobic AOB, has been detected.…”

Growth and Phytoremediation Potential of Watercress Nasturtium officinale R. Br. In Ammonium-rich Wastewater

“…In the recent past years de-ammonif ication processes, et al, et al, et al http://www.caves.res.in/ as a new technology for the treatment of nitrogen rich wastewaters, have been developed (Helmer 2000;VanDongen 2001). The introduction of deammonif ication process can reduce the cost of plant operation and make the management more sustainable.…”