This work describes the successful coupling of partial nitrification (nitritation) and anaerobic ammonium oxidation in a membrane-aerated biofilm reactor (MABR) with continuous aeration. Controlling the relative surface loadings of oxygen versus ammonium prevented complete nitrite oxidation and allowed anaerobic ammonium-oxidizing bacteria (AnaerAOB) to develop and be retained for > 250 days. Daily autotrophic nitrogen removal of 1.7 g N/m(2) (75% of influent N load) was achieved at an oxygen/nitrogen surface loading ratio of 2.2, with up to 85% of the influent N proceeding through AnaerAOB. During early nitritation, nitrogen oxide (NO(g), NO2(g), and N2O(g)) emissions comprised up to 10% of the removed influent nitrogen, but emissions disappeared after proliferation of AnaerAOB. Microbial communities were radially stratified, with aerobic ammonium-oxidizing bacteria (AerAOB) colonizing nearest to and AnaerAOB furthest from the membrane. Despite the presence of nitrite-oxidizing bacteria, this work demonstrated that these autotrophic processes can be successfully coupled in an MABR with continuous aeration, achieving the benefits of competitive specific N removal rates and the elimination of gaseous nitrogen oxide emissions.
Environmental Engineering Science, 2013, Vol 30, Issue 1, p. 38-45
autotrophic process; continuous aeration; microbial community; Microorganisms (Bacteria, Eubacteria, Microorganisms) - Bacteria  bacteria common bioindicator; ammonium 14798-03-9 oxidation; nitric oxide 10102-43-9; nitrite 14797-65-0 oxidation; nitrogen 7727-37-9 pollutant, water pollutant removal; nitrogen dioxide 10102-44-0; nitrogen oxide 11104-93-1; nitrous oxide 10024-97-2; oxygen 7782-44-7; 10060, Biochemistry studies - General; 31000, Physiology and biochemistry of bacteria; 37015, Public health - Air, water and soil pollution; 39008, Food microbiology - General and miscellaneous; membrane-aerated biofilm reactor MABR laboratory equipment; Bioprocess Engineering; Equipment Apparatus Devices and Instrumentation; Pollution Assessment Control and Management