The combination of aerobic ammonium oxidation (nitritation) and anerobic ammonium oxidation (anammox) enables an autotrophic conversion of ammonium to nitrogen. Compared to conventional nitrogen elimination it requires substantially less aeration energy and produces apparently less nitrous oxide. The sole carbon source for nitritation-anammox is carbon dioxide, making the organic carbon in waste water available for biogas production. An application in municipal wastewater treatment would reduce its costs and carbon footprint.
Adapting this combination of aerobic and anerobic ammonium oxidation to the conditions of municipal wastewater treatment means essentially acclimatizing bacteria to lower temperatures. Decelerated growth at low temperatures complicates cultivation of both aerobic and anaerobic ammonium oxidizing bacteria. Enhanced oxygen transfer at low temperatures at the same time favors unwanted nitrite oxidizing bacteria. Manipulating the microbial interaction by means of enhancing growth of aerobic and anaerobic ammonium oxidizing bacteria and reducing growth of nitrite oxidizing bacteria is the basis for the application in municipal waste water treatment.
This project focuses on understanding the microbial interaction at low temperatures. Various strategies to inhibit nitrite oxidizing bacteria are investigated in batch experiments and lab reactors. Accompanying microbial examinations and measurements of kinetics provide additional information about microbial growth. The objective is an extensive evaluation of certain process conditions and the specific effects on the different microbial groups.
