Analyses of the impact of main stream deammonification on the liquid and gaseous emissions of municipal wastewater treatment plants in Austria

The energy consumption of wastewater treatment is a significant cost factor for the communities. In many cases it is not possible to reach energy positive operation despite the use energy efficient equipment. An approach to tackle this problem is the introduction of deammonification where nitrogen removal is achieved via the conversion of ammonia and nitrite via special anaerobic biomass which leads to a significant reduction of the aeration demand. Based on the promising results from side stream application, the implementation of the deammonification in the main stream poses further energy saving potential. This has not been investigated on large scale so far. However, besides saving energy the process may lead to additional climate relevant emissions (N2O). Nitrous oxide and other intermediates may be released in significant amounts and have to be consideration for process evaluation.