Deammonification anaerobic oxidation of ammonia

The DEMON® process takes place in two steps in one reactor. The first step is partial nitritation, when ammonia is converted to nitrites at low dissolved oxygen values (< 0.5 mg/l). The second step is deammonification, where anammox bacteria convert residual ammonia and newly formed nitrites into gaseous nitrogen (N2) under anoxic conditions. The whole process takes place in a single sludge system, with AOB and anammox bacteria doing most of the work.

The control elements of DEMON® anammox technology and the method of physical separation of anammox bacteria are unique to this system. These elements promote the retention and growth of anammox bacteria while regulating the retention time of anammox bacteria and nitrite oxidizing bacteria in activated sludge. Due to the automated process, only minimal operator supervision is required.

The DEMON® anammox process is often implemented as a continuous operation, but can also be designed as a sequential reactor (SBR). Although it is possible to use both types of reactors, continuous operation is preferred due to lower overall demands on installed blowers and pumps. This type of operation also allows for higher specific loads, resulting in smaller reactor volumes.

Since anammox bacteria convert ammonia and nitrates into nitrogen gas without the use of organic carbon, treatment plants using DEMON® anammox technology can:
a) use more efficiently the carbon from the inflow for denitrification
b) direct more organic carbon into anaerobic ejection tanks for energy production
(c) minimize the use of external carbon sources such as methanol. This in all cases helps to reduce the carbon/emissions footprint of the WWTP.