ICON Project

Modelling and optimization of modern waste water treatment processes for nitrogen removal: the Anammox Process

ICON project page
The problem of polluted surface water becomes larger every day. Both the domestic and the non-domestic and industrial waste water treatment plants (WWTP) are doing all they can to make sure that the contents of polluting substances is limited under the legal norm. These norms become more and more stringent. Most innovations on the former type of WWTP are already a decade old. The research on the latter type of WWTP is fully ongoing. New processes are necessary to improve the water quality drastically. These new processes can be stand alone processes or they can be added to classic processes.

Modelling of waste water treatment processes gives a better insight in the process and makes optimisation possible in an efficient way. The aim of this EU sponsored project is to model and optimise the combined Sharon-Anammox process (Van Dongen et al., 2001). This process makes it possible to economically remove nitrogen from waste water with high nitrogen content. After all, biological nitrogen removal out of wastewater with high nitrogen contents can become a major cost factor, in particular when the wastewater in question contains only little amounts of biologically degradable carbon compounds (Seyfried et al., 2001).

In the Sharon process (Single reactor system for High Ammonia Removal Over Nitrite, see also the Sharon Project ). Ammonium is first oxidised under aerobic conditions to nitrite. With the addition of an external carbon source this nitrite is then converted to dinitrogen gas under anoxic conditions. All these conversions take place in a single reactor system (Hellinga et al., 1998). The oxidation of ammonium only to nitrite and not to nitrate leads to a considerable reduction of aeration costs. An additional cost in the Sharon process is however the external carbon source (usually methanol) that needs to be added. If this carbon source is not added, there is no conversion of nitrite to dinitrogen gas. This would give an effluent of the Sharon reactor which contains both ammonia and nitrite. This effluent can then be used as influent for the Anammox reactor.

In the Anammox process (ANaerobic AMMonium Oxidation) ammonium is oxidised with nitrite as electron acceptor (Jetten et al., 1999). Dinitrogen gas is the main reaction product. A small amount of nitrate is also formed. Since the Anammox organisms are autotrophic, no addition of an external carbon source is required. In order to obtain a high removal efficiency, it is however essential that ammonium and nitrite are fed to the reactor in molar ratio of one. This ratio can be obtained by operating the Sharon reactor in a controlled way without the addition of an external carbon source. Thus, by combining the Sharon and the Anammox process ammonium can be removed from waste water with high ammonium content without the addition of an external carbon source and with considerable less aeration costs in comparison with the classical methods. For more details concerning the Anammox process, please visit the website www.anammox.com . Recently, an Anammox reactor was constructed at the WWTP of Sluisjesdijk (The Netherlands). Some pictures of this construction can be seen here:

Anammox picture 1 Anammox picture 2

Optimisation of the Sharon reactor for the coupling with the Anammox reactor will be investigated both experimentally and with the use of simulations (see also the Sharon Project ). For the experimental study, a 2 litre labscale chemostat was built in the BIOMATH Lab:

Sharon 1

The reactor is fed with synthetic influent. Temperature, dissolved oxygen and the pH are monitored. The pH can be controlled by the addition of acid or base. This addition, as well as the data sampling happens completely automatic every minute. Ammonium, nitrite and nitrate measurements are done daily. For the moment the reactor has been start up and kinetic characterisation is fully going on. In the future, the influence of temperature and pH will be investigated.

The optimisation of the Anammox process will be done by simulations. In a later stage perhaps an Anammox reactor will be build in the BIOMATH Lab. Because Anammox organisms are slow growing organisms, the Anammox process is preferably performed in a biofilm reactor. The biomass concentration in this type of reactor is much higher than the biomass concentration in a conventional chemostat. The simulation environment WEST is an ideal tool to develop a mechanistic biofilm model. The influence of different process conditions such as the present of oxygen will be investigated.


  • Hellinga, C., Schellen, A.A.J.C., Mulder, J.W., van Loosdrecht, M.C.M. & Heijnen, J.J. (1998). The SHARON process: an innovative method for nitrogen removal from ammonium-rich wastewater. Wat. Sci. Techn. , 37, 135-142.
  • Jetten, M.S.M., Strous, M., van de Pas-Schoonen, K.T., Schalk, J., Van Dongen, U.G.J.M., van de Graaf, A.A., Logemann, S., Muyzer, G., van Loosdrecht, M.C.M. & Kuenen, J.G. (1999). The anaerobic oxidation of ammonium. FEMS, Micr. Rev., 22, 421-437.
  • Seyfried, C.F., Hippen, A., Helmer, C., Kunst, S. & Rosenwinkel K.-H. (2001). One-stage deammonification: nitrogen elimination at low costs. . Wat. Sci. Techn.: Water Supply, 1, 71-80.
  • Van Dongen, U.G.J.M., Jetten, M.S.M. & van Loosdrecht, M.C.M. (2001). The Sharon-anammox process for the treatment of ammonium rich wastewater. Wat. Sci. Techn. , 44, 153-160.

Project duration: 2001-02-01 - 2004-01-31

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Stijn Van Hulle
Department of Applied Mathematics, Biometrics and Process Control
Coupure links 653
9000 Gent
Tel: +32 (0) 9 264 5937
Fax: +32(0) 9 264 6220
Email: Stijn.VanHulle@biomath.rug.ac.be

Last update: 01 december 2008, webmaster@biomath.ugent.be

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