Cold anammox

Generic placeholder image The recent discovery of the metabolism of anammox bacteria (the acronym anammox stand for ANaerobic AMMonium OXidation) has completely changed the understanding of the nitrogen cycle.
Unlike conventional nitrogen removal techniques (nitrification and predenitrification) used in most of the wastewater treatment plants, the anammox process consists of two phases: a first phase of oxidation of about half of ammonium to nitrite (partial nitritation, PN) by aerobic ammonium oxidizing bacteria (AOB), followed by a second phase in which the anammox bacteria remove nitrogen through the production of molecular nitrogen released into the atmosphere.
The lower energy demand for aeration, the lower production of sludge and the absence of carbon substrates for denitrification, allow savings of management costs of over 40% compared to conventional processes.
The PN / anammox process also allows the removal of nitrogen without the need of organic substance, thus allowing the recovery of the chemical energy associated with it through its concentration in primary sludge and the production of biogas rich in methane through the process of anaerobic digestion.
However, to date, the process has found application for the treatment of hot discharges (e.g. hot industrial digesters and discharges), being the optimum temperature for the anammox process around 35°C. The temperature of urban waste water is far lower, especially in winter, and the challenge faced in the project is to apply the process even at room temperature, variable between summer and winter.

Generic placeholder image

The recent discovery of the metabolism of anammox bacteria (the acronym anammox stand for ANaerobic AMMonium OXidation) has completely changed the understanding of the nitrogen cycle.
Unlike conventional nitrogen removal techniques (nitrification and predenitrification) used in most of the wastewater treatment plants, the anammox process consists of two phases: a first phase of oxidation of about half of ammonium to nitrite (partial nitritation, PN) by aerobic ammonium oxidizing bacteria (AOB), followed by a second phase in which the anammox bacteria remove nitrogen through the production of molecular nitrogen released into the atmosphere.
The lower energy demand for aeration, the lower production of sludge and the absence of carbon substrates for denitrification, allow savings of management costs of over 40% compared to conventional processes.
The PN / anammox process also allows the removal of nitrogen without the need of organic substance, thus allowing the recovery of the chemical energy associated with it through its concentration in primary sludge and the production of biogas rich in methane through the process of anaerobic digestion.
However, to date, the process has found application for the treatment of hot discharges (e.g. hot industrial digesters and discharges), being the optimum temperature for the anammox process around 35°C. The temperature of urban waste water is far lower, especially in winter, and the challenge faced in the project is to apply the process even at room temperature, variable between summer and winter.


Planned activities within PerFORM WATER 2030

The experimental activities regarding the anammox process are part of the Water research line included in PerFORM WATER 2030. The design and construction of a pilot plant is envisaged, which allows to evaluate the technical feasibility of the process applied to urban waste water.

Objectives and expected results

  • Verification of the feasibility of the anammox process applied to urban waste water.

  • Identification of the key parameters that determine the stability of the process.

  • Development of a model for the biological process control.

Description of the activities

  • Design and construction of a pilot scale digester for treatment of: waste water treatment sludge, microalghe grown in digestate liquid fraction, OFMSW (Organic Fraction of Municipal Solid Waste) and other food waste.

  • Start-up, operation and monitoring of pilot scale digester, testing different operating condition in order to optimize the process.

  • Execution of specific lab test to obtain a biomass characterization and modellize the process.

Pilot site

The experimental activities will be located at Peschiera Borromeo WWTP (Wastewater treatment plant) operated by CAP Group.
For further information, please refer to the specific web-page dedicated to demonstration sites of PerFORM WATER 2030.

Partners involved

SEAM engineering led engineering and construction of pilot scale plant, while project basis and process support for design were ensured by DICA-AMB Department of Politecnico di Milano, which also gave a scientific support. Amongst POLIMI's activities it's also foreseen the support for the plant operation and the development of a process modellization, which will permit to develop a control system which can be used for future real scale plant control.

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