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Water Environment Solutions

High Concentration Nitrogen Removal System Using Anammox Bacteria

Advanced Nitrogen Treatment - Microbial Immobilization Technology

Our Key Technology

Microorganisms entrapment

Hitachi combined “anammox” and “Bacteria entrapment”.
→More effective biological treatment system



anammox bacteria easily wash out from the reactor due to the slow growth rate. (one- tenth that of nitrifier)

  • Reaction is slow
  • Performance is unstable


Microorganism entrapment by PEG
Hitachi has already used the gel entrapment technique in many installation.

  • Reaction is faster (Tank is smaller)
  • Performance is stable


Applications for Municipal Wastewater

  Facility NH4-N conc. PEGASUS
(Conventional nitrification)
anammox process
Biological tank Low(30-50)  
Post nitrogen treatment Low(15-30)
(On-going R&D)
For side stream nitrogen treatment High(500-1000)
(Multi-stage nitrification)
  Conventional process
(Nitrification- Denitrification)
anammox process
Reactor principle
Reactor volume Large Small
O2 supply Large Small
Chemical dosing
(for denitrification)
Need No Need
Sludge production Large Small
Optimum temp. Normal (10-37℃) High (25-37℃)

What is “anammox” ?

The anammox process is a cost-effective means of biological ammonia removal. (anammox : anaerobic ammonium oxidation)

Conventional process


anammox process


anammox: anaerobic ammonium oxidation