Integrated Partial Nitritation–Anammox Process (ISNA®)
Solving the challenge of low-consumption, high-efficiency treatment for high-ammonia wastewater.
Advancement
Fixed Asset Investment
20% Lower
Wastewater Treatment Cost
60% Lower
Carbon Emissions with Significant Green and Low-Carbon Benefits
70% Lower
Tolerance to High Ammonia Nitrogen Load vs. Conventional Biological Treatment
10×
Volumetric Nitrogen Removal Efficiency vs. Conventional Biological Treatment
5×
- Partial nitritation and anammox proceed simultaneously in a single tank, saving time, space and cost.
- A completely mixed flow regime enables precise control of NO₂⁻ and NH₄⁺ concentrations.
- A dedicated sludge separation system ensures the separation of granular sludge and floc sludge.
Process Features
ISNA® is a next-generation upgrade technology for biological nitrogen removal from low C/N ratio ammonia-containing wastewater.
Anaerobic ammonium oxidation (anammox) is carried out by anaerobic bacteria that create a "shortcut" in the nitrogen cycle, converting ammonia nitrogen into nitrogen gas under carbon-free, low-oxygen conditions.
Reaction Principle
AOB (Ammonia-Oxidizing Bacteria):
NH₄⁺ + 2HCO₃⁻ + 1.5O₂ → NO₂⁻ + 3H₂O + 2CO₂
Anammox (Anaerobic Ammonium Oxidation):
NH₄⁺ + 1.32NO₂⁻ + 0.066HCO₃⁻ + 0.13H⁺ → 1.02N₂ + 0.26NO₃⁻ + 2.03H₂O + Biomass
Process Route Comparison
Full Nitrification + Denitrification
NH₄⁺-N → Ammonia-Oxidizing Bacteria → NO₂⁻-N → Nitrite-Oxidizing Bacteria → NO₃⁻-N → Denitrifying Bacteria → N₂
Anaerobic Ammonium Oxidation (ISNA®)
NH₄⁺-N → Ammonia-Oxidizing Bacteria → NO₂⁻-N → Anammox Bacteria → N₂
No External Carbon Source · Low Oxygen Demand · Minimal Sludge Production
Because partial nitritation converts only half of the NH₄⁺ into NO₂⁻, oxygen demand and alkali consumption are reduced by 58% and 50% respectively compared with conventional nitrification.
In addition, the anammox process is autotrophic: anammox bacteria use ammonia nitrogen as the electron donor and nitrite as the electron acceptor, so no additional carbon source is required. The process produces very little sludge, cutting sludge disposal costs by 85%, and the red granular sludge can be sold as seed sludge.
Oxygen Demand ↓ 58% · Only half of the NH₄⁺ is oxidized.
Alkali Consumption ↓ 50% · Greatly reduced by partial nitritation.
Zero External Carbon Source · Autotrophic process.
Sludge Disposal Cost ↓ 85% · Minimal sludge production.
Red Granular Sludge · Can be sold as seed sludge.
Applications
The ISNA® process applies to the following scenarios:
High-Ammonia Wastewater from PV Cell Manufacturing
Ammonia-Containing Wastewater from Semiconductor Chip Manufacturing
New Energy Materials (Lithium-Ion Batteries and Silicon Materials) Wastewater
High-Strength Ammonia Nitrogen Wastewater from the Coal Chemical and Pharmaceutical Industries
Landfill Leachate Treatment
Municipal Sludge Digestate Liquor
Patented Technologies
Reactor Configuration Innovation
Targeted cultivation of granular sludge with composite ammonia-oxidizing bacteria and anammox bacteria.
Composite Microbial Community System
- Partial Nitritation + Anammox · Tolerant of fluctuations in influent ammonia nitrogen and water quality.
- Granular and Floc Sludge Separation System · Ensures the optimal living environment for each microbial community.
- Completely Mixed Flow with Precise Control · Real-time adjustment of the NO₂⁻/NH₄⁺ ratio.
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