DE NORA TETRA® Biological Filtration

The robust nature of DE NORA TETRA® filters creates an ideal environment for simultaneous biological and physical/chemical treatment. De Nora has over 50 years of experience removing nutrients, organic compounds, and solids in tertiary fixed-film biological filters. Common applications include polishing municipal wastewater effluent to reuse standards and/or regulatory discharge limits. Potable applications combine De Nora ozone and biological filtration technologies to oxidize micropollutants and to mitigate disinfection byproduct formation.


Easy to Operate and Maintain

Cost Saving

Reliability / Equipment Longevity

Regulatory Compliance

Small Footprint / Compact Design

DE NORA TETRA® biofilters can be designed in a variety of configurations to achieve optimal treatment for biological oxidation of organic compounds, nitrification, and denitrification. The De Nora flagship biofilter with over 300 installations is DE NORA TETRA Denite system, which biologically reduces soluble nitrates to nitrogen gas in an anoxic environment. In addition to nitrogen removal, DE NORA TETRA Denite solution often employs physical/chemical processes to enhance performance by also removing phosphorus and solids in a single-stage process. Media selection is influenced by a DE NORA TETRA® DeepBedTM filtration concept that is especially advantageous for biological applications where reaction time, solids holding capacity, and biomass inventory control are critical to performance.
DE NORA TETRA® ColOXTM, SAF, and NSAFTM are aerobic biofilters used for BOD/COD oxidation and nitrification. DE NORA TETRA® ABF biologically active filters combine ozone and biological filtration to treat Contaminants of Emerging Concern (CECs).


  • History of proven performance
  • Excellent distribution of backwash air and water keeps filter media clean
  • High loading capacity and superior performance at peak loads
  • No small openings, nozzles, screens or moving parts to clog or wear
  • Low dirty backwash water return volume; longer filter run times
  • Easy to upgrade existing De Nora media filters to biologically active mode
  • Can accommodate wide range of media types and sizes

Want to know more about our DE NORA TETRA® Biological Filtration Solutions?

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