DE NORA TETRA™ wastewater filters

One of the most trusted names in wastewater filters.



De Nora Water Technologies offers the DE NORA TETRA T Block™ and TETRA SNAP T® underdrain filter blocks for wastewater applications. The TETRA SNAP T® underdrain filter block features a revolutionary design incorporating interlocking blocks that promotes additional robustness to the well proven DE NORA TETRA T Block design. 

An underdrain system is required to support filter media and to separate the filter media from the bottom of the filter. In addition to providing support for the filter media, the underdrain system serves two primary purposes: to allow filtered water to pass through to the collection system and to start the distribution of backwash water and backwash air across the filter



DE NORA TETRA™ DeepBed Filters

The  DE NORA TETRA™ DeepBed tertiary gravity and pressure filtration systems from De Nora Water Technologies are an economical solution for the removal of total suspended solids (TSS). DeepBed filters also provide superior total phosphorus (TP) removal to meet stringent limits below 0.2 mg/l.  In addition to TSS removal, DE NORA TETRA™ DeepBed Filters are frequently specified to reduce BOD levels; achieve metal consents associated with chemical dosing for phosphate removal; improve effluent clarity for UV disinfection; and offer additional protection for works at risk of consent failure.


  • Excellent distribution of backwash air and water,
  • High loading capacity and superior capability at handling peak loads
  • No nozzles, screens or moving parts to clog or wear
  • Low dirty backwash water return of less than 4% (<2% typical)
  • Easily expanded into denitrification mode.


With Denite®, the denitrification process and the filtration process are combined in a single system and provide superior process synergy. NO3-N is converted to nitrogen gas and captured within the media bed along with suspended solids and biomass formed from the denitrification reaction. The Denite® gravity filter system operates in a downflow mode to maintain excellent suspended solids removal, thus avoiding the necessity for clarifiers or additional effluent polishing filters. The system integrates well with other plant treatment processes to provide superior total nitrogen (TN) below 3 mg/l and phosphorous removal.

  • Effective removal of nitrate-nitrogen
  • Proprietary TETRAPace® automatic dosing control offers savings of up to 30% in carbon consumption
  • Patented SpeedBump® operation removes accumulated gas that can build up in the filter. This can be accomplished without removing the reactor from service.
  • Consistent and proven performance - even with low water temperatures
  • Small footprint one tenth of the size of a conventional suspended growth system.
  • Low levels of wastewater return - less than 4% (<2% typical) of the plant’s forward flow

DE NORA TETRA Modular DeepBed Filters

The DE NORA TETRA™ Modular DeepBed Filter (MDBF) is a skid-mounted filtration system designed after the DE NORA TETRA™ DeepBed technology to be a competitive tertiary filtration plant for secondary effluent from smaller sized wastewater treatment facilities. Consisting of a number of stainless steel filter cells (normally 6, 8, 10 or 12), backwash water pumps, backwash blowers, pipework and control panel, the unit is fully assembled and tested to ensure simple and quick installation and setting to work.


The TETRA ColOX system is an advanced aerobic biological treatment system which combines the best elements of activated sludge (suspended growth) processes and trickling filter (attached growth/fixed-film) systems with innovative design features to achieve superior performance. Configured as a Submerged Packed Bed Reactor, the ColOX system utilizes both fixed-film and suspended growth biomass, offering

  • superior BOD oxidation and nitrification,
  • greater efficiency, operational reliability and versatility

TETRA™ SAF Submerged Aerated Filters

The TETRA SAF submerged aerated filters are a simple process for the biological oxidation of ammonia-nitrogen (NH3-N) and BOD for both municipal and industrial wastewaters.  TETRA SAF is an upflow, fixed-film biological reactor that uses coarse media requiring no backwashing

TETRA SAF offers

  • Exceptional performance, reliability, flexibility
  • No backwashing required
  • Small footprint
  • Low operational and maintenance cost savings over competitive systems.
  • A robust, small footprint system
  • Can be used for either secondary treatment (SAF/cSAF) or as a tertiary (nitrification) stage (NSAF)

In addition, the TETRA Nitrifying SAF (NSAF), is a robust solution, based on established TETRA SAF technology for tertiary ammonia removal. The up-flow, fixed film biological system represents a simple, proven and cost effective way of achieving ammonia standards down to as low as 1 mg/l on a 95 percentile basis



De Nora Water Technologies

De Nora Water Technologies - Wastewater Filtration