Nitrogen Reduction

To attain nutrient balance for land application or to meet other reuse constraints, Bennett Environmental can apply a 2-phased technology, consisting of an anaerobic reactor and an aerobic moving bed biofilm reactor (MBBR), coupled with algae raceways for efficient photosynthetic oxygenation of wastewater. This technology can reduce the concentration of nitrogen in the wastewater as desired and can even reduce to 10 ppm total nitrogen, (the drinking water standard). This is accomplished by inducing denitrification, harmlessly transforming the nitrogen in the wastewater to nitrogen gas, which composes 78% of the atmosphere that we breathe. The algae also absorbs some of the N into its biomass, and is a beneficial byproduct which can be used for bioplastic manufacture or high protein animal feed. 


Aerobic System Phase 2 (B+C) = Potential 95% Nitrogen Reduction



UASB Reactor – Phase 1: Anaerobic treatment

Phase 2

MBBR – Phase 2: Optional Aerobic treatment:

  • High quality water purification

  • Usage of algae as the oxygen source results in > 90% reduction in plant aeration energy (electrical) requirements

  • Dramatic reduction in TSS and BOD


Algae raceways:

  • Water treatment, oxygen production, and nitrogen assimilation into algae

  • Simple infrastructure



No lagoon needed for treatment

High horespower blowers aren't relied on for aeration

High rate process (~20-40x faster than covered lagoon)

Low maintenance

Remote operation

Smaller footprint


  • Anaerobic phase can reduce GHG, treat water, and provide renewable energy, similar to other anaerobic technologies.
  • Optional 2nd phase can provide an efficient higher level of water treatment. Plus, algae is separated out of water and can be used for bio-plastic, manufacture, fertilizer, cattle feed or other uses.
  • Denitrification can be induced with second phase, reducing nitrogen in the waste water mixture, potentially to less than 10 ppm total nitrogen as desired
    • The more area of algae raceways provided, the more N that can be harmlessly denitrified into N2 gas.
    • The design of the system is flexible and modular, and can be designed to match needs for N management.

Environmental Impacts: Benefits to Water

  • Reduction of N, when needed, to make room for N in well water or reduce land application area required;
  • Facilitates water use in subsurface drip irrigation (SSDI):
    • Water conservation by irrigation efficiency;
    • Increased nutrient efficiency – protection of groundwater quality;
    • Yield and quality increases – more crop per drop;
  • Allows potential future treatment to remove salt, once the organics are out of the way.