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Nutrient removal

Nutrients can be a resource or an issue. Discharges from typical human activities contain nitrogen and phosphorus, which can degrade surface water and groundwater.  Nutrients entering surface waters, such as lakes, can cause algal blooms, which deplete oxygen.  Oxygen depletion is detrimental to fish and other aquatic life.  Nitrogen entering groundwater can contaminate potable water supplies and have negative health effects.

Nutrients are a resource if recovered and reused. As an example, plant species need nutrients to sustain healthy growth.  Many of our systems reduce nutrients to safe levels or provide nutrients and water for shallow subsurface irrigation.  In the near future, many treatment systems will recover phosphorus, which is a finite supply.

Benefit statement

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Why nutrient removal?


  • Nitrate in excessive concentrations in water may constitute a risk to human health and the environment.
  • High performance treatment systems convert a proportion of the ammonia present to nitrate. Bacteria and other microbes oxidize or mineralize the organic nitrogen to ammonia, which is further oxidized to nitrites and nitrates.
  • Effluent discharge containing nitrate to subsurface dispersal has generally been considered acceptable as denitrification (the conversion of nitrate to nitrogen gas) will occur in the in-situ soil along with nitrate removal by uptake in plants.
  • However, regulations concerning nitrate-sensitive zones, like Chesapeake Bay, mean that some form and degree of nitrogen removal is becoming an increasingly common requirement for on-site treatment systems.
  • Where nitrate levels are known to be high or nitrate loading analysis indicates a potential problem, then the relevant environmental agency or regulatory body may stipulate that consideration be given to the use of on-site treatment systems that includes nitrogen removal of 50% or more.


  • Phosphorus is an essential element of life, but when there is too much in the wrong environment it can become a pollutant.
  • In natural waters, the low solubility of natural phosphates means that phosphate levels are low and phosphorus is usually the limiting nutrient.   Excess phosphorus from any source thus leads to abundant growth of plant material in water.  As oxygen is used up by decaying matter, waterways choke on their own production.  This process is known as eutrophication and is a natural process by which stagnant water bodies slowly turn into bogs. Enrichment speeds up this process and the sight of open lakes turning into bogs, as plants encroach on the open water is undesirable.
  • The risk of eutrophication posed by phosphorus is one of the major reasons why use of this nutrient in detergents is banned or highly discouraged.  Fertilizers are another source of phosphorus in surface waters as well as human and animal wastes.

Suitable Application

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Residential or Commercial properties located in:

  • Nutrient sensitive watersheds
  • Watershed protection areas
  • Shoreland areas
  • Critical fishing habitat areas
  • Pristine lake or marine environments


How it works

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Total Nitrogen Reduction


In standard treatment systems, most of the organic nitrogen and ammonia are converted into nitrite and nitrate.  This process converts one form of nitrogen into another but does not change the mass loading.


When reduction of total nitrogen is required, then the flow of nitrified effluent into an anoxic zone reduces the nitrate to nitrogen gas, which freely escapes to the atmosphere.  Some processes (e.g. sequencing batch reactor, in-ground pad dispersal) demonstrate near simultaneous nitrification-denitrification.  Because of the various processes, the reduction of total nitrogen concentrations is achieved.

Systems typically employ the following treatment zones for total nitrogen reduction:

  1. Primary
  2. Anoxic
  3. Aerobic
  4. Recirculation
  5. Clarification
  6. Post-anoxic
  7. Carbon and/or alkalinity feed, if required

Phosphorus Removal

Optional phosphorous removal can be incorporated into standard system configurations.


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Download brochure Puraflo Peat Fiber Overview Brochure (PDF)

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Download brochure PekaSys Bubbler Overview Brochure (PDF)

Download brochure PuraMax Overview Brochure (PDF)

Download brochure PuraMax Technical Specifications (PDF)

Operations and support

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Anua has the products and expertise to tackle the most extreme sites and meet the most stringent environmental regulations. Our knowledgeable team members are here to assist you.

  • Free technical support and consultation during all project stages
  • Support and interface with state/province, county/parish, township, or local regulators
  • Excel spreadsheet packages for easy design
  • Product manuals and drawings in CAD or PDF
  • Presentations, webinars, and training on products or requested topics
  • Network of local distributors throughout North America
  • Network of authorized installers and service providers throughout North America

Anua has been in business in North America for over 20 years. This longevity and commitment to product and support quality gives our customers peace of mind in a turbulent marketplace.

To find out more, or to purchase our products and services, contact Anua today