The PHOSPAQ™ process addresses a critical need of struvite mitigation at plants with high levels of Phosphorus in their sidestreams (typically due Biological Phosphorus (Bio-P) Removal or Thermal Hydrolysis Processes (THP) in their treatment schemes). The process can further be enhanced to include Phosphorus recovery in the form of a slow release fertilizer i.e. struvite formed as a byproduct in the process which can be used as an additional source of revenue for the plant. Additionally the system provides an excellent protective pre-treatment step ahead of deammonification particularly for plants with THP, by eliminating inhibitory and competition inducing organic compounds and Sulfides thereby allowing for optimization and uninterrupted operation of the downstream process without the need to add additional chemicals.

• Centrate
• Filtrate
• Digester Supernatant
• Landfill Leachate
• High Phosphorus Industrial/Municipal Streams
• Thermal Hydrolysis Process Enhanced Anaerobic Digestion Effluent

  • Flexibility of design – The PHOSPAQ™ system allows the flexibility to design for just Phosphorus removal or if needed Phosphorus recovery. The core process enables addressing of struvite mitigation/Phosphorus removal concerns at the plant, but additional unit processes can be easily added to take the process to Phosphorus recovery giving the client absolute control and flexibility in the upgrade.
  • Low O&M Costs – With no moving parts inside the reactor and the addition of Magnesium Oxide which adds alkalinity to the process entailing no additional alkalinity needs for struvite formation, helps keep the chemical and O&M requirements for the PHOSPAQ™ extremely low. Further, it helps downstream deammonification processes by maintaining the alkalinity in the influent for optimal biological activity and high removal rates.
  • Simple and compact construction – With no moving parts inside the reactor which essentially comprises of aeration, chemical feed and a separator mechanism, the PHOSPAQ™ process is simple to construct and operate with high loading rates enabling a compact design.
  • Enhanced Struvite precipitation with free BOD and Sulfides removal – Presence of aeration in the PHOSPAQ™ tank helps strip out Carbon dioxide which raises the influent pH which enhances the formation of struvite in the reactor. Further, the aeration accomplishes free BOD and Sulfides removal which helps protect downstream deammonification processes from heterotrophic competition as well as inhibition. The effect is even more pronounced in THP effluents where the PPHOSPAQ™ helps attenuate other inhibitory compounds in the influent to the deammonification system downstream enabling optimal performance and activity.
  • Longest experience with large reference base – There are over 11 PHOSPAQ™ references worldwide with some running continuously for over 10 years.

The PHOSPAQ process comprises an aerated tank to which the Nitrogen and Phosphorus rich sidestream is added. Magnesium Oxide or Magnesium Hydroxide is used to provide the Magnesium content to form Magnesium Ammonium Phosphate (MAP) aka Struvite. Air is primarily added to mix the tank but also helps strip out the Carbon dioxide increasing the pH thereby aiding formation of MAP while also providing free BOD removal. The aeration further helps with the crystallization process and as the crystals grow and become heavier and pass through the specially designed separator, the heavier crystals settle into the tank (to be withdrawn from the bottom), the cleaned effluent leaves through the top of the separator. The withdrawn struvite can just be dewatered with a drain belt, mixed with biosolids and disposed in case of the removal configuration. Alternately, additional unit processes can be added to further increase the dry matter content of the struvite enabling recovery as a bespoke fertilizer.


What levels of removal can be achieved by PHOSPAQ™ systems?

PHOSPAQ™ systems can easily achieve greater than 80 to 90% Phosphorus removal. However it is possible to get even greater removal as high as 98% (although economically it may not be preferred to go that high from a chemical costs point of view)

Can we just stop at Phosphorus removal, if recovery isn’t needed?

The flexibility to stop at just Phosphorus removal rather than going all the way to recovery is a key benefit of the PHOSPAQ™ process which makes it economically amenable for plants of all sizes. Should the plant choose to go towards the recovery route in the future, the associated unit processes can easily be just added on.

How many references are there for PHOSPAQ™?

There are over 11 PHOSPAQ™ references worldwide

What chemicals are needed for PHOSPAQ™?

The PHOSPAQ™ system requires only Magnesium Oxide or Magnesium Hydroxide. No additional chemicals (for alkalinity correction etc.) are required.

Can PHOSPAQ™ systems be retrofit into existing basins?

PHOSPAQ™ systems can easily be retrofit into existing tankage leading to significant savings in civil and construction costs.

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PHOSPAQ™ is a registered trademark of Paques BV