The EloVac®-P system is a completely skid-mounted, plug and play, compact phosphorus sequestration system that prevents struvite scaling on high Nitrogen (N) and Phosphate (P) streams. The process is an elegant, fully engineered system that helps plants with strict effluent P limits, by significantly reducing the recycle of the Phosphates back to the head of the plant. The Phosphate precipitation process further helps with significant improvement in dewaterability of the sludge, helping improve cake solids content while also reducing polymer consumption. The inherent vacuum based, low energy operation of the EloVac®-P coupled with enhanced biogas and CO2 capture, helps enable energy positive operation along with helping the plant reduce its Carbon footprint.
  • Municipal Anaerobic Digestate
  • Thermal Hydrolysis Enhanced Anaerobic Digestion Effluent
  • High Phosphate Industrial Streams


EloVac®-P Implementation in Plant Treatment Scheme


Reduced Phosphate by 80-95% in the return load to the head works
Depending on the reactive Magnesium content in the digestate and the Magnesium Chloride dosage, up to 95% PO4-P removal can be obtained, which significantly reduces the load going back to the head of the plant thereby helping the plant comply with their Phosphorus permits.

Improved dewatering by up to 5% points
The removal of Phosphates from the digestate prior to dewatering help enhanced removal of the bound water in the sludge during the dewatering operation, helping increase dewatered cake solids by up to 5% and helping reduce the sludge hauling costs by up to 20%

Reduced polymer consumption by up to 20%
The improvement in dewaterability is also seen with lower requirement for polymer for the dewatering operation leading to savings in the operating expenditure on polymer by up to 20%

Reduced downstream struvite scaling
By removing the Phosphates under controlled conditions inside the EloVac®-P reactor, they are made unavailable for depositing elsewhere in the plant including in the highly prone dewatering operations, thereby helping eliminate the maintenance man hours associated with nuisance struvite removal at the facility

Additional biogas capture leading to energy positive operation
The vacuum based operation of the EloVac®-P enables capture of significant amounts of biogas (methane) still entrapped in the digestate, helping not only offset the low energy demand of the unit but actually enabling an energy positive operation.

Reduced Carbon dioxide (CO2) footprint of plant by up to 25%
Significant amounts of CO2 and methane are entrapped in anaerobic digestate post digestion and the vacuum based operation helps capture of the same rather than releasing it to the atmosphere which can help reduce the greenhouse gas (GHG) footprint of the utility by up to 25%.

How It Works

The EloVac®-P is a continuous flow, skid mounted system for controlled struvite precipitation using Magnesium Chloride with the operating steps described below:


  1. Sludge is fed continuously to the degassing reactor.
  2. A vacuum pump extracts the methane and CO2 from the digested sludge to raise the pH in the reactor. The vacuumed gas enables an energy-positive operation by capturing additional biogas, while reducing greenhouse gas emissions.
  3. MgCl2 is added to the digested sludge in the reactor and with the higher pH, controlled struvite precipitation takes place.
  4. Continuous discharge of degassed sludge with the precipitated struvite to dewatering.

Figure 1: Full Scale Phosphate Removal from Digestate

P-Removal Operating Data

Figure 2: Impact of EloVac®-P on Cake Solids and pH

Dewatering & Phosphate Result (Lingen)


Figure 3: Impact of EloVac®-P on dewatering polymer consumption

Polymer Consumption (Lingen)

  • What percentage removals of PO4-P can be expected with the EloVac®-P system?
    • Depending on the Magnesium Chloride dosage up to 95% PO4-P removal from the digestate stream can be achieved


  • What improvements in dewaterability can be expected by the implementation of the EloVac®-P system?
    • Cake solids improvements up to 5.2% have been obtained with implementation of the EloVac®-P system after standard Mesophilic Anaerobic Digestion
    • Additionally up to 20% saving in polymer dosage can be attained without compromising the sludge dewaterability


  • Is there any impact of Thermal Hydrolysis on the system performance?
    • The EloVac®-P is a highly complementary process to Thermal Hydrolysis Process (THP) as it not only enables excellent Phosphate capture in the return streams but in conjunction with THP, up to 10% improvements in cake solids percentage after dewatering have been attained.


  • How much additional biogas capture can be expected with the system?
    • Depending on the upstream digestion process up to 49% additional biogas capture can be accomplished
  • Product Brochure 1

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EloVac® is a registered trademark of ELIQUO Water Group GMBH (https://www.eliquostulz.com)