Schwing Bioset, Inc Eric Wanstrom Schwing Bioset, Inc.
Nutrient (struvite) Recovery In partnership with:
Nutrient Recovery
Integrated Phosphate Management What are the Issues: Waste water inlet www.schwingbioset.com Pre treatment Primary Sedimentation Aeration Tank Secondary Sedimentation Post treatment 1 Digester Biogas tank Cogen Case Specific Issues = Case Specific Approach Sludge Thickener 1. Phosphorus return load 2. Pipe clogging / scaling issues 3. Struvite grit accumulation 3 5 2 Sludge Dewatering 4. Dewatering issues Bio-P 5. Stabilizing Bio-P process 6. Increased sludge with iron salt 4 6
Integrated Phosphate Management Plant Issues: Mechanical: Clogged pipes & damaged equipment Accumulations in tanks Regulatory: Reduced Phosphorous effluent limits Process: Poor dewatering characteristics resulting from biological phosphourus removal process
Nutrient Recovery
Integrated Phosphate Management Plant Opportunity: Struvite can be recovered by precipitating into prills High value fertilizer product with opportunity to market Improve dewaterbaility of biosolids Global steward of phosphate management
Integrated Phosphate Management Struvite recovery is a two stage process: Air Stripping Crystallization Two stages allow for: Greater process control Stabilize operations by limiting variables to control in each vessel Design flexibility to solve more/specific plant issues Process can be applied to Digestate streams, Filtrate streams or combination of both
Integrated Phosphate Management Features: Concentrations reduced to ~ 15-20 ppm PO4-P regardless of starting concentrations on centrate applications Reduced to ~40 ppm on digestate applications
Integrated Phosphate Management Current Installations since 2006 5 Municipal installations (4 operating, 1 PO received) 5 Industrial installations Municipal Installation List: Apeldoorn, Netherlands (Hybrid Solution) Aaenmaas Beijersbos, Belgium (Centrate Solution) Aquafin Aartselaar, Belgium (Digestate Solution) Nieuwegein, Netherlands (Digestate Solution) Braunschweig, Germany (Centrate Solution)
Integrated Phosphate Management Three primary configurations: 1. Digestate Improved dewatering due to residual Mg Eliminate scaling Harvest up to 50% of produced struvite Tanks twice the size as operating on Centrate Reduce PO4-P levels to 40-50 ppm regardless of starting concentration
Integrated Phosphate Management Three primary configurations: 2. Centrate Harvest up to 90% of produced struvite Air Stripper & Crystallizer tanks half the size as operating on digestate Does not help with dewatering performance Does not help with scaling control Reduce PO4-P levels to 15-20 ppm regardless of starting concentration
Integrated Phosphate Management Three primary configurations: 3. Hybrid Harvest up to 90% of struvite produced in Crystallizer Crystallizer tank half the size as operating on digestate Prevents scaling Does not help with dewatering performance Reduce PO4-P levels to 15-20 ppm regardless of starting concentration
Integrated Phosphate Management Struvite recovery is a two stage process: Stage 1: Stripping Reactor Blow air to remove CO 2 Raises ph to 7.5 8.0 ph acts like an accelerator in a car Higher ph = faster reaction o Smaller prills Lower ph = slower reaction o Larger prills Air Stripper
Integrated Phosphate Management Stage 2: Crystallization & Settling Reactor Magnesium Chloride is added (MgCl 2 ) Mg reacts with P and N Pure struvite crystals are formed Crystals are recycled to grow like pearl Prills can be harvested and then: Washed Optionally dried Bagged or truck loaded Truck Load MgCl 2 www.schwingbioset.com Settler Crystallizer SBI Proprietary & Confidential Information
Apeldoorn Hybrid 1. Digester 2. Equalization tank 3. Stripping reactor 4. Pumps 5. Blowers 6. Odor control (not necessary can use plant odor control) www.schwingbioset.com 1 2 SBI Proprietary & Confidential Information 4 3 6 5
Apeldoorn Hybrid Redundant pumps to transfer settled solids to dewatering. This struvite is not recovered and comes out of plant in dewatered biosolids www.schwingbioset.com SBI Proprietary & Confidential Information
Apeldoorn Hybrid Redundant blowers to pump air through diffusers within stripping tank. Air strips off the CO 2 and results in a ph increase to 7.5 8.0 In this ph range the magnesium that is present in the sludge will react and form struvite crystals www.schwingbioset.com SBI Proprietary & Confidential Information
Apeldoorn Hybrid 1. MgCl 2 storage tank 2. Primary crystallization reactor 3. Settling tank 4. Buffer tank to ensure optimum flow to hydrocyclones (area #6) (only used when high recovery rates required) 5. Finished product truck loadout from area #6 6. Additional process equipment indoors www.schwingbioset.com 5 1 SBI Proprietary & Confidential Information 4 3 2 6
www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
1. Air Stripper 2. Crystallization Reactors 3. MgCl 2 tank 4. MgCl 2 metering (wall mounted) 5. Blower 6. Product wash 7. Product loading www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate 4 3 5 7 6 2 1
1. Air Stripper 2. Reaction Tank 3. Settling Tank 4. Agitator no bearing in liquid 5. Hydrocyclone www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
View from below 1. Air Stripper 2. Reaction Tank 3. Recycle www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
MgCl 2 dosing system 1. Mg tank 2. Parallel metering www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
Blower for Air Stripper www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
Process pumps www.schwingbioset.com Bottom of washer SBI Proprietary & Confidential Information Aaenmaas Centrate Finished product
Finished product to storage www.schwingbioset.com Transport in Classifying screw SBI Proprietary & Confidential Information Aaenmaas Centrate Washing zone
Typical grit washer www.schwingbioset.com SBI Proprietary & Confidential Information Aaenmaas Centrate
Pilot Unit
Struvite Recovery 5 GPM digestate mode 10 GPM Centrate mode Can harvest produced struvite Con operate in conjunction with screw press
Questions