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PHOSPHORUS REMOVAL ON DAIRIES IN THE PACIFIC NORTHWEST

PHOSPHORUS REMOVAL ON DAIRIES IN THE PACIFIC NORTHWEST. Applying a Cone Shaped Fluidized Bed Phosphorus Crystallizer Ron Sheffield – U of Idaho Keith Bowers – Multiform Harvest Inc. Joe Harrison – U of Washington. Magnesium, Struvite Precipitation. Magnesium ammonia phosphate crystal

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PHOSPHORUS REMOVAL ON DAIRIES IN THE PACIFIC NORTHWEST

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  1. PHOSPHORUS REMOVAL ON DAIRIES IN THE PACIFIC NORTHWEST Applying a Cone Shaped Fluidized Bed Phosphorus Crystallizer Ron Sheffield – U of Idaho Keith Bowers – Multiform Harvest Inc. Joe Harrison – U of Washington

  2. Magnesium, Struvite Precipitation • Magnesium ammonia phosphate crystal • Similar to a Kidney Stone • Equilimolar concentrations of Mg, NH3 and PO4 • Naturally occurring in waste systems • Overflow pipes, recycle elbows, pump impeller • Very common in municipal and swine waste systems • Historically produced slow release fertilizer

  3. Magnesium, Struvite Precipitation • Theory: Magnesium acts as a coagulant to settle out phosphorus. • How it Works: Magnesium, ammonium and phosphate ions when at a pH of 7 to 11 will combine to form Struvite (MgNH4PO4*6 H2O) • Removal Efficiency: • 90% reduction in SP from a swine anaerobic treatment lagoon in NC

  4. Laboratory Crystallizer

  5. Fluidized-Bed Struvite (MgNH4PO4) Crystallizer Treated Effluent Crystallizer Cone Mg Dissolving Cone (optional) Anhydrous Ammonia Wastewater In Mg Harvested Struvite 4-20-0.25 Pilot Scale Crystallizer 2 gpm

  6. Si-Ellen Farm • 4,000 cow open lot • Flush feeding alleys • Primary Solids Removal – Slope Screen • Secondary Solids Removal – Gravity Basin • 3 Wastewater Storage Ponds - 18M gallons

  7. Werkhoven Dairy • 600 cow freestall • Flush manure handling • Primary Solids Removal – Gravity Basin • 3 Wastewater Storage Ponds - 18M gallons • Wastewater Analysis • TP = 85 mg/l • PO4 = 25.4 mg/l • pH = 7.8

  8. Results

  9. Crystalline Product • Advantages • Non-sludgy • Crystalline structure • Easily dried and handled • Concentrated Fertilizer - 4:20:0.25 Average ID analysis • Organic Product??? • Limitations • Slow Release • Low Nitrogen

  10. Wastewater Solubility vs Equilibrium - Ohlinger et al. 1998

  11. Conclusions • Cone shaped fluidized bed crystallizer was successful in removing P from dairy wastewater • TP removal was observed to be lower than as demonstrated with swine lagoon wastewater • PNW dairies showed higher Mg and TAN: possibly reducing TP removal via struvite harvesting

  12. Next Steps…..Struvite Crystallization • Acidification Pre-Treatment • pH, retention time • Portable Struvite Crystallizer • Trailer mounted • Evaluate various wastewaters • Full-Scale Crystallizer: >10M gallons/year • Organic Certification • Crop Response

  13. Next Steps…..Anaerobic Digestion • Phosphorus Pretreatment • Digester not for energy production rather as P removal systems • Investigate lowest Hydraulic Retention Time (HRT) to achieve highest PO4:TP • Smaller & Cheaper digester • Follow with Struvite Crystallization

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