Transcript UI Odor & Waste Management Program

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
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Magnesium ammonia phosphate crystal
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Equilimolar concentrations of Mg, NH3 and PO4
Naturally occurring in waste systems
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Similar to a Kidney Stone
Overflow pipes, recycle elbows, pump impeller
Very common in municipal and swine waste systems
Historically produced slow release fertilizer
Magnesium,
Struvite Precipitation
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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)
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Removal Efficiency:
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90% reduction in SP from a swine anaerobic
treatment lagoon in NC
Laboratory Crystallizer
Fluidized-Bed Struvite
(MgNH4PO4) Crystallizer
Treated
Effluent
Crystallizer
Cone
Mg Dissolving
Cone (optional)
Anhydrous
Ammonia
Mg
Wastewater In
Harvested
Struvite
4-20-0.25
Pilot Scale Crystallizer
2 gpm
Si-Ellen Farm
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4,000 cow open lot
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Flush feeding alleys
Primary Solids Removal – Slope Screen
Secondary Solids Removal – Gravity Basin
3 Wastewater Storage Ponds - 18M gallons
Werkhoven Dairy
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600 cow freestall
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Flush manure handling
Primary Solids Removal – Gravity Basin
3 Wastewater Storage Ponds - 18M gallons
Wastewater Analysis
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TP = 85 mg/l
PO4 = 25.4 mg/l
pH = 7.8
Results
PARAMETER
Bowers and
Westerman, 2003
Idaho Dairy
Washington Dairy
TP (ppm)
88
93
83
OP (ppm)
42
27
39
Mg (ppm)
60
155
241
TAN (ppm as N)
178
332
662
pH
7.7
7.5
7.8
TP removal (%)
66
19
6
(0 – 55)
(-41 – 63)
PO4 removal (%)
80
56
4
(-59 – 89)
(-55 – 38)
Crystalline Product
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Advantages
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Non-sludgy
Crystalline structure
Easily dried and handled
Concentrated Fertilizer 4:20:0.25 Average ID
analysis
Organic Product???
Limitations
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Slow Release
Low Nitrogen
Wastewater Solubility vs
Equilibrium - Ohlinger et al. 1998
Conclusions
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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
Next Steps…..
Struvite Crystallization
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Acidification Pre-Treatment
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Portable Struvite Crystallizer
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pH, retention time
Trailer mounted
Evaluate various wastewaters
Full-Scale Crystallizer: >10M gallons/year
Organic Certification
Crop Response
Next Steps…..
Anaerobic Digestion
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Phosphorus Pretreatment
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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