Designing Structures to Remove Phosphorus from Drainage Waters
C. Penn, J. Payne*, J. McGrath and J. VitaleOklahoma State University
University of Maryland
P transport to surface waters
Occurs primarily via surface flow:
- Particulate P – carried on eroded particles, not immediately bio-available
- Dissolved P – 100% biologically available
P loss to surface water
Soil test P
Potential for P loss
Low Optimum High
Risk increases as soil P increases
Nutrient Sensitive Watersheds
Chesapeake Bay
Illinois River Watershed
Both have:
- High density poultry production
- Urban development
- Limited cropland
- Water quality concerns
Legacy P
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 20100
100
200
300
400
500
600
Trt 1
Trt 2
Trt 3
Trt 4
Trt 5
Coale, F.J. and R. Kratochvil 2011: Unpublished data
Meh
lich-
3 P
hosp
horu
s (m
g kg
-1)
Plant optimum soil test P level
Cessation of fertilizer applications
Managing P Losses
Most traditional BMPs do:- target particulate P
- veg buffers, riparian areas- prevent soil P from increasing
- limit P applications
Managing P losses
Most traditional BMPs do not:- target dissolved P
- difficult to target High P soils will continue to produce
dissolved P for years
Runoff P vs. Soil Test P (Miami, OK)
y = 0.0016x + 0.287
R2 = 0.89
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 500 1000 1500 2000 2500
Soil Test P (ppm)
Ru
no
ff P
(p
pm
)
P sorbing materials (PSM)
PSM: -any material that chemically removes dissolved P from a solution, reducing soluble P.
Examples include: Al, Fe, Ca and Mg. Many by-products contain P sorbing minerals. Can be used for treatment of soil or manure;
however, P is not removed from system. Better use would be treatment of runoff
One tool: P removal structure
PSM layer with retained P
Low P water
Drainage layer (sand/perforated pipe)
High P water
Examples of waste product PSM’s
Acid mine drainage treatment residuals
Bauxite mining and production waste (red mud)
Steel slag waste
Drinking water treatment residuals
Fly ash
Waste recycled gypsum
Foundry Sand
Selection Process for PSMs
Material Availability
Cost & Transportation
Potential contaminants
Alkalinity/acidity
Soluble salts
Total, acid soluble,
and water soluble Na & heavy metalsSorption characteristics
Physical Properties
Particle size distribution
and bulk density
Hydraulicconductivity
Advantages of P removal structure
Remove both particulate and dissolved P Ability to remove PSM after saturation Various metals and pesticides are removed Target treatment in “hot spots” Potential to capture P from entire catchment
Potential application of PSM
Ag runoff
Urban runoff
Pilot scale filter at OSU
010203040506070
0 100 200 300
P re
mo
ved
(mg
/kg
)
P added (mg/kg)
Aug 2012Nov 2009
P removal structure – Golf course
Golf course runoff filter
Overflow weir
25% overall dissolved P removal after 8 months
Structure has handled flow rates over 100 gpm
Steel slag
Cost will vary per site
Cost: $2000 for steel and welder time
Slag was free (3 tons sieved)
$200 to sieve and transport slag
$2,200 total
Stormwater Pond Filter
Perforated steel box Vertically positioned
pipe inside box Filled with steel slag Drains from poultry
farm stormwater pond
Cartridge Ditch Filter
Portable, easy to install
Filled with slag Limited amount of
PSM
Tile Drained Filter
PSM over and under perforated pipes
Gypsum and slag Dam at end for slow
retention time
Tile Drained Filter
After re-vegetation
Model development
Developed with lab flow through studies and validated with pilot scale filter
Developed a user friendly empirical model Tested 16 different materials
- add P at constant rate- vary retention time and P concentration- measure P in outflow
Model use
Site hydrology Targeted P removal PSM characterization
Inputs
Outputs
Design parameters
Model vs. Actual P removal
P added (mg kg-1)
P r
emo
ved
(m
g k
g-1)
Moving to implementation
Possible interest in commercializing design Golf course industry Ag industry Potential NRCS cost share technology Nutrient credit brokers
TMDLs and Nutrient Trading:
P Sources
Illinois River Watershed Chesapeake Bay
NRCS Conservation Innovation Grant
Creek
flowdirection
poultry houses
proposed structure location
Awarded to Illinois River Watershed Partnership and OSU
Will be installed on poultry operation in Illinois River Watershed
Thank you!
Illinois River in Oklahoma
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