Phosphorus Treatment – Advanced Removal
Mechanisms & Amended Design for Stormwater BMPs
Scott Perry, CPSWQ
Nov. 17th, 2011
OverviewOverview Phosphorus BasicsPhosphorus Basics
NPS LoadsNPS Loads
Stormwater BMP Stormwater BMP
performanceperformance
Ways to Increase Ways to Increase
Phosphorus RemovalPhosphorus Removal
Advanced Removal MechanismAdvanced Removal Mechanism
Amended BMP DesignsAmended BMP Designs
Things to AvoidThings to Avoid
Phosphorus BasicsPhosphorus Basics Essential nutrient for lifeEssential nutrient for life
Cyclic between land & waterCyclic between land & water
Limiting nutrient in freshwaterLimiting nutrient in freshwater
Millions of Years
Canadian Canadian Experimental Experimental Lakes Area # Lakes Area #
226:226: Plastic Curtain Plastic Curtain
divides lakedivides lake
Carbon & Nitrogen Carbon & Nitrogen
added to both sidesadded to both sides
Phosphorus added Phosphorus added
to lower halfto lower halfFisheries and Oceans Canada - 1973
Phosphorus added
Lake Erie – Sept. 2008
Lake Erie – Sept. 2009
Lake Erie - Oct. 2010
Problem: Excess Phosphorus in fresh water Excess Phosphorus in fresh water
causes causes EutrophicationEutrophication (over (over enrichment):enrichment):
Algal bloomsAlgal blooms Micro-toxins … Micro-toxins … Cyanobacteria
HypoxiaHypoxiaFish killsFish kills Invasive speciesInvasive species
Lake ChamplainAP & VPR News - 2010
Additional Issues :
Taste & odor problems Fish & aquatic community Recreational quality Property values Drinking Water Cost
Charles River – Boston Metro
FertilizersFertilizers Animal & Pet WasteAnimal & Pet Waste Vegetation & Leaves Vegetation & Leaves DetergentsDetergents Erosion & Sediment LossErosion & Sediment Loss Hydrocarbons & LubricantsHydrocarbons & Lubricants Airborne Fallout: Dust, Pollen, Fossil Airborne Fallout: Dust, Pollen, Fossil
FuelsFuels Waste Water (CSO / Septic)Waste Water (CSO / Septic)
NPS Phosphorus NPS Phosphorus
SourcesSources
Chesapeake Bay Chesapeake Bay Pollen Load from Pollen Load from Outfalls APR09Outfalls APR09
Turf --- fertilizer and Turf --- fertilizer and
compacted soils/lawnscompacted soils/lawns
Chesapeake Bay WatershedChesapeake Bay Watershed
Relative Responsibility for Pollution Loads to the bayRelative Responsibility for Pollution Loads to the bay
NitrogenNitrogen PhosphorusPhosphorus SedimentSediment
Charles River WatershedCharles River Watershed
Phosphorus Stormwater Phosphorus Stormwater Loading by Land Use Loading by Land Use
0
0.5
1
1.5
Pounds
/ Acre
/ Y
ear
EPA Stormwater BMP Design Guide, 2004
Imperviousness Cover &Phosphorus Load
Center for Watershed Protection - Schueler and Caraco 2001
USGS Water-Resources Investigations Report 99–4021
Tota
l Ph
osp
horu
s (m
g/L
)
% Tree Canopy
Phosphorus Load with Increasing % Tree Canopy
USGS Water-Resources Investigations Report 99–4021
Tota
l Ph
osp
horu
s (m
g/L
)
% Tree Canopy
Roadway Phosphorus EMC with Increasing % Tree Canopy
Total Phosphorus (TP) Total Phosphorus (TP) PartitioningPartitioning
1. Particulate-Bound (PB) Phosphorus
2. Dissolved Phosphorus (DP)
Bio-availableBio-available
““QUICK SUGAR”QUICK SUGAR” for Algal Blooms for Algal Blooms
Sediment particle
Phosphorus Partitioning Phosphorus Partitioning by Land Useby Land Use
Residential Commercial Industrial Open Space
Ave. TP EMC (mg/L) 0.41 0.34 0.45 0.59
Ave. DP EMC (mg/L) 0.20 0.18 0.16 0.16
% PB 51 % 47 % 64 % 73 %
% DP 49 % 53 % 36 % 27 %
National Stormwater Quality Database
New York State DEC, 2008
TP = Particulate-bound phosphorus & Dissolved Phosphorus
DP = Dissolved Phosphorus
PB = Particulate-bound Phosphorus
Phosphorus in Phosphorus in StormwaterStormwater
TSS
+
50% TP --- Associated with TSS (sediment)
50% TP --- Dissolved (< 0.45-mircons)
Typical Urban Stormwater BMPs designed to captures 80% TSS:
80% TSS capture X 50% (particulate-bound phosphorus) = 40% (TP) Removal
Particulate-bound
Phosphorus (PB)
Sediment particle
Dissolved Phosphorus
(DP)
or
Range of Total Phosphorus (TP)
% Removal per BMP Type
Center for Watershed Protection,
National Pollutant Performance Removal Database version3, Sept. 2007
-100
-80
-60
-40
-20
0
20
40
60
80
100
Dry
Po
nd
s
We
t P
on
ds
We
tla
nd
Fil
teri
ng
Pra
cti
ce
s
Bio
rete
nti
on
Infi
ltra
tio
nP
rac
tic
es
Op
en
Ch
an
ne
ls
% R
emo
val E
ffic
ien
cy
Factors impacting Factors impacting Phosphorus Fate & Phosphorus Fate &
TransportTransport Water chemistry conditionsWater chemistry conditions
pHpH AlkalinityAlkalinity Temperature / SeasonalityTemperature / Seasonality Redox potentialRedox potential Particle chargeParticle charge ConcentrationConcentration
Time / Maintenance frequencyTime / Maintenance frequency
Phosphorus FatePhosphorus Fate Phosphorus speciation will shiftPhosphorus speciation will shift
ExamplesExamples Runoff pH
Concrete Road > 7.0 vs Asphalt < 5.0 Bottom of Lakes
Anaerobic activity / decaying organics
Stormwater TP Removal Stormwater TP Removal Mechanisms & Generalized Mechanisms & Generalized
CapabilityCapabilityUnit Process /
Removal Mechanism
Total Phosphorus (TP)
Sedimentation
Yes No
Filtration Yes Limited
Biological Uptake
Limited*assuming vegetative harvesting
Limited*assuming vegetative harvesting
Sorption No Yes
SorptioSorptio
nn
Adsorption Absorption
Combination of physiochemical Combination of physiochemical interactions;interactions; Adsorption - surface attachment Adsorption - surface attachment Absorption - internal attachment (sponge)Absorption - internal attachment (sponge) Ion Exchange - displacement of ions (Ca, Mg, Ion Exchange - displacement of ions (Ca, Mg,
Na)Na)
Sorption Capacity --- mg/g
Compared to soils … Ion Exchange Capacity --- meq/100g
Methods to Methods to Increase Increase
TP removal & TP removal & reduce variationreduce variation
Sediment particle
1 - Increase TSS Removal1 - Increase TSS Removal
Achieve > 80% TSS Removal
A. Remove the most particulate-bound phosphorus
• Silt-sized particles (Filtration)
(63-microns)
B. Prevent ResuspensionSediment particle
Particulate-Bound Particulate-Bound PhosphorusPhosphorus
TSS
Silt & Clay
Prevent or mitigate anaerobic Prevent or mitigate anaerobic conditionsconditions
Maintenance (removal of decaying Maintenance (removal of decaying materials)materials)
CatchbasinsCatchbasins ForebaysForebays WetlandsWetlands Underground SystemsUnderground Systems
2 - Mitigate Phosphorus 2 - Mitigate Phosphorus Speciation ShiftSpeciation Shift
Green InfrastructureGreen Infrastructure
Reduce Impervious Cover and/or ImpactReduce Impervious Cover and/or Impact Maximize InfiltrationMaximize Infiltration Maximize EvapotranspirationMaximize Evapotranspiration Combine Technology with Green Combine Technology with Green
InfrastructureInfrastructure
3 - Runoff Reduction --- 3 - Runoff Reduction --- i.e. Infiltrationi.e. Infiltration
Range of Total Phosphorus (TP)
% Removal per BMP Type
Center for Watershed Protection,
National Pollutant Performance Removal Database version3, Sept. 2007
-100
-80
-60
-40
-20
0
20
40
60
80
100
Dry
Po
nd
s
We
t P
on
ds
We
tla
nd
Fil
teri
ng
Pra
cti
ce
s
Bio
rete
nti
on
Infi
ltra
tio
nP
rac
tic
es
Op
en
Ch
an
ne
ls
% R
emo
val E
ffic
ien
cy
Advanced Removal Advanced Removal MechanismsMechanisms
4 - Target ALL Phosphorus 4 - Target ALL Phosphorus (i.e. ... The Dissolved Phase (i.e. ... The Dissolved Phase
too)too)
Particulate boundParticulate bound
Sediment particle
Dissolved Phosphorus
Advanced Removal Advanced Removal MechanismsMechanisms
Practices that do not Infiltrate 100%
Engineer to Capture Dissolved Engineer to Capture Dissolved PhosphorusPhosphorus
Amend & DesignAmend & Design Engineered MediaEngineered Media
Displace conventional media or Displace conventional media or aggregateaggregate
Polish exfiltrating systemsPolish exfiltrating systems
Quantifying Engineered Quantifying Engineered MediaMedia
Isotherm – Isotherm – Best Case Maximum capacity?
Kinetics – Kinetics – How fast can it be sorbed?
Breakthrough –Breakthrough – Volume of Pollutant/WQv treated?
(maintenance)
Desorption – Desorption – Retaining DP … is the bond strong enough?
Influent
Effluent
What is Breakthrough?What is Breakthrough?Phosphorus Breakthrough Curve
Thomas Equation
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 500 1000 1500 2000 2500 3000 3500
Number of Bed Volumes
% D
isso
lved
Ph
osp
ho
rus
Rem
ova
l
Dissolved Phosphorus Sorption Performance (T. Wu et al, Stormwater Phosphorus Adsorption on Oxide Coated Media, WEFTEC,2008)
Media Type(0.5 mm to 10 mm)
IsothermKf (mg/g)
Kineticsqe (mg/g)
Breakthrough Exhaustion
(BVs)
Desorption
Al-oxide Pumice 0.40 1.19 1,800 – 2,700 No
Al-oxide Aggregate 1.3 0.51 1,450 – 3,600 No
Zeolite / Perlite / Carbon (ZPG)
0.05 None 5 Yes
Perlite 0.002 1.37 < 10 No
Recycled Tire 0.003 None < 45 Yes
Expanded Shale 0.14 0.98 9 - 50 Yes
Very Finely Graded Medias (< 0.5 mm) with low hydraulic conductivity
Bioretention Soil 0.18 4.67 50 No
Concrete Sand < 0.01 < 0.001 < 5 No
Amended Amended Low Impact DevelopmentLow Impact Development
Surface Filters that ExfiltrateSurface Filters that Exfiltrate
ApplicationsApplications
Sorption based Media
Amended Surface FiltersAmended Surface Filters
(sand filters / bioretention)(sand filters / bioretention)
ApplicationsApplications
Sorption based Media
Amended Pervious PavementsAmended Pervious Pavements
ApplicationsApplications
Under Drain PVC
Sorption based Media
Green Roof ResearchGreen Roof Research
7-inches of growth media
Previous Research Previous Research Observed:Observed:
Runoff ReductionRunoff Reduction Increased Phosphorus Increased Phosphorus
DischargeDischarge
Green Roof ResearchGreen Roof Research Previous Research Previous Research
Observed:Observed: Runoff ReductionRunoff Reduction Increased Phosphorus Increased Phosphorus
DischargeDischarge
Greenroof Study Greenroof Study FindingsFindings
2009 Runoff Reduction = 42%2009 Runoff Reduction = 42% 2010 Runoff Reduction = 53%2010 Runoff Reduction = 53%
August - 77% versus October - 15%August - 77% versus October - 15%
NET EXPORTER of PhosphorusNET EXPORTER of Phosphorus TP discharged:TP discharged: ≈ ≈ 2 mg/L to 2 mg/L to ≈≈ 0.6 mg/L 0.6 mg/L
Engineered Media … Exfiltration Treatment:Engineered Media … Exfiltration Treatment: TP Reduction (87%): TP Reduction (87%): 1.18 to 0.16 mg/L1.18 to 0.16 mg/L SRP Reduction (82%): 0.63 to 0.11 mg/L 0.63 to 0.11 mg/L
Things to Avoid with Things to Avoid with “Sorption” Materials “Sorption” Materials
Things to Avoid with “Sorption” Things to Avoid with “Sorption” Materials Materials
Monitor the use of materials prone Monitor the use of materials prone to to desorptiondesorption
Organics / Compost / SoilsOrganics / Compost / Soils Evaluate MaterialEvaluate Material
Prevent Prevent leachingleaching of other Toxics of other Toxics pH, Heavy MetalspH, Heavy Metals
Slag, waste by-products
Things to Avoid with Things to Avoid with “Sorption” Materials “Sorption” Materials
Leaches Phosphoru
s
Summary Summary
Urban Runoff is a significant Urban Runoff is a significant Phosphorus contributorPhosphorus contributor
Infiltration should be the first Infiltration should be the first tool to combattool to combat
Exfiltration should treat Exfiltration should treat Dissolved PhosphorusDissolved Phosphorus (DP) (DP) with an Engineered Media with an Engineered Media
Scott Perry
301-279-8827
Questions?
AP/Larry Dupont – Lake Champlain