maximizing phosphorus load reduction

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Maximizing Phosphorus Load Reduction

Presented By: Derek M. Berg

Southeast New York Stormwater Conference

October 15, 2014

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Phosphorus: What is it and where does it come from? How do we address Phosphorus in Urban Runoff? Raising the bar on phosphorus removal the latest research

and innovation

Agenda

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Why do we care about Phosphorus?

Aren’t nutrients a good thing? Phosphorus is usually the most limiting nutrient

in freshwater systems Too much of a good things makes watersheds

sick

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Sources of Phosphorus Weathering of calcium phosphate minerals,

especially apatite Anthropogenic (human) P is often much greater

than natural inputs of P in many watersheds Common anthropogenic sources: agriculture,

wastewater, excess fertilizer, faulty septic Wildlife can also contribute significant amounts

of phosphorus to local watersheds               

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Forms of Phosphorus Total P: Is most common measure of phosphorus

concentrations in runoff and watersheds. TP = DIP + DOP + PP

We often measure both particulate and dissolved fractions of phosphorus◦ Dissolved P◦ Ortho P◦ Soluble Reactive P

TP is most commonly regulated

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Lake Productivity Classification

Total Phosphorus mg/L

Ultra-oligotrophic  <5

Oligotrophic 5-10

Mesotrophic 10-30

Eutrophic 30-100

Hypereutrophic  >100

Phosphorus in Lakes

Phosphorus concentrations in untreated stormwater are often many times higher than those in receiving waters!

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Phosphorus in Stormwater

• Phosphorus is often in both solid and soluble forms• Solid phosphorus tends to be associated with finer particles• Ratio of solid/soluble is often variable. Research suggests

50/50 split is a reasonable estimate (NYSDEC Chap. 10)• Previously captured particulate can be leached as soluble P

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Phosphorus in Stormwater

Source: NYSDEC Chap. 10 NYS Stormwater Management Design Manual

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How do we address TP in runoff?

• Good Housekeeping • Runoff Reduction• Sedimentation• Biofiltration• Media Filtration

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Source Washington State Water Quality Consortium

(Not So) Good House Keeping

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Preventing runoff from occurring or reaching receiving waters eliminates all of the pollutants that would be carried by that runoff

Reduce runoff via LID site design concepts Retain water onsite

o RWHo Bioretentiono Pervious paverso Infiltration Systems

Runoff Reduction

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Removing Phosphorus With Treatment

Three primary mechanisms to removal Phosphorus from Urban runoff:

Reactive FiltrationPhysical FiltrationSedimentation

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SedimentationExamples: Ponds, Vaults, Detention Systems, Hydrodynamic Separators

• Slow water down and allow solids to settle

• Longer residence time = finer particles captured

• Phosphorus removal often tied to residence time

• No capture of dissolved/soluble P• Leaching possible

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Physical Filtration

Examples: Screening, Media Filters, Sand Filters, Biofilters, Infiltration

• Physical barrier to solid particles• Good control of TSS and attached

pollutants• Good removal of particulate metals

and phosphorus• No removal of dissolved/soluble

pollutants• Leaching possible• Longevity must be considered

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Maximizing TP Removal

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Reactive Filtration/ ProcessesReactive filtration media with an affinity for target pollutants, organic matter,

• Often works in parallel with physical filtration and/or sedimentation

• Target pollutant is bound to media via adsorption, ion exchange etc.

• Effective removal of soluble/dissolved pollutants

• Boosts overall pollutant load reduction• Prevents leaching

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Common Treatment Practices

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Wet Pond (Sedimentation)

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SandFilter (Sedimentation, Physical Filtration)

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Bioretention/Biofiltration

Source: NYSDEC Chap. 5 NYS Stormwater Management Design Manual

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Raising the Bar on TP Removal With Innovative Solutions

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Case Study 4

Bioretention Soil Amendment

Fleming College, Ontario

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Bioretention Soil Mix Amendment with Phosphorus-Adsorbing Sorbtive Media

Fleming College, Centre for Alternative Wastewater Treatment

Ontario, Canada

Case Study 3

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Results: TDP Removal Efficiency

TDPs Influent Conc (0.2 mg/L)

TDPs Influent Conc (0.4 mg/L)

TDPs Influent Conc (0.6 mg/L)

TDPs Influent Conc (0.8 mg/L)

0

10

20

30

40

50

60

70

80

90

100

Control Sorbtive Media 5% Sorbtive Media 10%

% T

DP

Rem

ova

l

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Lakewood Park - Chautauqua Lake

Retrofit DI’s• Sorbtive Media applied

in a layer above underdrain pipe

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26

Filterra® Bioretention

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Optimized media gradation Functions as living biological system Simple Maintenance Consistent field removal of >60% TP Can be deployed boxless

Filterra Overview

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The Stormwater Management StormFilter®

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PhosphoSorb Media

Lightweight, oxide coated, non toxic, reactive media

Lab testing showed excellent removal of dissolved P

TAPE and TARP field testing showing >70% TP reduction and excellent removal of DP

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Solids Removal- SOL

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Phosphorus Removal- SOL

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Soil Mix Composition

Sand Peat Moss Sorbtive® Media AI 28x48

• High surface area phosphorus-adsorbing media• Sand-like gradation• Added to soil mix on volume basis, ranging 0% - 17%

Soil components mixed in buckets of 2 front-end loaders

Fleming College

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NYSDEC 80% TSS, 40% TP threshold is essentially pass fail Currently no review process in place to assign specific TP

credit to BMPs Limited value in achieving >40% TP without means of taking

regulatory credit In load sensitive watersheds

Regulatory Challenges

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Summary

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Derek Berg

dberg@conteches.com

207-885-6174

Questions???