phosphorus removal - ohiowea.org

© 2012 O’Brien & Gere

Phosphorus Removal Chemical versus Biological Methods

86th Annual OWEA Conference & Exhibit Expo, Aurora, OH, June 20, 2012

Mark Greene, Ph.D., Senior Technical Director

[email protected] / (315) 956-6271


Phosphorus Removal - Chemical versus Biological Methods

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Today’s presentation

Why is phosphorus important, a global perspective

Biological P removal methods

Chemical P removal methods

Case study comparison results

Phosphorus recovery

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Phosphorus Removal - Chemical versus Biological Methods


Sources of Phosphorus in Wastewater

Human excretion (urine): ~50%

Synthetic laundry detergents: ~30%

Food wastes

Household cleaners

Industrial and commercial discharges

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Phosphorus Cycle

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British-Based Soil Association 2010

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©Soil Association 2010


Phosphorus in the U.S.

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US produces 25% of world resources

Huge deposits in FL and GA

Surplus production limited to a few countries

High grade ore is expected to run out in less than 50 years

U.S. may have enough P for 200 years at current rate of consumption

Morocco has 6 times the deposits as the U.S.


Phosphorus Speciation

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TOTAL INFLUENT PHOSPHORUS TPINF

ORTHOPHOSPHATE SPO4

ORGANICALLY BOUND PHOSPHORUS

BIODEGRADABLE POB

UNBIODEGRADABLE

SOLUBLE SPB

PARTICULATE XPB

SOLUBLE SPI

PARTICULATE XPI

Phytic acid

http://en.wikipedia.org/wiki/File:Phosphat-Ion.svg

http://en.wikipedia.org/wiki/File:Phytic_acid.svg


Domestic Wastewater (Municipal)

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Total P (5.7-8 mg/L)

Ortho P (3-4 mg/L)

Poly P (2-3 mg/L)

Organic P (0.7-1 mg/L)


Industrial Wastewater

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Pharmaceutical (15-300 mg/L)

Brewery (20 mg/L)

Ice Cream (80 mg/L)

Dairy (50-200 mg/L)


Low Effluent TP

Solids removal is key to achieve very low effluent levels

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Biological vs Chemical P Removal

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Chemical Precipitation

Up to 150 mg/L of metal salt

Dilute wastewater

Small muni-WWTPs

Complete mix biological process

Effluent limits 0.05-5 mg/L

Lower capital cost

Polishing for very low effluent limits

EBioP

Minimal metal salt addition

Biological activity

Enhanced WWT process performance

Effluent limits 0.5-1 mg/L

Lower operating cost


BIOLOGICAL P REMOVAL

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EBioP – Phosphorus Removal

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5% TP in TSS

0.5 mg/L in 10 mg/L TSS in clarifier effluent

0.1-0.2 mg/L TP in single stage filtration

AN WW OX CLARIFIER AX AX OX

RAS


Fermentation Process for Phosphorus Removal

General Set-up

The VFA production - 0.1 to 0.2 g VFA/g VSS applied

Based on fermentation system configurations

20% to 50% for a static fermenter / thickener

90% for a complete mix fermenter

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Primary Sludge Static Fermenter (Thickeners)

Use gravity thickener for fermentation, supernatant (VFA) sent to BNR

A high-torque sludge scraper mechanism required, high thickener sludge concentration ~4 - 8%

Advantage

Independent operations and controls of the primary clarifier and fermenter / thickener

Disadvantage

Balancing sludge wastage and monitoring sludge blanket is very hard

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Primary Sludge Fermenter Configurations Unified Fermentation and Thickening (UFAT) Process

Consists of two thickeners in series:

First is operated as a fermenter

Settled solids and supernatant are recombined

Second thickener operated for solids separation

Elutriation water can be added to thickener to condition solids and improve settling

VFA-rich supernatant from second thickener is directed to BNR process, while settled solids are sent to solids processing

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VFA / Carbon Source

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Biological P Removal Basics

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Anaerobic-aerobic sequencing

Readily biodegradable COD in AN

Minimize DO/NO3 in AN

Avoid backmixing

Avoid secondary release

Limit GAO growth

Sufficient aeration in OX


ENR Biological Process


Advantages of EBioP

Elimination or reduction of chemical costs

Effluent Sol-P conc < 0.2 mg/L are possible

No increase in waste solids production

Provides better control of filamentous growths

Improves activated sludge settleability

Reduces oxygen transfer requirement in aeration basin for BOD removal

Improves oxygen transfer rate in aeration basin

Improves nitrification rate in aeration basin

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Disadvantages of EBioP

Requires modification of biological process

Anaerobic-aerobic sequencing

Modest additional capital expense

Effluent Sol-P conc determined by VFA:TP ratio in influent to anaerobic zone

Supplementation of VFAs may be necessary

May be affected by biological toxicity

Design and operation requirements are more sensitive

Requires more rigorous biological process control

WAS processing requirements are more complex

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CHEMICAL P REMOVAL

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Phosphorus Removal by Chemical Precipitation

Low effluent TP means high dose of chemicals

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Chemical Dosing Points

Metal salts can be added in several location to precipitate P

Clarification or filtration is required to remove precipitant

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EFFLUENT CLARIFICATION

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Final Clarifier Upgrades

Process modeling

Dye testing

Short circuiting

Effluent baffles

Collection limitations

Transport limitations

Improved solids capture → lower effluent TP

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0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 10 20 30 40 50 60

Tota

l Ph

osh

oru

s C

on

cne

trat

ion

(m

g/L)

TSS Concentration (mg/L)

Secondary Clarifier Effluent

Effluent TP and TSS

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High Rate Flocculation Settling (Ballasted Floc)

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CoMagTM Process (Phosphorus Removal)

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Effluent Filtration with Cloth Media Disk Filtration

Small footprint

Fine pore sizes

Reuse water applications

Limited competition

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Cloth Media Effluent Filters

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Hybrid Bio/Chem

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CASE STUDY

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Small Municipal WWTP

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Present Worth Analysis – Bio-P v. Chem-P

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PHOSPHORUS RECOVERY

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Recycle Stream / Side Stream Treatment

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Recycle stream rich in nutrient and increase nutrient load in plant headwork's (TN by 15 – 30 %, TP by up to 40 %)

Recycle stream treatment process


Phosphorus

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Ostara Process

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P-Removal Summary - Innovative Adsorptive Media

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Adsorptive Media Chemistry Comments

Layne RTTM Nano iron oxide on IX resin Commercially available Arsenic removal media applied to P-removal

GeoBindTM Red mud – bauxite process waste

Commercially used for Hg and Arsenic removal as Bauxsol

Proprietary Metal Impregnated Filter Paper or I X Resin

Proprietary electrostatic technology for metal bonding

Improved, lower cost innovation of Rem-Nut IX European technology

Gypsum, Limestone, Calcium Hydroxide, Calcium Carbonate

Ca based chemistry – waste Gypsum

Calcium Hydroxide and Calcium Sulfate exhibit P adsorption/removal capabilities - Ca(OH)2 more so than CaSO4.

PhosphorReducTM Fe or Ca based chemistry –steel slag byproduct

Sourced from EAF or BF steel operations

Iron oxide nano composite materials

Proprietary blend of Nano iron oxide and other nano sized materials

UALR’s low cost production technique enables the application of unique blends of nanocomposites for cost effective P-removal


The Power of Nano-Based Media

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P Removal Ion Exchange Chemistry

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When cation and anion regeneration solutions are properly mixed, and a soluble Mg salt (e.g., MgCl2) is added, the result yields a virtually non-toxic, sterile struvite-rich precipitate according to:

Mg2++ NH4+

(K+)+ HPO4= === MgNH4(K+)PO4 (s) + H+ where (s) = struvite

P Ion Exchange Chemistry 2R-Cl + HPO4

= === R2-HPO4 + 2Cl-

Where R = anion exchanger

Regenerated with NaCl

Zeolite IX Chemistry Z-Na + NH4

+ (K+) === Z-NH4 (K+) + Na+

Where Z = Zeolite

Regenerated with NaCl & NaOH


Nano Composite Materials - UALR

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GG1-43-2B (C-Ni, solution method), BET surface area: approx. 400 m2/g

GG1-59-4 (C-Ni, powder method), BET surface area: approx. 425 m2/g


Mark R. Greene, PhD / [email protected] / (315) 956-6271

phosphorus removal - ohiowea.org

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