Aquatic chemistry for engineers Water treatment in PHREEQC 89-12-2011 December 2011

Delft University of Technology

Challenge the future

Peter de Moel - TU Delft

Personal introduction … Record on water chemistry

• 1979 - 1980 : KIWA • KIWA report and computer program aggressive water

• 1980 - 2000 : DHV • • • •

Patent softening Amsterdam (Graveland cs) Publication / HP41 program on CaCO3 equilibrium Publications / presentations (H2O - JAWWA – Las Vegas) Design and build over 40 water treatment plants, wordwide

• 2000 - present : TU Delft (part-time) • BSc / MSc – education • OpenCourseWare

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Course program • Introduction Phreeqc (lecture) • PHREEQC – PHREEQCI - IPHREEQC

• Drinking water (lab 1a PHREEQC / lab 1b+c Excel)) • Chemistry: SI / CCPP / Buffercapacity / Corrosion • Engineering: Ionic balance / Conductivity / Mixing

• Gases in water (lab 2a+b+c Excel) • Chemistry: solubility O2, N2, CO2 , CH4 etc • Engineering: P*V/T = R / Biodegradation wastewater

• Hardness and pH (lab 3a+b Excel) • Chemistry: acid/base, solubility CaCO3, FeCO3, etc • Engineering: pH control / Neutralization / Softening Aquatic chemistry for engineers

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News statements

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Bad News • Our water chemistry is too simple to be true

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Good News • Complicated water chemistry is accessible now

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News statements

What do you mean: Simple vs Complicated ?

Simple:

Complicated:

• Ca 2+ + CO32- - > CaCO3

• Ca 2+ + CO32- < - > CaCO3

• Sulfate = SO42-

• Sulfate = SO4-2 CaSO4 MgSO4 NaSO4KSO4NH4SO4MnSO4HSO4CaHSO4+

Sulfate (US) = Sulphate (UK)

AlSO4+

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Saturation Index CaCO3 Netherlands / Germany

Netherlands

Germany

Standard

NEN 6533 (1990)

DIN 38404-10 (1995)

Based on

Jacobson/Langmuir (1974)

Eberle (1991)

CaCO3 (s-cor)

CaCO3 (s) CaHCO3+ / MgHCO3+ CaCO30 / MgCO30 CaSO4 / MgSO4 Aquatic chemistry for engineers

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Saturation Index CaCO3 USA

Standard Methods (1993/2000)

Simple

Better

Also CalciumCarbonate Precipitation Potential (CCPP)

+ / -

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PHREEQC

Development since 1980

pH - Redox – Equilibrium - Calculations Aquatic chemistry for engineers

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PHREEQC

pH - Redox - Equilibrium Calculations

• 25 elements • 21 redox states • 180 species • • • • •

72 solid phases 8 gas phases + Exchange eq. + Surface eq. + Rates

C Ca Mg Na etc C(+4) C(-4) etc C(+4) : CO2 HCO3 CO3 etc C(-4) : CH4 etc CaCO3 Fe(OH)3 etc CO2 H2S etc (ion-exchange) (activated carbon) (kinetics)

• 8 databases Aquatic Chemistry (Stumm & Morgan) in your laptop Aquatic chemistry for engineers

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PHREEQC

Freely available

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PHREEQC

Batch version (text) - since 1980/1995

PHREEQC

Windows / Linux / Mac input

database chemistry equation solver

output

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PHREEQC

Graphical user interface - since 2001

PHREEQCI

Windows input

database chemistry equation solver

output

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PHREEQC

Modules (COM / VS ) - since 2011

IPHREEQC

Excel / Matlab / VS input

database chemistry equation solver

output

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PHREEQC

Latest release : 3 month ago

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PHREEQC

Why is it so successful (in geohydrology) ?

PHREEQC is the ‘de facto’ standard in geohydrochemistry • • • • • • • •

Freely available Active and continuous development Scientific base, fully traceable Adapted to newest scientific knowledge Users can modify and extend the basics Active interaction between developers and users Large growing user group (mostly scientists) International assessment and recognition

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PHREEQC

Why is it not (yet) used in water treatment ?

PHREEQC is hardly/not known in water treatment • • • • • •

Requires above average skills in water chemistry Redox potential is not known/used as chemical concept in treatment High threshold for starters Absence of scientific literature on water treatment with PHREEQC Absence of educational material on PHREEQC for water treatment Requires modification for practical application (N-chemistry)

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PHREEQC

Why is it accessible now ?

PHREEQC is now accessible for our SE students • Applied in PhD Weren de Vet + Doris van Halem (groundwater) • Applied in MSc Harmen van der Laan + Laia Moré Roca + Jink Gude + Amir Haidari • Applied in BSc Tim van Dijk • Available as module for MatLab and Excel (since April 2011)

• Self study course TU Delft Sanitary Engineering: Aquatic Chemistry for engineers (since September 2011)

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PHREEQC

Basics: all elements – pe – pH - temperature

• elements (not species): • Ca, Fe, C, S, P etc

• pe (redox state): • natural water : pe = -8 – 15 • with Oxygen: pe > 12

• pH (acidity): • natural water : pH = 6 – 8 • CO2 – HCO3 – CO3

• temperature:

• natural water : temp = 0 – 25 0C

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PHREEQC

Basics: all elements – pe – pH - temperature

• elements (not species): • Ca, Fe, C, S, P etc

Fe:

• pe (redox state): • natural water : pe = -8 – 15 • with Oxygen: pe > 12

• pH (acidity): • natural water : pH = 6 – 8 • CO2 – HCO3 – CO3

• temperature:

• natural water : temp = 0 – 25 0C

PHREEQC gives all species, and SI for all solids and gases Aquatic chemistry for engineers

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PHREEQC

Basics: green area for water treatment

• acid – base • new pH after dosing and/or reactions

Fe:

• gases • solubility • gas phase (bubbles / air)

• precipitation/dissolution • CaCO3, Fe(OH)3 etc • CaCO3 (limestone filtration)

• modelling kinetics • to be developed in our research Aquatic chemistry for engineers

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PHREEQC

Basics: element – redox states - species

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PHREEQC

Basics: all equilibriums, full mass balances

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PHREEQC

Basics: concentrations as mol/kgw

• Solution in kgw • not Liter • not kg solution

• Amount in mol: • not mg • not mmol

change with temperature change by formation/use of H2O stoichiometric reactions equilibrium constants

• Concentrations: • input amount as g / mg / µg or mol / mmol / µmol • input as /L (with density in kgs/L) or /kgs or /kgw • output always as mol/kgw

• [Concentrations] and {Activities}: • [Ca] = 40 mg/L = 1 mmol/L ≈ 1 mmol/kgw • {Ca} = gamma * [Ca] Aquatic chemistry for engineers

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PHREEQC

Basics: data flow

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PHREEQC

Basics: kinetics in phreeqc.dat

• Calcite (CaCO3) (precipitation / dissolution)

• PWP model (Plummer, Wigley,Parkhurst), 1978 • Rate = f (temp H+ CO2 SI-calcite ) • dMass = Rate x Area x Timestep

• Organic C (oxydation) • Additive Monod kinetics • Rate = f ( O2 NO3 SO4 ) • dMass = Rate x Mass x Timestep

• plus Pyrite, K-feldspar, Albite, Pyrolusite • own models in user input Aquatic chemistry for engineers

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PHREEQC

Drinking water in PHREEQC

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PHREEQC

Drinking water in PHREEQC - input+output in Excel

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PHREEQC

Nitrogen - Equilibrium vs Kinetics

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PHREEQC

Nitrogen - Inert NH4 / Inert N2

• Modified database for water treatment: phreeqc_wt.dat • Inert N : Namm as inert NH4+ / Nga as inert N2 • To be expended for water treatment kinetics

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Examples

Calcite equilibrium

Phreeqc:

k

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Examples

Dissolution rate CaCO3 (Lime stone filtration)

Phreeqc:

k

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Examples

Precipitation rate CaCO3 (no seed material)

Phreeqc:

k

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Examples

pH for different treatment methods

Phreeqc:

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Examples

pH for different treatment methods (2)

Phreeqc:

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Aquatic chemistry for engineers Status

Completed: • Waterchemie voor drinkwater in PHREEQC (H2O-Dutch) • OCW website: Aquatic Chemistry for engineers • Volume 1: Starting with PHREEQC

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Aquatic chemistry for engineers Planning

Further development • Volume 2: PHREEQC for drinking and waste water • Volume 3: Water treatment in PHREEQC Summer school 2012 • Conference for water treatment researchers using PHREEQC

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Aquatic chemistry for engineers Treatment processes

Drinking water • Acid/Base dosing • Aeration and gas transfer • Fe/Mn/NH4/CH4 oxydation (redox reactions) • Precipitation/Crystallization • Ion-exchange (exchange equilibrium) • Activated carbon (surface equilibrium) • Membrane filtration (scaling) Waste water • Aeration and gas transfer • Biological conversion (chemistry) • PO4/Heavy metal removal Aquatic chemistry for engineers

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Aquatic chemistry for engineers Further information

OpenCourseWare website • http://drinkwater.citg.tudelft.nl/AquaticChemistry Contains • Lectures • Readings • Activities (Labs and Tests) • New developments • Database PHREEQC_WT.DAT (phreeqc.dat for Water Treatment, updated)

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Questions?

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Aquatic chemistry for engineers Water treatment in PHREEQC 89-12-2011 December 2011

Delft University of Technology

Challenge the future

Peter de Moel - TU Delft