As Removal-Presentation

As Removal-Presentation - Problem Norman pays Oklahoma City...

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Problem • Norman pays Oklahoma City $3.10/1000 gallons for drinking water • Previously from Lake Thunderbird and Norman wells ( Well flow rates of 1500 m 3 /day) • Arsenic (As) concentrations range from 1 to 42 parts per billion (ppb) • Lung, skin, urinary, bladder, and kidney cancers caused by As poisoning
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Challenge • Reduce concentrations to World Health Organization (WHO) standards of 10 ppb • Evaluate iron oxide ceramic membranes to remove this arsenic • Design treatment system using membranes
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Background • Arsenate and arsenite are common forms of arsenic found in water • Research at UT-El Paso found that these two forms adsorbed to iron oxide coated stones
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Background • Under Dr. Maria Fidalgo de Cortalezzi, current research is being performed on iron oxide membranes at El Instituto Tecnólogico de Buenos Aires Saturation Limit: 0.00011 kg As/kg Fe 2 O 3 Porosity: 0.4 Fe 2 O 3 on pilot membrane: 0.002 kg Membrane thickness, l m : 50 μm Pore diameter: 24 nm Flux: 9.02 x 10 -5 m 3 /m 2 s BET Surface Area: 120 m 2 /g
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Background • Pressure difference across membrane drives contaminated water across membrane • Arsenic adsorbs to iron oxide membrane SEM image of top the top surface of an iron oxide membrane From Cortalezzi, et al.
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Challenge • Must treat 8 contaminated wells with an iron oxide membrane system – Membrane Design Limitations: • Size (Brittleness, transporting…) • Porosity • Thickness • Saturation time
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Design Proposals Municipal Treatment System 1. Large membrane to place inside 33” pipe -Too brittle -Cannot transport -High production costs 2. Small membranes to make up 33” pipe - Sturdy - Low production costs At-Home Treatment System 3. Membrane size of faucet - High consumer costs
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D= Total Diameter Row 1 Row 2 Row 3 Row 4 D= Total diameter of support (inches) D membrane + Clearance= 3 inches n=number of membranes Looking at 1 quadrant of support: Row 1: n=D/(2*(D membrane +Clearance)) Row 2: n=(D/6)-1 Row 3: n=(D/6)-2 Row 4: n=(D/6)-3=(D/6)-((D/6)-1) Continue for any diameter and multiply by four for number of quadrants: - = - = 1 6 0 6 * 4 D x x D n M e m b r a n Scale Up
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Chosen Design 33” Pipe Insert membranes in support Support diameter
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Membrane Configuration Membrane Steel support Adsorbed arsenic Chosen Design
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Pressure Drop Across Membrane M v out in well l a P P Q μ ε ρε ρ 2 2 3 ) 1 )( 36 / 150 ( ) ( - - = Modified Ergun Equation, derived from Darcy’s Law for dead-end filtration, laminar flow of spherical particles (arsenic) in solution (water) into a porous membrane P Q W Q W z g v P well well = = + + 2 ) ( 2 Bernoulli Equation for work of the pump
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This note was uploaded on 08/31/2011 for the course CHE 4273 taught by Professor Staff during the Spring '10 term at Oklahoma State.

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As Removal-Presentation - Problem Norman pays Oklahoma City...

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