ARSENIC REMOVAL FROM OU WATER-POWERPOINT

ARSENIC REMOVAL FROM OU WATER-POWERPOINT - Arsenic Removal...

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Unformatted text preview: Arsenic Removal from OU Water Arsenic Sami Karam Randy Goll Ross Chaffin Arseniic Removall ffrom OU Water Arsen c Remova rom OU Water 5..2..2003 5 2 20 03 Roman Voronov OBJECTIVES OBJECTIVES To find an economical solution to the To Arsenic problem on the OU campus To make the OU campus self-sufficient To and compliant with the new 2006 EPA rule of 10 ppb instead of 50 ppb As. minimum 10 50 EFFECTS of ARSENIC EFFECTS Skin alterations and lesions Skin Repeated exposure may lead to Repeated cancerous mutations Nervous & Vascular system Nervous degenerative diseases GEOGRAPHY GEOGRAPHY GEOLOGY GEOLOGY Well Data Well Average pH Average ~8.97 Sulfate content Sulfate 40 ~ 55 mg/liter Arsenic Arsenic 35 ~ 45 ppb OU Situation OU Max production capacity: 1.8 × 10 6 gallons / day Max Average daily usage: Average 1 .1 × 10 gallons / day 6 2.0 ×106 gallons / day Peaks around August @ Peaks Projected growth over 20yrs: Projected 25 % Previous Solutions and Available Previous Options Previous Studies Previous CH2M-Hill: Colorado based consulting CH2M company (development, environmental solutions, design…) CH2M Hill Considered OU & the City of Norman as one problem CE 5244: Class project to find optimal solution CE CH2M-Hill Report CH2M Options Drill new wells Drill Coagulation/Filtration Coagulation/Filtration Ion Exchange Ion Nanofiltration Nanofiltration Blending water Blending CE 5244 Recommendations CE April 2001 Recommended reconfiguration, blending Recommended and Ion Exchange for Norman Recommended C/F for OU Recommended Water Purchase Option Water OU buys water from City of Norman OU exclusively Cost between $0.85/1000 gallons and Cost $1.14/1000 gallons of water Least work for OU Least May not be most economical option, lots of May parameters Nanofiltration Nanofiltration Uses membrane separation Uses Differences in pressure cause water to Differences separate into 2 streams Very large waste stream (>35%) Very Membranes have high capital cost Membranes Coagulation/Filtration Coagulation/Filtration FeCl3 is added to water FeCl is Precipitates Fe(OH)3 Precipitates Arsenic adsorbs to Fe(OH) Arsenic FeOH is filtered from the water FeOH Fair amount of waste Fair Ion Exchange Ion Water run through bed of resin Water Arsenic ions exchange with chloride Arsenic Resin bed is regenerated by brine Resin Very low capital cost!!! Very Very low operating cost!!! Very Annual and Capital Costs Annual Capital Costs NPC (after 20 years) over $10,000,000 over $10,000,000 $3,400,000 $5,700,000 Water Purchase ($1.14/1000 gal) None $5,565,000 Water Purchase ($0.85/1000 gal) None $4,150,000 $1,870,000 $3,600,000 Nanofiltration Coagulation/Filtration Ion Exchange Net Present cost ($millions) Solutions Comparison 16 14 12 10 8 6 4 2 0 WP IX CH2M-Hill WP: Water Purchase, C/F CE5244 IX: Ion Exchange, Nano: Nanofiltration Nano. Our Group C/F: Coagulation Filtration Preliminary Conclusion Preliminary Ion Exchange Ion most ideal solution!!! WHY? Economically Attractive Economically Self Sufficiency Self Immediate Implementation Immediate ARSENIC & ION EXCHANGE CHEMISTRY Arsenic Chemistry Arsenic Arsenic (III) Arsenic -Non ionic form (H3AsO3) -Arsenite Arsenic (V) Arsenic -Ionic form (HAsO42-) -Arsenate Arsenic/IX Chemistry Arsenic/IX Arsenite Arsenate Arsenite -Sodium Hypochlorite pre-treatment Arsenate ion trades places Arsenate with Chloride ion. - Resin has higher selectivity to sulfate. Bed causes pH to go Bed down. Arsenic/IX Chemistry Arsenic/IX Regeneration by Concentrated NaCl Regeneration -Le Chatelier’s Principle Arsenate goes to precipitation tank. Arsenate pH lowered by H2SO4 pH FeCl3 added to precipitation tank to FeCl added precipitate Fe(OH)3 ION EXCHANGE PROCESS Rinse Cycle Regeneration Back-Washing Normal Operation Safety • Process must be designed so that arsenic is not allowed to breakthrough. Economic Evaluation Economic (IX vs WP options) Preliminary Findings Previous Conclusions $16,000,000 Net Present Cost $14,000,000 $12,000,000 CH2M Hill $10,000,000 CE Group $8,000,000 Our Group $6,000,000 $4,000,000 $2,000,000 $0 WP IX C/F NF WP: water purchase, IX: Ion Exchange, C/F: Coagulation Filtration, NF: Nanofiltration Ion Exchange Plant Calculation Ion Exchange •Assume Constant Demand of 1.1 MGD • CI = $2.1 million (based on capacity) • OC = $110,000/year (labor, power, and chemical) •Project Lifetime =20yrs _______________________________________ Calculate NPC! Water Purchase Calculation Water •Assume Constant Demand of 1.1 MGD •Constant Water Price = $1.14/1000gal Low Estimate! Low •Project Lifetime = 20yrs ____________________________________ Calculate NPC Sources of Uncertainty Sources • Several Unknown Factors in Design: Future Water Price Future Future Water Demand Future Initial Plant Capacity Initial Unforeseen Changes In Well-field Unforeseen Later Additions To Existing Plant Later Calculation Complexity Calculation NPC for IX Initial Capacity Low Med High Future Plant Additions L M H L M H L M H Future Water Demand L M H L M H L M H L M H L M H L M H L M H L M H L M H Mathematical Model Description Mathematical Purpose – Simulate OU As situation Goal – Cheapest Solution (by minimizing NPC) Chooses between IX or WP Chooses Meets Water Demand Meets Decides When/How Much to Build Decides Expands Capacity As Needed Expands Buys Wholesale or Emergency Buys Borrows/Repays Money Borrows/Repays Mathematical Model Parameters •CI - $1.1 million ($428/1000gal per day of capacity) • OC - $38,000 ($111/1000gal per day of capacity) •Demand - 2002 figures; 25% growth (OU Physical Plant) •Water Price: $3.00/1000 gallons Demand Based $1.14/1000 gallons Whole Sale Capital Investment ($MM) Capital Investment and capacity 2.5 2 1.5 y = 0.4567x + 1.1 1 0.5 0 0 0.5 1 1.5 Capacity (MGD) • Fixed: Building, Feed Facility, Brine Unit • Capacity Based: Number and Sizing of Columns 2 2.5 A e g D ily C n u p n (1 0 g l) v ra e a o s m tio 00 a Water Consumption Projection 1800 1700 1600 1500 August (Peak) Consumption 1400 Average Consumption 1300 1200 1100 1000 0 5 10 15 20 Year • Solution must meet the needs of OU by month Significant Variables • Capital Investment and Operating Cost per 1000 gallons/day should show significant variation. • “Wholesale” water price should be shown for $1.14 (current) and $0.85 (possible) per 1000 gal / day. • Water Demand is randomly generated. Model in Math Language: Model TotalCost = ∑ ps C s Main Equations: s ( ) C s = ∑ C yr =∑ CI yr + OPyr + Pr ice yr * WPyr * (1 + i ) yr −1 − Borrowed yr + Repaid yr * df yr yr yr CI yr = a * z yr + b * Cap yr yr OPyr = α F ∑ zξ + β ∑ Q yr ,mo , s ξ =1 Demand yr ,mo , s = Q yr , mo , s + WPyr , mo , s ztot yr = ∑ zξ if ξ ≤ yr ξ mo Pr ice yr , s = WholeSale Pr ice * y yr , s + Emergency Pr ice * (1 − y yr , s ) Finance Equations: Debt yr , s = (1 + i ) * Debt yr −1, s + Borrowed yr , s − Repaid yr , s Main Constraints: CapTot yr = ∑ (Capξ + CapAdd ξ ) if ξ ≤ yr ξ CapTot yr ≥ Q yr ,mo , s Finance Constraints: Cap yr ≤ MaxCap * z yr ∑WP yr , mo , s mo C yr , s ≤ Budget Debt 20, s = 0 Repaid yr , s ≥ 2 * i * Debt yr −1, s − 1000 * y yr , s ≥ 0 Mathematical Model Code: Mathematical Model Results •Facility Built In Year 1 (1.6 MGD Capacity) •Loan (Repaid Over 10 Yrs) •Water Purchased In Peak Months • No Facility Upgrades For 20 Year Period • Net Present Cost Of $3.1 Million Implications of Model Results Implications 2600 ft2 Facility Area • 2000 Gallon Waste Brine Container • Four 6ft Dia. IX Columns • Requires Purchase Of Ferric Chloride, Sodium Hydroxide, Sulfuric Acid And Salt. • Highly Automated • Labor requirement of less than $20,000/year (CH2M Hill) GEOGRAPHY GEOGRAPHY Yearly Cost With Loan Cost ($/yr) 1000000 800000 600000 Water Purchase Facility 400000 200000 0 1 4 7 10 13 16 19 Project Lifetime (yr) Wholesale Water Price $1.14 Interest Rate = 9% Yearly Cost Without Loan 1800000 1600000 C s ($ r o t /y ) 1400000 1200000 1000000 W ater Purchase Ion Exchange 800000 600000 400000 200000 19 16 13 10 7 4 1 0 Years Wholesale Water Price $1.14 Interest Rate = 9% Savings per year Current Dollars Savings ($) $1,000,000 $1.14/1000 gallons $0.85/1000 gallons $800,000 $600,000 $400,000 $200,000 $0 1 3 5 7 9 11 13 15 17 19 Project Lifetime (yr) Savings Increase In Year 12! Net Present Cost Comparison 9 Net Present Cost($MM) 8 7 6 5 Ion Exchange Plant 4 Water Purchase 3 2 1 $1.14 $0.85 $0.45 Price of water ($/1000 gal) Water Costs $0.60/1000gal to Produce Risk Assessment Risk Maximum Field Capacity 9 Net Present Cost ($mil) 8 7 6 5 NPC 4 3 2 1 0 0 500 1000 1500 2000 2500 Maximum Field Capacity (1000 gal/day) Shows decisions if capacity is lower Water Price Sensitivity 3.3 Present Cost ($MM) 3.25 3.2 NPC 3.15 Linear (NPC) 3.1 3.05 3 0 2 4 6 Price of high-rate water ($/1000 gal) 8 O p e r a tin g C o s t $ /1 0 0 0 g a llo n s c a p a c ity Uncertainty Analysis Uncertainty 35 30 Area of Water Purchase 25 20 15 $1.14 10 5 Area of Treatment $0.85 0 0 1000 2000 3000 4000 Capital Investment $/1000 gal capacity 5000 values within “Treatment Area” • 400% (for $0.85) or 600% (for $1.14) cost increase required for WP to become favorable. • Even with high variability of parameters, treatment is favorable. O p e r a t in g C o s t $ /1 0 0 0 g a llo n s c a p a c it y • Doubled 35 30 25 $1.14 20 Area of Water Purchase 15 10 5 $0.85 Area of Treatment 0 0 1000 2000 3000 4000 Capital Investment $/1000 gal capacity 5000 Net Present Cost $3 $3 $3 $3 $3 $3 $3 $2 $2 $2 ,6 0 ,5 0 ,4 0 ,3 0 ,2 0 ,1 0 ,0 0 ,9 0 ,8 0 ,7 0 e 0 0 0 0 0 0 0 0 0 0 M or 0, 00 0, 00 0, 00 0, 00 0, 00 0, 00 0, 00 0, 00 0, 00 0, 00 Frequency Net Present Cost Probability Distribution 25 20 15 10 5 0 Safety Safety More Bed Volumes = Higher Number of Chemicals Required = Higher Operating Cost Safety Conclusion Conclusion Conclusion: • At either price level of water, Ion Exchange treatment costs less • Self-sufficiency and full utilization of natural resources via IX treatment •By treating water, OU will not contribute as greatly to scarcity of water in the Central Oklahoma Area • Waste produced roughly equivalent to one Norman-issued trashcan full of non-hazardous waste per day Recommendations Recommendations Explore waste dilution to reduce As content Explore to < 0.5% solid concentration (TC) Water by-pass to reduce regeneration Water Permissible TBLL for Norman Permissible Dried precipitate concentration to meet Dried TCLP Conclusion: 9 Net Present Cost($MM) 8 7 6 5 Ion Exchange Plant 4 Water Purchase 3 2 1 $1.14 $0.85 $0.45 Price of water ($/1000 gal) ...
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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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