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Dow-SWDRI Joint Collaboration Project for Operational Experience of UF & RO Technology with Arabian Gulf Water

SWDRI, Jubail KSA21st October, 2014

Nasir Moosa C.Eng

Importance of Pretreatment for Desalination

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Good Pretreatment

Improves RO Sustainability

Reduces RO cleaning frequency (chemicals)

Prevents high operation pressure (energy)

Reduces plant shutdowns

Good Pretreatment

Improves RO Sustainability } $

But why change from conventional pretreatment ?

UF-ROexample

• Pretreatment is crucial for enhanced RO performance!

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Pretreatment Issues with Conventional Technology

BIOFOULING

Caused by formation of biodegradable matter due to chlorination –dechlorination.

INORGANIC FOULING

Caused by leakage of coagulants to the RO system from pretreatment (e.g. FeCl3)

(images) (1): http://www.vedicsciences.net(2): http://www.ey.com/Media/vwLUImages(3): http://www.nature.com/srep/2013/130703/srep02125/full/srep02125.html

FLUCTUATIONS

Feed water quality changes not sufficiently captured by conventonial pretreatment.

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UF Vs. Conventional Pretreatment

DOW RESTRICTED(1) Y. M. Kim, S. J. Kim, Y. S. Kim, S. Lee, I. S. Kim, and J. H. Kim, "Overview of systems engineering approaches for a large-scale seawater desalination plant with a reverse osmosis network," Desalination, vol. 238, pp. 312-332, Mar 2009

• 30-60% smaller footprint .• Stable product quality independent of feed.• 20% Increase in RO flux.• 33% lower replacement for RO elements.• Significantly lower chemical consumption.

Other advantages• Lower fouling potential for RO• Shorter intake line• Better boron control

Conventional Pretreatment

RO

RO

UF Pretreatment

Main advantages for UF Pretreatment (1)

(Optional)

(with screening)

(with screening)

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Objectives & Key FindingsTo develop an optimized and sustainable desalination solution overcoming the challenges of Arabian gulf water.

Key Findings:Excellent water quality produced at constant rate by UF

Development of UF cleaning protocol suitable for Arabian Gulf application

Sustainable SWRO performance at high recovery of 50% and high flux (15.2 lmh).

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Plant Diagram – UF-RO

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UF1 UF2(x2) (x2)(130-micron)

Self-Cleaning Filters

UF TRAIN

RO TRAIN

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(x8)

Filmtec™ RO

UF SpecificationsDow UF - SFP 2880

Module Surface Area 77 m2

Flow Range 3.1 - 9.2 m3/h

Flow Configuration Out to In

Fiber Material H-PVDF

Nominal Pore Size 0.03 µm

Max. NaOCl 2,000 ppm

Max. TSS 100 mg/L

Max. Turbidity 300 NTU

Max. Particle Size 300 µm

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Cleaning Protocols

BW CEB CIP(Backwash) (Chemical-Enhanced

Backwash)(Clean In Place)

• No chemicals• Most frequent cleaning (<1hr)• Least effective• Short Duration (2 mins).

• NaOCl• less frequent cleaning (<24hrs)• Effective • Longer than a backwash (12-15 mins).

• NaOCl/Acid• Higher chemical concentration• least frequent cleaning (1/month)• Extremely effective • Longest duration (up to 2hrs)

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SPAIN

Water Profile and UF Fibers Physical Performance

Remarks:• Fibers robustness despite high turbidity & TSS events

• Good fiber integrity

Feed Water Conditions

Feed SDI (SWDRI) Avg. 5.66 (close to upper limit)

Feed water TSS (SWDRI lab) Up to 18 mg/L; Avg. <8mg/L

TOC (SWDRI lab) Avg. <3mg/L

Feed Water turbidity (DOW-online) Max 11 NTU; Avg. <3 NTU

Fiber Integrity Test Results during the project

Initial Pressure (Bar) 2.1

Final Pressure (Bar) 2.05

△ Pressure (Bar) 0.05

Duration (min) 10 min.

Results Pass

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✓

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Seawater SDI Evaluation

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< 3.00 !

9

✓

UF Filtrate SDI

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Optimizing UF Performance for Arabian Gulf Water

BW

CEB

CIP

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} CLEANING FIBERS

VS.

USE OF FILTRATE(USE OF CHEMICAL)

DOWNTIME

OPTIMIZE

BW

CEB

CIP

$COST UF LIFE

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Complete Operation of UF – Research Phases

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PHASE 1 UF Cleaning Research &

Optimization

PHASE 2Implementation of cleaning research

+ UF-RO Evaluation

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Flux: 85lmh

BW(min.): 60

CEB (NaOCl) 1/d

CIP 0

Recovery 95%

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PHASE 1: UF Cleaning Research & Optimization

Autopsy($) 2.53 cents/m3

Flux: 85lmh

BW(min.): 60

CEB (NaOCl) 1/w

CIP 1 Total

Recovery 95.4%

($) 2.46 cents/m3

Flux: 85mh

BW(min.): 60

CEB (NaOCl) 0

CIP 6 Total

Recovery 95.4%

($) 2.76 cents/m3

High Flux, Low Chemical conc.

High RecoveryHigh Cost

High Flux, Rare Chemical use

High RecoveryHigh Cost

High Flux, Low Chemical conc.

High RecoveryHigh Cost

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Autopsy Results Following Phase 1

• Moving cells were detected!• Fouling was a mixture of CaCO3 & Alumino

silicates .• Hydrocarbons, Esters, Acids and amines• Fe, Br, Sr, K, Ca, S, Cl, P, Si, Al, Na and Mg

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RECOMMENDED CLEANING SOLUTION BASED ON AUTOPSY RESULTS:• CIP NaOCl (2%) CIP Oxalic Acid (2%)

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CIP

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PHASE 2: Implementation of UF Cleaning Research

} Optimized performance & cost

New UF Modules Installed

Flux: 80lmh

BW(min.): 35

CEB (NaOCl) 2/d

CIP 1 Total

Recovery 92%

Flux: 80lmh

BW(min.): 35

CEB (NaOCl) 2/d

CIP 0 Total

Recovery 91%

($) 2.1 cents/m3 ($) 1.81 cents/m3

Med. Flux, Med. Chemical conc.

Med. RecoveryMed. Cost

Med. Flux, Med.+ Chemical conc.

Med. RecoveryLow Cost

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DOW FILMTEC RO –SW30HRLE-440i

Module Surface Area 440 ft2

Operating Flux

Recovery

15.2LMH

50%

Antiscalant 1ppm

Rejection*SW30HRLE-440iFlow*SW30HRLE-440i

99.8%

8,200 gpd

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RO Specifications

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RO Permeate Production and Quality

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• Five months of consistent RO Operation

• Permeate quality within close range (with exception to start-ups & stabilization period)

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How did we perform Vs Expectations?

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• Salt removal (conductivity) exceeded predictions by 15.6%

ROSA Conductivity(TDS)

Actual Conductivity

(TDS)

714 uS/cm(357 ppm)

602.4 uS/cm(301 ppm)

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Reverse Osmosis System Analysis (ROSA) Simulation software

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How did we perform Vs Expectations?

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• The average feed pressure surpassed highest temperature predictions by 4.75%

*Avg. feed pressure = 72.1 bar18

Reverse Osmosis System Analysis (ROSA) Simulation software

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Any Fouling on the RO?5-10% Normalized Salt Passage increase

DeltaP >3.2bar

10% drop in normalized permeate flow

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✘✘

✘ If any of these is observed, then chem. Cleaning is required.

* Based on DOW Filmtec Product Manual19

*

Again, confirming reliable UF filtrate quality!

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Summary

• Dow Ultrafiltration demonstrated reliable & sustainable operation:• High Filtrate quality independently of feed water fluctuations• Low chemical consumption based in cleaning research phase• Production rate is not compromised by feed water fluctuations

• Dow UF-RO integrated system demonstrated stable performance as the SWRO operated at 50% recovery with no required offline cleaning and no observable fouling

• Cost of water for Integrated UF-RO membrane based system for desalination$ 48 cents/m3 of RO permeate produced (Capex & Opex Incl)

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Thank You

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