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MMWD Seawater Desalination MMWD Seawater Desalination Pilot ProgramPilot Program

Patrick Treanor P.E

MMWD Seawater Desalination MMWD Seawater Desalination Pilot ProgramPilot Program

1.1. General BackgroundGeneral Background2.2. Virtual Tour Virtual Tour 3.3. Findings Findings 4.4. Energy RequirementsEnergy Requirements5.5. QuestionsQuestions

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Evaluating a DroughtEvaluating a Drought--Proof Water Proof Water Source Source

Droughts are a part of Droughts are a part of CaliforniaCalifornia’’s climate and s climate and may be more frequent due may be more frequent due to climate changeto climate changePotential for over 65% Potential for over 65% rationing without rationing without additional supplyadditional supplySeawater Desalination Seawater Desalination Pilot ProgramPilot Program–– Local, reliable droughtLocal, reliable drought--proof proof

water supplywater supply

Evaluating a DroughtEvaluating a Drought--Proof Proof Water Source Water Source

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Pilot Program: An Invaluable ToolPilot Program: An Invaluable ToolConfirm and demonstrate Confirm and demonstrate that that desaldesal water is safewater is safe

Conduct environmental Conduct environmental studies to support EIRstudies to support EIR

Inform customers on the Inform customers on the program and technologyprogram and technology

Evaluate best available Evaluate best available treatment technologiestreatment technologies

Determine fullDetermine full--scale system scale system design criteria and costsdesign criteria and costs

Pilot Program: An Invaluable ToolPilot Program: An Invaluable Tool

Understanding of Local ConditionsUnderstanding of Local ConditionsPractical ExperiencePractical ExperiencePilot Study Pays for itself: Pilot Study Pays for itself: –– Pilot study can save 5Pilot study can save 5--10% of the capital investment and up 10% of the capital investment and up

to 20% of the O&M for the full scale projectto 20% of the O&M for the full scale project

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May July Sep Oct Dec Jan Mar Apr

Date

Source Water Salinity and TurbiditySource Water Salinity and Turbidity

1st Major Storm

May July Sep Oct Dec Jan Mar Apr

Date

1st Major Storm

Source Water SalinitySource Water Salinity

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May July Sep Oct Dec Jan Mar Apr

Date

Source Water TurbiditySource Water Turbidity

1st Major Storm

Storms/Wind

Virtual TourVirtual Tour

BrineDisposal

Sea Water Reverse Osmosis (SWRO)

Sea Water Reverse Osmosis (SWRO)

PostTreatment

PostTreatment

EnergyRecoveryEnergy

Recovery

Pre-TreatmentPre-Treatment

FiltrationFiltration

ChemicalsChemicals

Intake

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Intake ScreeningIntake Screening11stst filtration stepfiltration stepDesigned to meet Designed to meet Federal and State Federal and State criteria for fish criteria for fish protectionprotection–– 3/323/32--inch openingsinch openings–– <0.3 fps velocity<0.3 fps velocity–– airburst cleaningairburst cleaning

Located at end of Located at end of existing 2000existing 2000--ft pierft pierMultiple screens for Multiple screens for fullfull--scale facility scale facility

Pretreatment ProcessPretreatment Process

22ndnd filtration stepfiltration stepSimilar to surface water treatment processSimilar to surface water treatment processRemoves algae, silts and other Removes algae, silts and other suspended solids from the bay watersuspended solids from the bay waterProtect Reverse Osmosis MembranesProtect Reverse Osmosis MembranesPilot program tested:Pilot program tested:

1.1. Conventional granular media filtrationConventional granular media filtration2.2. Microfiltration (MF) & Microfiltration (MF) & UltrafiltrationUltrafiltration (UF)(UF)

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Conventional Pretreatment ProcessConventional Pretreatment ProcessConventional Desalination Pretreatment

CoagulationCoagulation FlocculationFlocculation ClarificationClarificationGranular

Media Filtration

GranularMedia

Filtration

Seawater

DesalDesal

Conventional Granular Media FiltrationConventional Granular Media FiltrationRequires coagulant addition, Requires coagulant addition, flocculation & clarification flocculation & clarification before filterbefore filter

Particles captured through the Particles captured through the depth of the filterdepth of the filter

Coagulant addition sensitive to Coagulant addition sensitive to changes in source water changes in source water qualityquality

Anthracite

Sand

Under-drain

Garnet

Bay Water

Filtered Water to Desal

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StrainerStrainer MF/UF FiltrationMF/UF

Filtration

Seawater

DesalDesal

MF/UF Desalination PretreatmentMicro/Ultra Filtration Pretreatment ProcessMicro/Ultra Filtration Pretreatment Process

Micro/Ultra Filtration Pretreatment ProcessMicro/Ultra Filtration Pretreatment Process

StrainerStrainer MF/UF FiltrationMF/UF

Filtration

Seawater

DesalDesal

Strainer Pretreatment

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Micro/Ultra Filtration Hollow Micro/Ultra Filtration Hollow Fiber MembraneFiber Membrane

Immersed hollow Immersed hollow fibersfibersOutsideOutside--in in configurationconfigurationMF MF –– 0.2 microns0.2 micronsUF UF –– 0.02 microns0.02 micronsFibers can be Fibers can be backwashedbackwashed Outside-In

MembraneSurface

Silt Density IndexSilt Density Index

Micro-filtration Pretreatment

Conventional Pretreatment

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Micro/Ultra filtration is Micro/Ultra filtration is recommended pretreatmentrecommended pretreatment

Better filtered water qualityBetter filtered water qualityIncreased reliabilityIncreased reliabilityFewer process chemicals Fewer process chemicals Less fouling of Less fouling of desaldesalmembranesmembranesLess solids for disposalLess solids for disposalLess truck trafficLess truck trafficSmaller footprintSmaller footprint20% lower capital cost20% lower capital cost10% lower O&M cost10% lower O&M cost

Compared to conventional pretreatment, micro/ultra filtration provides:

Seawater Reverse Osmosis Seawater Reverse Osmosis DesalinationDesalination

RO pumps can RO pumps can supply water up to supply water up to 1,200 1,200 psipsi. [. [avgavg was was 600 600 psipsi]]Brine Pressure Brine Pressure Loss was about 25 Loss was about 25 psipsiLess energy than Less energy than desalting ocean desalting ocean waterwater2 gal of bay water 2 gal of bay water produces 1 gal produces 1 gal desalinateddesalinated

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PressurizedBay Water

Spiral Membrane

Fresh Water

Brine

Na+

Cl-Na+Na+

Na+

Na+

Na+

Cl-Cl-

Cl-Cl- Cl-

Cl-Na+

Fresh Water

Permeate Spacer

RO Membrane

Feed Spacer

RO Membrane

Reverse Osmosis (RO) Reverse Osmosis (RO) MembraneMembrane

Reverse Osmosis (RO) Reverse Osmosis (RO) Pressure RequirementsPressure Requirements

DiluteSolution

OsmosisNo external pressure

ConcentratedSolution

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Reverse Osmosis (RO) Reverse Osmosis (RO) Pressure RequirementsPressure Requirements

Reverse OsmosisExternal pressure

DiluteSolution

ConcentratedSolution

DiluteSolution

OsmosisNo external pressure

ConcentratedSolution

PharmaceuticalsPharmaceuticals

Not DetectedNot Detected0.0000000020.000000002ppmppmDilantinDilantin

Not DetectedNot Detected0.0000000020.000000002ppmppmNaproxenNaproxen

Not DetectedNot Detected0.0000000030.000000003ppmppmIbuprofenIbuprofen

Not DetectedNot Detected0.0000000010.000000001ppmppmEstroneEstrone

Not DetectedNot Detected0.0000000080.000000008ppmppmCaffeineCaffeine

Desalinated Desalinated WaterWater

SF Bay WaterSF Bay WaterUnitsUnitsConstituentConstituent

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Desalination Post TreatmentDesalination Post Treatment+ Add calcium and + Add calcium and

bicarbonate to match bicarbonate to match stability and taste of stability and taste of MMWD current water MMWD current water supplysupply

+ Disinfection similar to + Disinfection similar to current MMWD current MMWD practicespractices

FindingsFindings-- DesalDesal water tastes water tastes

GOOD!GOOD!-- Extensive Water Extensive Water

quality tests of Bay quality tests of Bay Water and RO Water and RO permeate say permeate say desaldesalwater is safe to drink!water is safe to drink!

-- Safe for SF bay Safe for SF bay ecology!ecology!

-- Full scale plant design Full scale plant design criteria developed criteria developed

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SWRO Energy Use is Lower than SWRO Energy Use is Lower than in the Pastin the Past

1980 1990 2000 2001 2005

15.319.2

23.0

30.7

kWh/ 1000 gal

Note:1. Numbers for energy consumption represent the RO process only. They do not

include any allowance for supply or distribution.

7.15-12 kWh/ 1000gal

7.15-12 kWh/ 1000gal

3.87.7

11.5

26.8

0

RO Process ONLY

DesalDesal Energy is Reduced byEnergy is Reduced by……

Taking advantage of lower salinity and Taking advantage of lower salinity and warmer SF Bay source waterwarmer SF Bay source waterUsing the most advanced and energy Using the most advanced and energy efficient desalination equipment including efficient desalination equipment including energy recovery energy recovery Designing and operating the plant at the Designing and operating the plant at the optimum conditions for energy efficiencyoptimum conditions for energy efficiency

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Benefits of Benefits of DesalDesal Water SourceWater SourceNew and Unlimited Sustainable Water Source New and Unlimited Sustainable Water Source with Consistent Water Qualitywith Consistent Water QualityDrought Proof SupplyDrought Proof SupplyReduced Impacts on Inland Water WaysReduced Impacts on Inland Water Ways–– Fisheries, Transportation, Riparian HabitatFisheries, Transportation, Riparian Habitat

Local Water means Less Conveyance CostLocal Water means Less Conveyance CostSecuritySecurityDiverse water portfolio for changing timesDiverse water portfolio for changing times–– Will water surpass energy as most precious Will water surpass energy as most precious

and valued utility?and valued utility?

Energy Recovery DeviceEnergy Recovery Device

575 psi Brine 10 gpm

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Energy Recovery DeviceEnergy Recovery Device

355 psi Feed 20 gpm

575 psi Brine 10 gpm

Energy Recovery DeviceEnergy Recovery Device

600 psi Feed 20 gpm

355 psi Feed 20 gpm

575 psi Brine 10 gpm

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Energy Recovery DeviceEnergy Recovery Device

600 psi Feed 20 gpm

355 psi Feed 20 gpm

575 psi Brine 10 gpm

43 psi Brine 10 gpm

Energy Recovery DeviceEnergy Recovery Device

600 psi Feed 20 gpm

355 psi Feed 20 gpm

575 psi Brine 10 gpm

43 psi Brine 10 gpm

85% Efficient Energy Recovery Provides 40% Reduction in Feed Pressure

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80 watts x 24 hrs

1.9 kWhr/day

270 gallons

Is Desalination a Feasible Water Source? Is Desalination a Feasible Water Source? On average, MMWD households use 270 gallons of water per day

At 7.15 kWh/1000 gal seawater desalination requires only 1.9 kWhr/day of power to produce 270 gallonsper day.

Typical PG&E household

18 kWhr/day

+

Questions?Questions?