Advanced Membrane TechnologiesStanford University, May 07, 2008Advanced Membrane TechnologiesStanford University, May 07, 2008

Membrane Technology – A Key Component in Water Reuse SystemsMehul Patel, P.E.Principal Process EngineerOrange County Water District

One Day Seminar for Treating Brackish Groundwater, Seawater, and Reclaimed Water

Stanford UniversityMay 7, 2008

Presentation OutlinePresentation Outline

►Common Reuse Applications of Membrane Technologies

►Historical Use of Membranes at OCWD►Advantages, Disadvantages, and Recommendations

for use of Membrane Technologies for Reuse Applications

►Examples of Reuse Applications: Water Factory 21 and the GWR System

Common Uses of Membrane Technology for ReuseCommon Uses of Membrane Technology for Reuse

► MF/UF used as a tertiary treatment process to meet Title 22 recycled water criteria for irrigation or industrial process water (carpet dye, paper processing)

► RO downstream of MF/UF for indirect potable reuse including seawater intrusion and surface spreading for groundwater replenishment

► Single or Two-Pass RO for ultra pure industrial processes such as boiler feed or computer chip manufacturing

► Water quality requirements govern over process costs as conventional treatment capital costs are normally less

Background On Use of RO at OCWD Background On Use of RO at OCWD

► RO used for Water Factory 21 since 1975 (RO for treatment of secondary effluent wastewater)

► Pilot scale polyamide TFC RO membranes tested downstream of MF/UF systems since 1994

► Involvement in design and initial operation of Arlington Desalter, Chino Desalter, and Tustin Desalter (RO for desalination of brackish groundwater)

► GWR System contains the largest RO system in US (70 mgd)► Partner for concept and planning of Irvine Desalter (RO for

contaminated groundwater on former Tustin Marine Corps Air Base)

Background on RO Applied Research and Testing at OCWDBackground on RO Applied Research and Testing at OCWD

► Cellulose acetate (CA) RO membranes used in WF-21 since the late 1970’s

► Pilot scale polyamide TFC RO membranes tested downstream of MF/UF systems since 1994

► Pilot scale tests using 4-inch diameter polyamide TFC elements showed lower operating pressure and higher rejection as compared with CA

► Testing also showed extended run time between cleaning due to MF/UF pre-treatment (tests also showed polyamide membranes not compatible with lime clarification pre-treatment)

Conventional Versus Advanced Water Treatment (Membrane Technologies)Conventional Versus Advanced Water Treatment (Membrane Technologies)

► Conventional treatment relies upon chemically enhanced settlement by gravity

► Disinfection is typically achieved solely through chemical addition

► Advanced treatment primarily relies upon physical separation by polymer based membranes

► Membranes offer two basic levels of treatment: particulate or dissolved contatminant removal (i.e. low pressure vs. high pressure membrane technology)

► Disinfection is achieved by chemical addition and/or altering the DNA of microorganisms

Advantages of Membrane Based TreatmentAdvantages of Membrane Based Treatment

► Footprint is typically 4 to 6 times less than conventional clarification

► Level of treatment is far greater than conventional treatment processes

► Process upsets occur less often due to nature of the treatment process

► Removal by physical separation allows for treatment of a broad range of water quality

► Allows for a high level of automation to potentially save on labor costs

Advantages of Membranes for Municipal ReuseAdvantages of Membranes for Municipal Reuse

► Most economical process for salinity reduction associated with secondary effluent (or other wastewater source) TDS levels

► Low Pressure membranes provide consistent water quality for non-potable reuse regardless of feedwater particulate content

► Stringent California DPH Draft Recharge Criteria water quality requirements best met using RO technology

► Safeguard against future contaminants of concern (i.e. Pharmaceuticals, EDC’s)

► Small footprint advantageous for areas where available land is at a premium

Disadvantages of Membrane Based TreatmentDisadvantages of Membrane Based Treatment

► Capital costs can be far greater than for conventional systems

► Current expertise of typical plant operators may not be up to level required

► Membrane replacement costs are high and must be budgeted for appropriately

► Proven track record at municipal scale is still being forged

► Concentrate and waste stream disposal issues

Roadblocks to Use of Membranes for Municipal ReuseRoadblocks to Use of Membranes for Municipal Reuse

► High initial capital costs for process equipment► O&M costs for membrane replacement► Lack of large operator level knowledge base ► Post treatment or blending issues due to corrosive nature of

product water► More economical technologies exist depending upon desired level

of treatment► Energy intensive nature makes process expensive in areas where

energy costs are high (i.e. California)

RO Is Not a Panacea: Low Molecular Weight Organic (LMWO) Rejection is not AbsoluteRO Is Not a Panacea: Low Molecular Weight Organic (LMWO) Rejection is not Absolute

► Not all LMWOs of concern are completely rejected by RO membranes

► Rejection of LMWOs is directly proportional to molecular weight and width of the compound

► NDMA is an example of a newly regulated compound not fully addressed by RO alone

► Approximately 35 - 40% of NDMA is rejected by PA TFC membranes; only 10 - 12% is rejected by CA membranes

► As lab methods improve more contaminants will be detected to far lower levels further demonstrating that RO capability to remove contaminants is not absolute

“Must Haves” if Membranes are to be Considered for Municipal Reuse“Must Haves” if Membranes are to be Considered for Municipal Reuse

► Pilot testing on source water for an extended period of time (6 months minimum for full benefit)

► Pilot testing must help establish realistic O&M costs► Thorough understanding of organic and inorganic make up of

source water► Proper pre-treatment (preferably low-pressure membrane

technology) if RO is considered► Strong membrane warranty language and technical support from

chosen MF/UF and RO manufacturer

Recommendations for Use of RO Technology for Reuse ApplicationsRecommendations for Use of RO Technology for Reuse Applications

► TDS and organics removal requirements typically drive the need for RO for reuse applications

► On-site pilot testing a must ► Level of pre-treatment determines the rate of O&M costs for RO ► State of CA water quality regulations for subsurface injection

indirectly require the use of RO► Newly regulated contaminants of concern (such as LMWOs) have

shown that RO alone may not be enough► A combination of low and high pressure membrane technology

reduces cost of possible downstream oxidation treatment (UV/peroxide, UV/Ozone, Ozone)

flocculationflocculation

clarificationclarification

recarbonationrecarbonation

filtrationfiltration

carbon adsorption (10 carbon adsorption (10 mgdmgd))

reverse osmosis reverse osmosis (5 (5 mgdmgd))

SecondarySecondarytreatedtreatedwastewaterwastewater

BlendingBlendingprior to prior to use in use in seawaterseawaterbarrierbarrier

lime sludgelime sludgeCOCO22

recycled limerecycled lime(up to 75% recovery)(up to 75% recovery)

transfertransfer thickeningthickening recalciningrecalcining

Water Factory 21 - The First Municipal Facilityto use RO for Reuse (1977 to 2004)

AOP (5 AOP (5 mgdmgd))(added later)(added later)

Water Factory 21 Conventional vs. MF/UF Treatment Prior to ROWater Factory 21 Conventional vs. MF/UF Treatment Prior to RO

GWR System – Microfiltration Pretreatment

ReverseOsmosis

Water Factory 21 – Conventional Pretreatment

Lime

Flocculation &Sedimentation FiltrationChlorinationRecarbonation

MicrofiltrationNaOCl CA vs. PA

86 86 mgdmgd70 70 mgdmgd 70 70 mgdmgd

GWR System Advanced Water Treatment Facility (AWTF) Flow DiagramGWR System Advanced Water Treatment Facility (AWTF) Flow Diagram

Ultraviolet Ultraviolet Light Light (AOP)(AOP)

Concentrate Concentrate OCSD OutfallOCSD Outfall

Backwash Backwash OCSD Plant 1OCSD Plant 1

MicrofiltrationMicrofiltration(MF)(MF)

Reverse Reverse OsmosisOsmosis

(RO)(RO)

Purified Purified WaterWater

with with hydrogenhydrogenperoxideperoxide

EnhancedSource Control

SecondaryTreatment

Surface Spreading & Seawater Intrusion Barrier

OCSD OCSD Secondary Secondary

EffluentEffluent

Lime Lime additionaddition

NaOClNaOCladditionaddition

GWR System ComponentsGWR System Components

Irvine

Fullerton

OceanOceanOutfallOutfall

OCWDOCWD

Groundwater BasinGroundwater Basin

Santa Ana River

N

Pacific Ocean

Santiago Creek

OCSDOCSDTreatmentTreatmentFacilitiesFacilities

HuntingtonBeach

AdvancedAdvancedWater PurificationWater PurificationFacilityFacility

Pumping Pumping FacilitiesFacilities

SeawaterSeawaterIntrusionIntrusion

BarrierBarrier

Kraemer BasinKraemer Basin

GWR PipelineGWR Pipeline

Future MidFuture Mid--BasinBasinInjection/RechargeInjection/Recharge

GWR System - Level of Treatment for Each ProcessGWR System - Level of Treatment for Each Process

► MF removes suspended solids, bacteria, and protozoa► MF pre-treatment increases efficiency of RO process► RO removes salinity (TDS), virus, dissolved organics► AOP process provides an additional barrier for

disinfection► AOP destructs low molecular weight organics ► Testing at OCWD has shown that the combination of

RO and AOP is effective against emerging compounds such as: low molecular weight organics, pharmaceuticals, and endocrine disruptors

AWTF Process Flow DiagramAWTF Process Flow Diagram

Microfiltration SystemMicrofiltration System

► 86 MGD Siemens CMF-S Microfiltration System (15,808 membrane modules)

► Removes bacteria, protozoa, and suspended solids

► 0.2 micron pore size

► In basin submersible membrane system

► Includes 2 CIP systems

MF System DesignMF System Design

► US Filter CMF-S system (immersed membrane)► Flux Rate = 20.4 gallons per ft2 per day► 22 minute backwash interval using reverse flow and air

agitation with complete drain of tank (cell) contents► 26 cells with 608 membrane modules each► 3 basins with 8 cells per basin (one additional basin

with only two cells)► 86 mgd total capacity► 21 day cleaning interval

GWRS CMF-S MF System Design (86 mgd)GWRS CMF-S MF System Design (86 mgd)

Train D Basins Train A Basins

Train B BasinsTrain E BasinsCell containing684 MF modules

Punch - out wall for future expansion

Empty cellsMembranes relocatedfrom temporary system

GWRS Reverse Osmosis SystemGWRS Reverse Osmosis System

►► 70 MGD Reverse Osmosis 70 MGD Reverse Osmosis System (15, 5 System (15, 5 mgdmgd units)units)

►► 15750 15750 HydranauticsHydranautics ESPAESPA--2 2 MembranesMembranes

►► Recovery Rate: 85% Recovery Rate: 85% ►► 3 3 –– stage array per unit in a stage array per unit in a

78:48:24 arrangement78:48:24 arrangement►► Removes salts, viruses, Removes salts, viruses,

organicsorganics►► Pressure range: 150 psi Pressure range: 150 psi ––

200 psi200 psi►► Includes 2 CIP systemsIncludes 2 CIP systems

RO System Process FlowRO System Process Flow

Threshold InhibitorSystem

Sulfuric Acid

System

MF Filtrate Pump

Station CIP System

Reverse Osmosis

Cartridge Filters

Concentrate to Ocean Outfall

Drain

Flush System

Feed Pump

To Post-

Treatment

Mixer

GWRS Ultraviolet Light /Advanced Oxidation SystemGWRS Ultraviolet Light /Advanced Oxidation System

►► 70 MGD Trojan 70 MGD Trojan UVPhoxUVPhoxSystemSystem

►► Low Pressure Low Pressure –– High Output High Output lamp systemlamp system

►► Nine 8.75 Nine 8.75 mgdmgd trains (3888 trains (3888 total lamps)total lamps)

►► Removes trace organicsRemoves trace organics►► Uses Hydrogen Peroxide to Uses Hydrogen Peroxide to

form an Advanced Oxidation form an Advanced Oxidation ProcessProcess

Post Treatment Process FlowPost Treatment Process Flow

To SeawaterIntrusion Barrier and Infiltration Basins

Barrier and Product Pump Stations

Decarbonators

Lime Addition(CaOH)

UV Disinfection

From ROSystem

DecarbonatorBypass

Stabilization and StorageStabilization and Storage

► Decarbonation and lime addition stabilize purified water

► GWR System water is pumped to seawater barrier and spreading basins

► Natural soil filtration and buffering provide final treatment prior to extraction after months of storage

$65.3ELA & Contingency

15.2Integrated Information System, Wells, Workshops & Insurance

19.8Phase 1 GWR System & Site Power

0.8Trailers

0.8Equipment Engineering

$480.9Total

17.1Barrier Facilities

63.2GWR Pipeline*

298.7Treatment Facilities

Escalated Cost ($M)Construction Contracts

*3 contracts

Estimated Capital CostEstimated Capital Cost

Estimated Annual O&M CostEstimated Annual O&M Cost

29.6Sub - Total

(3.8)Metropolitan Water District Subsidy

25.8Total

3.6

1.5

0.3

2.8

1.2

5.3

0.4

14.5

$ Million per Year

O&M Staff

Compliance Monitoring

UV Lamp Replacement

Membrane Replacement

Plant Refurbishment

Chemicals

Contract Maintenance

Power

Item

Federal, State, and Local FundingFederal, State, and Local Funding

Loans

$145.0► State Revolving Fund Loans

$92.5Total Grants

30.0► Department of Water Resources (Prop. 13)

37.0► State Water Resources Control Board (Prop.13)

5.0► State Water Resources Control Board

20.0► United States Bureau of Reclamation

0.5► Environmental Protection Agency

$ MillionGrants

CA DPH Regulatory Criteria for Injection

Subsurface InjectionSubsurface Injection CDPH Proposed CriteriaCDPH Proposed Criteria GWR SystemGWR System

Total Suspended SolidsTotal Suspended Solids <30 mg/L<30 mg/L NDND

FiltrationFiltration < 2 NTU< 2 NTU 0.2 NTU0.2 NTU

DisinfectionDisinfection 4 log < 2.2 total per 100 4 log < 2.2 total per 100 mLmL NDND

Underground Retention TimeUnderground Retention Time > 12 months> 12 months 24 months24 months

Horizontal SeparationHorizontal Separation > 2,000 feet> 2,000 feet 3,120 feet3,120 feet

Biochemical Oxygen DemandBiochemical Oxygen Demand < 30 mg/L< 30 mg/L NDND

Total NitrogenTotal Nitrogen < 5 mg/L< 5 mg/L 2.6 mg/L2.6 mg/L

Total Organic CarbonTotal Organic Carbon < 0.5 mg/L< 0.5 mg/L 0.26 mg/L0.26 mg/L

Drinking Water StandardsDrinking Water Standards < < MCLsMCLs < < MCLsMCLs

Department of Public Health and Regional Board Approval ProcessDepartment of Public Health and Regional Board Approval Process

► DHS Public Hearing - February 2003► DHS Findings of Fact and

Conditions► RWQCB incorporated DHS Findings

and Conditions into permit► RWQCB Hearing – March 2004 ► RWQCB issued requirements for

both Interim WF-21 and GWR System

► GWR System 70 MGD - largest IPR project in the world

Additional Requirements for GWR SystemAdditional Requirements for GWR System

► Buffer areas■ >500 ft for spreading■ >2000 ft for injection

► Retention time underground■ >6 months for spreading■ >1 year for injection

► Replacement water plan► Initial blending – 75% ramping up to 100%

RWC► Independent Advisory Panel (NWRI

appointed) for OMMP review

Water Quality Requirements for GWR SystemWater Quality Requirements for GWR System

► Comply with Drinking Water Standards plus TOC and Total N

► Non-aggressive water to reduce leaching potential

► Testing for Notification Level compounds like NDMA, perchlorate and 1,4-dioxane

► Testing for selected pharmaceuticals and endocrine disruptors

► Monitoring in plant, blend water and groundwater along flowpath to production wells

Treatment Requirements for GWR SystemTreatment Requirements for GWR System

► Enhanced Source Control by OCSD (Title 22, CCR, Division 4, Chapter 3. Recycling Criteria, Section 60320 General Requirements)

► Organics removal - <0.5 mg/L TOC ► Nitrogen removal - <5 mg/L Total N► Disinfection – UV system >4 logs virus

inactivation► UV photolysis for 1.2 log NDMA removal► AOP for unknown organic contaminants

For More InformationFor More Information

Email: mpatel@ocwd.com

Project Website: www.gwrsystem.com

OCWD Website: www.ocwd.com