membrane bioreactors: state of the art and technology exchange · membrane bioreactors: state of...

Membrane Bioreactors:Membrane Bioreactors:State of the Art andState of the Art and

Technology ExchangeTechnology Exchange

R. Shane Trussell, Ph.D., P.E.R. Shane Trussell, Ph.D., P.E.

Seminar for DOW Chemical

Midland, MI

June 21, 2007

OutlineOutline

•• IntroductionIntroduction

•• Membrane IssuesMembrane Issues

•• Other IssuesOther Issues

OutlineOutline

•• IntroductionIntroduction

––Brief historyBrief history

––Configurations and Configurations and

manufacturersmanufacturers

––MBR vs. ConventionalMBR vs. Conventional

•• Membrane IssuesMembrane Issues

•• Other IssuesOther Issues

IntroductionIntroduction

•• An MBR is not a An MBR is not a

membrane processmembrane process

•• An MBR is a An MBR is a

biological biological

process that process that

uses membranes uses membranes

for solidfor solid--liquid liquid

separationseparation

IntroductionIntroduction•• MBRMBR’’ss RootsRoots

–– Dorr Oliver (1960s)Dorr Oliver (1960s)

–– Successfully Successfully coupled activated coupled activated sludge (AS) to sludge (AS) to membrane separation membrane separation by early 1970s by early 1970s (sold 27 units (sold 27 units between 1974 and between 1974 and 1982)1982)

–– EMBR process with EMBR process with flatsheetflatsheet UF UF membranesmembranes

•• Cost prohibitiveCost prohibitive

–– Capital and O&MCapital and O&M

IntroductionIntroduction•• SMBR configurationSMBR configuration

–– University of Tokyo University of Tokyo Professors Professors AyaAya and and YamamotoYamamoto

–– 1989 1989 WatWat. . SciSci. Tech.. Tech.

•• JapanJapan

–– Kubota developed flatKubota developed flat--sheet SMBRsheet SMBR

–– Mitsubishi developed Mitsubishi developed horizontal hollow horizontal hollow fiber SMBRfiber SMBR

•• CanadaCanada

–– ZenonZenon developed developed vertical hollow fiber vertical hollow fiber SMBRSMBR

IntroductionIntroduction•• SMBR configurationSMBR configuration

–– Breakthrough for Breakthrough for commercialized MBR commercialized MBR technologytechnology

–– Reduced energy by 90%Reduced energy by 90%

•• JapanJapan

–– Kubota dominates with Kubota dominates with 60 60 MBRsMBRs by 1996 (total by 1996 (total 1.5 MGD)1.5 MGD)

•• UK, Canada, and USAUK, Canada, and USA

–– Milton, Ontario, CA Milton, Ontario, CA 19971997

–– Arapahoe, CO, USA 1998Arapahoe, CO, USA 1998

–– Kingston Seymour, UK Kingston Seymour, UK 19921992

IntroductionIntroduction•• SMBR manufacturers in the SMBR manufacturers in the

USA USA -- firstsfirsts

–– ZenonZenon was 1.0 MGD in was 1.0 MGD in Arapahoe, CO in 1998Arapahoe, CO in 1998

–– Mitsubishi was 0.10 MGD in Mitsubishi was 0.10 MGD in ByfieldByfield, MA in 2000, MA in 2000

–– Kubota was 0.6 MGD in Running Kubota was 0.6 MGD in Running Springs, CA in 2002Springs, CA in 2002

–– US Filter was 0.16 MGD in US Filter was 0.16 MGD in Lake Lake OconoceeOconocee, GAG in 2003, GAG in 2003

• Zenon is the predominant MBR manufacturer with the most experience and capacity

• Kubota is the runner-up with significant knowledge and installation capacity

Submerged MBR (SMBR)Submerged MBR (SMBR)Q

Primary Treated

Wastewater

WASTE

EffluentEffluentEffluentEffluentAeration Basin

Waste Activated SludgeWaste Activated SludgeWaste Activated SludgeWaste Activated Sludge

Solids RecycleSolids RecycleSolids RecycleSolids Recycle

QR = 3-5xQ

External MBR (EMBR)External MBR (EMBR)

Primary Treated Primary Treated Primary Treated Primary Treated

WastewaterWastewaterWastewaterWastewater


EffluentEffluentEffluentEffluentAeration BasinAeration BasinAeration BasinAeration Basin

Q

QR = 20-30xQ


““AirAir--liftlift”” EMBREMBR

Primary Treated Primary Treated Primary Treated Primary Treated

WastewaterWastewaterWastewaterWastewater


EffluentEffluentEffluentEffluent

Aeration BasinAeration BasinAeration BasinAeration Basin

Q

QR = 5-10xQ


DiffuserDiffuserDiffuserDiffuser

ZENONZENON

•• Hollow fiber Hollow fiber

membrane membrane

configurationconfiguration

•• Proprietary Proprietary

polymerpolymer

•• UltrafiltrationUltrafiltration

•• 1998 First MBR 1998 First MBR

Installation in Installation in

the USA was the USA was

operational at operational at

1.0 MGD in 1.0 MGD in

Arapahoe, COArapahoe, CO

ZENONZENON•• 48 modules combine 48 modules combine

to form a cassetteto form a cassette

•• One common headerOne common header

•• Permeate drawn Permeate drawn

from top and from top and

bottombottom

•• Intermittent Intermittent

coarse bubble coarse bubble

aeration (10s on/ aeration (10s on/

10s off)10s off)

ZENONZENON

•• Membranes submerged at end of aeration basinMembranes submerged at end of aeration basin

•• System capable of operating with System capable of operating with ““backpulsebackpulse””

or or ““relaxrelax””

Kubota / Kubota / EnviroquipEnviroquip

•• Flat sheet membrane Flat sheet membrane configurationconfiguration

•• PolyethylenePolyethylene

•• MicrofiltrationMicrofiltration

•• 2002 First MBR 2002 First MBR Installation in the Installation in the USA was operational USA was operational at 0.6 MGD in at 0.6 MGD in Running Springs, CARunning Springs, CA


•• 100 flat sheets 100 flat sheets combine to form combine to form cassettecassette

•• Each sheet has Each sheet has tube connection tube connection to headerto header

•• Constant coarse Constant coarse bubble aeration bubble aeration to mitigate to mitigate membrane foulingmembrane fouling


•• Cassette submerged in aeration basinCassette submerged in aeration basin

•• Double Double deckerdecker (DD) configuration(DD) configuration

•• System operates with membrane relax, no System operates with membrane relax, no

backpulsebackpulse

US Filter/ US Filter/ MemJetMemJet

•• Hollow fiber Hollow fiber membrane membrane configurationconfiguration

•• PVDF PVDF


•• 2003 First MBR 2003 First MBR Installation in the Installation in the USA was operational USA was operational at 0.16 MGD in Lake at 0.16 MGD in Lake Oconee, GAOconee, GA


•• Bundles of 4 Bundles of 4 membrane modulesmembrane modules

•• Common header for 4 Common header for 4 modulesmodules

•• Combination of Combination of air/liquid jet air/liquid jet ““Jet Jet TechTech”” is used to is used to provide crossprovide cross--flow flow to the membrane to the membrane surfacesurface


•• Separate tank Separate tank

for membranesfor membranes

•• Backwashing Backwashing

cycle:cycle:

45 s relax45 s relax

15 s permeate 15 s permeate

backflushbackflush

15 s coarse 15 s coarse

bubble airbubble air

Mitsubishi / GE IonicsMitsubishi / GE Ionics

•• Hollow fiber membrane Hollow fiber membrane configuration configuration (horizontal)(horizontal)

•• PolyethylenePolyethylene


•• 2000 First MBR 2000 First MBR Installation in the Installation in the USA was operational USA was operational at 0.10 MGD in at 0.10 MGD in ByfieldByfield, MA, MA


•• 50 membrane modules 50 membrane modules

for 1 membrane bankfor 1 membrane bank

•• Modules connect to Modules connect to

common headercommon header

•• Permeate drawn from Permeate drawn from

both sides (L and R)both sides (L and R)

•• Constant coarse Constant coarse

bubble aerationbubble aeration


•• Membranes submerged in aeration basinMembranes submerged in aeration basin

•• System operates with membrane relax, no System operates with membrane relax, no

backpulsebackpulse

Membrane ComparisonMembrane Comparison

--0.50.50.40.4MitsubishMitsubish

ii

170170--0.40.4KubotaKubota

4004000.20.20.080.08US FilterUS Filter

2902900.10.10.0350.035ZenonZenon

Membrane Membrane

Area/Footprint,Area/Footprint,

ftft22/ft/ft22

Absolute Absolute

MWCO,MWCO,

µµµµµµµµmm

Nominal Nominal

MWCO,MWCO,

µµµµµµµµmm

ManufacturerManufacturer

Koch Koch PuronPuron

EMBREMBR’’ss ““ReRe--BirthBirth””-- Air PumpsAir Pumps

How does MBR compare How does MBR compare to what is to what is ““commoncommon””wastewater practice?wastewater practice?

Drivers for Process Drivers for Process SelectionSelection

–– Intended use of treated waterIntended use of treated water

�� Effluent limitsEffluent limits

–– Scalability Scalability

�� Site constraintsSite constraints

�� Flexibility with Flexibility with

expansions/retrofitsexpansions/retrofits

–– Capital costCapital cost

–– O&M costO&M cost

–– Training/Expertise requirementTraining/Expertise requirement

TechnologiesTechnologies

Goal is to remove COD, TN, TSS, Goal is to remove COD, TN, TSS, and Pathogensand Pathogens

Small to medium capacity < 5 MGDSmall to medium capacity < 5 MGD

•• Oxidation DitchOxidation Ditch

•• Sequencing Batch Reactor (SBR)Sequencing Batch Reactor (SBR)

•• Membrane Bioreactor (MBR)Membrane Bioreactor (MBR)

Large capacity > 5 MGDLarge capacity > 5 MGD

•• Conventional activated sludgeConventional activated sludge

•• Pure oxygen activated sludgePure oxygen activated sludge

•• Membrane Bioreactor (MBR)Membrane Bioreactor (MBR)

Flow Scheme for Conventional Flow Scheme for Conventional Activated Sludge ProcessActivated Sludge Process

Backwash

Water

Secondary

Clarifier

Secondary

Clarifier

WASTE

To

Disinfection

Microfiltration

ConventionalConventionalAeration BasinAeration Basin

Primary Treated

Wastewater

Flow Schemes for the MBR and Flow Schemes for the MBR and Conventional Activated Sludge Conventional Activated Sludge

ProcessProcess

Primary Treated

Wastewater

Backwash

Water

Secondary

Clarifier

WASTE

To

Disinfection

Microfiltration

ConventionalAeration Basin

WASTE

MBR

Aeration Basin

To

Disinfection

Sequencing Batch Sequencing Batch ReactorsReactors

•• SBR is a fillSBR is a fill--and draw type and draw type

activated sludge systemactivated sludge system

»» Equalization, aeration and Equalization, aeration and

clarification all performed in the clarification all performed in the

same batch reactorsame batch reactor

React Settle Decant

Retrofitting SBR with MBR

Capacity increases by 8-fold • “Batch” becomes “Continuous”

• MLSS increases from 3 to 10 g/L

DisinfectionPrimary Treated

Wastewater

Waste

Activate

Sludge

Membrane TankAeration Tank

Solids Recycle

QR = 3-5•Q

Q

Oxidation DitchOxidation Ditch

Oxidation ditch is an activated sludge process

that utilizes long solids retention times

CAS SRT = 5 avg. days

Oxidation ditch SRT = 20 avg. days

Oxidation DitchOxidation Ditch

• Double Ditch

• Triple Ditch

• Mechanical aerators

• More capacity, more ditches

•Typical HRT is 24 h

TechnologiesTechnologiesAll conventional technologies that

compete with MBR use gravity for solid-liquid separation

•• Additional filtration process required to Additional filtration process required to attain recycled water statusattain recycled water status

•• Membrane filtration required to attain a Membrane filtration required to attain a similar water qualitysimilar water quality

•• MBR has great potential to reduce MBR has great potential to reduce disinfection requirements disinfection requirements

Commercial MBRs to date are not marketed in in a manner that allows operation similar to pure oxygen plants

•• Low SRT operation to prevent nitrification Low SRT operation to prevent nitrification and significantly reduce oxygen requirementsand significantly reduce oxygen requirements

•• This is because membrane fouling rates are This is because membrane fouling rates are increased with low SRT designsincreased with low SRT designs

TechnologiesTechnologiesObvious winner for MBR

•• Space limitationsSpace limitations

•• High quality effluent requiredHigh quality effluent required

Debate amongst practicing engineers in USA as to the economics of MBR compared to membrane filtration of secondary effluents for large wastewater treatment facilities

•• Less aeration required on settled Less aeration required on settled effluent because less solids presenteffluent because less solids present

•• Higher flux and reduced capital costHigher flux and reduced capital cost

•• Reality is established cleaning Reality is established cleaning intervals are different (2intervals are different (2ndnd effluent effluent every 3 to 4 weeks while MBR every 1 every 3 to 4 weeks while MBR every 1 to 3 months)to 3 months)

TechnologiesTechnologiesLarge membrane facilities treating secondary Large membrane facilities treating secondary

effluenteffluent

•• Orange County Water District 85 MGDOrange County Water District 85 MGD

•• West Basin Municipal Water District 40 West Basin Municipal Water District 40 MGDMGD

•• Clark County Water Reclamation District Clark County Water Reclamation District 30 MGD30 MGD

Large MBR facilitiesLarge MBR facilities

•• Traverse City 17 MGD facilityTraverse City 17 MGD facility

•• Tempe 10 MGD facilityTempe 10 MGD facility

•• King County King County BrightwaterBrightwater 38 MGD38 MGD

•• Irvine Ranch Water District 20 MGDIrvine Ranch Water District 20 MGD

MBRsMBRs economic viability depends on the economic viability depends on the entire picture of a given locationentire picture of a given location

•• Cost of land and availabilityCost of land and availability

•• Total present worth costsTotal present worth costs

•• Overall project goalsOverall project goals

Principle Advantages of Principle Advantages of MBR ProcessMBR Process

•• High quality High quality

effluenteffluent

•• Compact Compact

FootprintFootprint

•• High MLSS High MLSS

concentrationsconcentrations

•• Some obvious benefits Some obvious benefits

of of MBRsMBRs areare•• MBR produces an excellent MBR produces an excellent

effluent qualityeffluent quality

•• MBR has a much smaller MBR has a much smaller

footprintfootprint

•• smaller aeration tankssmaller aeration tanks

•• no clarifiersno clarifiers

•• no filters no filters

•• MBR has great potential for MBR has great potential for

being highly automated and being highly automated and

requiring little operator requiring little operator

attentionattention

MBR AdvantagesMBR Advantages

•• MBR eliminates the need MBR eliminates the need

for monitoring sludge for monitoring sludge

settleability as ansettleability as an

operational parameteroperational parameter»»Effluent quality is not Effluent quality is not

dependent on operationsdependent on operations

»»Not necessary to determine Not necessary to determine

TSS/VSS concentrations to TSS/VSS concentrations to

maintain desired SRTmaintain desired SRT

»»Can use fixed waste rate Can use fixed waste rate

SRT=V/QSRT=V/QWASWAS


•• Higher MLSS concentrations (More bug Higher MLSS concentrations (More bug mass per volume)mass per volume)

––Membrane provides solidMembrane provides solid--liquid liquid separationseparation

»»SBR or Ox. Ditch 2SBR or Ox. Ditch 2--4 g/L4 g/L

»»MBR 8MBR 8--12 g/L12 g/L

•• MBR makes longer MBR makes longer SRTsSRTs feasiblefeasible

––Reduced solids handling costsReduced solids handling costs

––More stable nitrogen removal processMore stable nitrogen removal process



Membrane provides an absolute barrier Membrane provides an absolute barrier

and effluent quality is no longer a and effluent quality is no longer a

concern.concern.

ND to 10ND to 101000 to 1000 to

10,00010,000

Fecal Fecal

Coliform, Coliform,

#/100 #/100 mLmL

<0.2<0.22 to 52 to 5Turbidity, NTUTurbidity, NTU

ND (<2)ND (<2)5 to 105 to 10TSS, mg/LTSS, mg/L

Typical MBR Typical MBR

EffluentEffluent

Well Well

Operated Operated

CAS CAS

EffluentEffluent

Water QualityWater Quality

ParameterParameter

•• Public Health BenefitPublic Health Benefit

––Membrane is an Membrane is an absolute barrier that absolute barrier that physically removes all physically removes all pathogenspathogens

–– Conventional Conventional technologies depend on technologies depend on highly selective highly selective chemical or chemical or photochemical reactionphotochemical reaction

»»Pathogens may repair Pathogens may repair themselves and reactivatethemselves and reactivate

–– Results from operating Results from operating MBR plants:MBR plants:


Total ColiformsTotal Coliforms

MitsubishiMitsubishi

ZenonZenon

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500

Time of Operation, h

Concentration, MPN/100mL

Primary Eff luent Total Coliforms MBR Permeate Total Coliforms

open symbols denote below detection limit

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500


Concentration, MPN/100 m

L

Primary Eff luent Total Coliforms MBR Permeate Total Coliforms

open symbols denote below detection limit

Fecal ColiformsFecal Coliforms

MitsubishiMitsubishi

ZenonZenon

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500

Time of Operation. h

Concentration, MPN/100mL

Primary Effluent Fecal Coliforms MBR Permeate Fecal Coliforms

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500


Concentration, MPN/100 m

L

Primary Effluent Fecal Coliforms MBR Permeate Fecal Coliforms

Indigenous Indigenous ColiphageColiphage

Mitsubishi

ZenonZenon

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

1.00E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500


Concentration, PFU/100 m

L

Primary Eff luent Total Coliphage MBR Permeate Total Coliphage

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

0 250 500 750 1000 1250 1500 1750 2000 2250 2500


Concentration, PFU/100 m

L

Primary Eff luent Total Coliphage MBR Permeate Total Coliphage

•• MBR Effluent Allows Modern Objectives to be MBR Effluent Allows Modern Objectives to be

RealizedRealized

–– Ideal for UV disinfectionIdeal for UV disinfection

»» All particulate matter and suspended solids that All particulate matter and suspended solids that

can interfere with UV have been rejected at can interfere with UV have been rejected at

membrane barriermembrane barrier

»» High percent High percent transmissivitytransmissivity (>70%)(>70%)

»» Dose of 80 mJ/cmDose of 80 mJ/cm22 adequate for MBR effluent, adequate for MBR effluent,

while 100 mJ/cmwhile 100 mJ/cm22 required for granular filtered required for granular filtered

wastewaterwastewater

–– Ideal pretreatment process for reducing TDSIdeal pretreatment process for reducing TDS

»»Suitable for direct feed to ROSuitable for direct feed to RO

»»ChloramineChloramine residual is requiredresidual is required

Why MBR?Why MBR?

0

25

50

75

100

125

150

175

200

0 250 500 750 1000 1250 1500 1750 2000


Net Operating Pressure, psi

0

5

10

15

20

25

30

35

40

Temperature, °C

Net Operating Pressure Temperature

Plant shutdow n

Feed TDS = 1200 mg/L

Aqua 2000 Bureau StudyAqua 2000 Bureau Study[[FilmtecFilmtec BW 30BW 30--4040, low pressure TFC RO membranes]4040, low pressure TFC RO membranes]

11 weeks

Principle Disadvantage of MBR Principle Disadvantage of MBR ProcessProcess

•• Ability to maintain hydraulic capacityAbility to maintain hydraulic capacity

•• All treated wastewater exiting an MBR All treated wastewater exiting an MBR

process must pass through the membraneprocess must pass through the membrane

•• Peak flows are Peak flows are a particularly a particularly significant significant issueissue

•• Cold weather Cold weather can further can further complicate this complicate this issueissue

Peaking StudiesPeaking Studies

•• Peaking studies are commonly Peaking studies are commonly

performed to estimate the sustainable performed to estimate the sustainable

flux under wet weather flow scenariosflux under wet weather flow scenarios

•• These peaking studies are frequently These peaking studies are frequently

performed during dry weather performed during dry weather

conditions and not during a storm conditions and not during a storm

eventevent

•• Typically, the flux is increased to Typically, the flux is increased to

mimic storm conditions for a period mimic storm conditions for a period

of hours or daysof hours or days

Peaking StudiesPeaking Studies

•• Three significant issues to be aware of:Three significant issues to be aware of:

–– New membranes do not provide New membranes do not provide

representative performancerepresentative performance

–– Temperature influence on TMP needs to be Temperature influence on TMP needs to be

accounted foraccounted forFlux @ 206C Overall Vacuum Pressure

–– Sustainable Sustainable

membrane flux membrane flux

is is greatly greatly

influencedinfluenced by by

mixed liquor mixed liquor

propertiesproperties

TechnologiesTechnologiesManufacturers and design engineers are

still learning how to address peak

flows

Store peak flow in equalization tanksStore peak flow in equalization tanks

•• Need adequate spaceNeed adequate space

•• Generally required for peaking factor > Generally required for peaking factor >

2.52.5

•• Economics will depend on the specific Economics will depend on the specific

applicationapplication

Purchase additional membrane capacityPurchase additional membrane capacity

•• Generally more expensive solution for Generally more expensive solution for

peaks > 2.5peaks > 2.5

•• Often preferred by the MBR manufacturerOften preferred by the MBR manufacturer

•• Design decisions need to be made with Design decisions need to be made with

extra membranes (e.g. operate or store)extra membranes (e.g. operate or store)

Break/Questions? Break/Questions?

membrane bioreactors: state of the art and technology exchange · membrane bioreactors: state of...

Documents