Chapter 16 -1.

Membrane Bioreactor (MBR)( )

Why do we NeedWhy do we Need Advanced Treatment & Processes ?

Although water resources are fixed,

1. The quality of available water resources steadily declines

2. New technology to detect contaminants developes

3. Environmental standards become more and more tight

4. Wastewater reuse becomes more and more important in line with climate changeg

Climate Change Water Environment

Global internal renewable resources per person

Climate Change Water Scarcityp p

per year (Source: GWI)

•

(2050년 물부족 인구: 40억)

•Water Quality & Quantity

• Water Pollution & Scarcity

3

Global warmingGlobal warming

-The numerous scientists agree reality of global warming:

Glaciers are melting,

plants and animals are being forced from their habitat,

and the number of severe storms andand the number of severe storms and droughts is increasing.

Source: USEPA

Global Water Shortage in 2025Global Water Shortage in 2025

Very high stress

High stress

Mid stress

No stress

No data

Source : International water management institute

- Water shortage population: 1.1 billions in 2005 and 3 billions in 2025. - WHO reports that 3.4 million per year were killed by waterborne diseases in 2005

국내외 환경시장 동향

패러다임의 변화 : 공해 방지사업 경제적 재화창출산업패러다임의 변화 : 공해 방지사업 경제적 재화창출산업물산업의 성장 : Black gold (20세기) Blue gold (21세기)

The life cycle of water quality

(Global market 2005~2015,IDA

Usage

• Agricultural : 74%• Municipal : 14%• Industrial : 12%

report): Core business

segment

f W

ate

r

S

Water Reuse• Advanced WWT• Reuse Treatment

• Desalination• Water Treatment

Qualit

y o Source

Wastewater Effluent• Surface / Ground water : 3%• Seawater : 97%

• Conventional WWT*

- Two of the most sustainable ways to create alternative water source:1) Ad d t t t t t d

Time Sequence

1) Advanced wastewater treatment and reuse MBR Process2) Seawater desalination RO Process

- Key for these treatment processes: Membrane TechnologyKey for these treatment processes: Membrane Technology

*Courtesy of Doosan heavy Industries and construction Co.

Driving forces for membrane separation

MembranePhase 1 Phase 2

PermeateFeed

Permeate

Driving forceDriving force(∆C, ∆P, ∆T, ∆E)

Pressure driven membrane separation processes

Membrane and Relative Size of Common MaterialsMembrane and Relative Size of Common Materials

MembraneUF

MFNanofiltration

MicrofiltrationUltrafiltration

MembraneUF

MFNanofiltration

MicrofiltrationUltrafiltration

Membrane

RO

NFReverse OsmosisMembrane

RO

NFReverse Osmosis

0.0001 0.001 0.01 0.1 1 10Size (μ m)

Cl- ion

0.0001 0.001 0.01 0.1 1 10Size (μ m)Size (μ m)

Cl- ionRelative SizeofCommon

Cl ionNa+ion

Pesticide, Organic Material

Zn2+ionF- ion Virus

Influenza Virus Algae, Mad

Vibrio CholeraeRelative SizeofCommon

Cl ionNa+ion

Pesticide, Organic Material

Zn2+ionF- ion Virus

Influenza Virus Algae, Mad

Vibrio CholeraeCommonMaterials

F ionPb2+ ion

NO3-ion

TrihalomethaneHepatitis A Virus

Polio Virus ColiformCryptosporidium

Bacillus anthracis

CommonMaterials

F ionPb2+ ion

NO3-ion

TrihalomethaneHepatitis A Virus

Polio Virus ColiformCryptosporidium

Bacillus anthracisTrihalomethane Bacillus anthracis

ApplicationSea Water Desalination

Drinking WaterWastewater Treatment

Brackish Water Desalination

Trihalomethane Bacillus anthracis

ApplicationSea Water Desalination

Drinking WaterWastewater Treatment

Brackish Water Desalinationpp

Wastewater Treatmentg

Drinking Water Drinking Water

pp

Wastewater Treatmentg

Drinking Water Drinking Water

“Toray”

UF/MF M bRO/NF M b

Separation Characteristics of Various MembranesSeparation Characteristics of Various Membranes

UF/MF MembranesRO/NF Membranes

Lo MW organic ma Middl hi h MW

Monovalent ions

Low MW organic materials

(Mw 200) IonsDissolved matter

Suspended Solid Particles

Middle to high MW materials

(Mw >200)

Multivalent ions

Water

Monovalent ionsPermeatio

nand

Water

Multivalent ions

Membrane

andrejection Membrane

Separationh i

RO: Molecular interactionSolution diffusionEl t i l i

MF: Dynamic separation

Size exclusion

RO <1 UF: 10~100 nm

mechanism Electric repulsionNF: Size exclusion UF: Electric repulsion

RO: <1 nm NF: 1~10 nm

UF: 10~100 nmMF: >100 nmPore siz

e“Toray”

Role of Membrane Technology in Water Environment

수자원부족 환경규제강화수질악화

막분리 정을이용한 수처리기술

수자원부족 환경규제강화수질악화

막분리공정을이용한고도수처리기술(Membrane Process for Water and Wastewater Treatment and Reuse - MF, UF, NF, RO, ED, ...)혼 성

생물학적 처리, 흡착, 응집, 화학침전, 고급산화, 광촉매, 이온교환

시스템

21세기: 새로운혼성시스템개발, 새로운막모듈 개발, 막오염제어기술의혁신등

Water Mining: 중수 청정기술: 폐수재이용/유가양질의 음용수및

21세기: 새 운혼성시 템개발, 새 운막 듈 개발, 막 염제어기술의혁신등

g생산 및 재이용 자원 회수, 무방류 시스템공업용수 생산

Application of Membrane Processes in Water EnvironmentApplication of Membrane Processes in Water Environment

수질공학 분자생물학 계면화학나노입자/나노세공

융합기술

난배양성 미샘물모니터링 바이오필름 미시유체역학 균일상촉매

우주 정거장 항공기

빌딩/사무실 위락시설

가정/주택 공장/공단가정/주택

생태 용수

공장/공

지하수생태 용수 지하수

C ti l A ti t d Sl d (CAS)

CAS vs. MBR- Conventional Activated Sludge (CAS)

Activated Sludge Reactor Sedimentation

TankInfluent Effluent

Reactor

Returned SludgeWasted Sludge

Activated SludgeReactor

- Membrane Bioreactor (MBR)

Permeate(Effluent)

Membrane UnitReactor

Influent

Retentate

MBR operation mode ( Side Stream vs. Submerged )

Side stream (Crossflow) MBR Submerged (dead-end)MBR

Types of MBR

a) Traditional wastewater treatment

(전통적인 생물학적 처리공정)

b) External crossflow and side stream

(외부 십자흐름 분리형)(외부 십자흐름 분리형)

c) Internal submerged (내부 침지형)

d) External submerged

(분리 침지형)(분리 침지형)

A submerged MBR facility

A submerged MBR facilityKIMAS-MBR 공정 (Kolon)

Characteristics of MBR

1) Microbial flocs are completely rejected by a membrane so thatbacteria which would carry over from the settling tank in CAS areretained in the reactor.

selection of bacteria is no more based on settleability

sludge bulking is no more problem.g g

settleability of the sludge is no more an important designparameter

2) It is possible to increase the biomass concentration up to 20or 30 g/L3 and to strongly mix the aeration tank with eventualor 30 g/L and to strongly mix the aeration tank with eventualbreakage of the flocs (Pinpoint floc).

Characteristics of MBR

3) As a consequence of retaining high biomass concentration,the substrate utilization rate increases thus allowing morethe substrate utilization rate increases thus allowing morecompact equipment ( smaller hydraulic residence time )

4) Higher biomass concentration means longer sludge age (SRT)with beneficial effects on the efficiency and on net sludgeproduction.

[ ]22.31−== μθχ bfdsystemtheinbiomassactive

]355[aVX=θ

[ ]μχ biomassactiveofrateproduction

]35.5[wa

wea

e XQXQ +=xθ

1 ∧ SdX ]5.3[-1 bSK

Sdt

dXX decsyn

a

a +=+== μμμμ

Characteristics of MBR5) MBR operation under side stream mode generally needs

high shear stress resulting in floc breakage (Pinpoint floc) andproduction of microflocs which make more efficient the oxygenproduction of microflocs which make more efficient the oxygenand substrate transfer.

6) The small particles and the colloids less easily degradablethan solutes are rejected by the membrane and stay in thethan solutes are rejected by the membrane and stay in theaeration tank until they are in good conditions for beingdegraded

7) The quality of the treated water is not only due directly to) q y y ythe membrane but also indirectly to the different and moreefficient conditions in the bioreactor.

Characteristics of MBR

8) Th bi l i l t b id d C ti Sti d8) The biological reactor may be considered as a Continuous StirredTank Reactor (CSTR ).

9) The membrane is continuously in contact with a suspension containing

two fractions :two fractions :

i) the microflocs ( size 10 to 100 ㎛)ii) the interstitial liquid which quality is almost that of the biologicallyii) the interstitial liquid which quality is almost that of the biologically

treated water

The physicochemical interactions between membrane and broth constituents give rise to membrane fouling.

Advantages of MBR

1) Small Hydraulic Residence Time (HRT)

Compactness of Reactor

2) Large Sludge Residence Time (SRT)2) Large Sludge Residence Time (SRT)

High concentration of microorganismsHigh efficiency of BOD removalHigh efficiency of BOD removalsmall excess sludge productionenhancement of slow growing bacteriaAlmost complete nitrificationAlmost complete nitrification

3) Complete rejection of microbial flocs and colloids

High quality of treated waterEffluent of very low turbidityhighly effective disinfection

Sludge production for various wastewater treatment processes

Treatment process Sludge production(kg/kgBOD-1)

Submerged MBR 0.0~0.3Structured media BAF 0.15~0.25Trickling filter 0.3~0.5Conventional activated sludge 0.6Granular media BAF 0 63~1 06Granular media BAF 0.63~1.06

* BAF ; biological activated filter

T. Stephenson

Disadvantage of MBR

1) Higher energy consumption than CAS (conventional activated sludge).( g )

2) Membrane Fouling which gives rise to flux decrease2) Membrane Fouling which gives rise to flux decrease and eventually membrane replacement.

Comparison of energy consumption between cross-flow and submerged MBR

ProcessAverage power consumption (kWh/m3)

Process

T. Ueda P. Cote

Conventional Activated sludge 0.2 - 0.3 -

Cross-flow MBR 3 – 4 4 - 12

Submerged MBR 2.0 0.3 - 0.6

Comparison between the power costs of MBR and conventional activated sludge

Maximum Throughput /Average Throughput MBR Activated Sludge

1,400 / 650 m3/day 10,000 ₤ / year 13,000 ₤ / yeary y y

22 500 / 10 500 m3/day 106 917 ₤ / year 148 070 ₤ / year22,500 / 10,500 m /day 106,917 ₤ / year 148,070 ₤ / year

Membrane modules for MBR

Hollow fiber Plate Tubular

MF MF UFOut-In Out-In In-Out

Submerged Crossflow/ Submerged

Crossflow

Membrane modules for MBR

1) Plate & Frame type

1) Plate & Frame type

Membrane modules for MBR 2) Hollow fiber type

2) Hollow fiber type

Membrane modules for MBR

3) Tubular type

Ceramic membrane

3) Tubular type3) Tubular type

Comparison of Membrane Modulesp

Membrane Manufacturers for MBR systems

MBR Manufacturers in North America

Others3%

Koch2%USFilter

10%

GE-Zenon65%

Kubota20%

65%

NA Market Share, RevenueGraeme Pearce, 2008,