Chapter 16.

Membrane Bioreactor (MBR)

Why 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 change

Global internal renewable resources per person per year (Source: GWI)

Climate Change Water Scarcity

•

•Water Quality & Quantity

• Water Pollution & Scarcity

(2050년 물부족 인구: 40억)

Climate Change Water Environment

3

Global warmingGlobal warming

Source: USEPA

-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 and droughts is increasing.

Global Water Shortage in 2025Global Water Shortage in 2025

- 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

Very high stress

High stress

Mid stress

No stress

No data

Source : International water management institute

패러다임의 변화 : 공해 방지사업 경제적 재화창출산업 물산업의 성장 : Black gold (20세기) Blue gold (21세기)

국내외 환경시장 동향

The life cycle of water quality

- Two of the most sustainable ways to create alternative water source:1) Advanced wastewater treatment and reuse MBR Process2) Seawater desalination RO Process

- Key for these treatment processes: Membrane Technology

Qualit

y of W

ate

r

Source

Usage

Wastewater

Water Reuse

Effluent

Time Sequence

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

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

(Global market 2005~2015,IDA report)

: Core business segment

• Advanced WWT• Reuse Treatment

• Conventional WWT*

• Desalination• Water Treatment

*Courtesy of Doosan heavy Industries and construction Co.

FeedPermeate

MembranePhase 1 Phase 2

Driving force(∆C, ∆P, ∆T, ∆E)

Driving forces for membrane separation

Pressure driven membrane separation processes

- Conventional Activated Sludge (CAS)

SedimentationTank

Influent Effluent

Returned SludgeWasted Sludge

Activated Sludge Reactor

Permeate(Effluent)

Retentate

Membrane UnitActivated Sludge

Reactor

Influent

- Membrane Bioreactor (MBR)

CAS vs. MBR

MBR operation mode ( Side Stream vs. Submerged )

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

a) Traditional wastewater treatment

(전통적인 생물학적 처리공정)

b) External crossflow and side stream

(외부 십자흐름 분리형)

c) Internal submerged (내부 침지형)

d) External submerged

(분리 침지형)

Types of MBR

A submerged MBR facility

KIMAS-MBR 공정 (Kolon)

A submerged MBR facility

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.

settleability of the sludge is no more an important designparameter

Characteristics of MBR

2) It is possible to increase the biomass concentration up to 20or 30 g/L3 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 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.

]35.5[wa

wea

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XQXQVX

x

22.31 biomassactiveofrateproductionsystemtheinbiomassactive

]5.3[-1 ∧

bSK

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a

a

5) MBR operation under side stream mode generally needshigh shear stress resulting in floc breakage (Pinpoint floc) andproduction 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 theaeration tank until they are in good conditions for beingdegraded

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

Characteristics of MBR

8) 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 :

i) the microflocs ( size 10 to 100 ㎛)ii) 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.

Characteristics of MBR

Advantages of MBR

1) Small Hydraulic Residence Time (HRT)

Compactness of Reactor

2) Large Sludge Residence Time (SRT)

High concentration of microorganisms High efficiency of BOD removal small excess sludge production enhancement of slow growing bacteria Almost complete nitrification

3) Complete rejection of microbial flocs and colloids

High quality of treated water Effluent of very low turbidity highly 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 0.63~1.06

* BAF ; biological activated filter

T. Stephenson

Disadvantage of MBR

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

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

ProcessAverage power consumption (kWh/m3)

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 of energy consumption between cross-flow and submerged MBR

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 ₤ / year

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

Hollow fiber Plate Tubular

MF MF UFOut-In Out-In In-Out

Submerged Crossflow/ Submerged

Crossflow

Membrane modules for MBR

1) Plate & Frame type

Membrane modules for MBR

1) Plate & Frame type

Membrane modules for MBR 2) Hollow fiber type

2) Hollow fiber type

3) Tubular type

Membrane modules for MBR

Ceramic membrane

3) Tubular type

Frost & Sullivan, Global Membrane Bioreactor (MBR) Market, 2013

Global MBR Market: Treatment Volume and Revenue Forecast, 2008-2018

CAGR (2011-2018) = 22.4%

Global European MBR market

65 new refs/year

45 new refs/year

30 new refs/year

Total Municipal in EuropeAbout 2 millions e.p (0.5% population)

36

세계 MBR시장에서 새로운 기업체의 부상

• Kubota • Toray • Mitsubishi

• 코오롱• 한화건설• 대우건설• LG 전자• Lotte Chemical• Econity

• Siemense• BASF-Inge• Veoilia• Suez

• GE-Zenon

Microdyn Nadir Norit – X-Flow Novasep SFCU Weisse WS Wehrle Umwelt A3 Water Solutions Berghof Huber Koch-Puron Martin Systems

1. 창업기술 소개 – 세계 주요 MBR 업체

Membrane Manufacturers for MBR systems

Comparison of Membrane Modules

하폐수 유입 MBR 여과수

하폐수처리용

분리막

미생물

여과수

(음용수)

정수처리용

분리막

(중수도)

한강 원수

분리막 생물반응조(MBR, membrane bioreactor)

현재 MBR 시스템의 단점 및 핵심장애물 (생물막 형성)

하폐수 유입 MBR 여과수

정밀여과막(MF)

/ 한외여과막(UF)

활성슬러지 반응조

RO 여과수

(음용수)

역삼투막(RO)

MBR여과수 (Permeate)

분리막 표면

“생물막(Biofilm)”

투수도(Water flux) 감소

(중수도)

RO 공정

MBR 시스템의 핵심 장애물

낮은 투수도 : 10~20 L/m2h짧은 막 수명 : 3-5 년높은 에너지 소모 : 0.3~0.6 kWh/m3

높은 설치비 및운전비

Textural parameters Volumetric parameters

Porosity TexturalEntropy

Biovolume(×105μm3)

AXRL(μm)

AYRL(μm)

AZRL(μm)

High DO 0.78(±0.07)

7.24(±0.30)

3.3 (±0.9)

1.34(±0.30)

1.31(±0.30)

6.85(±2.67)

Low DO 0.63(±0.04)

8.08(±0.60)

2.1(±1.6)

1.52(±0.38)

1.49(±0.37)

3.33(±1.23)

(높은 투수도)(낮은 투수도)

270 μm

Membrane

70 μm

Membrane

출처 Yun et.al. Wat. Res (2006)

CLSM –Image Analysis

Biofouling in lab. Scale MBR

44

Used membrane modules just before chemical cleaning

ChemicalsMembrane

replacement

Equipment

Energy40%

37%

15%

8%

√√

√

√ ; Directly Related to Biofilm

Analysis of MBR Operating Cost

Factors Affecting MBR Performance

0

100

200

300

400

500

600

700

800

# of

pap

ers

in m

embr

ane

wat

er &

w

aste

wat

er tr

eatm

ent

MBR

PRO

FO

NF

RO

Etc.

# of papers of membranes for water & wastewater treatment (1994 ~ 2012)

# of papers for MBR(1994 ~ 2012)

0

50

100

150

200

250

300

# of

pap

ers

in M

BR Fouling

Etc.

49

Various approaches to biofouling control in MBR

Biofouling control

•New material

•Surface modification

• New module

Membrane Development Chemical Physical Biological

•Chemical cleaning

•Chemical additives(activated carbon, ozone, etc.)

•Critical flux

•Flow regime

•Hydrodynamics

•Back flushing

•Intermittent aeration

•SRT, DO, MLSS

•Quorum quenching

•Disruption of EPS

Desired Membrane Technology

Conventional thinking

Currentmembrane Technology

Creative imagination

Challenge to the current membrane technology

1) High flux2) High selectivity3) Long life span4) Less fouling5) Low energy

1) Fouling2) High energy3) Tortuous pores4) Wide range of pore sizes

Membrane Fouling & TMP Rise-up in submerged MBR

TMP

Operating time

Chemical Recovery Cleaning

ChemicalBackwashing

Physical Backwashing

30kPa

60kPa

Step 1gradual increase in ΔP

Step 2rapid increase in ΔP

At constant flux (J)

Possible mechanisms for the TMP rise

“Factors affecting the membrane performance in submerged membrane bioreactor”Journal of membrane science, Vol 284. 54-66

Zhang, Fane, et.al. (2006)

Quorum Sensing ?

: Signal molecules (autoinducer)

Symbiosis

Virulence

Competence

Conjugation

Antibiotic production

Motility

Sporulation

Biofilm formation

: Bacteria

Group behaviorsMicrobial community

We can not avoid the 2nd phase TMP rise-up even under the critical flux

TM

P

Time

Step 1

gradual increase in ∆P

Step 2

Rapid increase in ΔP

----------

Quorum Sensing

Dual Phases in TMP rise up in MBR: Slow and then Rapid rise up

Quorum quenching based biofouling control in MBR

Molecular level(Destruction of autoinducer)

Micro-scale(membrane-biofilm)

Engineering system(Uproot of Biofouling)

BiofilmMembrane

X • High flux• Low energy• Long life-span

• Low flux• High energy• Short life-span

K.M. Yeon, C.H.Lee et al., Environmental Science and Technology, 43 ,380-385, 2009

The Little David defeated the Giant Goliath !- from the Old Testament -

BiofilmMembrane

X • High flux• Low energy• Long life-span

• Low flux• High energy• Short life-span

Nano size molecules 100.000 ton /day MBR Plant

57

1. 창업기술소개– 정족수 감지 억제 기술의 정의

생물막분리막

X • 장시간 높은 투수율 유지

• 높은 에너지 효율

• 분리막 수명 증가

정족수 감지

(QS: Quorum sensing)

MBR

paradigm shift for the biofouling control in MBR:

Quorum Quenching

Molecular level(신호전달 물질의 파괴)

Micro-scale(생물막)

Engineering system

(막오염 제어)

정족수 감지 억제

(QQ: Quorum quenching)

미생물 :

58

MBR

+

미생물 사회학

정족수 감지

미생물 군집

정족수 감지 억제

미생물 군집

: 신호분자(AHL)

정족수 감지 억제 미생물

WEMTSeoul National Univ.

< Raw membrane > < Acylase-coated membrane >

~315 μm

~315 μm

x400 x400

Green: GFPRed: EPS

2009.08.25

J.H. Kim, C.H.Lee, ES&T, 2010

Bacteria with EPS Bacteria without EPS

61

QQ미생물 고정용기 & 유동성담체

QQ 미생물

Control MBR QQ MBR

Control MBR QQ MBR

기존 MBR 공정에 추가설비 없이 적용 가능!

62

QQ MBR 적용 예시

QQ MBR 관련 해외 기조/초청강연

QQ-MBR 주제의국제학회 기조/초청강연(6년간: 총 40 여회 )

Paradigm Shift in Biofouling Control in MBR :

Bacterial Quorum Quenching

“ Girls and Boys, be Ambitious ! ”

.