Chapter 12.

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 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 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 Process

2) 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.

하폐수 유입 MBR 여과수

하폐수처리용

분리막

미생물

여과수

(음용수)

정수처리용

분리막

(중수도)

한강 원수

분리막 생물반응조(MBR, membrane bioreactor)

MBR과 물부족 문제

1990.7.2MBR의 국내 소개

13

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

세계 주요 MBR 업체

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

2013

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

CAGR (2011-2018) = 22.4%

65 new refs/year

45 new refs/year

30 new refs/year

Total Municipal in Europe

About 2 millions e.p (0.5% population)

Global European MBR market

Factors Affecting MBR Performance

현재 MBR 시스템의단점 및 핵심장애물 (생물막형

성)

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/m2h

짧은 막 수명 : 3-5 년

높은 에너지 소모 : 0.3~0.6 kWh/m3

높은 설치비 및운전비

18

Various approaches to biofouling control in MBR

Biofouling control

•New material

•Surface modification

• New module

Membrane

DevelopmentChemical 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

0

100

200

300

400

500

600

700

800

# o

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in

mem

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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

# o

f p

ap

ers

in

MB

R Fouling

Etc.

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)

Sedimentation

Tank

Influent Effluent

Returned SludgeWasted Sludge

Activated Sludge

Reactor

Permeate(Effluent)

Retentate

Membrane Unit

Activated 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 that

bacteria which would carry over from the settling tank in CAS are

retained 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 design

parameter

Characteristics of MBR

2) It is possible to increase the biomass concentration up to 20

or 30 g/L3 and to strongly mix the aeration tank with eventual

breakage of the flocs (Pinpoint floc).

Characteristics of MBR

3) As a consequence of retaining high biomass concentration,

the substrate utilization rate increases thus allowing more

compact equipment ( smaller hydraulic residence time )

4) Higher biomass concentration means longer sludge age (SRT)

with beneficial effects on the efficiency and on net sludge

production.

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5) MBR operation under side stream mode generally needs

high shear stress resulting in floc breakage (Pinpoint floc) and

production of microflocs which make more efficient the oxygen

and substrate transfer.

6) The small particles and the colloids less easily degradable

than solutes are rejected by the membrane and stay in the

aeration tank until they are in good conditions for being

degraded

7) The quality of the treated water is not only due directly to

the membrane but also indirectly to the different and more

efficient conditions in the bioreactor.

Characteristics of MBR

8) The biological reactor may be considered as a Continuous Stirred

Tank 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

1) Plate & Frame type

Membrane modules for MBR

1) Plate & Frame type

Membrane modules for MBR

Membrane modules for MBR

2) Hollow fiber module

2) Hollow fiber type

Membrane modules for MBR

3) Tubular type

Membrane modules for MBR

Ceramic membrane

3) Tubular type

Membrane modules for MBR

Comparison of Membrane Modules

Comparison of Membrane Materials

Membrane Manufacturers for MBR systems