Chapter 12. Membrane Bioreactor (MBR)

Transcription

1 Chapter 12. Membrane Bioreactor (MBR)

2 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

3 Climate Change Water Environment Climate Change Water Scarcity Global internal renewable resources per person per year (Source: GWI) (2050 년물부족인구 : 40 억 ) Water Quality & Quantity Water Pollution & Scarcity 3

4 Global 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 and droughts is increasing. Source: USEPA

5 Global 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 WHO reports that 3.4 million per year were killed by waterborne diseases in 2005

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9 국내외환경시장동향 패러다임의변화 : 공해방지사업 경제적재화창출산업 물산업의성장 : Black gold (20 세기 ) Blue gold (21 세기 )

10 Quality of Water The life cycle of water quality Agricultural : 74% Municipal : 14% Industrial : 12% (Global market 2005~2015,IDA report) : Core business segment Usage Desalination Water Treatment Advanced WWT Reuse Treatment Water Reuse Source Surface / Ground water : 3% Seawater : 97% Wastewater Conventional WWT* Effluent Time Sequence - 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 *Courtesy of Doosan heavy Industries and construction Co.

11 MBR 과물부족문제 ( 중수도 ) 정수처리용 분리막 하폐수유입 MBR 여과수 여과수 ( 음용수 ) 하폐수처리용 분리막 한강원수 미생물 분리막생물반응조 (MBR, membrane bioreactor)

12 MBR 의국내소개

13 세계주요 MBR 업체 세계 MBR 시장에서새로운기업체의부상 Siemense BASF-Inge Veoilia Suez Microdyn Nadir Norit X-Flow Novasep SFCU Weisse WS Wehrle Umwelt A3 Water Solutions Berghof Huber Koch-Puron Martin Systems 코오롱 한화건설 대우건설 LG 전자 Lotte Chemical Econity Kubota Toray Mitsubishi GE-Zenon 13

14 Global MBR Market: Treatment Volume and Revenue Forecast, CAGR ( ) = 22.4% Frost & Sullivan, Global Membrane Bioreactor (MBR) Market, 2013

15 Global European MBR market 65 new refs/year Total Municipal in Europe About 2 millions e.p (0.5% population) 45 new refs/year 30 new refs/year

16 Factors Affecting MBR Performance

17 현재 MBR 시스템의단점및핵심장애물 ( 생물막형성 ) ( 중수도 ) 하폐수유입 정밀여과막 (MF) / 한외여과막 (UF) MBR 여과수 역삼투막 (RO) RO 공정 생물막 (Biofilm) RO 여과수 ( 음용수 ) 활성슬러지반응조 MBR 시스템의핵심장애물 MBR 분리막표면 여과수 (Permeate) 투수도 (Water flux) 감소 낮은투수도 : 10~20 L/m 2 h 짧은막수명 : 3-5 년 높은에너지소모 : 0.3~0.6 kwh/m 3 높은설치비및운전비

18 Various approaches to biofouling control in MBR Biofouling control Membrane Development Chemical Physical Biological Critical flux New material Chemical cleaning Flow regime SRT, DO, MLSS Surface modification New module Chemical additives (activated carbon, ozone, etc.) Hydrodynamics Back flushing Quorum quenching Disruption of EPS Intermittent aeration 18

19 # of papers in membrane water & wastewater treatment # of papers of membranes for water & wastewater treatment (1994 ~ 2012) MBR PRO FO NF RO Etc

20 # of papers in MBR # of papers for MBR(1994 ~ 2012) Fouling Etc

21 Driving forces for membrane separation Phase 1 Membrane Phase 2 Feed Permeate Driving force ( C, P, T, E)

22 Pressure driven membrane separation processes

23 CAS vs. MBR - Conventional Activated Sludge (CAS) Influent Activated Sludge Reactor Sedimentation Tank Effluent Returned Sludge Wasted Sludge - Membrane Bioreactor (MBR) Activated Sludge Reactor Membrane Unit Influent Permeate(Effluent) Retentate

24 MBR operation mode ( Side Stream vs. Submerged ) Side stream (Crossflow) MBR Submerged (dead-end)mbr

25 Types of MBR a) Traditional wastewater treatment ( 전통적인생물학적처리공정 ) b) External crossflow and side stream ( 외부십자흐름분리형 ) c) Internal submerged ( 내부침지형 ) d) External submerged ( 분리침지형 )

26 A submerged MBR facility

27 A submerged MBR facility KIMAS-MBR 공정 (Kolon)

28 Characteristics of MBR 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 2) It is possible to increase the biomass concentration up to 20 or 30 g/l 3 and to strongly mix the aeration tank with eventual breakage of the flocs (Pinpoint floc).

29 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. active biomass in the system production rate of active biomass x Q e X X av Q e a w X w a [5.35] dx 1 a syn dec a dt X S K S -b [3.5]

30 Characteristics of MBR 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.

31 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 μm ) 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.

32 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

33 Membrane modules for MBR 1) Plate & Frame type

34 Membrane modules for MBR 1) Plate & Frame type

35 Membrane modules for MBR 2) Hollow fiber module

36 Membrane modules for MBR 2) Hollow fiber type

37 Membrane modules for MBR 3) Tubular type Ceramic membrane

38 Membrane modules for MBR 3) Tubular type

39 Comparison of Membrane Modules

40 Comparison of Membrane Materials

41 Membrane Manufacturers for MBR systems