Slide 1Activated Sludge ProcessAttached Biofilm ProcessCarriersMembrane Bioreactor Process (MBR)Fouling formation in membrane surfaceCommercial MembraneAttached MBR ProcessTypical attached MBR system (Lee et al., 2001)Slide 10Case study (Lee et al., 2006)Case study (Lee et al., 2006)Case study (Yang et al., 2006 and Lee et al., 2006)ConclusionSlide 15PO-HENG (HENRY) LEESURVEY OF THE FOULING CHARACTERISTICS BETWEEN ATTACHED AND SUSPENDED SUBMERGED MEMBRANE BIOREACTORActivated Sludge ProcessPrimary ClarifierAeration tankSecondary ClarifierBlowerThe drawbacks of Activated Sludge Process (ASP)•Low volumetric loading rate•Large space•Slow growing bacteria (nitrifiers) are easily washed out•At low operating temperature •At short sludge age•Low SRT•Foaming•BulkingAttached Biofilm ProcessPrimary ClarifierAeration tankSecondary ClarifierBlowerAdvantage of attached system•Achieves high biomass in the reactor through biomass attachment on the surface of media•Settling problemCarriersPhoto of (from left to right) Kaldnes type K1, K2 and K3 biofilm carriers. (Rusten et al, 2006)Membrane Bioreactor Process (MBR)Primary ClarifierAeration tankSecondary ClarifierBlowerCharacteristics of MBR•Maintains high SRT through complete retention of biomass (High SRT)•Short HRT•High quality effluent•Short footprint •FoulingFouling formation in membrane surfaceCommercial MembraneElectron micrographs of non-woven polypropylene (NWPP) and polysulphone (PS) membranes: (a) PS (0.3 mm); (b) NWPP (5 mm); (c) NWPP (3 mm); (d) NWPP (1.5 mm). (Chang, 2001)Attached MBR ProcessPrimary ClarifierAeration tankSecondary ClarifierBlowerAdvantage of attached MBR system•Low HRT•High SRT•High quality effluent•Low fouling rateTypical attached MBR system (Lee et al., 2001)Summary of the attached membrane system operational conditions and performanceLee et al., 2006Leiknes and Ødegaard 2007Melin et al., 2005Yang et al., 2006Basu and Huck 2005Lee et al., 2001Influent COD = 1,000 mg/LCOD = 7-24 gCOD/m2d (178-242 mg/L)COD = 4.1-26.6 g COD/m2 d)COD = 1310- 1810 mg/LTOC =2.43-4.33 mg/LCOD = 250 mg/LEffluent COD < 20 mg/LN.D. COD < 50 mg/L - 1.0-2.05 mg/L COD = 3-5 mg/LHRT 10 h 45-180 min 3.45-4 h 7.2 - 8SRT 10 d - - 50 -Flux(l/m2 h)25 20-60 3.3-5.6 4.5 38 25TMP < 30 kPa 0.1-0.5 bar 0.1-0.55 bar 5-30kPa 0-8 bar 26 kPaMedium volume fraction (%)5-20 60-70 > 6 20 0-40 -Air flow rate 5-9 L/min - - 0.15 m3/h - 2.5 L/minDO (mg/L) 4.9-5.1 - - - - 6.0-6.2pH 6.5-7.5 - - - - 6.8-7.2Working Volume (L)6 - 60 10 - 5Suspended biomass (mg/L)4,500-5,500 - 200-800 - - -Attached biomass (mg/L)3,900-4,700 - - - - -Membrane porous size(m)0.1(Polyethylene hollow fiber)30kD(hollow fiber)30kD(hollow fiber)0.1-0.2 polyethyleneZenon ZW-1 membrane0.1(Polyethylene hollow fiber)Attached media 1.3 cmVirgin polyurethane cubes coated with7-15 mm(Polyethylene Kaldnes K1 media)7-15 mm(Polyethylene Kaldnes K1 media)1.0 mm -Biomatrix (Looped cord media)Attached media surface area (m2/m2)35,000 350 350 Porosity = 90 % 690 4.37m2 (Total surface area)Temperature(oC)25 - - - - 25Surface Area (m2)0.1 0.8 0.8 0.4 - 0.1Case study (Lee et al., 2006)TMP variation as a function of media volume fraction and flow rateCase study (Lee et al., 2006)Comparison of TMP rise-up between membrane modules with and without the iron netComparison of cake layer formed on the membrane surface (A) with and (B) without the iron netCase study (Yang et al., 2006 and Lee et al., 2006)SEM images of cake layers on external membrane surfaces after fouling Analysis of bound EPS concentration in suspended flocs as a function of air flow rate and media volume fractionConclusionCapital cost of membrane and O & M costHigh effluent quality required to meet stringent discharge limits with the requirements of capacity treatment increaseAn alternative process for shortage of land of upgrading existing water pollution control facilityNutrient