The MBR Book: Principles and Applications of Membrane

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Fundamentals 61 Moreover, the potential for membrane fouling from both organic materials and hardness (Oldani et al., 1992) has not yet been explored. The relative expense of the ion-exchange membrane (Crespo et al., 2004) is likely further to constrain development of this process for the duty of drinking water denitrification. 2.3.3.3 Diffusive MBRs As already stated, the use of hydrogen (H 2) as the electron donor combined with either carbon dioxide or bicarbonate as the carbon source (Mansell and Schroeder, 2002) obviates the organic carbon contamination issue, since hydrogen gas does remain dissolved in the water. Such autotrophic (or “hydrogenotrophic”) denitrification can be considered both inexpensive and non-toxic (Haugen et al., 2002), as well as producing a relatively low biomass yield (Lee and Rittmann, 2002). As with MABRs, diffusive H 2 MBRs typically employ microporous HF membranes or silicon tubes (Ho et al., 2001) to deliver gas directly to biomass (in this case a denitrifying biofilm) attached to the shell-side of the membrane (Fig. 2.24b) providing up to 100% gas transfer (Mo et al., 2005). Although around 40% slower than heterotrophic denitrification according to some batch measurements (Ergas and Reuss, 2001), high nitrate removal rates have none-the-less been reported in hydrogenotrophic MBRs (Haugen et al., 2002; Ho et al., 2001). These are apparently attained through high H 2 gas mass transfer rates sustained by limiting fouling. Fouling is mainly manifested as thick and dense biofilms (Roggy et al., 2002) and, possibly, scalants (Ergas and Reuss, 2001; Lee and Rittmann, 2002) at the membrane surface, though precipitation of mineral deposits appears not to adversely affect H 2 transfer in all studies (Lee and Rittmann, 2003; Roggy et al., 2002). The disadvantage of gas transfer MBRs is, as with the extractive processes, that the membrane is not used for filtration, but it also does not retain the biomass. As such, product water is prone to “sloughed” biomass and other organic matter in the same way as any fixed film biological process. Also, regulation of the gas flux through the membrane due to the partial pressure drop along the membrane fibre length (Ahmed and Semmens, 1992) can produce uneven biofilm growth. In addition, doubts about the safety of dosing water with hydrogen remain, notwithstanding the apparent near quantitative retention of hydrogen by the biomass. Finally, the poor adaptability of the autotrophic bacteria under drinking water denitrification conditions demonstrated in several studies by long acclimatisation periods of 40 and 70 days (Ergas and Reuss, 2001; Ho et al., 2001) casts doubt on the suitability of this configuration for full-scale operation. 2.3.3.4 Biomass rejection MBR In the conventional configuration the membrane is actually used to filter the water, and both nitrate and the electron donor enter the developed biofilm in the same direction (Fig. 2.24c). Both heterotrophic and autotrophic systems have been investigated using acetate (Barrieros et al., 1998), ethanol (Chang et al., 1993; Delanghe et al., 1994; Urbain et al., 1996) and elemental sulphur (Kimura et al., 2002) as electron donors, though studies based on an iMBR specifically for drinking water duties appear to be limited to Kimura et al. (2002). These authors used rotating disc modules to “control” fouling, thus avoiding aeration and maintaining an anoxic
62 The MBR Book environment, and sustained a flux of 21 LMH for 100 days with limited fouling. Fouling in denitrification MBRs has not been characterised, though reported data suggest the biomass has a higher fouling propensity than that generated from sewage treatment (Delanghe et al., 1994; Urbain et al., 1996). This can apparently to some extent be controlled by reducing the flux to below 10 LMH and operating at crossflows of 2 m/s in sMBRs (Urbain et al., 1996). Nitrate removal efficiencies of up to 98.5% have generally been reported in these studies but, as with previous configurations reported, several investigators reported organic carbon (Delanghe et al., 1994) and elevated assimilable organic carbon (AOC) concentrations (Kimura et al., 2002) in the product water. A full-scale 400 m 3 /day (0.4 megalitres per day (MLD)) nitrate removal MBR process was constructed in Douchy, France, incorporating powdered activated carbon (PAC) dosing for pesticide removal. Stabilised fluxes between 60 and 70 l m �2 h �1 were obtained at full scale and, contrary to previous investigations, having optimised C:N dosing, treated water of low organic carbon concentration as well as tri-halo methane formation potential (THMFP) was reported. The author hypothesised that the low effluent organic content was a consequence of effective membrane rejection of biomass byproducts of high-molecular-weight organic matter (Urbain et al., 1996). 2.3.3.5 Hybrid MBR systems A system ingeniously using electrolysis to generate hydrogen and feed a biofilm on a granular activated carbon (GAC) support, coupled with a downstream membrane to filter the water, has been trialled (Prosnansky et al., 2002). This system provided treated water nitrate levels of 5–10 mg NO 3 � -N/L once optimised by employing high-specific area GAC. The low nitrate removal rates were a consequence of influent DO concentration affecting hydrogen dissolution, difficulties with pH control, hydrodynamic limitations and the influence of the anode on nitrate migration on increasing electric field intensity. Furthermore, the process is somewhat limited in application due to an intensive energy requirement and, once again, formation of hydrogen bubbles which impose a safety risk. More recent research (Mo et al., 2005) has focused on incorporating both gas transfer and immersed pressure-driven membranes into the same reactor. The authors focused treatment on suspended biomass rather than biofilms to minimise mass transfer problems previously reported with biofilm development (Crespo et al., 2004; Ergas and Reuss, 2001). Nitrate loading rates between 24 and 192 mg NO 3 � -N/(L/day) were trialled, with all but the higher loadings resulting in 100% removal performance. However, average effluent dissolved organic carbon (DOC) concentrations of approximately 8 mg/L were also recorded, possibly due to the regular mechanical removal of biofilm from the membrane surface which would otherwise act to reject organic matter. 2.3.3.6 Synopsis The use of MBRs for drinking water denitrification is very much at the research and development stage. Three different MBR configurations have been studied for this application and, as yet, only one full-scale plant has been installed. Challenges for all three configurations remain, specifically contamination of the treated water by organic carbon arising either from the electron donor in a heterotrophic system or from the
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The MBR Book
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The MBR Book: Principles and Applic
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Contents Preface ix Contributors xi
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Contents vii 4.2.5 The Industrial T
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Preface What’s In and What’s No
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Term Meaning Common units MLD Megal
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Contributors A number of individual
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Contributor(s) Association/Organisa
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Introduction With acknowledgements
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such as the filtration market, tech
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D R IVE R S R EST R AI N TS Bathing
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Introduction 7 Much of the legislat
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of non-point source pollution contr
Page 28 and 29: exploitation index (WEI), the value
Page 30 and 31: 1 500 000 1 250 000 1 000 000 750 0
Page 32 and 33: Alternative immersed FS and HF memb
Page 34 and 35: 1.6 Conclusions Whilst the most sig
Page 36 and 37: Introduction 19 USEPA (2006b) www.e
Page 38 and 39: Fundamentals With acknowledgements
Page 40 and 41: they can be put, which then provide
Page 42 and 43: 3µm (a) (b) membrane is chemically
Page 44 and 45: Table 2.2 Membrane configurations C
Page 46 and 47: 2.1.4 Membrane process operation 2.
Page 48 and 49: only pseudo-steady-state (or stabil
Page 50 and 51: P max P dP/dt backwash cycle t b Ba
Page 52 and 53: Fundamentals 35 2.1.4.6 Critical fl
Page 54 and 55: neo-exponential increase at fluxes
Page 56 and 57: Screened raw sewage biologically ar
Page 58 and 59: Table 2.4 Microbial metabolism type
Page 60 and 61: which affords the operator complete
Page 62 and 63: Cumulative %ile undersize 1 0.8 0.6
Page 64 and 65: occurs from the surrounding air to
Page 66 and 67: (Madoni et al., 1993). The inter-re
Page 68 and 69: Viscosity (mPa s) 100 10 1 Viscosit
Page 70 and 71: on discharged P levels have been im
Page 72 and 73: Membrane process mode Diffusion Ext
Page 74 and 75: energy demand in kWh/m 3 permeate p
Page 76 and 77: Table 2.5 System facets of denitrif
Page 80 and 81: iomass. There are also issues with
Page 82 and 83: Table 2.6 Effect of pore size on MB
Page 84 and 85: Fundamentals 67 fouling to be influ
Page 86 and 87: Fundamentals 69 fouling (i.e. membr
Page 88 and 89: 2.3.6 Feed and biomass characterist
Page 90 and 91: Fouling relative distribution (%) 1
Page 92 and 93: has been proposed by Cho and co-wor
Page 94 and 95: Fundamentals 77 in the influent. Ab
Page 96 and 97: MLSS sample Centrifugation 5 min 50
Page 98 and 99: Table 2.11 Concentration of SMP com
Page 100 and 101: Fundamentals 83 correlation of MBR
Page 102 and 103: (Cui et al., 2003) by inducing liqu
Page 104 and 105: Fundamentals 87 air cannot be used
Page 106 and 107: Table 2.12 Dynamic effects Determin
Page 108 and 109: Fundamentals 91 Table 2.13 Sub-crit
Page 110 and 111: Fundamentals 93 sludge (Cho and Fan
Page 112 and 113: Fundamentals 95 2.3.9.2 Employing a
Page 114 and 115: Fundamentals 97 Whilst ultrasonic c
Page 116 and 117: and immersed hybrid PAC-MBR (Kim an
Page 118 and 119: Lastly, the vast majority of all st
Page 120 and 121: Fundamentals 103 Brookes, A., Judd,
Page 122 and 123: Fundamentals 105 Côté, P., Buisso
Page 124 and 125: Fundamentals 107 Fuchs, W., Schatzm
Page 126 and 127: Fundamentals 109 Howell, J.A., Chua
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Fundamentals 111 Krauth, K. and Sta
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Fundamentals 113 Liu, R., Huang, X.
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Fundamentals 115 Nielson, P.H. and
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Fundamentals 117 Sato, T. and Ishii
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Fundamentals 119 Van Lier, J.B. (19
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Fundamentals 121 Zhang, Y., Bu, D.,
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Design With acknowledgements to: Ch
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Other contributions to pumping ener
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where J c is the cleaning flux. Fro
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Table 3.1 Main features of aeration
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Table 3.2 Biological operating para
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Table 3.3 Physical operating parame
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Table 3.4 Comparative pilot plant t
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Table 3.7 O&M data Design 137 Kubot
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Table 3.8 Feedwater quality, PLWTP
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Table 3.11 Cleaning protocols for t
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Figure 3.1 The planned location of
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Table 3.14 O&M data, Pietramurata W
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Design 147 Table 3.17 Design inform
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Maintenance CIP was conducted throu
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Permeability, LMH/bar 800 700 600 5
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Table 3.22 Summary of pilot plant p
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Table 3.25 Feedwater specification
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Table 3.34 Aeration design Paramete
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In short, the design calculation de
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complications arise when estimating
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Chapter 4 Commercial Technologies W
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4.1 Introduction Available and deve
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Commercial technologies 167 suction
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synonymous with R V Equation (3.13)
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(a) (b) Figure 4.8 The Huber VRM ®
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and is very robust. However, the la
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Commercial technologies 175 (a) (b)
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(a) (b) (c) Commercial technologies
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Other equipment 1.11% Process air b
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Thus far, almost all of the install
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Figure 4.22 A rack of Memcor B10R m
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Tensile elongation retention (%) 10
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Figure 4.28 Pilot plant at Mooka Co
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at 10 000-12 000 mg/L. The membrane
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4m 4m 1m Commercial technologies 19
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Figure 4.36 Ejector aerator Commerc
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Denitrification Nitrification Waste
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modules, with pore sizes ranging fr
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(a) (b) Figure 4.46 (a) Han-S Envir
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aerobic counterpart. This may be pa
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of the particularly large-diameter
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(c) air channelling, the risk of wh
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Case Studies With acknowledgements
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5.1 Introduction Membrane Bioreacto
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Case studies 211 Table 5.1 Comparis
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Case studies 213 0.6 m 3 per unit.
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Case studies 215 area of 15 840 m 2
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Aeration tank 1 FBDA FBDA 32 x J200
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Case studies 219 In this UNR config
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Table 5.6 Design criteria, Running
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Works inlet Inlet works Storm tank
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Case studies 225 to be treated to a
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Case studies 227 membranes, assembl
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Figure 5.16 A Naston package plant
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Air Influent DN N M Figure 5.18 The
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Table 5.9 Toray membrane-based MBR
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Figure 5.23 Aeration tank and cover
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Figure 5.24 The original plant at B
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Main permeate header Permeate pump
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Case studies 241 flow. Sludge waste
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Table 5.15 Water quality data, Unif
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TMP (Kpa) 80 70 60 50 40 30 20 10 0
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10 LMH; the plant operated at fluxe
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Table 5.17 Feed and treated water q
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Table 5.18 Water quality, Sobelgra
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Figure 5.37 Airlift municipal WWTP,
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Case studies 255 has been 20 g/L, b
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Case studies 257 The company had in
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Filtrate (ml) 25 20 15 10 5 IIndust
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Inflow Buffer tank Filtration Denit
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Figure 5.45 The VHP MBR (a) (b) Cas
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Figure 5.47 The Eden Project MBR Ba
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Table 5.25 Basis for process design
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5.4.7 Other Orelis plant Case studi
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two membrane module configurations.
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Appendix A Blower Power Consumption
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or or (A.4) where � is the ratio
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Appendix B MBR Biotreatment Base Pa
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Y 0.61 g VSS/g COD Fan et al. (1996
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Appendix C Hollow Fibre Module Para
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L being the internal module length
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Appendix D Membrane Products
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Table D.3 Membrane module details o
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Table D.4 (continued) Supplier Asah
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Table D.5 Membrane module details o
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Appendix E Major Recent MBR and Was
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Conference title meet Dates Locatio
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Event Last held Location Website Fo
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Appendix F Selected Professional an
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Japan Water Works Association (JWWA
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Nomenclature � Separation (m) �
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Nomenclature 305 Rsup Hydraulic res
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Abbreviations The following lists k
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PES Polyethylsulphone PP Polypropyl
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Glossary of Terms A number of key t
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Floc Aggregated solid (biomass) par
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Glossary of terms 315 Relaxation Ce
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Index A � factor 47, 49-50 and vi
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investment 9 for membrane replaceme
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I Iberia 2 immersed biomass-rejecti
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Nordkanal wastewater treatment work
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SUR unit 180 surface porosity 30 Su
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