The MBR Book: Principles and Applications of Membrane

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and immersed hybrid PAC–MBR (Kim and Lee, 2003). Decreased membrane fouling has also been demonstrated in studies of the effects of dosing MBR supernatant at up to 1 g/L PAC (Lesage et al., 2005) and dosing activated sludge itself (Li et al., 2005c), for which an optimum PAC concentration of 1.2 g/L was recorded. In the latter study, floc size distribution and apparent biomass viscosity were identified as being the main parameters influenced, resulting in a reduced cake resistance, when PAC was dosed into the bioreactor. Conversely, no significant improvement in performance was recorded when a concentration of 5 g/L of PAC was maintained in the bioreactor without sludge wastage (Ng et al., 2005). It was postulated that, under these conditions, the PAC was rapidly saturated with organic pollutants and that fouling suppression by PAC relies on its regular addition brought about by lower SRTs. Experiments conducted with different system configurations based on immersed HF membranes allowed direct comparison of hydraulic performances for pre-flocculation and PAC addition. Under the operating conditions employed, pre-flocculation provided higher fouling mitigation than that of PAC addition (Guo et al., 2004). However, the use of both strategies simultaneously provided the greatest permeability enhancement (Cao et al., 2005; Guo et al., 2004). A detailed mathematical model has been proposed for predicting performances for hybrid PAC–MBR systems (Tsai et al., 2004). The model encompasses sub-processes such as biological reaction in bulk liquid solution, film transfer from bulk liquid phase to the biofilm, diffusion with biological reaction inside the biofilm, adsorption equilibria at the biofilm–adsorbent interface and diffusion within the PAC particles. Numerous other studies in which the use of PAC has been reported for fouling amelioration have generally been limited in scope and have not addressed the cost implications of reagent usage and sludge disposal. Tests have been performed using zeolite (Lee et al., 2001b) and aerobic granular sludge, with an average size around 1 mm (Li et al., 2005b) to create granular flocs of lower specific resistance. Granular sludge was found to increase membrane permeability by 50% but also lower the permeability recovery from cleaning by 12%, which would be likely to lead to unsustainable operation. A novel “membrane performance enhancer” MPE50, a cationic polymer-based compound, has recently been developed by the company Nalco for use in MBRs. The addition of 1 g/L of of the reagent directly to the bioreactor led to the reduction of SMPc from 41 to 21 mg/L (Yoon et al., 2005). The interaction between the polymer and the soluble organics in general, and SMPc in particular, was identified as being the main mechanism responsible for the performance enhancement. In another example, an MBR operated at an MLSS level as high as 45 g/L yielded a lower fouling propensity when 2.2 g/L of polymer was dosed into the bioreactor. The product has been tested at full scale (Section 5.2.1.4). 2.4 Summary Fundamentals 99 Membrane separation processes applied to MBRs have conventionally been limited to MF and UF for separation of the permeate product from the bioreactor MLSS. Other processes, in which the membrane is used to support a biomass and facilitate gas transfer into the biofilm (Section 2.3.2–2.3.3), have not reached the commercial
100 The MBR Book stage of development. Membrane module configurations employed for biomass separation MBRs are limited to FS and HF for immersed processes (where the membrane is placed in the tank), and mainly MTs where it is placed outside the tank. The latter provide shear through pumping, as with most other membrane processes, whereas immersed processes employ aeration to provide shear. Shear enhancement is critical in promoting permeate flux through the membrane and suppressing membrane fouling, but generating shear also demands energy. A considerable amount of research has been devoted to the study of membrane fouling phenomena in MBRs, and there is a general consensus that fouling constituents originate from the clarified biomass. Many authors that have employed standard chemical analysis on this fraction have identified the carbohydrate fraction of the SMPs (SMPc) arising from the bacterial cells as being mainly responsible for fouling, rather than suspended solid materials. However, recent attempts to predict fouling rates by EPS/SMP levels have not translated well across different plants or studies since biomass characteristics vary significantly from one plant to another. Moreover, achieving a consensus on the relative contributions of candidate foulants to membrane fouling is constrained by the different analytical methodologies and instruments employed. There are also cross-disciplinary issues in the area of membrane fouling. There appears to be little interconnection between foulant analysis in the wastewater and potable applications, and membrane cleaning between the industrial process and municipal water and wastewater sectors. Studies in the potable area tend to point to colloidal materials and Ca-organic carboxylate complexation as being the two key foulant types, and this may apply as much to wastewater as potable water membrane applications. Within the municipal sector, the number of studies devoted to characterisation of foulants vastly exceeds that for optimising chemical cleaning, notwithstanding the fact that it is the latter which controls irrecoverable fouling and so, ultimately, membrane life. Membrane cleaning in industrial process water applications, however, is rather more advanced – dating back to the 1980s – with protocols arguably developed on a more scientific basis than those in the municipal sector. Dynamic effects exert the greatest influence on consistency in MBR performance, ultimately leading to equipment and/or consent (i.e. target product water quality) failures. Specifications for full-scale MBR installations are generally based on conservative estimates of hydraulic and organic (and/or ammoniacal) loading. However, in reality, these parameters fluctuate significantly. Moreover, even more significant and potentially catastrophic deterioration in performance can arise through equipment malfunction and operator error. Such events can be expected to produce, over short periods of time: ● decreases in the MLSS concentration (either through loss of solids by foaming or by dilution with feedwater), ● foaming problems, sometimes associated with the above, ● loss of aeration (through control equipment malfunction or aerator port clogging), ● loss of permeability (through misapplication of backflush and cleaning protocol, hydraulic shocks or contamination of the feed with some unexpected component).
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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
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exploitation index (WEI), the value
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1 500 000 1 250 000 1 000 000 750 0
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Alternative immersed FS and HF memb
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1.6 Conclusions Whilst the most sig
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Introduction 19 USEPA (2006b) www.e
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Fundamentals With acknowledgements
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they can be put, which then provide
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3µm (a) (b) membrane is chemically
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Table 2.2 Membrane configurations C
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2.1.4 Membrane process operation 2.
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only pseudo-steady-state (or stabil
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P max P dP/dt backwash cycle t b Ba
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Fundamentals 35 2.1.4.6 Critical fl
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neo-exponential increase at fluxes
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Screened raw sewage biologically ar
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Table 2.4 Microbial metabolism type
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which affords the operator complete
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Cumulative %ile undersize 1 0.8 0.6
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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 78 and 79: Fundamentals 61 Moreover, the poten
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 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
Page 128 and 129: Fundamentals 111 Krauth, K. and Sta
Page 130 and 131: Fundamentals 113 Liu, R., Huang, X.
Page 132 and 133: Fundamentals 115 Nielson, P.H. and
Page 134 and 135: Fundamentals 117 Sato, T. and Ishii
Page 136 and 137: Fundamentals 119 Van Lier, J.B. (19
Page 138 and 139: Fundamentals 121 Zhang, Y., Bu, D.,
Page 140 and 141: Design With acknowledgements to: Ch
Page 142 and 143: Other contributions to pumping ener
Page 144 and 145: where J c is the cleaning flux. Fro
Page 146 and 147: Table 3.1 Main features of aeration
Page 148 and 149: Table 3.2 Biological operating para
Page 150 and 151: Table 3.3 Physical operating parame
Page 152 and 153: Table 3.4 Comparative pilot plant t
Page 154 and 155: Table 3.7 O&M data Design 137 Kubot
Page 156 and 157: Table 3.8 Feedwater quality, PLWTP
Page 158 and 159: Table 3.11 Cleaning protocols for t
Page 160 and 161: Figure 3.1 The planned location of
Page 162 and 163: Table 3.14 O&M data, Pietramurata W
Page 164 and 165: 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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