3541—Prelims—29/3/2007—07:41—VELU—233095—XMLMODELC–pp.1–23 3541—Prelims—29/3/2007—07:41—VELU—233095—XMLMODELC–pp.1–23 3541—Prelims—29/3/2007—07:41—VELU—233095—XMLMODELC–pp.1–23 CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2007 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20140113 International Standard Book Number-13: 978-1-4200-0521-9 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the valid- ity of all materials or the consequences of their use. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Dedication To my wife, my daughter, and my granddaughter – Zbigniew Lewandowski To my father, my son, and my wife – Haluk Beyenal 3541—Prelims—29/3/2007—07:42—VELU—233095—XMLMODELC–pp.1–23 3541—Prelims—29/3/2007—07:42—VELU—233095—XMLMODELC–pp.1–23 Table of Contents Preface Acknowledgments Authors Chapter1 Introduction toBiofilms andto Biofilm Research....................................................1 1.1 Introduction..............................................................................................................................1 1.2 Terminology..............................................................................................................................3 1.2.1 Biofilms, Biofouling, and BiofoulingDeposits..........................................................3 1.2.2 Biofilm Systems,BiofilmProcesses, and Biofilm Reactors ......................................4 1.2.3 Nutrient Utilization Rate andSpecific Nutrient Utilization Rate..............................6 1.2.4 Biofilm Activity ..........................................................................................................7 1.2.4.1 BiofilmActivity from Macroscale Measurements...................................... 7 1.2.4.2 BiofilmActivity from Microscale Measurements ...................................... 8 1.2.5 Biofilm Structure ........................................................................................................9 1.2.5.1 BiofilmHeterogeneities: Structural,Chemical, Physiological, andOther.............................................................................. 9 1.2.6 InternalMass Transport inBiofilms ........................................................................10 1.2.6.1 Local Mass Transport Coefficient, Local Diffusivity, and Local Flow Velocity............................................................................ 10 1.3 Characterizing the Compartments ofBiofilmSystems ........................................................10 1.3.1 Characterizing Surfaces and Their Components......................................................11 1.3.1.1 Surface Properties andMicrobial Colonization of Surfaces .................... 11 1.3.1.2 Surface Analysis ........................................................................................ 14 1.3.2 Characterizing Biofilms and Their Components......................................................22 1.3.2.1 Microbial Growth ...................................................................................... 22 1.3.2.2 Kineticsof Microbial Growth.................................................................... 23 1.3.3 Characterizing the ExtracellularPolymeric Substances ..........................................35 1.3.3.1 Viscoelastic Properties of EPS .................................................................. 37 1.3.4 Characterizing Mass Transport inBiofilms..............................................................38 1.3.4.1 Distributionof Effective Diffusivityand BiofilmDensity........................ 38 1.3.5 Characterizing Nutrient Solutionsand Their Components......................................41 1.3.5.1 Distributionof ChemicalComponents in the Nutrient SolutionCompartment................................................................................ 44 1.3.5.2 Distributionof Flow Velocity inthe Nutrient Solution Compartment.............................................................................................. 46 1.3.6 Characterizing the Gas Phase....................................................................................49 1.4 Strategy of Biofilm Research ................................................................................................50 1.4.1 The Goal of the Study ..............................................................................................50 1.4.2 Hypotheses ................................................................................................................51 1.4.3 Selecting the Relevant BiofilmProcesses, Reactors,Microorganisms, andGrowth Media ....................................................................................................51 1.4.4 The Tasks ..................................................................................................................52 1.4.5 Research Program......................................................................................................52 1.4.6 Characterizing the Reactors......................................................................................53 3541—Prelims—29/3/2007—07:42—VELU—233095—XMLMODELC–pp.1–23 1.4.7 Selecting the Operational Parameters ......................................................................53 1.4.7.1 Selecting the ControlVariables.................................................................. 53 1.4.7.2 Selecting the Measured Variables.............................................................. 53 1.4.8 Interpretingthe Results ............................................................................................53 References........................................................................................................................................54 Chapter2 Laboratory Biofilm Reactors andTheir Applications............................................63 2.1 Variablesin Biofilm Reactors................................................................................................64 2.1.1 Types ofVariables....................................................................................................64 2.1.2 Relatingthe MeasuredVariables tothe Controlled Variables ................................66 2.1.3 Hydrodynamics inLBRs ..........................................................................................68 2.1.3.1 Flow Velocity ............................................................................................ 68 2.1.3.2 Momentum.................................................................................................. 69 2.1.3.3 ReynoldsNumber ...................................................................................... 70 2.1.4 Dimensionless Groups Quantified inBiofilmReactors............................................72 2.1.5 Hydrodynamic Entry Length ....................................................................................75 2.2 LBRs as Scale Models............................................................................................................76 2.3 Factors Affecting BiofilmProcesses inLBRs ......................................................................77 2.3.1 Stress andStraininthe BiofilmMatrix....................................................................77 2.3.1.1 Compression andStretching ...................................................................... 78 2.3.1.2 Shear Deformation...................................................................................... 78 2.3.1.3 Elasticand Viscoelastic Deformations of Biofilms .................................. 79 2.3.1.4 Shear Stress................................................................................................ 80 2.3.1.5 Pressure Drop.............................................................................................. 82 2.3.1.6 Effect of Biofilmon the Flow inBiofilmReactors .................................. 85 2.3.2 External Mass Transport in Biofilms........................................................................86 2.4 Operating Modes of LBRs ....................................................................................................90 2.4.1 LBRs Without Recycle: Once-Through Mode ofOperation ..................................90 2.4.2 LBRs With Recycle ..................................................................................................91 2.4.3 LBRs With Recycleand a Mixing Chamber............................................................91 2.5 LBRs and Their Typical Applications ..................................................................................92 2.5.1 Flat-PlateReactors....................................................................................................92 2.5.1.1 Open-Channel Flat-PlateReactors ............................................................ 92 2.5.1.2 Flat-Plate Vapor-Phase Reactors................................................................ 98 2.5.1.3 SimplifiedOpen-Channel Flat-PlateReactors ........................................ 100 2.5.2 Rotating Reactors....................................................................................................103 2.5.2.1 Rotating Disc Reactor.............................................................................. 103 2.5.2.2 AnnularReactors...................................................................................... 107 2.5.3 TubularReactors......................................................................................................109 2.5.3.1 Example ofResults from aBiofilmStudy Using a Tubular ReactortoStudy the Effect of Biofilm Formationon Pressure Drop............................................................................................ 109 2.5.3.2 TubularReactors for Quantifying Biofilm Structure .............................. 111 2.5.4 Packed-Bed Reactors ..............................................................................................111 2.6 Using LBRs inConjunction with Other Tools to Explore Biofilm Processes at the Microscale..................................................................................................115 2.6.1 Quantifying Mechanisms bywhich BiofilmHeterogeneity Affects Biofilm Activity..........................................................................................115 2.6.2 Quantifying Mechanisms ofMass Transport inBiofilms......................................121 3541—Prelims—29/3/2007—07:42—VELU—233095—XMLMODELC–pp.1–23 2.7 Functionality of LBRs..........................................................................................................126 References......................................................................................................................................128 Chapter3 SensorsUseful in Biofilm Research......................................................................131 3.1 Fundamental Conceptsin Electrochemistry and Principles of Electrochemical Sensors ......................................................................................................131 3.1.1 Electric Charges......................................................................................................132 3.1.1.1 Electric Potential...................................................................................... 132 3.1.1.2 ElectrodePotential and the Nernst Equation .......................................... 135 3.1.1.3 Reference Electrodes................................................................................ 140 3.1.1.4 Electric Current........................................................................................ 140 3.1.1.5 MeasuringPotential and Current ............................................................ 141 3.1.2 Electrochemical Cells..............................................................................................142 3.1.2.1 Electrodes and the Mechanisms ofElectric Charge Transfer ................ 144 3.1.3 Significance ofthe ElectrodePotential ..................................................................157 3.1.4 Galvanic andElectrolytic Cells..............................................................................159 3.1.4.1 The Concept of Overpotential.................................................................. 161 3.1.5 The Rate ofElectrode Reactions: The Butler–Volmer Equation ..........................162 3.1.5.1 Butler–Volmer EquationWhen the Electrode is Not Polarized.............. 170 3.1.5.2 Limiting Current Density ........................................................................ 171 3.1.5.3 Membranes of Amperometric Sensors .................................................... 173 3.1.5.4 Functions ofthe Membranes onPotentiometric and Amperometric Sensors...................................................................... 173 3.1.6 Amperometric Sensors............................................................................................174 3.1.7 Potentiometric Sensors............................................................................................175 3.2 Microsensors ........................................................................................................................176 3.2.1 Potentiometric Microelectrodes..............................................................................181 3.2.1.1 Redox Microelectrodes ............................................................................ 181 3.2.1.2 Ion-Selective Microelectrodes.................................................................. 181 3.2.1.3 Sulfide Microelectrodes............................................................................ 182 3.2.1.4 pH Microelectrodes.................................................................................. 182 3.2.1.5 Carbon Dioxide Microelectrodes ............................................................ 184 3.2.2 Amperometric Microelectrodes ..............................................................................185 3.2.2.1 Dissolved-Oxygen Microelectrodes ........................................................ 185 3.2.2.2 Sulfide Microelectrodes............................................................................ 186 3.2.2.3 Microelectrodes for Measuringthe Concentration ofOxidants.............. 188 3.2.2.4 Hydrogen Peroxide Microelectrodes........................................................ 188 3.2.2.5 Microbiosensors........................................................................................ 189 3.2.2.6 GlucoseMicrosensors.............................................................................. 189 3.2.2.7 Microelectrodes for QuantifyingMass Transport Rates inBiofilms................................................................................................ 189 3.2.3 Fiberoptic Microsensors..........................................................................................192 Symbols..........................................................................................................................................195 References andSuggested Readings ............................................................................................196 Chapter4 Microsensors: Construction, Instrumentation, and Calibration............................199 4.1 ConstructingMicroelectrodes..............................................................................................200 3541—Prelims—29/3/2007—07:42—VELU—233095—XMLMODELC–pp.1–23