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Aquaculture Engineering

354 Pages · 2007 · 14.18 MB · English

  • Aquaculture Engineering

    Aquaculture Engineering


    Odd-Ivar Lekang


    Department of Mathematical Sciences and Technology,


    Norwegian University of Life Sciences This Page Intentionally Left Blank Aquaculture Engineering


    Odd-Ivar Lekang


    Department of Mathematical Sciences and Technology,


    Norwegian University of Life Sciences © 2007 by Odd-Ivar Lekang


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    First published 2007 by Blackwell Publishing Ltd


    ISBN:978-1-4051-2610-6


    Library of Congress Cataloging-in-Publication Data


    Lekang,Odd-Ivar.Aquaculture engineering / Odd-Ivar Lekang.


    p.cm.


    Includes bibliographical references and index.


    ISBN:978-1-4051-2610-6 (hardback :alk.paper)


    1. Aquacultural engineering. I. Title.


    SH137.L45 2006


    639.8–dc22


    2006019514


    A catalogue record for this title is available from the British Library


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    www.blackwellpublishing.com Contents


    Preface xi


    1 Introduction 1


    1.1 Aquaculture engineering 1


    1.2 Classification of aquaculture 1


    1.3 The farm:technical components in a system 2


    1.3.1 Land-based hatchery and juvenile production farm 2


    1.3.2 On-growing sea cage farm 4


    1.4 Future trends:increased importance of aquaculture engineering 6


    1.5 This textbook 6


    References 6


    2 Water Transport 7


    2.1 Introduction 7


    2.2 Pipe and pipe parts 7


    2.2.1 Pipes 7


    2.2.2 Valves 10


    2.2.3 Pipe parts – fittings 12


    2.2.4 Pipe connections – jointing 12


    2.2.5 Mooring of pipes 13


    2.2.6 Ditches for pipes 14


    2.3 Water flow and head loss in channels and pipe systems 15


    2.3.1 Water flow 15


    2.3.2 Head loss in pipelines 16


    2.3.3 Head loss in single parts (fittings) 18


    2.4 Pumps 18


    2.4.1 Types of pump 19


    2.4.2 Some definitions 21


    2.4.3 Pumping of water requires energy 22


    2.4.4 Centrifugal and propeller pumps 23


    2.4.5 Pump performance curves and working point for centrifugal pumps 25


    2.4.6 Change of water flow or pressure 27


    2.4.7 Regulation of flow from selected pumps 29


    References 31


    3 Water Quality and Water Treatment:an Introduction 32


    3.1 Increased focus on water quality 32


    3.2 Inlet water 32


    iii iv Contents


    3.3 Outlet water 33


    3.4 Water treatment 35


    References 36


    4 Adjustment of pH 37


    4.1 Introduction 37


    4.2 Definitions 37


    4.3 Problems with low pH 38


    4.4 pH of different water sources 38


    4.5 pH adjustment 39


    4.6 Examples of methods for pH adjustment 39


    4.6.1 Lime 39


    4.6.2 Seawater 41


    4.6.3 Lye or hydroxides 41


    References 42


    5 Removal of Particles 44


    5.1 Introduction 44


    5.2 Characterization of the water 45


    5.3 Methods for particle removal in fish farming 45


    5.3.1 Mechanical filters and micro screens 45


    5.3.2 Depth filtration – granular medium filters 49


    5.3.3 Settling or gravity filters 52


    5.3.4 Integrated treatment systems 55


    5.4 Hydraulic loads on filter units 56


    5.5 Purification efficiency 56


    5.6 Dual drain tank 57


    5.7 Sludge production and utilization 57


    5.8 Local ecological solutions 60


    References 61


    6 Disinfection 63


    6.1 Introduction 63


    6.2 Basis of disinfection 64


    6.2.1 Degree of removal 64


    6.2.2 Chick’s law 64


    6.2.3 Watson’s law 64


    6.2.4 Dose-response curve 65


    6.3 Ultraviolet light 65


    6.3.1 Function 65


    6.3.2 Mode of action 65


    6.3.3 Design 65


    6.3.4 Design specification 67


    6.3.5 Dose 68


    6.3.6 Special problems 68


    6.4 Ozone 68


    6.4.1 Function 68


    6.4.2 Mode of action 68


    6.4.3 Design specification 70


    6.4.4 Ozone dose 70


    6.4.5 Special problems 71


    6.4.6 Measuring ozone content 71 Contents v


    6.5 Other disinfection methods 72


    6.5.1 Photozone 72


    6.5.2 Heat treatment 72


    6.5.3 Chlorine 73


    6.5.4 Changing the pH 73


    6.5.5 Natural methods:ground filtration or constructed wetland 73


    References 74


    7 Heating and Cooling 75


    7.1 Introduction 75


    7.2 Heating requires energy 75


    7.3 Methods for heating water 76


    7.4 Heaters 77


    7.4.1 Immersion heaters 77


    7.4.2 Oil and gas burners 79


    7.5 Heat exchangers 79


    7.5.1 Why use heat exchangers? 79


    7.5.2 How is the heat transferred? 80


    7.5.3 Factors affecting heat transfer 80


    7.5.4 Important parameters when calculating the size of heat exchangers 81


    7.5.5 Types of heat exchanger 83


    7.5.6 Flow pattern in heat exchangers 85


    7.5.7 Materials in heat exchangers 86


    7.5.8 Fouling 86


    7.6 Heat pumps 87


    7.6.1 Why use heat pumps? 87


    7.6.2 Construction and function of a heat pump 87


    7.6.3 Log pressure–enthalpy (p–H) 89


    7.6.4 Coefficient of performance 89


    7.6.5 Installations of heat pumps 90


    7.6.6 Management and maintenance of heat pumps 91


    7.7 Composite heating systems 91


    7.8 Chilling of water 94


    References 95


    8 Aeration and Oxygenation 97


    8.1 Introduction 97


    8.2 Gases in water 97


    8.3 Gas theory – aeration 99


    8.3.1 Equilibrium 99


    8.3.2 Gas transfer 100


    8.4 Design and construction of aerators 101


    8.4.1 Basic principles 101


    8.4.2 Evaluation criteria 102


    8.4.3 Example of designs for different types of aerator 103


    8.5 Oxygenation of water 106


    8.6 Theory of oxygenation 108


    8.6.1 Increasing the equilibrium concentration 108


    8.6.2 Gas transfer velocity 108


    8.6.3 Addition under pressure 108 vi Contents


    8.7 Design and construction of oxygen injection systems 109


    8.7.1 Basic principles 109


    8.7.2 Where to install the injection system 109


    8.7.3 Evaluation of methods for injecting oxygen gas 110


    8.7.4 Examples of oxygen injection system designs 111


    8.8 Oxygen gas characteristics 115


    8.9 Sources of oxygen 115


    8.9.1 Oxygen gas 115


    8.9.2 Liquid oxygen 116


    8.9.3 On-site oxygen production 117


    8.9.4 Selection of source 119


    References 120


    9 Ammonia Removal 121


    9.1 Introduction 121


    9.2 Biological removal of ammonium ion 121


    9.3 Nitrification 121


    9.4 Construction of nitrification filters 123


    9.4.1 Flow-through system 123


    9.4.2 The filter medium in the biofilter 125


    9.4.3 Rotating biofilter (biodrum) 125


    9.4.4 Fluid bed/active sludge 126


    9.4.5 Granular filters/bead filters 127


    9.5 Management of biological filters 127


    9.6 Example of biofilter design 128


    9.7 Denitrification 128


    9.8 Chemical removal of ammonia 129


    9.8.1 Principle 129


    9.8.2 Construction 129


    References 130


    10 Recirculation and Water Re-use Systems 133


    10.1 Introduction 133


    10.2 Advantages and disadvantages of re-use systems 133


    10.2.1 Advantages 133


    10.2.2 Disadvantages of re-use systems 134


    10.3 Definitions 134


    10.3.1 Degree of re-use 134


    10.3.2 Water exchange in relation to amount of fish 136


    10.3.3 Degree of purification 136


    10.4 Theoretical models for construction of re-use systems 136


    10.4.1 Mass flow in the system 136


    10.4.2 Water requirements of the system 137


    10.4.3 Connection between outlet concentration,degree of re-use and effectiveness


    of the water treatment system 138


    10.5 Components in a re-use system 139


    10.6 Design of a re-use system 141


    References 143


    11 Production Units:a Classification 144


    11.1 Introduction 144 Contents vii


    11.2 Classification of production units 144


    11.2.1 Intensive/extensive 144


    11.2.2 Fully controlled/semi-controlled 147


    11.2.3 Land based/tidal based/sea based 147


    11.2.4 Other 148


    11.3 Possibilities for controlling environmental impact 149


    12 Egg Storage and Hatching Equipment 150


    12.1 Introduction 150


    12.2 Systems where the eggs stay pelagic 151


    12.2.1 The incubator 151


    12.2.2 Water inlet and water flow 152


    12.2.3 Water outlet 152


    12.3 Systems where the eggs lie on the bottom 153


    12.3.1 Systems where the eggs lie in the same unit from spawning to fry ready for


    starting feeding 153


    12.3.2 Systems where the eggs must be removed before hatching 155


    12.3.3 System where storing,hatching and first feeding are carried out in the same


    unit 157


    References 157


    13 Tanks,Basins and Other Closed Production Units 158


    13.1 Introduction 158


    13.2 Types of closed production units 158


    13.3 How much water should be supplied? 160


    13.4 Water exchange rate 161


    13.5 Ideal or non-ideal mixing and water exchange 162


    13.6 Tank design 162


    13.7 Flow pattern and self-cleaning 165


    13.8 Water inlet design 167


    13.9 Water outlet or drain 169


    13.10 Dual drain 171


    13.11 Other installations 172


    References 172


    14 Ponds 174


    14.1 Introduction 174


    14.2 The ecosystem 174


    14.3 Different production ponds 174


    14.4 Pond types 176


    14.4.1 Construction principles 176


    14.4.2 Drainable or non-drainable 177


    14.5 Size and construction 178


    14.6 Site selection 178


    14.7 Water supply 179


    14.8 The inlet 179


    14.9 The outlet – drainage 180


    14.10 Pond layout 182


    References 182


    15 Sea Cages 183


    15.1 Introduction 183 viii Contents


    15.2 Site selection 184


    15.3 Environmental factors affecting a floating construction 185


    15.3.1 Waves 185


    15.3.2 Wind 191


    15.3.3 Current 191


    15.3.4 Ice 193


    15.4 Construction of sea cages 193


    15.4.1 Cage collar or framework 194


    15.4.2 Weighting and stretching 195


    15.4.3 Net bags 195


    15.4.4 Breakwaters 197


    15.4.5 Examples of cage constructions 197


    15.5 Mooring systems 198


    15.5.1 Design of the mooring system 198


    15.5.2 Description of the single components in a pre-stressed mooring system 201


    15.5.3 Examples of mooring systems in use 204


    15.6 Calculation of forces on a sea cage farm 204


    15.6.1 Types of force 205


    15.6.2 Calculation of current forces 206


    15.6.3 Calculation of wave forces 210


    15.6.4 Calculation of wind forces 210


    15.7 Calculation of the size of the mooring system 210


    15.7.1 Mooring analysis 210


    15.7.2 Calculation of sizes for mooring lines 211


    15.8 Control of mooring systems 213


    References 213


    16 Feeding Systems 215


    16.1 Introduction 215


    16.1.1 Why use automatic feeding systems? 215


    16.1.2 What can be automated? 215


    16.1.3 Selection of feeding system 215


    16.1.4 Feeding system requirements 215


    16.2 Types of feeding equipment 216


    16.2.1 Feed blowers 216


    16.2.2 Feed dispensers 216


    16.2.3 Demand feeders 217


    16.2.4 Automatic feeders 218


    16.2.5 Feeding systems 222


    16.3 Feed control 224


    16.4 Feed control systems 224


    16.5 Dynamic feeding systems 225


    References 225


    17 Internal Transport and Size Grading 227


    17.1 Introduction 227


    17.2 The importance of fish handling 227


    17.2.1 Why move the fish? 227


    17.2.2 Why size grade? 228


    17.3 Negative effects of handling the fish 232


    17.4 Methods and equipment for internal transport 233


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