Aquaculture Engineering

354 Pages·2007·14.18 MB·English

Aquaculture Engineering
Odd-Ivar Lekang
Department of Mathematical Sciences and Technology,
Norwegian University of Life Sciences
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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
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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