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 Blackwell Publishing editorial of?ces: Blackwell Publishing Ltd,9600 Garsington Road,Oxford OX4 2DQ,UK Tel:+44 (0)1865 776868 Blackwell Publishing Professional,2121 State Avenue,Ames,Iowa 50014-8300,USA Tel:+1 515 292 0140 Blackwell Publishing Asia Pty Ltd,550 Swanston Street,Carlton,Victoria 3053,Australia Tel:+61 (0)3 8359 1011 The right of the Author to be identi?ed as the Author of this Work has been asserted in accordance with the Copyright,Designs and Patents Act 1988. All rights reserved.No part of this publication may be reproduced,stored in a retrieval system,or transmitted,in any form or by any means,electronic,mechanical,photocopying,recording or otherwise,except as permitted by the UK Copyright,Designs and Patents Act 1988,without the prior permission of the publisher. 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. 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For further information on Blackwell Publishing,visit our website: www.blackwellpublishing.com Contents Preface xi 1 Introduction 1 1.1 Aquaculture engineering 1 1.2 Classi?cation 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 – ?ttings 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 ?ow and head loss in channels and pipe systems 15 2.3.1 Water ?ow 15 2.3.2 Head loss in pipelines 16 2.3.3 Head loss in single parts (?ttings) 18 2.4 Pumps 18 2.4.1 Types of pump 19 2.4.2 Some de?nitions 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 ?ow or pressure 27 2.4.7 Regulation of ?ow 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 De?nitions 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 ?sh farming 45 5.3.1 Mechanical ?lters and micro screens 45 5.3.2 Depth ?ltration – granular medium ?lters 49 5.3.3 Settling or gravity ?lters 52 5.3.4 Integrated treatment systems 55 5.4 Hydraulic loads on ?lter units 56 5.5 Puri?cation ef?ciency 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 speci?cation 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 speci?cation 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 ?ltration 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 Coef?cient 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 Nitri?cation 121 9.4 Construction of nitri?cation ?lters 123 9.4.1 Flow-through system 123 9.4.2 The ?lter medium in the bio?lter 125 9.4.3 Rotating bio?lter (biodrum) 125 9.4.4 Fluid bed/active sludge 126 9.4.5 Granular ?lters/bead ?lters 127 9.5 Management of biological ?lters 127 9.6 Example of bio?lter design 128 9.7 Denitri?cation 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 De?nitions 134 10.3.1 Degree of re-use 134 10.3.2 Water exchange in relation to amount of ?sh 136 10.3.3 Degree of puri?cation 136 10.4 Theoretical models for construction of re-use systems 136 10.4.1 Mass ?ow 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 Classi?cation 144 11.1 Introduction 144 Contents vii 11.2 Classi?cation 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 ?ow 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 ?rst 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 ?oating 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 ?sh handling 227 17.2.1 Why move the ?sh? 227 17.2.2 Why size grade? 228 17.3 Negative effects of handling the ?sh 232 17.4 Methods and equipment for internal transport 233