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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 © 200...

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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 Blackwell Publishing editorial offices: 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 identified 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. SH137.L45 2006 639.8–dc22 2006019514 A catalogue record for this title is available from the British Library Set in 9.5/11.5 pt Times by SNP Best-set Typesetter Ltd., Hong Kong Printed and bound in Singapore by Markono Print Media Pte Ltd The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. For further information on Blackwell Publishing, visit our website: www.blackwellpublishing.com

Contents

Preface

xi

1

Introduction 1.1 Aquaculture engineering 1.2 Classification of aquaculture 1.3 The farm: technical components in a system 1.3.1 Land-based hatchery and juvenile production farm 1.3.2 On-growing sea cage farm 1.4 Future trends: increased importance of aquaculture engineering 1.5 This textbook References

2

Water Transport 2.1 Introduction 2.2 Pipe and pipe parts 2.2.1 Pipes 2.2.2 Valves 2.2.3 Pipe parts – fittings 2.2.4 Pipe connections – jointing 2.2.5 Mooring of pipes 2.2.6 Ditches for pipes 2.3 Water flow and head loss in channels and pipe systems 2.3.1 Water flow 2.3.2 Head loss in pipelines 2.3.3 Head loss in single parts (fittings) 2.4 Pumps 2.4.1 Types of pump 2.4.2 Some definitions 2.4.3 Pumping of water requires energy 2.4.4 Centrifugal and propeller pumps 2.4.5 Pump performance curves and working point for centrifugal pumps 2.4.6 Change of water flow or pressure 2.4.7 Regulation of flow from selected pumps References

7 7 7 7 10 12 12 13 14 15 15 16 18 18 19 21 22 23 25 27 29 31

3

Water Quality and Water Treatment: an Introduction 3.1 Increased focus on water quality 3.2 Inlet water

32 32 32

iii

1 1 1 2 2 4 6 6 6

iv

Contents 3.3 3.4

Outlet water Water treatment References

33 35 36

4

Adjustment of pH 4.1 Introduction 4.2 Definitions 4.3 Problems with low pH 4.4 pH of different water sources 4.5 pH adjustment 4.6 Examples of methods for pH adjustment 4.6.1 Lime 4.6.2 Seawater 4.6.3 Lye or hydroxides References

37 37 37 38 38 39 39 39 41 41 42

5

Removal of Particles 5.1 Introduction 5.2 Characterization of the water 5.3 Methods for particle removal in fish farming 5.3.1 Mechanical filters and micro screens 5.3.2 Depth filtration – granular medium filters 5.3.3 Settling or gravity filters 5.3.4 Integrated treatment systems 5.4 Hydraulic loads on filter units 5.5 Purification efficiency 5.6 Dual drain tank 5.7 Sludge production and utilization 5.8 Local ecological solutions References

44 44 45 45 45 49 52 55 56 56 57 57 60 61

6

Disinfection 6.1 Introduction 6.2 Basis of disinfection 6.2.1 Degree of removal 6.2.2 Chick’s law 6.2.3 Watson’s law 6.2.4 Dose-response curve 6.3 Ultraviolet light 6.3.1 Function 6.3.2 Mode of action 6.3.3 Design 6.3.4 Design specification 6.3.5 Dose 6.3.6 Special problems 6.4 Ozone 6.4.1 Function 6.4.2 Mode of action 6.4.3 Design specification 6.4.4 Ozone dose 6.4.5 Special problems 6.4.6 Measuring ozone content

63 63 64 64 64 64 65 65 65 65 65 67 68 68 68 68 68 70 70 71 71

Contents 6.5

Other disinfection methods 6.5.1 Photozone 6.5.2 Heat treatment 6.5.3 Chlorine 6.5.4 Changing the pH 6.5.5 Natural methods: ground filtration or constructed wetland References

7

Heating and Cooling 7.1 Introduction 7.2 Heating requires energy 7.3 Methods for heating water 7.4 Heaters 7.4.1 Immersion heaters 7.4.2 Oil and gas burners 7.5 Heat exchangers 7.5.1 Why use heat exchangers? 7.5.2 How is the heat transferred? 7.5.3 Factors affecting heat transfer 7.5.4 Important parameters when calculating the size of heat exchangers 7.5.5 Types of heat exchanger 7.5.6 Flow pattern in heat exchangers 7.5.7 Materials in heat exchangers 7.5.8 Fouling 7.6 Heat pumps 7.6.1 Why use heat pumps? 7.6.2 Construction and function of a heat pump 7.6.3 Log pressure–enthalpy (p–H) 7.6.4 Coefficient of performance 7.6.5 Installations of heat pumps 7.6.6 Management and maintenance of heat pumps 7.7 Composite heating systems 7.8 Chilling of water References

8

Aeration and Oxygenation 8.1 Introduction 8.2 Gases in water 8.3 Gas theory – aeration 8.3.1 Equilibrium 8.3.2 Gas transfer 8.4 Design and construction of aerators 8.4.1 Basic principles 8.4.2 Evaluation criteria 8.4.3 Example of designs for different types of aerator 8.5 Oxygenation of water 8.6 Theory of oxygenation 8.6.1 Increasing the equilibrium concentration 8.6.2 Gas transfer velocity 8.6.3 Addition under pressure

v 72 72 72 73 73 73 74 75 75 75 76 77 77 79 79 79 80 80 81 83 85 86 86 87 87 87 89 89 90 91 91 94 95 97 97 97 99 99 100 101 101 102 103 106 108 108 108 108

vi

Contents 8.7

8.8 8.9

9

Design and construction of oxygen injection systems 8.7.1 Basic principles 8.7.2 Where to install the injection system 8.7.3 Evaluation of methods for injecting oxygen gas 8.7.4 Examples of oxygen injection system designs Oxygen gas characteristics Sources of oxygen 8.9.1 Oxygen gas 8.9.2 Liquid oxygen 8.9.3 On-site oxygen production 8.9.4 Selection of source References

Ammonia Removal 9.1 Introduction 9.2 Biological removal of ammonium ion 9.3 Nitrification 9.4 Construction of nitrification filters 9.4.1 Flow-through system 9.4.2 The filter medium in the biofilter 9.4.3 Rotating biofilter (biodrum) 9.4.4 Fluid bed/active sludge 9.4.5 Granular filters/bead filters 9.5 Management of biological filters 9.6 Example of biofilter design 9.7 Denitrification 9.8 Chemical removal of ammonia 9.8.1 Principle 9.8.2 Construction References

109 109 109 110 111 115 115 115 116 117 119 120 121 121 121 121 123 123 125 125 126 127 127 128 128 129 129 129 130

10 Recirculation and Water Re-use Systems 10.1 Introduction 10.2 Advantages and disadvantages of re-use systems 10.2.1 Advantages 10.2.2 Disadvantages of re-use systems 10.3 Definitions 10.3.1 Degree of re-use 10.3.2 Water exchange in relation to amount of fish 10.3.3 Degree of purification 10.4 Theoretical models for construction of re-use systems 10.4.1 Mass flow in the system 10.4.2 Water requirements of the system 10.4.3 Connection between outlet concentration, degree of re-use and effectiveness of the water treatment system 10.5 Components in a re-use system 10.6 Design of a re-use system References

133 133 133 133 134 134 134 136 136 136 136 137

11 Production Units: a Classification 11.1 Introduction

144 144

138 139 141 143

Contents 11.2

11.3

Classification of production units 11.2.1 Intensive/extensive 11.2.2 Fully controlled/semi-controlled 11.2.3 Land based/tidal based/sea based 11.2.4 Other Possibilities for controlling environmental impact

12 Egg Storage and Hatching Equipment 12.1 Introduction 12.2 Systems where the eggs stay pelagic 12.2.1 The incubator 12.2.2 Water inlet and water flow 12.2.3 Water outlet 12.3 Systems where the eggs lie on the bottom 12.3.1 Systems where the eggs lie in the same unit from spawning to fry ready for starting feeding 12.3.2 Systems where the eggs must be removed before hatching 12.3.3 System where storing, hatching and first feeding are carried out in the same unit References

vii 144 144 147 147 148 149 150 150 151 151 152 152 153 153 155 157 157

13 Tanks, Basins and Other Closed Production Units 13.1 Introduction 13.2 Types of closed production units 13.3 How much water should be supplied? 13.4 Water exchange rate 13.5 Ideal or non-ideal mixing and water exchange 13.6 Tank design 13.7 Flow pattern and self-cleaning 13.8 Water inlet design 13.9 Water outlet or drain 13.10 Dual drain 13.11 Other installations References

158 158 158 160 161 162 162 165 167 169 171 172 172

14 Ponds 14.1 14.2 14.3 14.4

Introduction The ecosystem Different production ponds Pond types 14.4.1 Construction principles 14.4.2 Drainable or non-drainable 14.5 Size and construction 14.6 Site selection 14.7 Water supply 14.8 The inlet 14.9 The outlet – drainage 14.10 Pond layout References

174 174 174 174 176 176 177 178 178 179 179 180 182 182

15

Sea Cages 15.1 Introduction

183 183

viii

Contents 15.2 15.3

15.4

15.5

15.6

15.7

15.8

Site selection Environmental factors affecting a floating construction 15.3.1 Waves 15.3.2 Wind 15.3.3 Current 15.3.4 Ice Construction of sea cages 15.4.1 Cage collar or framework 15.4.2 Weighting and stretching 15.4.3 Net bags 15.4.4 Breakwaters 15.4.5 Examples of cage constructions Mooring systems 15.5.1 Design of the mooring system 15.5.2 Description of the single components in a pre-stressed mooring system 15.5.3 Examples of mooring systems in use Calculation of forces on a sea cage farm 15.6.1 Types of force 15.6.2 Calculation of current forces 15.6.3 Calculation of wave forces 15.6.4 Calculation of wind forces Calculation of the size of the mooring system 15.7.1 Mooring analysis 15.7.2 Calculation of sizes for mooring lines Control of mooring systems References

184 185 185 191 191 193 193 194 195 195 197 197 198 198 201 204 204 205 206 210 210 210 210 211 213 213

16 Feeding Systems 16.1 Introduction 16.1.1 Why use automatic feeding systems? 16.1.2 What can be automated? 16.1.3 Selection of feeding system 16.1.4 Feeding system requirements 16.2 Types of feeding equipment 16.2.1 Feed blowers 16.2.2 Feed dispensers 16.2.3 Demand feeders 16.2.4 Automatic feeders 16.2.5 Feeding systems 16.3 Feed control 16.4 Feed control systems 16.5 Dynamic feeding systems References

215 215 215 215 215 215 216 216 216 217 218 222 224 224 225 225

17 Internal Transport and Size Grading 17.1 Introduction 17.2 The importance of fish handling 17.2.1 Why move the fish? 17.2.2 Why size grade? 17.3 Negative effects of handling the fish 17.4 Methods and equipment for internal transport

227 227 227 227 228 232 233

Contents

17.5

17.4.1 Moving fish with a supply of external energy 17.4.2 Methods for moving of fish without the need for external energy Methods and equipment for size grading of fish 17.5.1 Equipment for grading that requires an energy supply 17.5.2 Methods for voluntary grading (self grading) References

ix 233 243 245 245 253 254

18 Transport of Live Fish 18.1 Introduction 18.2 Preparation for transport 18.3 Land transport 18.3.1 Land vehicles 18.3.2 The tank 18.3.3 Supply of oxygen 18.3.4 Changing the water 18.3.5 Density 18.3.6 Instrumentation and stopping procedures 18.4 Sea transport 18.4.1 Well boats 18.4.2 The well 18.4.3 Density 18.4.4 Instrumentation 18.5 Air transport 18.6 Other transport methods 18.7 Cleaning and re-use of water 18.8 Use of additives References

256 256 256 257 257 257 258 259 259 259 260 260 261 261 261 262 263 263 264 264

19 Instrumentation and Monitoring 19.1 Introduction 19.2 Construction of measuring instruments 19.3 Instruments for measuring water quality 19.3.1 Measuring temperature 19.3.2 Measuring oxygen content of the water 19.3.3 Measuring pH 19.3.4 Measuring conductivity and salinity 19.3.5 Measuring total gas pressure and nitrogen saturation 19.3.6 Other 19.4 Instruments for measuring physical conditions 19.4.1 Measuring the water flow 19.4.2 Measuring water pressure 19.4.3 Measuring water level 19.5 Equipment for counting fish, measuring fish size and estimation of total biomass 19.5.1 Counting fish 19.5.2 Measuring fish size and total fish biomass 19.6 Monitoring systems 19.6.1 Sensors and measuring equipment 19.6.2 Monitoring centre 19.6.3 Warning equipment 19.6.4 Regulation equipment 19.6.5 Maintenance and control References

266 266 267 267 268 268 269 269 269 270 271 271 273 274 275 275 277 280 281 281 282 283 283 283

x

Contents

20 Buildings and Superstructures 20.1 Why use buildings? 20.2 Types, shape and roof design 20.2.1 Types 20.2.2 Shape 20.2.3 Roof design 20.3 Load-carrying systems 20.4 Materials 20.5 Prefabricate or build on site? 20.6 Insulated or not? 20.7 Foundations and ground conditions 20.8 Design of major parts 20.8.1 Floors 20.8.2 Walls 20.9 Ventilation and climatization References

284 284 284 284 284 285 285 287 288 288 289 289 289 290 291 293

21 Design and Construction of Aquaculture Facilities 21.1 Introduction 21.2 Land-based hatchery, juvenile and on-growing production plant 21.2.1 General 21.2.2 Water intake and transfer 21.2.3 Water treatment department 21.2.4 Production rooms 21.2.5 Feed storage 21.2.6 Disinfection barrier 21.2.7 Other rooms 21.2.8 Outlet water treatment 21.2.9 Important equipment 21.3 On-growing production, sea cage farms 21.3.1 General 21.3.2 Site selection 21.3.3 The cages and the fixed equipment 21.3.4 The base station 21.3.5 Net handling 21.3.6 Boat References

294 294 294 294 294 304 306 310 310 311 311 311 314 314 314 314 317 317 319 320

22 Planning Aquaculture Facilities 22.1 Introduction 22.2 The planning process 22.3 Site selection 22.4 Production plan 22.5 Room programme 22.6 Necessary analyses 22.7 Drawing up alternative solutions 22.8 Evaluation of and choosing between the alternative solutions 22.9 Finishing plans, detailed planning 22.10 Function test of the plant 22.11 Project review References

321 321 321 322 322 324 325 328 328 328 328 329 329

Index

330

Preface

includes systematic methodology for planning a full aquaculture facility. The book is based on material successfully used on BSc and MSc courses in intensive aquaculture given at the Norwegian University of Life Science (UMB) and refined over many years, the university having included courses in aquaculture since 1973. In 1990 a special Master’s course was developed in aquaculture engineering (given in Norwegian), and from 2000 the university has also offered an English language international Master’s programme in aquaculture (see details at www.umb.no). During the author’s compilation of material for use in this book, and also for earlier books covering similar fields (in Norwegian), many people have given useful advice. I would like especially to thank Svein Olav Fjæra and Tore Ensby. Further thanks also go to my colleagues at UMB: B.F. Eriksen, P.H. Heyerdal, T.K. Stevik, and from earlier, colleagues and students: V. Tapei. Mott, A. Skar, P.O. Skjervold, G. Skogesal and D. E. Thommassen. Tore Ensby has drawn all the line illustrations contained in the book. All the photographs included in the book have been taken by the author.

The aquaculture industry, which has been growing at a very high rate for many years now, is projected to continue growing at a rate higher than most other industries for the foreseeable future. This growth has mainly been driven by static catches from most fisheries and a decline in stocks of many major commercially caught fish species, combined with the ever increasing need for marine protein due to continuing population growth. An increased focus on the need for fish in the diet, due to mounting evidence of the health benefits of eating more fish, will also increase the demand. There has been rapid development of technology in the aquaculture industry, particularly as used in intensive aquaculture where there is high production per m3 farming volume. It is predicted that the expansion of the aquaculture industry will lead to further technical development with more, and cheaper, technology being available for use in the industry in the future years. The aim with this book is to give a general overview of the technology used in the aquaculture industry. Individual chapters focus on water transfer, water treatment, production units and additional equipment used on aquaculture plants. Chapters where equipment is set into systems, such as land-based fish farms and cage farms, are also included. The book ends with a chapter which

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1 Introduction

production systems. It is therefore a challenge to bring together both technological and biological knowledge within the aquaculture field.

1.1 Aquaculture engineering During the past few years there has been considerable growth in the global aquaculture industry. Many factors have made this growth possible. One is development within the field of aquaculture engineering, for example improvements in technology allowing reduced consumption of freshwater and development of re-use systems. Another is the development of offshore cages: sites that until a few years ago not were viable for aquaculture purposes can be used today with good results. The focus on economic efficiency and the fact the salaries are increasing have also resulted in the increased use of technology to reduce staff numbers. The development of new aquaculture species would not have been possible without the contribution of the fisheries technologist. Even if some techniques can be transferred for the farming of new species, there will always be a need for technology to be developed and optimized for each species. An example of this is the development of production tanks for flatfish with a larger bottom surface area than those used for pelagic fish. Aquaculture engineering covers a very large area of knowledge and involves many general engineering specialisms such as mechanical engineering, environmental engineering, materials technology, instrumentation, and monitoring, and building design and construction. The primary aim of aquaculture engineering is to utilize technical engineering knowledge and principles in aquaculture and biological production systems. The production of fish has little in common with the production of nails, but the same technology can be used in both

1.2 Classification of aquaculture There are a number of ways to classify aquaculture facilities and production systems, based on the technology or the production system used. ‘Extensive’, ‘intensive’ and ‘semi-intensive’ aquaculture are common ways to classify aquaculture based on production per unit volume (m3) or unit area (m2) farmed. Extensive aquaculture involves production systems with lo...