Aquaculture Engineering

Preface xvii 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 7 2 Water Transport 9 2.1 Introduction 9 2.2 Pipe and pipe parts 9 2.2.1 Pipes 9 2.2.2 Valves 12 2.2.3 Pipe parts: fittings 14 2.2.4 Pipe connections: jointing 15 2.2.5 Mooring of pipes 15 2.2.6 Ditches for pipes 16 2.3 Some basic hydrodynamics 17 2.3.1 Boundary layer theory 17 2.3.2 Bernoulli’s equation 18 2.4 Water flow and head loss in channels and pipe systems 19 2.4.1 Water flow 19 2.4.2 Head loss in pipelines 20 2.4.3 Head loss in single parts (fittings) 23 2.4.4 Gravity feed pipes 23 2.5 Pumps 26 2.5.1 Types of pump 26 2.5.2 Some definitions 26 2.5.3 Pumping of water requires energy 29 2.5.4 Centrifugal and propeller pumps 30 2.5.5 Pump performance curves and working point for centrifugal pumps 32 2.5.6 Change of water flow or pressure 35 2.5.7 Regulation of flow from selected pumps 37 References 39 3 Water Quality and Water Treatment: An Introduction 41 3.1 Increased focus on water quality 41 3.2 Inlet water 41 3.3 Outlet water 43 3.4 Water treatment 44 References 46 4 Fish Metabolism, Water Quality and Separation Technology 47 4.1 Introduction 47 4.2 Fish metabolism 47 4.2.1 Overview of fish metabolism 47 4.2.2 The energy budget 49 4.3 Separation technology 49 4.3.1 What are the impurities in water? 50 4.3.2 Phosphorus removal: an example 51 References 53 5 Controlling pH, Alkalinity and Hardness 55 5.1 Introduction 55 5.2 pH 55 5.2.1 Water dissolves in water 55 5.2.2 What is pH 56 5.2.3 The carbonate system 57 5.2.4 Total carbonate carbon 60 5.2.5 Open or closed system 60 5.2.6 A mathematical approach 63 5.2.7 pH of different water sources 64 5.2.8 Recommended pH for aquaculture 64 5.3 Alkalinity 65 5.3.1 How to avoid pH fluctuations 65 5.3.2 Titration is necessary 65 5.3.3 A buffer 66 5.3.4 The term equivalent weight 68 5.3.5 Alkalinity given as mg/L CaCO3 68 5.3.6 Alkalinity of different water sources 69 5.3.7 Recommended alkalinity for aquaculture 69 5.4 Hardness 69 5.4.1 The concentration of bivalent cations 69 5.4.2 Hardness may lead to precipitation 70 5.4.3 Hardness of different water sources 71 5.4.4 Recommended hardness 71 5.5 Chemical agents to use for regulation of pH, alkalinity and hardness 72 5.6 Examples of methods for pH adjustment 73 5.6.1 Lime 73 5.6.2 Sea water 75 5.6.3 Lye or hydroxides 76 5.6.4 pH regulation in RAS 76 References 77 6 Removal of Particles: Traditional Methods 79 6.1 Introduction 79 6.2 Characterization of the water 80 6.3 Methods for particle removal in fish farming 80 6.3.1 Mechanical filters and microscreens 81 6.3.2 Depth filtration: granular medium filters 84 6.3.3 Settling or gravity filters 87 6.3.4 Integrated treatment systems 90 6.4 Hydraulic loads on filter units 91 6.5 Purification efficiency 92 6.6 Dual drain tank 92 6.7 Local ecological solutions 94 References 94 7 Protein Skimming, Flotation, Coagulation and Flocculation 97 7.1 Introduction 97 7.1.1 Surface tension, cohesion and adhesion 99 7.1.2 Surfactants 102 7.2 Mechanisms for attachment and removal 102 7.2.1 Attachment of particles to rising bubbles by collision, typically in flotation 103 7.2.2 Improving colloid and particle removal rates: pretreatment 105 7.2.3 Attachment of surface‐active substances, typically in protein skimmers 111 7.2.4 Particle attachment by nucleation 112 7.3 Bubbles 113 7.3.1 What is a gas bubble? 113 7.3.2 Methods for bubble generation 113 7.3.3 Bubble size 115 7.3.4 Bubble coalescence 115 7.4 Foam 116 7.4.1 What is foam? 116 7.4.2 Foam stability 117 7.4.3 Foam breakers 118 7.5 Introduction of bubbles affects the gas concentration in the water 118 7.6 Use of bubble columns in aquaculture 118 7.7 Performance of protein skimmers and flotation plants in aquaculture 119 7.7.1 What is removed in inlet or effluent aquaculture water with the use of protein skimmers? 119 7.7.2 Factors affecting the efficiency of protein skimming in aquaculture 121 7.7.3 Use of ozone 122 7.7.4 Bubble fractionation 123 7.8 Design and dimensioning of protein skimmers and flotation plants 123 7.8.1 Protein skimmers: principles and design 123 7.8.2 Protein skimmers: dimensioning 125 7.8.3 Flotation plant 126 7.8.4 Important factors affecting design of a DAF plant 127 References 129 8 Membrane Filtration 135 8.1 History and use 135 8.2 What is membrane filtration? 136 8.3 Classification of membrane filters 137 8.4 Flow pattern 139 8.5 Membrane shape/geometry 140 8.6 Membrane construction/morphology 142 8.7 Flow across membranes 143 8.8 Membrane materials 143 8.9 Fouling 144 8.10 Automation 146 8.11 Design and dimensioning of membrane filtration plants 146 8.12 Some examples of results with membranes used in aquaculture 149 References 150 9 Sludge 153 9.1 What is sludge 153 9.2 Utilization of the sludge 154 9.3 Dewatering of sludge 155 9.4 Stabilization of sludge 156 9.5 Composting of the sludge: aerobic decomposition 156 9.6 Fermentation and biogas production: anaerobic decomposition 158 9.7 Addition of lime 159 9.8 Drying of sludge 159 9.9 Combustion of sludge 160 9.10 Other possibilities for treatment and utilization of the sludge 161 References 161 10 Disinfection 163 10.1 Introduction 163 10.2 Basis of disinfection 164 10.2.1 Degree of removal 164 10.2.2 Chick’s law 164 10.2.3 Watson’s law 165 10.2.4 Dose–response curve 165 10.3 Ultraviolet light 165 10.3.1 Function 165 10.3.2 Mode of action 165 10.3.3 Design 166 10.3.4 Design specification 166 10.3.5 Dose 168 10.3.6 Special problems 168 10.4 Ozone 168 10.4.1 Function 168 10.4.2 Mode of action 169 10.4.3 Design specification 169 10.4.4 Ozone dose 170 10.4.5 Special problems 170 10.4.6 Measuring ozone content 172 10.5 Advanced oxidation technology 172 10.5.1 Redox potential 172 10.5.2 Methods utilizing AOT 173 10.6 Other disinfection methods 175 10.6.1 Photozone 175 10.6.2 Heat treatment 175 10.6.3 Chlorine 175 10.6.4 Changing the pH 176 10.6.5 Natural methods: ground filtration or constructed wetland 176 10.6.6 Membrane filtration 176 References 176 11 Heating and Cooling 179 11.1 Introduction 179 11.2 Heating requires energy 179 11.3 Methods for heating water 180 11.4 Heaters 181 11.4.1 Immersion heaters 181 11.4.2 Oil and gas burners 183 11.5 Heat exchangers 183 11.5.1 Why use heat exchangers? 183 11.5.2 How is the heat transferred? 184 11.5.3 Factors affecting heat transfer 184 11.5.4 Important parameters when calculating the size of heat exchangers 185 11.5.5 Types of heat exchanger 187 11.5.6 Flow pattern in heat exchangers 189 11.5.7 Materials in heat exchangers 190 11.5.8 Fouling 191 11.6 Heat pumps 192 11.6.1 Why use heat pumps? 192 11.6.2 Construction and function of a heat pump 192 11.6.3 Log pressure–enthalpy (p–H) 193 11.6.4 Coefficient of performance 194 11.6.5 Installations of heat pumps 194 11.6.6 Management and maintenance of heat pumps 196 11.7 Composite heating systems 196 11.8 Chilling of water 199 References 201 12 Gas Exchange, Aeration, Oxygenation and CO2 Removal 203 12.1 Introduction 203 12.2 Gas exchange in fish 203 12.3 Gases in water 204 12.4 Gas solubility in water 206 12.5 Gas transfer theory: aeration 210 12.5.1 Equilibrium 210 12.5.2 Gas transfer 212 12.6 Design and construction of aerators 213 12.6.1 Basic principles 213 12.6.2 Change of gas composition in the water for testing purposes 214 12.6.3 Evaluation criteria 215 12.6.4 Example of designs for different types of aerator 217 12.7 Oxygenation of water 223 12.8 Theory of oxygenation 224 12.8.1 Increasing the equilibrium concentration 224 12.8.2 Gas transfer velocity 224 12.8.3 Addition under pressure 224 12.9 Design and construction of oxygen injection systems 225 12.9.1 Basic principles 225 12.9.2 Where to install the injection system 225 12.9.3 Evaluation of methods for injecting oxygen gas 227 12.9.4 Examples of oxygen injection system designs 227 12.10 Oxygen gas characteristics 231 12.11 Sources of oxygen 231 12.11.1 Oxygen gas 231 12.11.2 Liquid oxygen 232 12.11.3 On‐site oxygen production 234 12.11.4 Selection of source 235 References 236 13 Removal of Ammonia and Other Nitrogen Connections from Water 239 13.1 Introduction 239 13.1.1 Nitrogen connections 239 13.1.2 Total nitrogen: Kjeldahl nitrogen 239 13.1.3 Amount of NH3 in the water is pH dependent 239 13.1.4 NH4+‐N 240 13.1.5 Nitrogen, a part of a cycle 241 13.1.6 Measurement of nitrogen compounds 241 13.1.7 Reference values for aquaculture 241 13.2 Biological removal of ammonium ion 242 13.3 Nitrification 242 13.4 Construction of nitrification filters 244 13.4.1 Flow‐through system 244 13.4.2 The filter medium in the biofilter 245 13.4.3 Rotating biofilter (biodrum) 246 13.4.4 Moving bed bioreactor (MBBR) 246 13.4.5 Granular filters/bead filters 248 13.5 Management of biological filters 248 13.6 Example of biofilter design 248 13.7 Denitrification 249 13.8 Other bacteria cultures 250 13.9 Inoculation and boosting of biological filters 251 13.10 Chemical removal of ammonia 251 13.10.1 Principle 251 13.10.2 Construction 251 13.11 Other methods 253 References 253 14 Recycling Aquaculture Systems: Traditional Recirculating Water Systems 257 14.1 Introduction 257 14.2 Advantages and disadvantages of re‐use systems 257 14.2.1 Advantages of re‐use systems 257 14.2.2 Disadvantages of re‐use systems 258 14.3 Definitions 259 14.3.1 Degree of re‐use 259 14.3.2 Water exchange in relation to amount of fish or to supplied amount of feed 260 14.3.3 Degree of purification 260 14.3.4 Intensity of the RAS 261 14.4 Theoretical models for construction of re‐use systems 261 14.4.1 Mass flow in the system 261 14.4.2 Water requirements of the system 261 14.4.3 Connection between outlet concentration, degree of re‐use and effectiveness of the water treatment system 262 14.5 Components in a re‐use system 264 14.5.1 Freshwater, brackish water and seawater RAS 267 14.6 Accumulation of substances, hydrogen sulphide problem and earthy taste removal 267 14.6.1 Accumulation of substances 267 14.6.2 Earthy taste removal 267 14.6.3 The hydrogen sulphide problem 268 14.7 Water maturation, disinfection and use of probiotics 269 14.8 Design of a re‐use system 270 14.9 Evaluation of performance of a RAS 272 References 273 15 Natural Systems, Integrated Aquaculture, Aquaponics, Biofloc 275 15.1 Characterization of production systems 275 15.2 Closing the nutrient loop 275 15.3 Re‐use of water: an interesting topic 275 15.4 Natural systems, polyculture, integrated systems 277 15.4.1 Integrated multitropic aquaculture 277 15.4.2 Biological purification of water: some basics 278 15.4.3 Examples of systems utilizing photoautotrophic organisms: aquaponics 279 15.4.4 Examples of systems utilizing heterotrophic bacteria: active sludge and bioflocs 279 15.4.5 The biofloc system 281 References 283 16 Production Units: A Classification 285 16.1 Introduction 285 16.2 Classification of production units 285 16.2.1 Intensive/extensive 288 16.2.2 Fully controlled/semi‐controlled 288 16.2.3 Land based/tidal based/sea based 288 16.2.4 Other 289 16.3 Possibilities for controlling environmental impact 290 17 Egg Storage and Hatching Equipment 291 17.1 Introduction 291 17.2 Systems where the eggs stay pelagic 292 17.2.1 The incubator 293 17.2.2 Water inlet and water flow 293 17.2.3 Water outlet 294 17.3 Systems where the eggs lie on the bottom 294 17.3.1 Systems where the eggs lie in the same unit from spawning to fry ready for start feeding 295 17.3.2 Systems where the eggs must be removed before hatching 298 17.3.3 Systems where storing, hatching and first feeding are carried out in the same unit 298 References 299 18 Tanks, Basins and Other Closed Production Units 301 18.1 Introduction 301 18.2 Types of closed production unit 301 18.3 How much water should be supplied? 303 18.4 Water exchange rate 304 18.5 Ideal or non‐ideal mixing and water exchange 305 18.6 Tank design 306 18.7 Flow pattern and self‐cleaning 308 18.8 Water inlet design 310 18.9 Water outlet or drain 312 18.10 Dual drain 314 18.11 Other installations 315 References 315 19 Ponds 317 19.1 Introduction 317 19.2 The ecosystem 317 19.3 Different production ponds 318 19.4 Pond types 320 19.4.1 Construction principles 320 19.4.2 Drainable or non‐drainable 320 19.5 Size and construction 321 19.6 Site selection 322 19.7 Water supply 322 19.8 The inlet 322 19.9 The outlet: drainage 323 19.10 Pond layout 324 References 325 20 Sea Cages 327 20.1 Introduction 327 20.2 Site selection 328 20.3 Environmental factors affecting a floating construction 329 20.3.1 Waves 329 20.3.2 Wind 336 20.3.3 Current 336 20.3.4 Ice 338 20.3.5 Site classification 339 20.4 Construction of sea cages 339 20.4.1 Cage collar or framework 340 20.4.2 Weighting and stretching 341 20.4.3 Net bags 342 20.4.4 Breakwaters 346 20.4.5 Examples of cage constructions 347 20.5 Mooring systems 351 20.5.1 Design of the mooring system 352 20.5.2 Description of the single components in a pre‐stressed mooring system 354 20.5.3 Examples of mooring systems in use 360 20.6 Calculation of forces on a sea cage farm 360 20.6.1 Types of force 362 20.6.2 Calculation of current forces 363 20.6.3 Calculation of wave forces 367 20.6.4 Calculation of wind forces 367 20.6.5 Calculation of weight on materials in water 368 20.7 Calculation of the size of the mooring system 368 20.7.1 Mooring analysis 368 20.7.2 Calculation of sizes for mooring lines 369 20.8 Control of mooring systems 371 References 371 21 Feeding Systems 375 21.1 Introduction 375 21.1.1 Why use automatic feeding systems? 375 21.1.2 What can be automated? 375 21.1.3 Selection of feeding system 375 21.1.4 Feeding system requirements 376 21.2 Types of feeding equipment 376 21.2.1 Feed blowers 376 21.2.2 Feed dispensers 376 21.2.3 Demand feeders 378 21.2.4 Automatic feeders 378 21.2.5 Feeding systems 383 21.3 Feed control 385 21.4 Feed control systems 385 21.5 Dynamic feeding systems 386 References 386 22 Internal Transport and Size Grading 389 22.1 Introduction 389 22.2 The importance of fish handling 390 22.2.1 Why move the fish? 390 22.2.2 Why size grade? 391 22.3 Negative effects of handling the fish 394 22.4 Methods and equipment for internal transport 395 22.4.1 Moving fish with a supply of external energy 395 22.4.2 Methods for moving fish without the need for external energy 405 22.5 Methods and equipment for size grading of fish 406 22.5.1 Equipment for grading that requires an energy supply 406 22.5.2 Methods for voluntary grading (self‐grading) 416 References 416 23 Transport of Live Fish 419 23.1 Introduction 419 23.2 Preparation for transport 419 23.3 Land transport 420 23.3.1 Land vehicles 420 23.3.2 The tank 420 23.3.3 Supply of oxygen 421 23.3.4 Changing the water 422 23.3.5 Density 422 23.3.6 Instrumentation and stopping procedures 423 23.4 Sea transport 423 23.4.1 Well boats 423 23.4.2 The well 424 23.4.3 Density 425 23.4.4 Instrumentation 425 23.4.5 Recent trends in well boat technology 426 23.5 Air transport 426 23.6 Other transport methods 427 23.7 Cleaning and re‐use of water 428 23.8 Use of additives 429 References 429 24 Instrumentation and Monitoring 431 24.1 Introduction 431 24.2 Construction of measuring instruments 432 24.3 Instruments for measuring water quality 432 24.3.1 Measuring temperature 433 24.3.2 Measuring oxygen content of the water 433 24.3.3 Measuring pH 434 24.3.4 Measuring conductivity and salinity 435 24.3.5 Measuring total gas pressure and nitrogen saturation 435 24.3.6 Spectrophotometers for water analysis 436 24.3.7 Other 439 24.4 Instruments for measuring physical conditions 439 24.4.1 Measuring the water flow 440 24.4.2 Measuring water pressure 442 24.4.3 Measuring water level 443 24.5 Equipment for counting fish, measuring fish size and estimation of total biomass 444 24.5.1 Counting fish 444 24.5.2 Measuring fish size and total fish biomass 445 24.6 Monitoring systems 448 24.6.1 Sensors and measuring equipment 449 24.6.2 Monitoring centre 449 24.6.3 Warning equipment 451 24.6.4 Regulation equipment 451 24.6.5 Maintenance and control 451 24.7 Remotely operated vehicle (ROV) technology 451 References 452 25 Buildings and Superstructures 455 25.1 Why use buildings? 455 25.2 Types, shape and roof design 455 25.2.1 Types 455 25.2.2 Shape 456 25.2.3 Roof design 457 25.3 Load‐carrying systems 457 25.4 Materials 458 25.5 Prefabricate or build on site? 460 25.6 Insulated or not? 460 25.7 Foundations and ground conditions 461 25.8 Design of major parts 461 25.8.1 Floors 461 25.8.2 Walls 462 25.9 Ventilation and climate control 463 References 465 26 Design and Construction of Aquaculture Facilities: Some Examples 467 26.1 Introduction 467 26.2 Land‐based hatchery, juvenile and on‐growing production plant utilizing flow‐through technology 467 26.2.1 General 467 26.2.2 Water intake and transfer 468 26.2.3 Water treatment department 477 26.2.4 Production rooms 479 26.2.5 Feed storage 483 26.2.6 Disinfection barrier 484 26.2.7 Other rooms 484 26.2.8 Outlet water treatment 484 26.2.9 Important equipment 484 26.3 Land‐based juvenile and on‐growing production plant utilizing RAS technology 486 26.3.1 Introduction 486 26.3.2 Fish tanks and production department 488 26.3.3 Water treatment department 489 26.3.4 Retention time and number of turnover per day 492 26.3.5 Heating/chilling 493 26.3.6 H2S problem 493 26.3.7 Sludge treatment system 493 26.3.8 Fish handling 494 26.3.9 Others 494 26.4 On‐growing production, sea cage farms 494 26.4.1 General 494 26.4.2 Site selection 494 26.4.3 The cages and the fixed equipment 495 26.4.4 The base station 498 26.4.5 Net handling 499 26.4.6 Boat 500 References 501 27 Planning Aquaculture Facilities 503 27.1 Introduction 503 27.2 The planning process 504 27.3 Site selection 504 27.4 Production plan 505 27.5 Room programme 505 27.6 Necessary analyses 505 27.7 Drawing up alternative solutions 508 27.8 Evaluation of and choosing between the alternative solutions 511 27.9 Finishing plans, detailed planning 511 27.10 Function test of the plant 511 27.11 Project review 511 References 511 Index 513