assesment of a novel filter system for recirculating aquaculture

245 Pages·2015·24.47 MB·English

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ASSESMENT OF A NOVEL FILTER SYSTEM
FOR RECIRCULATING AQUACULTURE
LUCA MONTORIO
A thesis submitted for the degree of
DOCTOR OF PHILOSOPHY
Institute of Aquaculture
University of Stirling
March 2004
Declaration
This thesis is a compilation of original research conducted by the candidate and has
not been submitted for any other qualification. Information from the work of others
(published and unpublished) has been duly acknowledged.
Luea Montorio
Professor James F. Muir
Principal Supervisor
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Acknowledgements
A special thanks goes to Mr Stewart Owers, managing director of Alexander and
Sandison & Sons Ltd., for enabling me to do this project and for constantly helping
me in numerous ways.
I would like to express my sincere gratitude to my supervisors Dr. James Muir, Dr
Ewan McQueen and Mr John Bostock for providing advice and support when most
needed. I am particularly grateful to James and Ewan for patiently reading this thesis
and making constructive suggestions and useful comments.
I would like to thanks Mr Billy Stroder and Mr Linton Brown of the Institute of
Aquaculture for provision of laboratory facilities and technical support.
Companionship and aid during the data collection at Quoys hatchery in Shetland was
given by Ewan, Lindsay, Supersonic and Lawrence. I am also thankful to the happy
Macauly family for their friendship and providing me with entertainment during my
stay in Shetland.
Many thanks also to my family for their continuous encouragement and support
during all those years.
Finally, thanks to Liz for giving me inspiration ... and for everything she means to me.
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Abstract
The aim of this project was to investigate the usage of manganese dioxide ore as a
bio-filter media to remove metabolites in aquaculture closed system, and to determine
whether manganese toxicity would at the same time represent a risk to fish.
Initial work investigated the physical properties of manganese dioxide and its
chemical interaction with ammonia and nitrite in the absence of biological activity.
Subsequently, two pilot-scale pressurised filters were installed in a commercial scale
hatchery in order to compare the metabolite removal performance of manganese
dioxide against silicate sand in the presence of biological activity commonly found in
aquaculture conditions.
The investigation suggests that Mn medium is more reliable in converting ammonia to
nitrate without producing a residual output of nitrite. The superior performance ofMn
media compared with sand appears to be mainly related to the physical structure of
the manganese ore. Furthermore, the Mn medium did not appear to be soluble in the
ambient conditions normally found in aquaculture-closed system.
From the design point of view, due to the higher ammonia and nitrite removal rates, a
shorter retention time and a lower volume of media are required in the case of
manganese dioxide technology compared with sand media. As a result, it is much
easier to size a biofilter with Mn media.
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Manganese systems have a comparable total costs to conventional sand media, but
using the Mn technology provides a more reliable control of toxic nitrite, thereby
reducing risks offish loss and hence with reduced expected production costs.
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Glossary
BET Brunauer-Emmett-Teller
BOD Biological Oxygen Demand
BVs Bed volumes
CaS0 Calcium sulphate
4
CO Carbon dioxide
2
CaC0 Calcium carbonate
3
DD Double distilled
EBCT Empty bed contact time
GAC Granular activated carbon
HC0 Bicarbonate
3-
KCI Potassium cloride
NaHC03 Sodium bicarbonate
NH+ Ammonia ionised form
4
NH3 Ammonia un-ionised form
NH3-N Ammonia nitrogen
NH 0H Hydroxylamine
2
N0 - Nitrite
2
N03- Nitrate
MgS0 Magnisium sulphate
4
Mn Manganese
[Mnsoll Concentration of soluble manganese
rMntotl Concentration of total manganese
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Mn0 Manganese dioxide
2
Oxygen
°2
RASs Recirculating aquaculture systems
SEM Scanning electron microscopy
SO Sintered glass
SS Silicate sand
SSA Specific surface area
TAN Total ammonia nitrogen
TKN Total Potassium Nitrogen
TSS Total suspended solid
VMS Universal Mineral Supplies Ltd
VR Volcanic rock
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Table of contents
Page
Declaration
11
Acknowledgements
III
Abstract lV
Glossary
Vl
Table of contents viii
List of tables Xl
List of figures xv
Chapter 1: Introduction
1.1 The potential for development of recirculation systems in aquaculture 1
1.2 The technological backgrOlmd of recirculation systems in aquaculture 7
1.2.1 Removal of metabolites 8
1.2.2 Aeration/Oxygenation 11
1.2.3 pH control 12
1.2.4 Process flow 13
1.3 Biological filter principles in aquaculture 13
1.3.1 Microbial metabolism principles 15
1.3.2 Nitrification in treatment systems 22
1.3.3 Nitrification in filters 25
1. 4 The aim of the project 31
Chapter 2: A conceptual background on manganese dioxide
2.1 Chemical background 36
2.1.1 Properties of hydrous manganese dioxide 36
2.1.2 Sorptive characteristics of hydrous manganese dioxide 40
2.2 Redox chemistry of nitrogen and manganese 45
2.3 The application of manganese dioxide to water treatment 47
2.4 Manganese oxidation and reduction in natural environment 50
2.5 Potential drawbacks of a Mn0 filter system 55
2
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Chapter 3: Laboratory trials
3.1 Introduction 65
3.2 Materials and methods 69
3.2.1 Specific surface area developed on different commercial granular 69
media
3.2.2 Surface morphology observations 71
3.2.3 Manganese ore solubility and chemical action of silicate sand and 71
manganese dioxide on ammonia and nitrite
3.2.4 Batch trials experimental procedure 75
3.2.5 Pilot trials experimental procedure 79
3.3 Results 81
3.3.l Specific surface area developed by different commercial granular 81
media
3.3.2 Scanning electron microscopy images 83
3.3.3 Batch trials of manganese ore solubility and chemical action of 94
silicate sand and manganese dioxide on ammonia and nitrite
3.3.4 Pilot trials of manganese performance and solubility 103
Chapter 4: Hatchery emuent field trials
4.1 Introduction 110
4.1.1 RASs characteristics used for the field research 112
4.2 Materials and methods 118
4.2.1 Equipments 118
4.2.2 Materials 119
4.2.3 Experimental procedures 120
4.3 Results 125
4.3.1 Biological start-up period 125
4.3.2 Observations carried out after biological start-up was completed 127
4.3.3 Affect of reduced contact time on filter performance 139
4.3.4 Manganese solubility 150
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Chapter 5: Technical and financial analysis
5.1 Introduction 152
5.1.1 Commercial scale RAS technical background 153
5.2 Technical analysis 161
5.3 Financial analysis 170
Chapter 6: Discussion and conclusion
6.1 Laboratory studies 177
6.l.1 Specific surface area and surface morphology 177
6.1.2 Manganese solubility 179
6.l.3 Chemical action of silicate sand and manganese dioxide on ammonia 181
and nitrite
6.2 Field studies 182
6.3.1 Biological start-up 183
6.2.2 The effect offilter backwashing 185
6.2.3 Effect of reduced contact time 190
6.2.4 Manganese solubility 192
6.3 Technical analysis 194
6.4 Conclusions 197
References 200
Appendices
Appendix A: Brunauer-Emrnett-Teller (BET) measurements 216
Appendix B: Materials and methods used for water analysis 218
Appendix C: Batch trials results 225
Appendix D: Pressurised filter characteristics 227
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