Opportunities and Challenges of Multi-Loop Aquaponic Systems

179 Pages·2017·5.21 MB·English

Opportunities and Challenges of

Multi-Loop Aquaponic Systems

Simon Goddek

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Thesis com mittee

Promotor
Prof. Dr Johan A.J. Verreth
Professor of Aquaculture and Fisheries
Wageningen U niversity & Research

Co-promotors
Prof. Dr Karel J. Keesman
Personal chair at Biobased Chemistry & Technology
Wageningen Un iversity & Research

Dr Sven Würtz
L eader Research Group Ecophysiology and Aquaculture
Leipniz-Institut e of Freshwater Ecology and Inland Fisheries, Berlin, Germany

Other members
Prof. Dr Jaap Molenaar, Wageningen University & Research
Dr Harry Bruning, Wageningen University & Research
D r Chris G. J. van Bussel, Skretting Aquaculture Research, Stavanger, Norway
Dr Paul Rye Kledal, IGFF, Hellerup, Denmark

This research was conducted under the auspices of the Graduate School for Socio-Economic and Natural
Sciences of Environment (SENSE)
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Opportunities and Challenges of

Multi-Loop Aquaponic Systems

Simon Goddek

Thesis
submitted in fulfilment of the requirements for the deg ree of doctor
at Wageningen Univer sity
by the authority of the Rector M agnificus,
Prof. Dr A.P.J. Mol,
in the presence of the
Thesis Committee appointed by the Acad emic Board
to be defended in publ ic
on Tuesday 24 October 2017
at 4 p.m. iinii the Aula.
Simon Goddek
O pportunities and Challenges of Multi-Loop Aquaponic Systems,
170 pages.
PhD thesis, Wageningen University, Wageningen, the Netherlands (2017)
With references, with summaries in English, Dutch, and Portuguese

DOI: 10.18174/412236
ISBN: 978-94-6343-172-9
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Which of us is not familiar with this situation during the student time: on a Wednesday night,
Preface
one wants to go out to grab a beer (“just one Duveltje”) with friends. Until the end of the
night (and several beers later) one was trapped in several discussions about religion,
politics, and one’s field of study. I have to admit, that I have been involved in plenty of such
discussions, which also stems from the fact that I am a very discussion-friendly and curious
person. However, I caught myself often saying the same sentence “well, the idea is great, but
it actually does not really work as it should” with respect to two topics: Aquaponics and
Communism. This might appear to be a somewhat far-fetched statement, however, for those
who have neither read Marx nor followed the development of aquaponics the last 30 years:

in a nutshell it can be stated that both of these ideas follow bottom-up (i.e. local and circular)

approaches (i.e. for small farmers and individuals).
Additionally to the above, I honestly believe that in times of the financial crisis - in which
multinational corporations such as [think of big corporations that produce GMO seeds that
are immune to their pesticides] increase their quasi-monopoly positions on the global food
market - a paradigm shift back to human-centred and sustainable agricultural development
is required to ensure both (1) healthy (i.e. pesticide free) diets and (2) food independence.
In contrast, organic, fair trade, and GMO-free food have recently gained rapidly increasing
popularity. Consumers want transparent and extensive information about the origin and
manufacture of the foodstuffs they buy. The development of agriculture and how to use
(finite) resources efficiently will be crucial with respect to the global development and the
future of the earth in general. Right now, we are at a crossroads in our history that will
determine whether either the people or the corporations will be empowered. I intended to

provocatively illustrate this new class conflict on the book cover with the objective to

polarize and thus energize the readers themselves to make thoughts and reflections.
So far, I have dedicated over 4 years of my life to study and improve aquaponic systems in
the hope that one day their production efficiency will be able to compete with state-of-the-
art hydroponic food production systems, while improving circularity. In this thesis, I will try
to demonstrate why aquaponics does not face the same pitfalls as communism, while sharing

the empowering people-minded and bottom-up qualities that are required in the 21st
century.
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Preface Ta ble of Contentsvi
Chapter 1 General Introduction 1
Chapter 2 Challenges of Sustainable and Commercial Aquaponics 13
Chapter 3 LettuceL (actuc a sativa L. var. Sucrine ) Growth Performance 39
in Complemented Aquaponic Solution Outperforms
Hydroponics

Chapter 4 Comparison oLfa ctuca sativa Growth Performance in 55
Hydroponic and RAS-based Hydroponic Nutrient Solutions

Chapter 5 The Effect of Anaerobic and Aerobic Fish Sludge Supernatant 67
on Hydroponic Lettuce.

Chapter 6 Navigating towards Decoupled Aquaponic Systems: A System 81
Dynamics Design Approach
Chapter 7 The Necessity of Desalination Technology for Designing and 113
Sizing Multi-Loop A quaponic Systems
Chapter 8 General Discussion 127

Reference s 139
Appendix 152
Summary 157
Samenvatting 160
Resumo 163
Acknowledgemen ts 166
About the author 167
List of publications 168
Graduate school certificate 169
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Chapter 1
General Introduction
1.1 Global Food Challenges
A constantly rising world population and a corresponding increase in consumption confront
the world with constantly new challenges. In theory, population and food consumption
should be a linear relationship: the more people live on the planet, the more food will be
consumed. However, there is a discrepancy between the reality and this relationship. The
reasons can vary, the consequences are nonetheless worrying.

While more and more food needs to be produced to meet the increasing food demands,
usable land for agricultural practices decreases since intensive agriculture tends to land and
soil to degrade. Arid and semi-arid regions also experience more droughts and water
shortages due to climate change (FAO, 2012a). Agriculture uses 70% of the fresh water
worldwide. According to FAO (2009), the severe water scarcity will increase in the next 25
years due to the expected population growth to more than 9 billion people, as approximately
60% more food will be needed. Water scarcity is even expected in areas that have relatively
sufficient water resources. Major policy changes are required to avoid such trends (Criscuolo
and Menon, 2015). These phenomena, in addition to other effects, cause that huge areas of
precious rain forests are destroyed, which leads to aggravating soil erosion and therefore to
the loss of fertile soils. Also, rainforests help reducing the amount of solar radiation reflected
back into the atmosphere, leading to a mitigation of the greenhouse effect. Considering that
climate change speeds up by depleting this biodiversity-rich ecosystem shows that we are
trapped in a vicious cycle (Brown, 2009).

Another issue that conventional agriculture faces is that generating three centimetres of
topsoil takes approximately 1000 years. Regarding the United Nations, the world’s top soil
could be gone within 60 years if current rates of degradation continue (Arsenault, n.d.).
Additionally to that, the FAO of the United Nations reports that the amount of arable land by
2050 will only be a quarter of the level in 1960. This can be attributed to both the growing
population and soil degradation. Meanwhile, fertilizer consumption per ha of arable land has

risen from 105 kg in 2002 to 135 kg in 2013 to counteract soil degradation (FAO, n.d.).
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In addition to nitrogen and potassium, phosphorus is one of the three major nutrients that is
required for plant growth and improving soil quality for following crops. Approximately
80% of all mined rock phosphate is synthesized to agricultural fertilizer (Ekardt et al., 2010).
Like oil, phosphorus is a non-renewable resource. There are no substitutes for phosphorus
in agriculture to sustain crop yields. A number of scientists have demonstrated that rock
phosphate reserves may be depleted within 50-100 years (Cordell et al., 2011; S. Cordell et
al., 2009; Ragnarsdottir et al., 2011; Steen, 1998), while phosphorus demand is constantly
increasing. The global phosphorus peak is predicted to occur in coming decades (D. Cordell
et al., 2009; Walan et al., 2014). According to Sverdrup and Ragnarsdottír (2011),
phosphorus will become an expensive material in the future. Recycling policies and
innovative agriculture systems are consequently necessary to avoid world hunger and mass
mortality (Mórrígan, 2010; Ragnarsdottir et al., 2011) and are still expected to meet the UN
Sustainable Development Goal number 1 that addresses eradication of extreme poverty and
hunger. A sustainable approach is required in order to prevent tackle the above mentioned
issues.

1.2 Aquaponics
Traditionally, aquaponics refers to an integrated system in which aquatic animals and
soilless-growing plants are cultivated together. In this study, and in line with Nichols and
Savidov (2012) as well as Seawright (1998) aquaponics can be defined as a multi-trophic
food production system comprising of a recirculating aquaculture system (RAS) and
hydroponic (HP) elements (Figure 1.1). In these one-loop aquaponic systems, RAS-derived
nutrient-rich water from the HP element is directly constantly directed to the hydroponic
unit providing the plants with essential nutrients for plant growth instead of being
discharged (Liang and Chien, 2013; Vermeulen and Kamstra, 2013). In one-loop aquaponic
systems, the partly demineralized water is led back to the RAS (Graber and Junge, 2009;
Licamele, 2009; Rakocy et al., 2006). The advantage of this approach is that both fish and
plants can be produced in an environmentally-friendly way. Furthermore, high levels of
water reuse (Graber and Junge, 2009a) as well as nutrient recycling (Palm et al., 2015, 2014;

Vermeulen and Kamstra, 2013) are ensured.

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