Microalgae for aquaculture

158 Pages·2015·3.84 MB·English

Microalgae for aquaculture
Michiel H.A. Michels
Thesis committee
Promotor
Prof. Dr R.H. Wijffels
Professor of Bioprocess Engineering
Wageningen University
Co-promotor
Dr M.H. Vermuë
Assistant professor, Bioprocess Engineering
Wageningen University
Other members
Prof. Dr A.C. Smaal, Wageningen University
Prof. J. Pruvost, University of Nantes, France
Dr W.A. Brandenburg, Wageningen University
Dr T.V. Fernandes, NIOO (Netherlands Institute of Ecology), Wageningen
This research was conducted under the auspices of the Graduate School VLAG
(Advanced studies in Food Technology, Agrobiotechnology, Nutrition and Health
Sciences).
Microalgae for aquaculture
Michiel H.A. Michels
Thesis
submitted in fulfillment of the requirements for the degree of doctor
at Wageningen University
by the authority of the Rector Magnificus
Prof. Dr M.J. Kropff,
in the presence of the
Thesis Committee appointed by the Academic Board
to be defended in public
on Wednesday 13 May 2015
at 1.30 p.m. in the Aula.
Michiel H.A. Michels
Microalgae for aquaculture
158 pages
PhD thesis, Wageningen University, Wageningen, NL (2015)
With references, with summaries in Dutch and English
ISBN 978-94-6257-224-9
Contents
Chapter 1 7
General introduction
Chapter 2 15
Effects of shear stress on the microalgae Chaetoceros muelleri
Chapter 3 35
Effect of biomass concentration on the productivity of Tetraselmis
suecica in a pilot-scale tubular photobioreactor using natural sunlight
Chapter 4 59
Growth of Tetraselmis suecica in a tubular photobioreactor on
wastewater from a fish farm
Chapter 5 77
Effect of cooling in the night on the productivity and biochemical
composition of Tetraselmis suecica
Chapter 6 99
Cultivation of shear stress sensitive and tolerant microalgal species
Chapter 7 125
General discussion: Prospects of microalgal production in tubular
photobioreactors for hatcheries
Summary 139
Samenvatting 143
Acknowledgments 149
About the author 153
Publications 155
Overview of completed training activities 157
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CHAPTER 1
General introduction

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Introduction
The research of this thesis was imbedded in the Zeeland Sole project. Before
describing the actual research performed for the thesis in detail, the project as a
whole will be introduced.
The Zeeland Sole Project (Zeeuwse Tong Project)
In 2004, the project ‘Zilte Zoom’ was initiated in order to develop new economic
activities at the boundary of sea and land. One of the ideas was to develop an
innovative aquaculture system for the production of sole (Solea solea). Sole is the
most valuable flatfish, which accounts for 35% of the value of all auctioned fish in
the Netherlands. The Dutch quota for sole fisheries decreased from about 15,000 to
9,000 ton in the last 10 years and it was estimated that there would be room for the
production of 15,000 ton of sole per year in fish farms for the (export) market.
The Dutch fish farming sector, culturing fish species like catfish, eel and turbot, is
mainly using recirculating aquaculture systems (RAS). In these systems fish are
reared from fingerlings to the size for consumption. The wastewater produced by the
fish is recycled after treatment. Despite the efficient use of water, these systems are
still highly capital and labor intensive.
As an innovative and costs reducing alternative for culturing sole, an integrated multi-
trophic aquaculture system was suggested (Fig. 1). In this approach, the indoor
production of fingerlings was proposed, followed by a grow-out phase in basins
outside. The grow-out phase of sole would be combined with ragworm (Nereis virens)
culture in the same basins. The nutrient-rich wastewater produced by the sole, could
be used to grow microalgae. The algae can be used as feed for the ragworms or as
feed for shellfish (Broodman, 2006).
Based on this idea, the foundation ‘Zeeuwse Tong’ was initiated on the 26th of June
2007 (Stichting Zeeuwse Tong, 2009). A consortium of different companies and
research institutes was formed, financially supported by the province of Zeeland in
the Netherlands.
The overall aim of the Zeeuwse Tong project was to develop a new competitive land-
based aquaculture sector, which is producing sole, ragworms, algae, shellfish and
saline crops in close harmony with nature. Within the project, two concepts for an
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integrated multi-trophic aquaculture were defined: The development of an integrated
saline aquaculture farm and the development of an integrated nursery. This last
concept forms the direct base for the research described in this thesis.
First concept: The integrated saline aquaculture farm
The integrated saline aquaculture farm is a land-based integrated multi-trophic
aquaculture activity. Recycling and reusing water and nutrients is a main part of this
type of aquaculture. Together with the sole, ragworms are produced in basins as feed
for the sole. The wastewater from the basins is full of nutrients and these are used
to stimulate the production of algae and saline crops. The produced algae can then
be used as feed for shellfish and ragworms (Fig. 1). The main reasons for coupling
the production of ragworms, fish, algae, shellfish and saline crops are to reduce the
losses of nutrients to the environment preventing eutrophication and to reuse these
nutrients as a valuable source for the assimilation into the food production chain via
algae and plants, which are the basis for food production.
Fig. 1 Integrated multi-trophic aquaculture as concept in the Zeeland Sole project.
A demonstration aquaculture farm ‘Zeeuwse Tong’ was built in Colijnsplaat, the
Netherlands. During 4 years, from 2010 till 2014, research was done on the technical
and economic feasibility of this innovative concept of integrated multi-trophic
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aquaculture. The demonstration aquaculture farm consisted of 12 experimental
basins of 1,000 m2 each for the cultivation of ragworms, sole, shellfish and algae.
They were either produced in multi-culture mode or in separate cultures. Seawater
from the Easterscheldt was supplied via pipes, constructed underneath the dike.
Before sending the water to the basins it was filtered and its temperature was
adjusted. Cooling and heating of the water was achieved by an aquifer thermal
energy storage.
In February 2014 this part of the Zeeuwse Tong project was finalized, and the main
conclusion was that integrated multi-trophic aquaculture is technically feasible.
Currently, negotiations are going on to initiate new businesses at the demonstration
aquaculture farm and its facilities in Colijnsplaat, the Netherlands.
Second concept: Integrated nursery
In the integrated nursery the rearing of fingerlings of sole is combined with the
cultivation of microalgae as feed for shellfish larvae and spat inside a greenhouse
(Bot et al., 2009). The advantages of the integrated nursery in a greenhouse are
the lower costs for a greenhouse when it is constructed as a multipurpose use of
space, the possibility of combining sole culture with the cultivation of microalgae
and shellfish larvae or spat, an integrated thermoregulation and the possibility for
reusing the nutrients from the wastewater of the fish basins for microalgal production
in closed photobioreactors (PBRs). The idea is to cultivate microalgae in closed
PBRs, which can also function as solar collectors. The captured sunlight is not only
used for the growth of the microalgae. A lot of the energy can be used to keep
the temperature of the basins in which the fingerlings are reared at the optimal
temperature. Furthermore, waste heat of power engines needed for the electricity
supply can be used as well. Surplus of heat in summer months can be stored in
aquifers, which can be used for temperature control in winter. The groundwater of
the aquifer will be cooled in winter, which can be applied for cooling the PBRs during
warm periods.
For the design of the nursery, different options for the lay-out of the PBRs are
possible, of which a layer of horizontal tubular PBRs above the fish basins and racks
of horizontal vertically stacked tubular PBRs between the fish basins are depicted
in Fig. 2.
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