PHOTO BIOREACTORS
From: [mailto:owner-AQUA-L@killick.ifmt.nf.ca]On Behalf Of María
Vicenta Valdivia
To: AQUA-L@killick.ifmt.nf.ca
Sent: August 23, 2000
QUESTION:
I need information about photo bioreactor systems commercially
available for microalgae mass culture.
Maria Vicenta Valdivia S.
Aquacultural Engineer
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COMMENTS 1:
The best bio-reactor is HISTAR - a computer controlled system, now
commercially available, for possibly any micro-algal species on a
medium or very large scale. I have built and tested one along side
several others; it's well published in the peer reviewed literature, very
viable and economical (but not cheap).
Suggest you contact:
Dr. Kelly Rush
2402-B CEBA Bldg.
Dept. Civil & Environ. Engineering
Louisiana State Univ.
Baton Rouge, LA 70803
225-388-8528
E-mail: krusch@unix1.sncc.lsu.edu
A. David Scarfe Ph.D., D.V.M., M.R.S.S.A.
Chesapeake Shellfish Aquaculture, Inc.
& OVA-CAP Veterinary & Consulting Services
53 E Muirfield Dr.
Reading PA 19607 USA
Phone: 610-775-9793
Fax: 610-796-7756
4303 Atlantic Ave., Suite 1
Ocean City MD 21842 USA
410-289-6186
Fax: 410-723-0776
e-mail: mburkett@epix.net
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COMMENTS 2:
Can I ask what you consider medium or large scale (i.e. 100,000 L)?
Michael A. Borowitzka
School of Biological Sciences & Biotechnology
Murdoch University
Perth, W.A. Australia 6150
tel: +61 8 9360 2333
fax: +61 8 9360 6303
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COMMENTS 3:
Scale should be determined by production, not volume. Twice the
density, half the depth can produce the same amount of algae. The
volume is more a function of other economic factors such as trying to
get adequate mass transfer in very shallow water or having a system
with slower response times and easier to control (lower density,
higher volume).
Dallas E. Weaver, Ph.D.
E-mail: deweaver@gte.net
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COMMENTS 4 :
This is my short list of commercial or near-commercial
automated/continuous algal production systems. If anyone has
additonal sites or contacts, I would like to see them.
Addavita Limited
http://www.addavita.demon.co.uk/
Biosynthesis aka Bio-Fence
http://www.biosynthesis.co.uk/
HISTAR
http://www.newswise.com/articles/1997/12/ALGAE.LSU.html
developer: KRusch@unix1.sncc.LSU.edu
Seasalter Shellfish Ltd.
http://www.uk-travelguide.co.uk/seasalter/seasalt.htm
Paul L. Hundley, Jr., P.E.
President/Principal Engineer
Applied Aquatics, Inc.
tel 843-971-9639
fax 843-971-9641
AAquatics@aol.com
www.AppliedAquatics.com
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COMMENTS 5:
About HISTAR, do you have any data about productivity for a given
microalga? And what do you mean by large scale, large laboratory scale or
large industrial scale?
Have you tested other kinds of photobioreactors comparing with this
one?
Joao Navalho
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COMMENTS 6 :
I usually calculate production in kg dry weight but can also convert to cell densities for most species. Can you give me some idea of the scale you are talking about?
Michael A. Borowitzka
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COMMENTS 7:
In theory, the scale is unlimited. In practice, the largest system
that has been built is a little less than 10,000 liters. That system
can produce up to 400-500 g dry wt./day.
Of course, there is a limitation on how small a "commercial"
system can be due to economics, but the theory is based on hydraulic
manipulation of algal reactors to mitigate contaminants. The
hydraulic manipulation can be achieved on any size or type of reactor
vessel (tank, pipe, pond, etc.). Currently, the system that is
available commercially is a ~10,000 liter system with open-top, fiberglass
tanks.
However, the primary component of the system is the control and
monitoring hardware and software, not the tanks. The control package
is size independent, and is therefore a fixed cost (except for a few
options), hence the reason a small system would not be economical.
Mike Christensen
E-mail: mchris@unix1.sncc.lsu.edu
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COMMENTS 8 :
When discussing scale from an engineering standpoint, you need to
look at the scalability of the basic design concept. Some basic
design concepts can't be scaled up and some don't scale down.
For
example, high percentage removal per pass fluidized bed biofilters do
not scale down very well. If you decrease the vertical
dimension,
the % removal per pass will decrease. Some biological reactors
depend upon vertical/horizontal dimension ratios, which constrains
appropriate scale ranges.
From looking at the design concepts and mathematics behind the
HISTAR systems, they should be infinitely horizontal scalable, which
means you can build as large of system as you want. I can
visualize
that you could get into some mixing time vs. residence time issues
and some CO2 mass transport issues when the size gets into 100 to
1000+ kg per day dry wt class system. This basic design concept
doesn't scale down to laboratory size, without the economics getting
out of hand (you have a reasonable large fixed cost in the control
systems, which is almost independent of scale --- but it scales
up
real well when that fixed cost get spread over larger production).
Algae production is not my field, but scalability questions are a lot
closer to home.
Dallas Weaver
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COMMENTS 9 :
I am very much impressed with the discussion on the designs of
photobioreactors. I am interested in knowing the volume of
culture that can be grown in HISTAR system, and also the type of
microalgae which are tested. I have the experience of growing
microalgae like nitrogen fixing cyanobacterium, Dunaliella, Chaetoceros,
Skeletonema, Tetraselmis and Isochrysis; different growth systems like
tubular reactors, open raceways, fibre-glass tanks, rectangular cement
tanks with water holding capacity of more than ten tonnes and polythene
bags. Also each system has its own merits and drawbacks.
Michael had requested for the production of microalgae in terms of
dry
weight basis. Normally the productivity of microalgae is
expressed in terms of dry weight for the purpose of evaluating the reactor
designs and also to determine the quantum of feeding at different timing
intervals. However, in aquaculture practices it is not still
understood in some parts of the world. For instance, in India the feeding
of shrimp larvae is still(?) based on cell densities. This perhaps
impedes the development of viable bioreactors for local conditions and it
also often is difficult to convince the entrepreneurs on the systems
available which would take care of the large quantities of microalgae they
need on daily basis.
Also the productivity of microalgae in bioreactors is controlled by
factors other than Dallas has outlined. Besides, the basic
photobioreactor designs (coiled tubular reactors, horizontal tubular
reactors, flat panel reactors etc.,) developed so far are practically
scalable to produce large amounts of microalgae. It still remains to
be seen which system is good in terms of productivity, cost-effectiveness,
suitability to the local conditions and vulnerable to control the
contaminants. Since aquaculture activities are enlarging in greater
proportions in India and other regions like West Asia, there appears to be
a vast scope for these photobioreactors.
It would be interesting in the context to know the design of HISTAR
photobioreactor.
Govindachary, Sridharan Ph.D
# 2, 4870, Rue Emile-Jean
Trois Rivieres (Quebec)
G8Y 4A3 Canada
Tel : (Lab) 1-819-376-5077 Ext. 3311
Tel (Res) 1-819-693-6597
E-mail : sridhora@hotmail.com
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COMMENTS 10 :
Here are some of the articles available on the HISTAR system. I am
working on a more descriptive paper right now.
The 400 mg dry-wt/day is a continuous production out of the last
reactor and harvested by a continuous flow centrifuge. We can get up
to 2-2.5 kg (maximum) of wet paste per day; peanut butter consistency.
The paste is generally about 80-85% water weight, so the dry weight is in
the 400-500 mg range. These numbers are consistent if the system is
well looked after and the water conditions are appropriate (proper
nutrient levels, CO2, salinity, mixing, etc.). More typically we
will see harvests in the 1.5 kg because some parameters may not be well
attended. Eventually, piping and tanks will require some type of
cleaning, so the longest we've run the system is about 3 months.
We've produced Chaetoceros, Thallasiosira, Nannochloropsis, C-iso, T-iso,
Chlorella, and Selenastrum in the HISTAR system. The system is
pretty consistent among species, but the harvests will obviously change
because of the different size and densities of the
different species.
Mike Christensen
Research Associate
Louisiana State University
Rusch, K.A., Christensen, J.M. 1998. Description and operation of a Hydraulically Integrated Serial Turbidostar Algal Reactor (HISTAR). Journal of Shellfish Reseach, 17, p. 338
Rusch, K.A., Malone, R.F. 1998. Microalgal production using a hydraulically integrated serial turbidostat algal reactor (HISTAR): a conceptual model. Aquaculture Engineering, 18, pp. 251-264
Theegala, C.S., Malone, R.F., Rusch, K.A. 1999. Contaminant washout in a hydraulically integrated serial turbidostat algal reactor (HISTAR). Aquacultural Engineering, 19, pp. 223-241
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COMMENTS 11:
The concepts associated with scalability must include economics.
Closed reactor designs such as coiled tubular reactors, horizontal
tubular reactors, flat panel reactors etc are not truly scalable to
very large sizes. There is almost no economies of scale with
this
class of designs (all the economies of scale are related to the
support functions such as harvesting, water treatment, etc).
Scaling
these designs is really just putting a lot of parallel units in the
same place.
Scaling a Histar design can result in economies of scale up to very
large systems with continued economic improvement in production cost
per Kg of algae.
For laboratory scale and small hatchery systems, these non-scalable
designs are fine and have a lower control system cost. However,
doubling the length or area of a tubular reactor almost doubles the
capital cost and the pumping cost. Doubling the area of a
Histar
system doesn't double the capital or energy cost. We are
talking
about hydraulic system design where lots of non-linearities in cost
vs size occur, let's take advantage of them, but that requires a
fundamental design approach that can utilize these characteristics.
Dallas Weaver
PS: I have nothing to do with Histar other than being an outside
observer who enjoys creative concepts.
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COMMENTS 12:
I'd like to point out some additional facts about the Histar system.
Most people seem to think of Histar (those that know about it, anyway) as
a "competitor" to some of the other technologies that have been
discussed, i.e. tubular reactors, bag cultures, etc. Although we do
now have a commercially available Histar "system", Histar itself
is not actually a "system", it is a conceptual approach.
The conceptual approach could in reality be used in conjunction with most,
if not all, of these other technologies. However, the one difference
that the Histar approach allows for is the use of open-top reactors for an
amplification process. We are still limited on the front end by the
same problems that might plague any other "system", most notably
growth of attached contaminants. But, if we can maintain the front
end (traditional continuous cultures just like most of the other "systems")
on small scale, we are able to use the amplification portion of the
approach to scale up almost indefinitely. Obviously there are some
engineering limitations that have been discussed, such as mixing and CO2
transport, but these limitations are comparatively much easier to deal
with in open-top reactors than in closed-pipe reactors, glass-plate
reactors, bags, or any of the other novel ideas.
The Histar is not a miracle "system" by any means. It
is just a different
approach using some well known engineering principles. But,
these principles can help us achieve the economy of scale.
Mike Christensen
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COMMENTS 13:
I can agree with Dallas when he says that photobioreactors don't
scale-up well. Nevertheless if we take in consideration labor costs we can
find economies of scale on "putting a lot of parallel units in the
same
place".
Also thinking about the "support functions (harvesting, pumping,
water
treatment...)" one must consider the system carrying capacity.
Running a system at 2 or 3 g/l biomass (dry weight basis) is
different than a
system at 0.2 or 0.3 g/l. Even if you save more scaling up the second
system, you will need to scale A LOT to reach the first system "support
functions" costs (kg biomass produced basis).
To compare the size at each system can be scaled up you need also to
think on the system productivity. What's the use of scaling a
40g/m3/day microalgae production system to 10,000 liters when you can
scale a 400g/m3/day system to 2, 4 or 5,000 liters? An interesting issue
is to scale up a 400g/m3/day system to 100,000 liters.
Joao Navalho
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