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PBR's the ultimate design!? 7

In my early days I confess to growing algae in open tanks. I would take raw seawater and add a NPK fertilizer and aerate it. Interesting exercise but not very useful if you were trying to feed it to a filter feeder. Too much NPK and the dominant strain would be some sort of green filamentous algae which is useless.

Then I started using photobioreactors (PBR's) even though in those days they were never called that. Carboys, bags were what they were. About 15 years ago I was introduced to continuous culture in a PBR and, to me anyway, there is no better method of culturing a high quality monoculture.

Something that has caught my attention over the years is that people always state that open pond systems are cheaper to construct and operate than PBR's. I have never seen any data to support this assumption. One important specific that many people forget is that the number of cells per mL is (somewhat) inversely proportional to volume when comparing closed systems to open ones. Red tides are usually visible at a concentration of about a million cells per litre, yet that concentration is useless to people who want (at least) several million cells per millilitre to make growing algae viable.

Any comments?
Thu May 06 2010 03:13:48 PM by Alby 1424 views

Comments - 7

  • Kumar wrote:
    Thu May 06 2010 03:21:23 PM

    See now a days every one chosen PBR only. U can see most of the artice is focussed on PBR. Less people only supporting open pond. Nice article.

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  • Sean wrote:
    Thu May 06 2010 03:28:26 PM

    Excellent Observation Alby.
    Over here in North Ireland we got excited as the Carbon Trust published a funding program to support the evergrowing interest in Algae. Alas our excitment was short lived when we discovered that they have decided to focus on Pond Culturing as being the most viable use of their funding. I personally believe that in the quest to try solve the "replace fossil fuels" dilema, organisations such as this must be prepared to think "out of the box" the solutions simply do not lie in the bowels of previous experience and research, if they did we would not have a problem today. To believe that any answer lies in Algae without embracing the concept of 24/7/365 via photobioreaction and controlled environment enclosures is confirming my belief in Einsteins observation that the same kind of thinking that created a problem should not be used to solve the problem. We need outright innovation, intuition, and unencumbered clear thinking to deal with this issue. Sean

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  • Alby wrote:
    Thu May 06 2010 03:49:32 PM

    Sean, I think we need to push this idea of 'Thinking outside the box'. Too may people are fixated on open ponds, yet where is the evidence to support such a method if we are taking about carbon fixation? If we are talking about using waste CO2, how is this beneficial if it is bubbled into an open system? It would just vent to the atmosphere. Others have experimented with increasing amounts of CO2 in PBR's and the results are tantalizing. It appears that CO2 is not a limiting factor, but if you use coal based feedstock it is SOX, or O2 concentration or the limitation of N.

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  • Fri May 07 2010 05:07:26 AM

    Closed PBRs is the way to go, because of cross contamination. Atificial light can also be applied 24/7 along with Co2 and nutrients.
    www.algalsolution.com

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  • Manohar wrote:
    Sat May 08 2010 04:24:23 AM

    What is the simplest pbr ?

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  • Alby wrote:
    Wed May 12 2010 01:25:21 PM

    A plastic bag! In many places in Asia simple plastic bags are suspended from a pole or similar. Water is chlorinated and allowed to sit in the sun for a couple of days by when the chlorine has been neutralized by the sun. Add some inoculum and an air line and there you go. These are usually harvested as batch cultures. How simple is that?

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  • Manohar wrote:
    Mon May 17 2010 01:13:25 PM

    Sounds great Alby ! About 370 million people - population equivalent of North America live in India with an income less than 0.5 $s per day.
    If thru the plastic bag / bags we can let them grow some algae and give them 0.5 $ per day or even per two days, they will be very happy. Not just the masses. Even the Gov will come forward to support, such a thing. Is it possible to grow algae worth $ 1 per day from a plastic bag or from two plastic bags ?
    Alby ?

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