Growing Algae For Fun And Profit

Supposedly, writes [Severin], algae is a super food, can be used as biofuel, and even be made into yoga mats. So he’s built an algal reactor at Munich Maker Lab, to try to achieve a decent algal yield.

You might expect that  sourcing live algae would be as simple as scraping up a bit of green slime from a nearby pond, but that yields an uncertain mix of species. [Severin] wanted Chlorella algae for his experiment because its high fat content makes it suitable for biodiesel experiments, so had to source his culture from an aquatic shop.

The reactor takes the form of a spiral of transparent plastic tube surrounding a CFL lamp as a light source, all mounted on a lasercut wooden enclosure housing a pump. A separate glass jar forms a reservoir for the algal-rich water. He does not mention whether or not he adds any nutrient to the mix.

Left to its own devices the machine seems to work rather well, a 48 hour session yielding an impressively green algal soup. Sustained running does cause a problem though, the pipes block up with accumulated algae and the machine needs cleaning by blasting it with high pressure water and a healthy dose of nuts and bolts.

This isn’t the first algal reactor we’ve featured here on Hackaday, we had this Arduino-powered one back in 2009. But mostly the algae that have appeared here have been of the bioluminescent variety, as with this teaching project, or this night light.

53 thoughts on “Growing Algae For Fun And Profit

      1. Cooking vegetables breaks down the pectin, not the cell membranes. Cooking meat breaks down the connective fibers, not the cell membranes. So cooking isn’t necessarily the answer, no. If our digestive system can’t crack the cell membranes of algae, it’s not digestible without processing.

        What I’m wondering: why not have a large clear cylindrical container/bucket, with inward-facing LEDs of the specific wavelengths the algae needs (CFLs almost certainly put out a lot of light the algae doesn’t photosynthesize), and paddle scrapers that keep the walls clean? A large Cambro container would probably work well and not be too expensive…

        Example wavelengths:

          1. Does the algae need to surround the light? Some wet lab people I know just have jugs of algae and separate lights a couple feet away. Also air bubblers like out of a fish tank.

          2. I think you would need some sort of circulation using one or probably several air stones, but obviously I’ve never tried it.

            All I can say is that if jugs and separate lights work, I can’t argue with success. Although “jug” implies a narrow necked container, which sounds like it makes it difficult to harvest all the algae.

        1. Cooking really does break down cell membranes, which are primarily lipids (with proteins in them). Heck, even drying (or putting in pure-ish water) formerly living tissue will break down cell membranes.

          The cell walls of the algae on the other hand are primarily cellulose based. This material doesn’t break down exactly during most cooking, but the typical plant cell wall will become disorganized upon cooking. The cellulose of specialized cell types like wood or xylem/phloem is a bit more robust and would survive conventional cooking.

          1. It’s been along time since my biology lessons.

            But I remember certain organisms cells hd more than the phosolipid bilayer (like we do) heating will smash that apart.

            Like plants have a cell wall made of ?cellulose which even after cooking remains mostly intact until you’ve ruined the nutrients or they have leached out? They ol’ don’t cook veg for more than 15 minutes thing.

  1. Fairly simple design. I wounder if it may be made simpler by having a bucket with A hole in the bottom that is filled by an inverted container for the light or perhaps from above?

      1. remember that algae are plants and therefore need light AND CO2 so having an all closed design will absolutely not work… the pump is here to make the grow liquid splash around a bit in the jar thereby allowing gas exchange to happen…

  2. I regularly scoop handfuls of thick green algae from my turf scrubber. The secret to growing algae is gas exchange, red light, and nitrates. Running a thin layer of water over a textured surface with a good reddish light source over it is a sure fire way to grow thick mats of algae. You must have a thin layer of water rapidly moving over the grow material. It assists with gas exchange tremendously. Upflow algae growing is slower because bubbles don’t actually increase gas exchange of water till they reach the surface and pop. It’s the agitation of the meniscus. You might be able to do it with micro bubbles though. As far as nutrients, algae thrives on phosphates and nitrates. These come from the breakdown of organic waste by bacteria in the water.

    1. So I have containers in my yard which stagnate water. Within the water I can see it’s murky, there are little critters moving around and often there is green slime.
      If I was to agitate (pump) this over the textured plate, do I need to look to add nutrients or does the atmosphere, items like leaves and dirt falling in give enough contribution to grow algae ?
      Basically, what’s the least amount of work needed (not having to provide feedstock) to grow lots of algae. Outdoors, in the sun, solar power providing the electric to run the pump.

      1. Take a look at an algae turf scrubber. We use them in the reef building community to rid our tanks of nutrients by providing a prime growing area for algae, usually outside the tank in a “maintenance” tank. By providing a good textured surface, a strong source of red and blue light, and agitation of the surface, algae will grow from the natural crap falling in the water. Leaves and other dead plant material are excellent, however you will need some source of nutrients. The algae can grow on just sunlight, but it grows remarkably faster when you provide it with nitrates and phosphates. The secret to a great turf scrubber is using a very thin layer of running water over a textured surface. This textured surface is usually a plastic mesh screen used for things like needle point. You can do it several other ways. Many people pump the water up into a pipe, which then turns into a 90 elbow and into another shorter pipe with holes cut into it. They hang the mesh screen below the horizontal pipe, so water drains down over the screen, back into the source. Algae then grows rapidly. Since you are using this outside, sunlight will give you several orders of magnitude more radiation and it should really take off.

        1. You should never EVER put any type of copper into a fish tank. This method is used to kill off things like ick, however you must use it in a tank for sick fish only. This tank must never be used for anything other than treating sick fish. Use of copper in most cases will kill your natural bacteria filter and any inverts like crabs and snails. The copper will impregnate into the silicone seals and leach back into the water, turning most display tanks into a fish graveyard.

      1. I bought a bag of copper sulfate pentahydrate a couple weeks back and haven’t gotten around to using it yet. I basically just drained the system and I’m trying to find something to soak the pump in to clear it out… I think the hoses are probably a total loss because of how soft the material is. I saw bleach mentioned in a thread on CNC Zone or something, but haven’t tried it yet either.

    1. Are you using tap water or deionized water, and is your water reservoir relatively well-sealed, or is it open-top?

      I’d shock it with chlorine bleach or hydrogen peroxide, physically cleaning anything you can reach (like disassembling the pump for example to clean it thoroughly), and then use a biocide. You’ll probably have to undo all the hose connections because algae might hide in the cracks between the fitting and hose. Google around for terms like “laser cutter biocide”…and if you know anyone who does beer brewing, they might have tips on disinfecting the system.

      At the end of the day you might have to clean the tube with various chemicals and then replace the hose.

      Check with the laser tube manufacturer to make sure whatever you use is safe for the mirrors, if they’re part of the cooling circuit…

      1. Most homebrewers use food grade phosphoric acid + a surfactant (aka StarSan) or iodophor solution. Big breweries also flush their stainless steel with hot (+150F) lye solution, but that’s a fairly dangerous undertaking that isn’t worth it for most people.

        I’d also add in the water cooled PC crowd who would have some good coolant anti-biofouling additives as many of them like to light up their cases and have clear tubes.

      2. Thanks for the advice!

        Distilled water is the best I could do locally– at least without some digging –and this temporary reservoir was semi-open. (It was covered, but not tightly.) I was still working on my final, sealed, opaque, reservoir with its inline safety interlock (to disable the laser if the coolant stops flowing) when some more pressing projects distracted me. :(

        Yeah, I think I’m going to have to replace the stock hoses as it is because they’re pretty crappy and soft, I feel like the algae has probably pretty well impregnated the surface of the rubber… I already have some reinforced vinyl hose but I’m worried about busting the glass fittings on the tube when I go to change them…

        I’ve pretty much come up with a procedure like: bleach the hell out of and physically clean the pump, then run like a 70/30 bleach/water solution through the system for a couple hours to kill anything in the tube, dump all that coolant, flush it out again, and if the tube and everything is clean, then start a new batch of distilled water coolant with some copper sulfate pentahydrate in it as a biocide agent.

        What’s the deal with the water? Should I be using deionized water? (Assuming I can find any…)

  3. Someone wanting to do this should look at how fishtank enthusiats have been fighting the algae problem for years. A simple google for fish tank algae scrubber should show what you need (which is normally a plastic sheet on a incline, with some sort of surface for the algae to grip and then a thin layer of water constantly flowing over it.). A large light facing this surface also helps.

    You pretty rapidly end up with something looking like this :

    1. Start with a controlled version; study and measure intensely all factors that affect algae growth; compile data for further analysis; synthesize for larger scale (with better equipment like solar cells with goals towards direct sunlight); wash, rinse, repeat till it works at a scale truly beneficial to humanity. Or have we forgotten how to engineer all of a sudden?

      In short, give him time. If you’re so inclined, replicate his project with the additions you speak of. It would go a longer way.

  4. ahhh so awesome reminds me of my bachelor thesis i worked with those little buggers :P. we considered the tube reactor design but in the end went for a more traditional glas mantle reactor with air bubles as the co2 deliver method.for anyone interested there was a huge research effort in the 80-90 from the DOE about growing and using algae as fuel. its really a treasure-trove of information that almost noone knows about. and best of all its free for anyone to read. careful huge PDF warning its over 300 pages long

    1. did you even read the article? it said so in the first sentence in the long term algae could be used as food , fuel and source for biopolymers. but why does everything has to be “profitable” in the first place in life money is not everything you know……

  5. Looks like a fun project, but if you are after a food production system just make sure you do get the right green goo because the wrong stuff could be one that produces a particularly cruel neurotoxin that destroys your brain’s ability to form new long term memories, if it doesn’t kill you completely.

  6. want to see biophotovoltaic or MFC made from chlorella.
    For food, watermeal (found in cuisine from North/North-eastern of Thailand) may be interested for cultivation.

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