Rolling Algae Scrubber (RAS),The new method for culturing algae

[ifa2002]

Ok …So in this new method I decided to remove the problems of ATS and UAS and design a system that is quite simple and effective…

large growing area in Limited space
Low power consumption
No need for additional pumps ( or air pumps)
No problem when the water flow stopped for a long time
Reduction in pods populations (vertigo takes them !!? Practical work needs to prove)

Waiting for your comments…
Thanks and sorry for bad English!

http://uploadpic.ir/up/images/ras.jpg

[kerry]

This has been around for awhile and no one has really talked of any success with it that I have heard of. The bad part about them is that its one sided, to be very efficient it needs to be lit on both sides.

[Garf]

On a positive note, your English is better than mine, so no problems there !

[jnad]

Hmm, might work, i like to test tings, you should test it. But i think the mechanical design by having some thing rotating is a drawback.

Ps! I have been thinking, and testing, thinking, and testing scrubbers so mutch that i actually forgot maintaining my tank :) this was of topic.

Jnad

[dryworm]

im interested in seeing it in action. i'll be following along

[gmoney243]

yea its been thought of before. i knew someone who used one. the problem is the wheel spins constant and fast so the algae never gets much light. even if you kept the light on 24/7 the screen will be dark about 75% of the time due to it spining out of sight of the light. and without constant light algae doesnt grow as well. it cant really get the light it needs with only short bursts of light as it passes around. it would probly work if you could figure how to light the whole screen constantly for 18hours/day so the algae never gets out of sight of light untill you tunr it off.

[Floyd R Turbo]

I think something is being missed here and it has to do with the concept of flashing. Rotating builds of the past have used standard light levels and then blamed failure on the fact stated above, >75% of the time, the algae is dark. Studies going back to the 1930s showed that alternating light and dark periods on the order of milliseconds produce just as much photosynthetic results as constant light. The key is and always comes back to intensity.

T5HO and CFL lights will not do in a setup like this, even with the best reflectors. You must use LEDs, and likely with lenses so that the light is extremely, extremely intense on top of the screen so that the cells get blasted with light, then go dark and transfer that energy to the next step of the process so they can be ready to absorb light again.

I'm talking a row of 660s almost stacked one on top of the other. Get the Philips Luxeons from Steve's LEDs + lenses and put them a few inches away, that should do it.

[kerry]

LOL, I thought the same thing after posting to Floyd. Have you got your timer built yet? I have not attempted anything yet.

[Floyd R Turbo]

I wish I could build time. That would be awesome.

[kerry]

I wish I could build time. That would be awesome.

Timer, my bad.

[Floyd R Turbo]

Nope. Probably not for another week or so.

[herring_fish]

This product has indeed been around for around 20 years. I believe that this design was created as a way to get around a patent so that it could be made available for retail sale. Unfortunately, sales never got too high.

I will do a little rambling so I hope that you don't mind. I think that there have been some good points that have been brought up and I will simply play devil's advocate to spark a little more thought on the subject. I haven't really formed and opinion here. It might be a great experiment. LED's can be expensive but they can be re-applied to a more standard design if it does not work out.
When I read those papers, the light periods where much less than a second. As Floyd said, many studies used algae beds that were flashed thousands of time per second. This leads me to believe that light photons are process at very very high rates.

A wheel rotates slowly, relative to the "sub light speed" of a good flasher. The algae may be exposed to light for ...say three seconds. Light saturation happens instantly, for all practical purposes. I don't remember many studies that are run under a much longer flash cycle. I drum might take 1 to 5 second to turn around or much more, depending on the speed. The algae would be lit for maybe one quarter of that time, coming to a peak for and eighth?

I would guess saturation will happen no matter what speed the drum turns. My first thought was that what you are left with is too much darkness in the cycle.

On the other hand Floyd might have some part of a very valid point after all because the studies were initiated from questions around the flashing that comes from waves in the sun light concentrating light on the algae. I don't remember the term but wave flashing can have somewhat long "low light" periods. There needs to be more studies on longer photo periods.

Another, probably bigger, issue with the drum is that the motion of the drum or wheel produces water flow over the algae but that flow is still laminar so the algae can still become packed down or clumped. Algae grows much better in turbulent water motion.

[<Edited In> It would be hard to do but if you could get the incoming water distributed evenly along the entire drum and running in the opposite direction of rotation. This would help to add turbulence and it might help but....]

That is why bubbles, flow surge devices, dump buckets, motor driven shifting screens or rocking trays are used. These designs increase the efficiencies per square inch of lighted screen.

Finally, the earlier point is true that the separate issue of efficiency per cubic foot of scrubber unit space is lower because of the one sided nature of the design.

[RkyRickstr]

I wish i had the space to just test it. Can some ine just test this?.. lol