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    Move Over BioPellets, Rice Is Here…

    Using rice like a solid carbon source “biopellet”? Some daring aquarists are giving it a try…

    rice biopellet

    Using solid “biodegradable” materials as a carbon source in aquariums is a relatively new trend that has caught on with rapid pace–and it’s already taking some offbeat twists. The lastest material some daring aquarists have begun experimenting with is rice.  Yes, the abundant grain that can be found virtually anywhere for a a few bucks.

    What sparked this recent discussion? In 2009 a study on the use of rice husks as a carbon source in waste water denitrification was published by the Tonji University in Shanghai [PDF]. They found nitrate removal efficiency was increased with rice husks and the material could be an economically effective carbon source for wastewater treatment. See the abstract below:

    In this research, rice husk, a lignocellulosic waste from agroindustry, was investigated as the sole carbon source as well as biofilm carrier in the biological denitrification of wastewater in up-flow laboratory reactors.An artificial wastewater with a temperature in the range of 27–33 ?C was used. Fast startup of the reactor and a high nitrate removal efficiency was observed. The highest rates of denitrification about 0.096 kg/m3 d were achieved when flow rate and nitrate concentration were 41.4 L/d and 25.0 mg/L, respectively.

    Nitrite accumulation in treated water was practically zero during the experiments. Flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. A very sharp decline was observed when the flow rate reached 30 L/d. The reactor had the ability to accommodate a wind range of pH(6.5–8.5) and DO(1.5–4). A time-dependent decrease in nitrate removal ratewas observed after 72 days of operation. And the addition of new rice husk brought about a rapid increase of the nitrate removal efficiency. The results showed that rice husk could be an economical and effective carbon source for the nitrate removal process.

    Can rice act as a carbon source for bacteria? Yes, but I wouldn’t recommend it–and that’s coming from someone who loves to experiment. If your worried about costs, try sugar. Not only is it much cleaner it allows the dosing to be adjusted. The notion that you cannot “overdose” a solid carbon source is quite misleading.

    [image: IMH creative commons]

    11 Comments

    1. Shrimpchips
      July 22, 2010 at 9:20 AM | Permalink

      I don't know the size of ther reactor they used, but at 41.4l/d or 0.46 gph through the reactor, it's sounds more like an anaerobic denitrator, especially with that 10+ week maturation time required it to function properly.

    2. Jake Adams
      July 22, 2010 at 10:04 AM | Permalink

      Hey Bo, watch this!

    3. July 22, 2010 at 2:10 PM | Permalink

      Does it do anything for phosphate?

    4. Hesham El-Adly
      July 22, 2010 at 7:28 PM | Permalink

      Can you explain how a solid carbon source can be overdosed?

    5. Danny
      July 23, 2010 at 10:56 AM | Permalink

      the same thing has already been done with bails of hay in public aquariums bc the bacteria that break down the hay also use up the compounds that you are attempting to eliminate

    6. Alex
      July 26, 2010 at 12:20 AM | Permalink

      Please note “rice husk” <> “rice”

    7. RC Demon
      July 26, 2010 at 11:15 PM | Permalink

      check out the chemistry forum on rc. This rice thing looks very promising.

    8. Nugburner
      August 3, 2010 at 11:43 AM | Permalink

      long story short, if you add to much pellets at once all the beneficial bacteria has no place to go in your tank. this overabundance of bacteria causes a bacteria bloom and sucks all the available oxygen from the water killing or stressing out the fish and inverts. since both aerobic and anaerobic bacteria can change at will what type of bacteria they want to be, it makes it hard to save the tank. added aeration makes them mad, water changes makes them really mad and they reproduce 50% more making the water worse than it was. only thing that worked for me was removing a amount of pellets and allowing the bacteria to find its way around the tank and back into the reactor. here is the science http://www.npbiopellets.com/index.php/how-it-works

    9. Nugburner
      August 3, 2010 at 6:43 AM | Permalink

      long story short, if you add to much pellets at once all the beneficial bacteria has no place to go in your tank. this overabundance of bacteria causes a bacteria bloom and sucks all the available oxygen from the water killing or stressing out the fish and inverts. since both aerobic and anaerobic bacteria can change at will what type of bacteria they want to be, it makes it hard to save the tank. added aeration makes them mad, water changes makes them really mad and they reproduce 50% more making the water worse than it was. only thing that worked for me was removing a amount of pellets and allowing the bacteria to find its way around the tank and back into the reactor. here is the science http://www.npbiopellets.com/index.php/how-it-works

    10. RC member
      August 21, 2010 at 6:34 PM | Permalink

      IMO rice breaks down too quickly and due to its porous nature can break down from the inside out which isn’t good. There is also a small amount of protein locked in the rice which will cause nitrates not rid them. There are also a lot of unknowns regarding the other minerals contained within the rice.

    11. Schwa6970
      October 4, 2010 at 11:24 PM | Permalink

      I tried it in a filter sock stuffed in one of the baffles in my sump. It seemed to work good at first but soon started to affect the inhabitants in my tank coral tips started bleaching and my 2 chalices lost their color. I took the rice out after about a month and it smelled like a rotten egg I am presuming due to production of Hydrogen Sulfide due to not enough flow. I have since started using Biopellets in a Rena XP-3 canister filter. I think I should have enough flow going through it now and hopefully wont have the same issue as the rice.

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