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Thread: Photosynthetically Induced Phosphate Precipitation

  1. #21

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    Garf im doing some testing at the momment tell me what you think. Im rumming a full dose of bio pellets im my tank its been 4 weeks im waiting till the 6 or 8th week to make sure the pellets are on full power and then im gonna start my algae scrubber . My belive on this is that the pellets consume all the nitrates and some phosphates so whem I add my scrubber I fill force it to start growing on phosphates and maybe I get lucky and get the magical phosphates removing algae. The scrubber will never have chance to consume nitrates since the pellets consume nitrates at a much faster rate than algae

  2. #22
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    Been doing a bit more reading;

    The first maximum, at approximately pH 8.75, is due to precipitation of P onto and/or into the cell walls of the algal turf, in accordance with the method disclosed and claimed herein. The maximum rate of P removal,at about pH 8.75, was about 0.22 mg/U15 min in this example. The preferred pH range for precipitating P onto and/or into the cell walls of the algae, in this example, ranges from about pH 8.3 to about pH 9.4. The decrease in rate of P removal above the maximum at pH 8.75 reflects the deleterious effects of increasing pH above about pH 8.75 on the efficiency of P removal due to precipitation onto and/or into the cell walls of the algal turf, for this example. The pH of maximum rate of P removal, the slope of the curve on either side of the maximum, and the maximum rate of P removal all may vary with changes in the particular water flowing through the floway. Such changes include variations such as initial pH, salt concentration, nutrient concentration, and the concentration of other species which may have an effect on the algae. The dashed line tailing away from this peak represents the inferred rate of P removal due solely to precipitation of P onto and/or into the cell walls of thealgae as the pH continues to increase.
    So, 8.75 is the maximum but benefits increase from 8.3 to 8.75 (the algae cells then attain a pH of 9.9 which causes the precipitation)

    a portion of the algal turf is harvested after pollutants, such as phosphorus, have precipitated onto and/or into the cell walls of the algae forming the algal turf. The harvested algal turf may contain atleast 2.0% phosphorus, for example, per unit dry weight of algae. When phosphorus is precipitated according to the invention, the harvested algal turf may comprise at least 1.5% phosphorus in the form of phosphate precipitated on the walls of the algae. In addition, if phosphorus in the form of particulates is in the water, adjustments may be made to algal biomass and/or composition to also trap the particulates. Such trapping would increase the phosphorus content of the harvested algal turf in somesituations to about 5% of dry weight. A significant portion of the phosphate obtained is attributable to the site-specific precipitation action provided by the method of the present invention. The actual level is a function of many variables, including concentration in the wastewater, the relative particulate versus dissolved concentration of the phosphorus, and how the floway operational parameters are controlled. However, of the 5% dry weight maximum amount cited, approximately 0.5% is due to metabolic uptake, at least 2.0% due to precipitation, and at least 1.5% due to particulate trapping. Clearly, the precipitation element is very important to the efficiency of pollution removal on a large scale.
    Running this as a precipitation filter alone, could increase the phos removed by 400% + any trapped particulates.
    Running the screen effluent through some sort of a particulate filter (horizontal scrubber for example) could increase phos removal by 1000%

    Now I'm trying to check if any other good stuff precipitates out at the same time (perhaps that's why some screens just don't work)

  3. #23

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    Quote Originally Posted by Garf View Post
    Been doing a bit more reading;



    So, 8.75 is the maximum but benefits increase from 8.3 to 8.75 (the algae cells then attain a pH of 9.9 which causes the precipitation)



    Running this as a precipitation filter alone, could increase the phos removed by 400% + any trapped particulates.
    Running the screen effluent through some sort of a particulate filter (horizontal scrubber for example) could increase phos removal by 1000%

    Now I'm trying to check if any other good stuff precipitates out at the same time (perhaps that's why some screens just don't work)
    You're going to have to translate all of this when you have it figured out

  4. #24

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    Quote Originally Posted by Garf View Post
    Been doing a bit more reading;



    So, 8.75 is the maximum but benefits increase from 8.3 to 8.75 (the algae cells then attain a pH of 9.9 which causes the precipitation)



    Running this as a precipitation filter alone, could increase the phos removed by 400% + any trapped particulates.
    Running the screen effluent through some sort of a particulate filter (horizontal scrubber for example) could increase phos removal by 1000%

    Now I'm trying to check if any other good stuff precipitates out at the same time (perhaps that's why some screens just don't work)
    Interesting. Where did the numbers come from? Adey? I'm glad to see quantitative analysis beyond the theory Adey proposed to occur. I had a good idea that this may have been occurring in my scrubber system a few years ago.

  5. #25

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    So running effluent through a filter sock, for example? If that's the case, won't that trap all the "food" that we're creating by running scrubbers in the first place?

  6. #26

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    Quote Originally Posted by WannaRace View Post
    So running effluent through a filter sock, for example? If that's the case, won't that trap all the "food" that we're creating by running scrubbers in the first place?
    Shouldn't be necessary and may not work as well as it may first seem, since it may be able to redissolve in such a situation. Precipitate granules should adhere to the algal strands themselves to some extent or another, as do many particles. As stated already, this would be even more exaggerated in horizontal or slightly more angled setups vs. vertical ones.

  7. #27
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    Ummm.. wow? So we are saying a horizontal scrubber may in fact work much better than a vertical scrubber if built correctly? To me this seems like a huge deal if proven to be true.

  8. #28

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    Quote Originally Posted by Ace25 View Post
    Ummm.. wow? So we are saying a horizontal scrubber may in fact work much better than a vertical scrubber if built correctly? To me this seems like a huge deal if proven to be true.
    Not sure . Vertical ones still have their superior features, namely sheer surface area vs. space consumed. I think enough precipitation can be induced in many cases with vertical scrubbers, if that is the end goal. On my last scrubber, I used plain kalkwasser (no vinegar) and system pH always remained high (like 8.4), so I can imagine it was even higher on the scrubber. PO4 was almost always undetectable using Hanna. I simply picked up feeding to force a tiny bit of PO4 to reduce nitrate. A bit lopsided, but not a bad situation to have from what I could tell. Current tank is way too young to make any conclusions, nor do I have any PO4 or NO3 reagents and/or tests left. Honestly, I'm not even going to worry about it unless I start seeing problems start. The only tests I have are calcium, alkalinity, and magnesium.

  9. #29
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    Ace - i think if anyone needs to increase phos removal rate 10 fold to normal algae uptake rates, there may be a problem lying elsewhere The 4 fold increase should prove more than enough to manipulate phos levels as desired. Here's a chart used to prove the principle. You'll notice that it indicates "Average" pH of the process water (not necessarily display water).


  10. #30

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    I was thinking that if higher PH water at the surface of the algae will cause more absorption or utilization of PO4 by the algae on the scrubber screen, one can drip kalwasser into the overflow of that is what is directly feeding the scrubber? Is this what's being suggested?

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