I am curious about why it is different from carbon. Carbon does best with the most flow. So far the only fact is 'everyone says so' with no scientific or factual support.
This would be a good situation for an experiment. Setup 500g of tumbling GFO
in a reactor and see: how long it takes to be exhausted (exhausted defined as phosphate no longer undetectable in the output water) and the effect on the main water column. Compare this to 500g of GFO
in a reactor with a much higher flow rate and compare the two. I think that the higher flow will be more effective. Either way you should get undetectable phosphate in the output water, the difference will be how long it takes to become exhausted, sooner meaning the method is more effective (the same amount of GFO
exhausted sooner means it removed the same amount of phosphate in a shorter amount of time). Or they last the same amount of time but the impact on the phosphate concentration on the water column is different.
Even if the higher flow rate doesn't produce an undetectable phosphate concentration in the output water it could still be more effective. I think lower flow may get a lower concentration in the output water, but will not be as effective on the concentration in the water column, which is more important.
If anyone wants to set this up that would be amazing (should be very easy for anyone running GFO