Compiled by: Jay Warecki, Ph.D.
Director, Superior Aquaculture, LLC
(Report Released Sept., 2015)

  1. Fish Feed is normally the largest source of phosphorus to aquaculture systems.
  2. Approximately 70% of the phosphorus consumed can pass in feces. (Hakanson, et al. 1990)
  3. Similarly, Brown found that, “…the collected and dried waste from the raceways equaled 70.8% of the dry weight fed.”  (Brown, 2010)
  4. Additionally, in many cases, only 50 % of the total nutrients fed are utilized by the fish.
  5. Superior Floating Raceways offer the ability to effectively capture and remove, either automatically or manually, some huge percentage of the nutrient-rich feces.
  6. Specially integrated sediment collection pods are available and recommended.
  7. Because phosphorus rapidly leaches from feces, the feces should be removed every 6-36 hours, depending upon load, feed qualities, temperature, pH, etc.  (kabria, et al. 1997)
  8. Collected feces can be used in aquaponics, de-watered and fed to other animals, or used in fertilizers, mulch, etc.
  9. In addition to feces collection, the system also collects virtually all uneaten, settleable feed – which contains additional phosphorus.
  10. Uneaten feed and feces, “… are believed to contain most of their phosphorus in a water soluble, unstable form readily available to plants.”  (Butz and Vens-Cappell, 1982)
  11. While soluble reactive phosphorus in the form of fish urine may be minor in comparison to feces, it should be mitigated as possible.
  12. When Superior Floating Raceways are used in a pond setting, the soluble reactive phosphorus from the urine can be absorbed by macrophytes, algae, and bottom sediments – which can be quite acceptable when within reason.
  13. However, Superior Raceways offer the farmer a means of collecting the dissolved fraction of P once it has been absorbed by the algae. The fact is that the raceways serve as excellent “traps” for both algae and valuable zooplankton.
  14. “The phosphorus collected in the raceways was actually greater (138%) than the total phosphorus fed in the fish feed.”  (Brown, 2010)  This was attributed to the phosphorus in the lipid-rich algae and valuable and zooplankton.
  15. Further reductions in raceway nutrient discharge can be achieved by the addition of in-line, small particle, collection modules – as commonly used in in-door RAS operations.
  16. Fish farm settling ponds offer opportunities for both increased levels of phosphorus extraction and potential production expansions.

To discuss your potential application or to view the “complete report”, give us a call or contact us by email.

References
Brown, Travis. 2010. Intensive Culture…in a Commercial-Scale, In-Pond Raceway. Ph.D. Dissertation, Auburn University.

Butz, I. & Vens-Cappell, 1982. Organic load from metabolic products of rainbow trout fed with dry food. In Albaster, J.S. (ed), Report of the EIFAC Workshop on Fish Farm Effluents, EIFAC Tech. Pap. 41:57-70.

Kibria, G.D. Nugegoda, R. Fairclough, & P. Lam. Hydrobiologia 357: 165-171, 1997. Kluwer Academic Publishers.

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