Li asked
>Q1: Is it mandatory to remove phosphorus in effluents from rainbow trout
>farming in your country? If so, what is the criterion?

A: The EPA (Environmental Protection Agency) is currently gathering data
to develop general regulations for the aquaculture industry in the USA.
The trout industry in Idaho has to reduce the discharge of phosphorus by
40% over the next 5 years and I'm sure that they will choose the most
cost effective methods. The P in their water is typically less than 0.3
ppm, which I believe is too low to grow marketable crops using our
system of production while reducing it much further. I'm not sure you
can go much below 0.5 and still remove P to less than 0.01. Our trout
production system was a recycle system, so nutrient levels were higher
than in raceway systems.

>Q2: Who will pay for removing phosphorus?

A: First the farmers will pay and then they will raise their prices and
the consumers will pay.

>Q3: Is your technology suitable for warm water fish farming?

A: Our production system can be used to grow plants on any effluents. It
is a system to maximize removal of nutrients. In our specific situation,
we discharged the effluent, it did not return to the fish system. The
water was too warm to return to grow trout. The trout production system
recycle rate is determined by water temperature, i.e., they bring enough
water in to maintain the water temperature at the best level for trout
production. The CPS maintains a relatively contant biomass, so nutrient
removal remains relatively constant and luxury consumption allows
removal of nutrients to very low levels.

Paul
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Paul R. Adler, Ph.D.
USDA-ARS, Kearneysville, USA
Web site http://afrsweb.usda.gov