Hello Paul

thank you for a very interesting and well written paper. I have some
comments and questions.

>In this fish production system, solids are removed with a triangle
>filter. The triangle filter is able to remove about 80% of the P excreted
>by the fish with the biosolids, leaving about 20% of the P in the effluent.

what do you do with the filtered material, is there any use for this material ?

>Production of 50,000 pounds of rainbow trout (will consume
>about 60,000 pounds feed at a feed conversion ratio of
>1.2 pounds feed/pound gain) generates 98.4 Kg P. Of that
>98.4 Kg P, 22.6 Kg P is in the effluent and the rest (77%) is
>in the biosolids (Heinen et al., 1996). It will take
>12,600-16,700 ft 2 greenhouse space to remove 22.6 kg of P
>from the effluent.

If we compare the above scenario operation to that of a conventional
hydroponic lettuce production of the same scale, what would the costs of
chemicals/plant nutrient input costs ?

Could it be that the use of effluent would be require less and low costs
for chemicals/plant nutrients ?

regards
jacky foo
Coordinator - IBSnet
http://www.ias.unu.edu/proceedings/icibs/ibs/ibsnet/directory.html