February 15-18, 2009 Washington State Convention Center Seattle ...

4
GREENHOUSE GAS EMISSIONS ASSOCIATED WITH DIRECT ENERGY INPUTS FOR A
WARMWATER LOW-SALINITY RECIRCULATING AQUACULTURE SYSTEMS
Max Davis*, Timothy J. Pfeiffer and Paul Wills
Florida Atlantic University
Boca Raton, FL. 33431 USA
bdavis35@FAU.edu
Recirculating aquaculture systems offer a solution to declining natural finfish stocks while limiting nutrient outputs and eutrophication
of effluent waters. Because water is reused in these systems, the solids must be efficiently removed by mechanical
treatment devices otherwise the solids buildup in these systems cause the cultured fish to be unpalatable and more importantly
unmarketable. This study evaluated particle size distribution and removal efficiency (RE) of three paired tank clarifiers in
three 43 m³ systems used in rearing juvenile red drum for stock enhancement purposes. The three clarifiers being tested for
removal efficiency were the 0.6 m³ swirl separator, 0.6 m³ static bed filter and the 0.6 m³ moving bed torrus filter. Water samples
were collected from the influent and effluent lines of each filter and serial fractionated through sieves ranging from 200 to 55
microns. Total suspended solid analysis was conducted on each set of influent and effluent samples to determine the particle
size distribution and percent removal efficiency of each filter type. The static bed filter had the highest removal efficiency for
total suspended solid particles (44% RE), and greater than 45% removal efficiency of all particles in the 200 through 55 micron
size range. The swirl separator had removal efficiency of over 45% for particles greater than 200 um. The moving bead torrus
filter had the least removal efficiency of particles between 200 to 55 microns but removed 9% of particles less than 55 microns.
Over 90% of solids in the influent and effluent samples were less than 55 microns in size the static bed demonstrated the best
removal of particles in this size range. The static bed clarifier removed 23% of particles in the less than 55 micron size range.
Overall, the static bed had the best removal efficiency of particles of all size ranges and was the most efficient clarifier. The
moving bed torrus filter had the second best total removal efficiency of 16% of which half of those particles were less than 55
microns in size.