7819

• UCREFRP Catalog Number: 7819
• Author: Many
• Title: Journal of Applied Aquaculture
• USFW Year: 1992
• USFW - Doc Type: 1‎(3)‎
• Copyright Material: YES

Palter 21
TAIILE 3. Sensitivity of a model that predicts the carrying capacity of biofilters.
Tabulated values arc the~percent changes in carrying capacity resulting from 20%
and 40% increases in each parameter of the model described in this paper. Each
parameter was varied individually, while the others were held constant.

Parameter

Symbol Parameter
increase
of 20t: Parameter
increase
of 40~
Flow rate (1/min} F 6.1 10.8
Ammonia concentration (mg/1) C 20.0 90.0
Ammonia production
(mg/kg fish/min) A -16.6 -28.6
Temperature (°C) T 18.6 37.2
Freshwater flush (1/min) L 3.3 6.6
Biofilter depth (cm) D 8.8 16.1
Biofilter cross- X 8.8 16.1
sectional area (cmZ}
Ammonia removal R 16.7 33.4
were multiplied to yield Biofilter volume. Freshwater flush rate was
reduced to zero for similar reasons; all other parameters were kept
at the standard values. Carrying capacity differed little between
high ammonia removal (R = 0.63) S-1 and 2S-t biofilters when
flow rates were very low (Figure 4). As the flow rate increased, the
carrying capacity of both biofilters increased; but that of the 25-1
Biofilter increased far more than that of the S-1 biofitter. In both
biofilters, the relationship between flow rate and carrying capacity
was asymptotic. This simulation indicated that increasing the size
of a biofitter will not necessarily increase carrying capacity unless
the flow rate is also increased.
Figure 4 illustrates that carrying capacity initially increases rap-
idly with flow rate but eventually reaches a level at which further
increases in flow rate have little effect. To optimize performance, it
is desirable to operate at flow rates higher than those in the steeply
ascending portion of this curve but below those near the asymptote.
Very low flows are inefficient because they result in a large loss of
potential carrying capacity. Very high flows are inefficient because