TABLE OF CONTENTS Pages Symposium 1 - the National Sea ...

The Cyclone Sand Biofilter: A New Design Concept and
Field Evaluation
Background
Michael B. Timmons, Professor
Agricultural and Biological Engineering, Cornell University
Ithaca, NY 14853
Neil Helwig, Engineer
Marine Biotech, Inc
Beverly, MA 01915
Steven T. Summerfelt, Research Engineer
Conservation Fund Freshwater Institute
Shepherdstown, WV 25443
Being economically competitive in world fish production will require that we implement
large scale fish farms that require ammonia assimilation rates on the order of 40 kg
TAN/day (1,000,000 lb per year fish farms). This requires 40 m 3 of bed volume in a
granular biofilter 1 or about 5x this volume (about 200 m 3 ) for a more typical biofilter
using media with much lower specific surface areas than sand. Table 1 summarizes the
estimated costs associated just with the biofilter for a 1,000,000 lb (454 MTON) per year
tilapia farm.
Table 1. Capital costs associated with biofilter choices for a tilapia farm producing
1,000,000 lb (454 MTON) annually. Cost is listed as $ per PPY (i.e., pound per year).
Biofilter Type Farm Cost Cost, $ per PPY
Rotating Biological Contactor 1
$668,000 $0.68
Trickling Biofilter 2
$620,000 $0.62
Bead Filter 3
$296,000 $0.30
Conventional Fluidized-Sand Biofilter 2
$124,000 $0.12
Cyclo Biofilter 3
1
Timmons et al. (1993).
2
Extrapolated from Summerfelt (1999).
$76,000 $0.08
3
Prices provided by the commercial manufacturer or their catalogs.
The manufacturers of alternate biofilters would probably argue with the above table and
the authors do not intend to disparage alternatives. For example, the bubble wash filter
can be used as a solids collection device as well, which reduces its "effective" cost for
biofiltration. Yet, Table 1 is fairly demonstrative in showing the large economic
advantage to a cyclone biofilter.
1 See Timmons and Summerfelt (1998) to see methodology for estimating bed volume requirements.
1