ROTATING BIOLOGICAL CONTACTOR TREATMENT
OF SHELLFISH PROCESSING WASTEWATERS
James W. Hudson, Research Associate
Jeffery P. Smith, Graduate Student
Frederick G. Pohland, Professor
School of Civil Engineering
Georgia Institute of Technology
Atlanta, Georgia 30332
INTRODUCTION
There has in recent years been noticeable evidence of an increased regulatory concern
by federal, state and local environmental protection authorities oriented toward the
definition and resolution of waste management problems associated with many industrial
discharges.   This has been particularly apparent for those industries for which basic
characterization and treatment information has been lacking.   The shellfish processing
industry falls into this grouping and, consequently, has been placed under greater pressure
to find and implement waste discharge procedures which promote fulfillment of current
national objectives.
Previous investigations [1-3] have primarily focused upon basic wastewater characterization and various conventional treatment methods applicable to shellfish processing
discharges.   These findings have indicated a potential for applying conventional technology
with production of high effluent quality.   However, adoption of conventional field-scale
treatment methods may be prohibitive when considering a normal processor's financial
perspective.   To possibly enhance the stature of on-site treatment as a viable alternative,
investigations have been conducted to establish the applicability and/or limitations of a
less conventional, but potentially more economical treatment mode, the rotating biological
contactor (hereafter referred to as RBC).
WASTEWATER SOURCE AND SAMPLING
Wastewater samples emanating from a Georgia coastal shrimp processing plant were
collected and transported to the Sanitary Engineering  laboratories at the Georgia Institute
of Technology as required to conduct the experimental runs.   The plant surveyed produces
on the annual average 40,000 lb/day of  processed (breaded and frozen) shrimp with
little seasonal variation.   Production line operations followed essentially the same flow
pattern as described by Horn [ 1 ].
All processing wastewater was screened prior to discharge to remove gross solids.
The screened wastewater was collected with a submersible pump at a manhole located
prior to the final discharge port.   Approximately 140 gal of wastewater was so collected
in three 55-gal barrels, immediately transported to the research laboratory, and placed
in a 37 F cold room.   All collections occurred within the same daily time period in an
effort to minimize the wastewater character differences normally associated with periodic
"grab-type" sampling.   As a result, the processing operations of grading, peeling-deveining
and breading which occurred during the sampling period were the only operations which
influenced the final wastewater character.
LABORATORY APPARATUS AND EXPERIMENTAL METHODS
Schematic representation of the experimental RBC apparatus is presented in Figure 1.
The apparatus was composed of two distinct stages with 17 plexiglass discs in each.   The
two sets of discs were set in a single-unit assembly on an "A" frame which allowed
simultaneous placement into the reactor basins.   Both sets of discs were then rotated by
a single variable-speed motor with "0"-ring linkages.   Overall dimensions of the total unit
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