FIELD PERFORMANCE OF THREE RBC AERATION
MODES TREATING INDUSTRIAL WASTES
Charles Chi-Su Chou, Manager
New Products Development
Robert J. Hynek, Manager
Process Verification and Pilot Plant Program
Autotrol Corporation
Milwaukee, Wisconsin 53209
Present rotating biological contactor (RBC) processes and equipment have evolved to a
considerably higher degree of understanding, application and mechanical design from the
original concept of rotating flat wooden, metal or polystyrene discs for wastewater treatment or mass transfer of gases to liquids. This evolution from the turn of the century to
1980 followed an event curve similar to many other technologies in which the most rapid
advances occurred in the latter 25% of the time span. In this case, RBC advances in equipment took the form of changing to more economical and cost effective high density polyethylene media with an internal honeycomb structure of greater surface area density.
From a process application standpoint, RBC wastewater treatment has advanced from
only BOD removal to nitrification, in combination or alone, and to nutrient removal and
denitrification [ 1 ]. In addition, significant process and operational advantages have been
gained by the utilization of aeration within the liquid to increase specific BOD removal
rates. This latter development not only resulted in a revolutionary method of rotation
[21, it also resulted in a unique method for upgrading existing activated sludge plants at
a minimum cost [3] .
This new development eventually extended to a detailed study which confirmed the
cost effectiveness of providing supplemental aeration under existing mechanically driven
RBC equipment [4].
This paper will discuss application of the three modes of RBC aeration at installations
treating beef and poultry processing, dairy and refinery wastewaters.
BIO-SURF TREATMENT OF BEEF AND FOWL PROCESSING WASTE
Wastewater Characteristics
The wastewater treatment plant of Gibbon, Nebraska receives a combination of beef
slaughtering waste, turkey processing waste and community sewage. The treatment plant
serves a population of only 1,500 and the major waste load (94% of BOD loading, 75% of
hydraulic loading) is from the industrial section. Normally, the meat packing company
slaughters 500 head of cattle per day and discharges 200,000-300,000 gpd after pretreatment by skimming and sedimentation. The turkey plant operates 8-10 months a year and
contributes as much as 550,000 gpd of waste flow [51 ; however, its waste strength is lower
than the beef slaughtering waste.
Pretreatment
The beef plant has a basic pretreatment system, a flow-through settling tank where a
skimmer removes grease before the effluent goes to the combined treatment plant. The
poultry plant pretreats its waste with a set of screens and microstrainer, followed by
primary settling. Both of the industrial streams are monitored regularly and the monthly
average results from March, 1979 to February, 1980 are summarized in Table I and Figure 1.
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