Systemation in Using the Rotating
Biological Surface (RBS) Waste
Treatment Process
ROBERT H. JOOST, Manager
Environmental Pollution Control, Inc.
Oconomowoc, Wisconsin
INTRODUCTION
The rotating biological surface (RBS) waste treatment process will emerge as a
very significant contribution to the waste treatment industry. The many basic advantages of this process, enhances its selection in an application over the trickling
filter and the many activated sludge processes. In addition to the basic advantages of
the RBS, close attention to the physical characteristics and process variations can
lead to other advantages and alternative solutions heretofore not available to the
engineer. It is the purpose of this paper to present some of the many valuable aspects
of this process and to outline some of the inherent characteristcs. Knowledge of
these aspects and characteristics will give to the engineer additional tools in his
determination to supply not only successful, but self satisfying waste treatment
systems. Use of the alternatives available and incorporation of the flexibility inherent
with this process, hopefully will be the result of this paper.
BACKGROUND
It may be well to review just what the RBS process is. . . and how it is basically
used. Figure 1 is a diagram showing the typical trickling filter and activated sludge
secondary waste treatment process. Removing lines A and B from this diagram will
produce a flow diagram of the RBS secondary waste treatment process. The biological
reactor is both a unit operation and a unit process which has the classic definition,
"the commercialization of a chemical reaction under such conditions as to be economically profitable." This latter part may be well to remember as profits are what
the RBS is all about. The biological reactor may be the aeration tank of the activated
sludge, the biological support media in the trickling filter or the RBS.
Figure 2 depicts the RBS biological reactor. Physically the RBS is a series of
closely spaced vertical discs, mounted on a horizontal driven shaft. The shaft is supported by bearings and is slowly rotated by power driven equipment. The rotating
shaft alternately dips the disc surfaces into the waste material and then into the air.
Waste material continuously flows parallel to the discs. The waste level is slightly
less than half the disc diameter. Intimate contact between the waste material and
disc surfaces is provided by contoured tank bottoms.
Figure 3 is a cutaway view of the rotating discs. During initial operations, a
biomass is quickly established on the disc surface.   These colonies of bacteria will
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