A Pilot Scale Evaluation of Rotating Biological Surface
Treatment of Pulp and Paper Mill Wastes
WILLIAM J. GILLESPIE, Regional Engineer
National Council for Air and Stream Improvement, Inc.
Gainesville, Florida 32604
DUANE W. MARSHALL. Regional Engineer
ALAN M. SPRINGER, Research Engineer
National Council for Air and Stream Improvement, Inc.
Kalamazoo, Michigan 49001
INTRODUCTION
The history and description of the Rotating Biological Surface (RBS) method of
secondary treatment is well documented elsewhere (I, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11).
Consequently, these matters will be dealt with only briefly in this presentation.
The early development of the process took place in Europe where it is widely applied as
a treatment method for domestic sewage and some industrial wastes. Commercial development of the process in the United States gained momentum in the 1960's. To date there
are numerous applications in domestic sewage plants and such industries as food and
beverage processing and packing plants. A review of the available literature on these
installations suggests that 1) prior to this study there was no experience with this system
treating wastes of pulp and paper origin, and 2) the bulk of the literature has its origin in
the manufacturers of RBS equipment. It was therefore decided that an independent evaluation of the system's capabilities on pulp and paper wastes was in order.
For those unfamiliar with the basics of the system. Figure 1 should provide the
highlights. The heart of the system consists of a series of disc-like surfaces mounted
perpendicular to a horizontal shaft. The shafts are mounted over trough-shaped basins so as
to place the discs about half-submerged in the wastewater being treated. Slow rotation of
the shafts causes alternate submersion and atmospheric exposure of the biomass attached
to the disc surfaces. Excess biomass is eventually sloughed off these surfaces, hence
secondary clarifiers are needed to assure acceptable effluent suspended solids
concentrations. Alight shelter is required to prevent rain scour of the attached biomass and
some insulation may be necessary depending on ambient and wastewater temperatures.
Figure I — Typical     RBS    treatment
plant (11).
Advantages claimed by the manufacturer for these systems include: 1) Simplicity of
operation — there is no need for either effluent or secondary sludge recycle, hence no need
for matching recycle rate with effluent flow or strength; 2) Low maintenance — all moving
parts of the low speed variety; 3) Low power consumption — the shafts are essentially
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