Section Three
BIOLOGICAL SYSTEMS-A. AEROBIC
14   TOXIC ORGANIC SHOCK LOADING OF ROTATING
BIOLOGICAL CONTACTORS AND SEQUENCING
BATCH REACTORS
Suzanne L. Pisano, Graduate Student
James C. O'Shaughnessy, Professor
Danielle LaMarre, Undergraduate Student
Christine Gray, Undergraduate Student
Steve Pederson, Undergraduate Student
Mike Sykes, Undergraduate Student
Department of Civil Engineering
Worcester Polytechnic Institute
Worcester, Massachusetts 01609
INTRODUCTION
Rapid developments in industrial technology have introduced increasing amounts of organics,
nutrients, and toxins into all water resources. Regulation and source reduction cannot completely
eliminate the presence of these substances in wastewater. Therefore, environmental engineers must
evaluate and quantify the impact of these pollutants on wastewater treatment processes. Biological
treatment systems, because of their sensitivity to loading variation, external conditions, and toxins,
are of particular concern.
Two reactors commonly found in our infrastructure, the rotating biological contactor (RBC) and
the activated sludge system, have been studied under toxic loading conditions. The RBC system is
considered to be a quasi plug flow reactor. The activated sludge usually operates whether in quasi plug
flow or completely mixed flow regime.
Over the past decade, rotating biological contactors have become widespread in municipal and
industrial wastewater treatment plants. Congram1 reported that an RBC system installed for the
removal of phenol from wastewaters achieved acceptable removal of organics. Godlove2 found that
RBCs quickly recovered when subjected to shock loads treating petroleum wastewaters. Some other
studies reviewed the ability of RBC systems to removed priority pollutants.3,4 High degrees of phenol
and chlorinated pesticides were reported in a study by Redfield.5
Numerous studies using the activated sludge process have been performed to evaluate the treatment
of priority organic pollutants.6"10 Petrasek et al. quantified the behavior of organic priority pollutants
in conventional water treatment plants.7 The experiment showed that typical treatment plants with
activated sludge processes can significantly reduce the concentration of the organic priority pollutants
studied but that municipal wastewater treatment plants are not a totally effective system for the
treatment of all priority pollutants.7 A study by Rozich and Gaudy8 modeled the activated sludge
process response to phenolic shocks. Herzbrun et al. found that sequencing batch reactors accomplished a high degree of treatment for hazardous wastewaters and exhibited an ability to resist shock
loadings.
The fate of a pollutant in biological treatment processes should depend on its inherent biodegrada-
bility. The primary goal in the design of biological process treating priority pollutants should be to
achieve maximum expression biodegradability." The priority pollutants chosen for this study-
toluene, benzene and 2,4,6-trichlorophenol-all exhibited significant biodegradation with rapid acclimation in a static culture flask biodegradability screening test.12
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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