Response of the Bio-Disc Process to
Fluctuating Wastewater Flows
RONALD L. ANTONIE, Manager
Water Pollution Control Department
Research and Development Center
ALLIS-CHALMERS
Milwaukee, Wisconsin
INTRODUCTION
One of the problems in providing biological treatment to industrial wastes is
the pattern of wastewater flow from industrial operations. Shift operation, holidays
and weekends create the problem of treatment plant operation with little or no
wastewater flow. Cyclic operations and clean up periods present requirements for
treatment plant operation with varying flows and hydraulic surges. Conventional
biological treatment processes can be effectively used for treating industrial waste
flow patterns when hydraulic surges are by-passed, when the process is designed for
peak flow or when a holding tank is provided to even out flow patterns and retain
enough wastewater for operation during periods of low wastewater flow.
Previous papers on the BIO-DISC process have discussed its operating flexibility and BOD removal capacity when treating concentrated wastes. This paper
describes the performance of the BIO-DISC process under wastewater flow conditions just described to illustrate its stable operation when applied to industrial wastewater treatment.
BIO-DISC PROCESS
The BIO-DISC process is a secondary biological treatment system. It consists of
a number of closely spaced discs which are mounted on a horizontal shaft and slowly
rotated while partially submerged in wastewater. Shortly after start-up a biological
growth develops on the surface of the discs to provide an abundant population of
aerobic microorganisms for treatment of the wastewater. As the discs rotate, the
growth is continuously contacted with the wastewater and the wastewater is aerated.
Some of the organic materials in the wastewater are oxidized by the growth, some
are synthesized into additional bio-mass and some are stored in the growth for
oxidation or synthesis at a later time. Shearing forces resulting when the growth is
passed through the wastewater cause excess bio-mass to slough into the mixed liquor.
Bio-mass solids are kept in suspension by the mixing action of the discs, and as
treated wastewater flows out of the tank containing the discs, it carries the sloughed
solids to a clarification step where they are separated for ultimate disposal.
BIO-DISC SYSTEM EQUIPMENT AND OPERATION
Figure 1 is a process flow sheet of the BIO-DISC pilot plant used. A synthetic
wastewater was used for the tests. It consisted of dairy whey solids, (NH^U HPO^,
and K2HP04 mixed in tap water in the ratio of 1.0 to 0.095 to 0.70 by weight.
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