47    INDUSTRIAL WASTE IMPACT ASSESSMENT ON
DOMESTIC ACTIVATED SLUDGE TREATMENT
PLANTS USING RESPIROMETRY
Garry A. Palmateer, Head, Microbiology Dept.
Ontario Ministry of Environment and Energy
Southwestern Region Laboratory
London, Ontario, Canada N6E 1V3
Philip C. Thomas, Partner/President
Entoxicon Systems
Forest, Ontario, Canada NON 1J0
INTRODUCTION
In the Province of Ontario, the need to treat increasing quantities of sewage through activated
sludge secondary and tertiary treatment plants has escalated dramatically during the 1990s. However, the economy is such that enlarging the existing waste pollution control plants or constructing new plants to meet the treatment requirements is unrealistic. In addition, new industries are
moving into communities whose pollution control plants have not been involved in the treatment
of industrial wastes. The demand on these pollution control plants to process industrial wastes
has also intensified.
Operators of activated sludge treatment plants are having to manage these plants not only to
meet the new sewage treatment requirements, but also to ensure that the plant discharge continuously meets the effluent guidelines. The Ontario Ministry of Environment and Energy monitors
the effluent quality with regard to Certificates of Approval and ensures that effluent criteria are
being met.
The combination of increasing treatment demands and decreasing finances for treatment plant
expansion has led to the optimization of all aspects of the activated sludge processes. To accomplish this, a variety of approaches have been employed. In the situation where industrial wastes
have been implicated as the cause of poor treatment, one technique used is to analyze the industrial sewer discharges for potential toxicants.
While inhibitory metals and specific organic compounds may be detected in an industrial
waste, that data in itself does not prove that the growth of the bacteria and protozoa comprising
the biomass of the treatment plant is being suppressed. Analytical scans can also be very expensive and provide only circumstantial evidence as to the inhibitory nature of the waste. For example, a particular industrial waste may be treatable at a specific concentration. However, metal and
organic scans, or even toxicity assays, would provide minimal information on the extent to
which it could be processed.
An alternative approach to evaluating the impact of industrial wastes on domestic activated
sludge treatment plants, using respirometry and biokinetics1 described in the literature was investigated. A methodology that demonstrates a process of monitoring the growth rate of bacteria
when fed sewage typical of that received by domestic activated sludge treatment plants has been
reported. 2~3
Bacterial Growth
To comprehend the essence of this biokinetic evaluation of the biomass growth using
respirometry, a basic knowledge of bacterial growth and cell division is necessary. Bacteria are
prokaryotic, single cell microorganisms, some of which, if conditions are optimal, are capable of
51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press. Inc.. Chelsea. Michigan 48118.
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