ATP AS A MEASURE OF ACTIVE BIOMASS CONCENTRATION
AND INHIBITION IN BIOLOGICAL WASTEWATER
TREATMENT PROCESSES
Shin Joh Kang, Head
Advanced Technology Department
Lucy B. Pugh, Engineer
McNamee, Porter, & Seeley
Ann Arbor, Michigan 48104
Jack A. Borchardt, Professor
Civil Engineering Department
University of Michigan
Ann Arbor, Michigan 48109
INTRODUCTION
Successful operation of biological treatment processes depends upon the health of biological
cultures. The ability to monitor this health is essential in order that the operator can take appropriate
corrective actions as necessary. The need for rapid and reliable measurement of biological activity in
industrial facilities is even greater than in most municipal counterparts, mainly due to inherent fluctuations in quantity and quality of wastewater.
Conventional methods of measuring biological activity in general lack sensitivity and accuracy;
they typically lack either the ability to differentiate active biological cells from inactive solids present
in the system, or the ability to reflect biochemical changes taking place within active cells.
Recent developments in instrumentation and progress made in biochemistry helped the emergence
of a new methodology, offering definite advantages over the conventional methods in measuring active biomass concentrations. This methodology is based on analysis of adenosine triphosphate (ATP)
in biomass. ATP, a high energy compound, is known to be present in all living cells and can be measured by several instruments [1,2]. Many researchers have attempted to further the fundamental
understanding of the methodology and also to determine applicability to diverse biological cultures
ranging from a marine species to a pure culture of E. Coli. In the wastewater treatment field, several
researchers have reported successful application of this methodology to activated sludge control and
have proposed its use as a tool in monitoring metabolic activity of activated sludge.
The objectives of the study reported herein were two-fold. The first was to establish applicability
of the ATPmethodology as a measure of active biomass concentration in biological wastewater treatment processes, not only in activated sludge but also in rotating biological contactors (RBC) for the
first time. Selected cultures studied were heterotrophic organisms responsible for oxidation of organic
materials and autotrophic nitrifying microorganisms responsible for oxidation of inorganic ammonia.
The second objective was to demonstrate the utility of the ATP methodology in measuring the
presence of materials inhibitory to biological cultures and subsequently in determining an acceptable
concentration of inhibitor for a given culture based on biological growth kinetics. Specific inhibitory
materials studied were heavy metals and organic biocides.
The scope of the work included data collection from both a pilot scale and a full scale municipal
activated sludge plant and a full scale municipal RBC plant in Michigan, comparison of various
methods for biomass measurement and analysis of inhibition caused by certain inhibitory substances.
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