46    FUNDAMENTALS OF RESPIROMETRY:
INSTRUMENT TYPES AND BASIS OF OPERATION
James C. Young, Kappe Professor of Environmental Engineering
The Pennsylvania State University
University Park, Pennsylvania 16802
INTRODUCTION
Respirometers of various types have been used since as early as 1908 to provide direct and
continuous measures of oxygen uptake in biological reactions, and improvements and new developments since that time have been numerous and varied. Considerable interest was shown in the
1950s in using respirometers to supplement or replace standard five-day dilution BOD measurements. Most of this interest seemed to stem from an article published in 1948 by Caldwell and
Langelier.1 These authors concluded that respirometric measurements had several advantages
over the standard dilution method for measuring BOD. The respirometer was recommended for
used in routine examination of municipal sewage and industrial wastes and in the control of
wastewater treatment processes. It was especially recommended for research studies because of
the ease and precision with which variables could be controlled.
Gelman and Heukelekian2 in 1951 conducted an extensive investigation of the use of
respirometers for BOD determinations. The variables studied included the effects of pH, nutrient
addition, substrate concentration, volume and source of seed culture and seed adaptation. In
1954, Lee and Oswald3 published results of further comparative studies of the Warburg and the
dilution BOD methods. Fresh and sterile sewage and synthetic wastes were used. These investigators concluded that respirometers could be used effectively for BOD determinations; and they
indicated that as the number of required points on the oxygen uptake curve increased, the
respirometer was favored, whereas the dilution test was more convenient when measuring only
one or a few points.
A rather comprehensive review of the use of respirometers for the study of sewage and industrial wastes was published in 1960 by Jenkins.4 He concluded that
There has been recently a realization that a deeper understanding of the processes involved in treatment of sewage and industrial wastes, and of those underlying problems
of river pollution, can be gained by methods, which unlike the standard 5-day BOD
test and chemical methods, do not give a single numerical answer, but rather a continuous picture of the whole (biological) process.
The use of a manometric method for determining BOD would eliminate any errors introduced by dilution, would give a much quicker answer, and if a standard apparatus
could be developed, the course of oxidation of a representative sample of the liquid
could be followed by the changes in the chemical nature of the sample as well as by
observing directly the exact course of oxygen uptake.
Work did progress to the point that a tentative respirometric procedure was published in the
I0lh and ll1" editions of Standard Methods.5 Attempts to establish an acceptable standard
seemed to have failed because of a number of factors including a lack of justification of its need,
conflict with established procedures, inability to develop a consistent correlation between
respirometric and dilution test data, and the variety of types of commercially available instruments. This situation should not, however, have deterred the use of respirometers because much
useful biological data can be obtained which cannot be obtained by the dilution method.
51st Purdue Industrial Waste Conference Proceedings, 1996. Ann Arbor Press. Inc.. Chelsea. Michigan 481 18.
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