The Significance of
Nitrification in Stream Analysis —
Effects on the Oxygen Balance
ROBERT J. COURCHAINE, Sanitary Engineer
Michigan Water Resources Commission
Lansing, Michigan
INTRODUCTION
In I960 the Michigan Water Resources Commission undertook a self-purification study of the Grand River at Lansing. To date this agency has completed seven
such comprehensive studies of seven Michigan streams. Those streams receive industrial and domestic wastes and create, at times of drought flow, a lowering of
stream dissolved oxygen below desirable limits. For the first time in these studies,
the factor of nitrification was encountered and was found to have a highly significant demand on stream dissolved oxygen below the city of Lansing. The Grand
River study implies that removal or oxidation of nitrogenous material in waste
treatment units may be necessary to protect the dissolved oxygen resources of such
streams during periods of drought flow.
This paper discusses the phenomenon of nitrification, its application in the
Grand River study and effect on the dissolved oxygen assets of the stream. Data
referred to are taken from the 1962 publication ofthe Michigan Water Resources
Commission entitled, "Report of Oxygen Relationships of Grand River, Lansing to
Grand Ledge."
The oxidation of organic material by natural self-purification processes is essentially a chemical reaction but, insofar as it is brought about by biological
agencies -- principally bacteria or their immediate products, bacterial enzymes
-- it is properly termed a biochemical reaction. The oxygen demand of this organic material in sewage, sewage plant effluents, industrial wastes, and polluted
waters is exerted by two classes of materials: 1) carbanaceous organic material
which is usable as a source of food by aerobic organisms, and 2) oxidizable nitro -
gen which serves as food for specific bacteria.
There are numerous references from the literature indicating that oxidation
of organic matter during self-purification takes place in two stages as shown by
Figure 1. Klein states that during the first or carbonaceous oxidation stage, about
70 to 80 per cent ofthe organic carbon is oxidized; during the second or nitrification stage biochemical oxidation of ammonia nitrogen occurs and at the same
time the remaining 20 to 30 per cent of the organic carbon is utilized by the bacteria for their nutrition and growth. Various workers, however, have indicated
that nitrification and oxidation of carbonaceous matter may proceed simultaneously.
GRAND RIVER STUDIES
Our studies of the Grand River, from which much of the data for this paper
have been obtained, confirms this latter view.
Figure 2 shows BOD curves for a sample of Grand River water collected at the
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