The Nitrogen and Phosphorus
Requirements for the Biological
Oxidation of Wastewaters
BERNARD R. SACHS, Chemical Engineer
Water Sewage and Industrial Wastes Section
Federal Water Pollution Control Administration
U. S. Department of the Interior
Cincinnati, Ohio
WALDRON D. SHEETS, Professor
Chemical Engineering Department
The Ohio State University
Columbus, Ohio
INTRODUCTION
Purpose
The purpose of the investigation (1) was to determine the optimum levels of
nitrogen and phosphorus necessary to achieve the greatest oxidation in the shortest
time for sugar beet wastewater, and to determine the best form of nitrogen to add
to the wastewater for such achievement.
An increase in the rate of oxidation would allow an increased degree of treatment in a given time or allow a large amount of waste to receive the same treatment in a given time.
Background
Sugar, which is commonly sucrose, C-^HooOn. is a carbohydrate and a
basic food in the human diet. The average annuaTconsumption rate in the United
States is nearly 100 lb/capita, or 10 million tons. Sugar is extracted from sugarcane and sugar beets. This study is concerned with the wastewater from the sugar
beet industry. In 1965, 63 plants in the United States produced beet sugar and
were the source of one-third of the sugar consumed in this country (2).
The industry process extracts the sugar with water and this is followed by purification and crystallization. The liquid wastes result from the fluming (or transporting) and washing of beets, purification and evaporation of the extracted sugar,
and final disposition of the beet pulp (3). These liquid wastes from the sugar beet
industry present a significant water pollution problem and research is needed to
find methods of abating the industrial pollution created.
The overall investigation was concerned with the consumption of oxygen by
the wastewater, which is measured as BOD. The BOD is defined as the amount of
oxygen used by aerobic bacteria in the stabilization of decomposable organic matter in a time period. This time period is usually five days. Decomposable may
be interpreted to mean that the organic matter can serve as substrate for the bacteria, with energy being derived from the oxidation (4). BOD measurement includes the amount of oxygen needed for the various oxidation reactions (5).
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