Influence of Nitrogen Supply
on Biological Treatment
WALTER HALTRICH, Graduate Biologist
Badische Anilin and Soda-Fabrik AG
Ludwigshafen am Rhein
Federal Republic of Germany
INTRODUCTION
In recent decades, as a result of the rapidly increasing demand for plastics and
other organic materials, such as synthetic fibers, a tremendous growth in production
of these materials has been registered, and the removal of the resulting wastes has
become a subject of increasing importance.
At the BASF in Ludwigshafen in West Germany, whose production of organic
materials has likewise climbed in the past few years, the problem of biologically
purifying organically polluted production effluents arose. Investigation of this waste
showed that it consisted chiefly of pure carbon compounds and did not contain
sufficient amounts of nitrogen for biological purification.
LITERATURE REVIEW
The nitrogen supply for biological treatment of sewage has been discussed in
numerous publications, e.g., Nolte (1), Sawyer (2), Logan (3), Helmers (4), Hattingh
(5), and Wuhrmann (6). The nitrogen demand varied to a great extent and was a
characteristic peculiar to the waste. Values of 4.3 to 6.3 mg N/100 mg BOD have
been reported as the minimum requirement. Helmers (4) observed that the treatment
time for a waste could be shortened as the supply of nitrogen was raised. The ratio of
nitrogen consumed to BOD removed varied, depending on the investigation, between
2.2 and 7.9 (Table I).
Hence, the degree to which the bacteria reabsorbed the nitrogen also depended
on the type of bonds in the nitrogen compound.
According to Weinberger (7), nitrogen in the form of ammonium compounds is
fully utilized by the bacteria; urea must first be hydrolyzed. Helmers, et al. (8),
found only 30 to 70 per cent utilization of organically bound nitrogen. Symons and
McKinney (9) have reported that nitrite and nitrate nitrogen is less available than
ammonia nitrogen. The composition of the activated sludge varied according to the
type and amount of nitrogen supplied and the type of waste; the nitrogen content
fluctuated between 1.5 and 11.3 per cent; and the ratio of C to N, from 3.8 to 30
(Table II).
On the basis of the above investigations, it was evident that experiments would
have to be conducted to determine the amount of nitrogen required for the biological purification of the BASF wastes.
WASTE WATER
The waste for the experiments comprised the effluents of various plants within
the factory. The extremely heterogeneous impurities in the waste were arranged
according to class of compound. It can be seen that relatively simple aliphatic com-
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