Purification of
Starch Industry Waste Water
CARL F. SEYFRIED, Deputy Chief Engineer
Ruhrverband
Essen, Germany
INTRODUCTION
Before the war the demand for starch and starch products in Germany was
covered by home production. As the larger part of the plants is located beyond
the Iron Curtain, after the war the Federal Republic of Germany was forced to
import a great deal of starch. Later on starch industry in the Federal Republic was
rapidly booming. Since 1950 production has approximately doubled. At present
more than 250,000 tons of starch are produced annually. Above all maize and
potatoes are processed, to a smaller extent also wheat flour, broken rice and
manioc. The present water consumption of the starch industry can be estimated
at more than 10 million cu m/year (2. 64 billion US gals/year). During the season the quantity of polluting matter discharged by the starch industry equals more
than one million population equivalents per working day.
As in Germany there was only a small knowledge available on the amount
and concentration of starch wastes and their treatment, the Institut fur Siedlungs-
wasserwirtschaft of the Technical University in Hannover was ordered to conduct
investigations. This report, which also makes use of the few dates stated in European literature, will be a short survey on these investigations and on the results of
pilot plants.
WASTEWATER AND POLLUTION
The principle of starch production is similar for all kinds of starch. The
fruits used as raw material are carefully washed and conditioned. The material is
ground or crushed. Thus the starch cells are broken and the starch granules can be
extracted. The starch granules are washed out of the ground stock. The crude
starch milk flowing out contains pollution residues. The crude starch milk is separated from the other constituents such as protein, minerals, soluble carbohydrates,
etc. The washed starch mixed with water is called starch milk. The starch is
separated from the starch milk and dewatered. Then it is either dried, sifted and
packed or further processed.
Maize Starch Plants
A maize starch plant is a complex manufacturing process (Figure 1). It has
been indicated that quantity and concentration of the waste can be decreased to
about 10 per cent of the original amount byinternal arrangements. Table I shows
the average wastewater values of these plants.
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