Characteristics and Amounts of Potato
Wastes from Various Process Streams
A.M. COO LEY, Professor of Chemical Engineering
E. D. WAHL, Assistant Professor of Chemical Engineering
G. O. FOSSUM, Professor of Civil Engineering
University of North Dakota
Grand Forks, North Dakota
The processing of vegetable products in the Red River Valley of North Dakota
and Minnesota has brought new problems which could well limit the increase of
the industry unless these problems are solved.
The Red River Valley is flat farm land formerly covered by Lake Aggasiz.
Streams are small and meandering, having dependable flow only during the spring
runoff. Their capacity, with the exception of the Red River itself, as a source of
industrial water is small and any discharge of industrial wastes into these streams
immediately results in nuisance development.
The Red River Valley of North Dakota and Minnesota is usually third in the
production of potatoes in the United States, ranking below Idaho and Maine; with
the increased use of processed potatoes, a sizeable processing industry has developed. Approximately 2,664,000 hundred weight of potatoes were processed during
the 1961-62 crop year and 2,900,000 hundred weight were processed during the
1962-63 season. These included dehydrated potatoes, frozen french fries, potato
flour, and starch. This is a rather modest amount when compared with some of
the older processing areas but the prospects are good for continued growth.
The problem of waste disposal is one which could limit this industry unless
satisfactory solutions can be found. The magnitude of the problem is evident
when it is realized that approximately one bushel of potatoes in four is discarded
as preparation waste in processing.
The first phase of the present study supported by the National Institutes of
Health was the study of the pollutional loads from the various processing steps in
potato starch plants, potato chip plants, potato flour plants, and potato flake
plants. Plant surveys were made and the characteristics of the various wastes were
studied. These studies showed also how better in-plant methods might be used in
order to decrease these wastes.
The various process wastes studied were very different in nature and the characteristics of the wastes, such as settleability, pH, etc., have a great effect on
subsequent processes used in treating and stabilizing the effluents.
Lye peeling, steam peeling, and abrasive peeling wastes were studied and
also the waste from potato starch manufacture in which the entire potato is disintegrated and the starch recovered by hydraulic methods.
The potatoes which are processed have widely different analyses and characteristics, depending upon their source. Potatoes processed for chips or flakes
are usually higher in solids and run from 18.5 percent solids to 23 per cent solids.
Those used for potato flour or starch are usually grade outs and "B ' size potatoes
and may be as low as 17 per cent solids.
An analysis for white potatoes is presented in Table I.
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