Experimental Treatment of Citrus
Waste Water
ROBERT R.  MCNARY, RICHARD W.  WOLFORD, and
MARSHALL H. DOUGHERTY
Research Fellows
Florida Citrus Experiment Station
Lake Alfred, Florida
The experience of the citrus processing industry has followed a
familiar pattern in regard to its wastes. In the early days the operations
of the canning plants were on a relatively small scale and usually intermittent. Wastes did not accumulate so fast that they became burdensome. Waste disposal was in what might be called the wheelbarrow
stage. It required little foresight or planning. A little extra labor to
man the wheelbarrow was all that was needed to dispose of the wastes.
As the production was stepped up a change in procedure was unavoidable. Planning ahead of time was necessary for the satisfactory disposition of the wastes. This was especially true of solid wastes such as peel,
rag, and seeds. Piles of decomposing orange and grapefruit peel were
not only malodorous and unsightly but usually were also "in the way"
and had to be moved elsewhere. The necessity for doing something
about the solid wastes fostered the development of their dehydration to
cattle feed. This by-product known as dried citrus pulp has been a
satisfactory and profitable solution to the problem of disposition of solid
wastes.
Liquid citrus wastes are not in as favorable a position as are the
solid wastes. While it is true that some of the more concentrated liquid
wastes, such as press liquor obtained during the manufacture of dried
pulp, are usually evaporated to citrus molasses, most of the weaker
liquid wastes are discarded with little or no treatment. Liquid wastes
are easily removed from the premises by gravity flow, which requires
no attention. Indeed, attention is too often the last thing given liquid
citrus wastes even though they may be creating a nuisance. The market
value of citrus molasses fluctuates widely since it follows the price of
blackstrap molasses. At times its manufacture results in an economic
loss. No other by-product has been developed which will utilize the
more concentrated waste sugar solutions. While it is true that some
ethyl alcohol is produced from citrus liquids, these liquids are concen-
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