Vegetable processing wasteflows: liability or asset

The U.S. fruit and vegetable processing industry annually discards about 114 billion gallons of by-product liqud wasteflow. Because of high BOD levels, these wastestreams cannot be released to surface waters but must be processed at high expense to the generating industries. By selectively processing a portion of these wasteflows through ultrafiltration/reverse osmosis facilities, most of the fermentable sugars in fruit and vegetable processing wastes could be recovered as a 20% sugar concentrate suitable for bioconversion to liquid fuel. The value as feedstock of approximately 1.6 million tons of fermentable sugar, the major reduction in wasteflow BOD and disposal costs, and the reuse value of reverse osmosis permeate water would exceed process costs by a wide margin. Industrial participation in sugar concentrate production by membrane processes would turn a liability into an asset and provide sufficient feedstock to produce approximately 217 million gallons of alcohol annually. The net energy yield of the alcohol is about one-half of the total energy used by the fruit and vegetable processing industry.