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VEGETABLE AND FRUIT DEHYDRATION 139 



diseases which often spread rapidly. The storage bins or containers 

 should be washed after the removal of each lot; otherwise infection 

 will spread to other raw materials brought in later. 



Water Supply 



A most essential matter is a good water supply, which is both 

 pure and abundant. It should be analyzed frequently because the 

 character of water changes. Many times the waste from the plant 

 itself contaminates the water supply. In general, hot water does a 

 better cleaning job than cold water. The use of a steam hose can 

 be very beneficial, but the steam must be applied under pressure 

 directly to the area to be cleaned. 



Detergents added to water are valuable in removing secretions 

 of organic material from plant and equipment. Soap and cleaning 

 compounds are excellent detergents. The efficiency of the cleaning 

 operations may be enhanced by the use of chemical compounds con- 

 taining chlorine. The use of a germicide alone without the cleansing 

 operation is valueless, however. It should be associated with or im- 

 mediately follow cleaning. 



Waste Disposal 



The selection of a dehydration plant site should include careful 

 consideration of the waste-disposal problem. The capacity of the 

 intended place of final disposal (creek, treatment plant, disposal bed, 

 etc.) must be carefully evaluated. If the permissible loading is 

 found to be less than that transported by the plant wastes, it will 

 be necessary either to treat the wastes to lower their organic loading 

 to the permissible value or else to move the plant to some other loca- 

 tion where treatment will not be required. 



The waste-disposal system is another matter of great importance, 

 especially if an adequate municipal sewerage system is not available. 

 Unless the wastes are properly conducted away from the plant, there 

 is likelihood of pollution of the plant water supply, of odor nuisance, 

 and even legal suits by property owners in the vicinity. Waste ma- 

 terials from vegetable-dehydration plants may be classified as "solid 

 wastes" and "liquid or water-borne wastes." Solid wastes, such as 

 trimmings, are in most cases readily disposed of as garbage, and do 

 not enter into the liquid-waste disposal problem. 



Liquid wastes from vegetable-dehydration plants are derived from 

 the various washing operations. Most important are the wastes from 

 the peeling units and the wastes resulting from washing the vege- 

 tables after they have been cut into small-sized cubes, bars, slices, or 

 other shapes. Of lesser importance are the wastes derived from 

 washing the raw product and the intermittent plant wash-up waters. 

 Those liquid wastes are difficult to dispose of not only because of their 

 volume, but also because of the large quantities of soluble and sus- 

 pended organic matter which they transport. The organic material 

 contained in the wastes from a potato-dehydration plant of 20 tons 

 (unprepared basis) daily capacity, for example, may be roughly 

 equivalent to that contained in the sewage flow from a town of 8,000 

 people. This organic matter will combine chemically with oxygen, 

 when it is present, so that if the wastes are dumped into a small creek, 

 drainage ditch, or other small body of water, the dissolved oxygen 

 resources of that body of water will be quickly depleted, 



