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Recycling wastes through thermophilic fermentation Shepherd, David William

Abstract

Efficient treatment of waste materials from agricultural operations is a problem in most of the countries of the world. This is particularly true where livestock are being reared in large high-production confinement housing systems. There are several treatment systems available to handle the wastes from this type of operation. These systems are described with particular emphasis on thermophilic fermentation. Thermophilic treatment of wastes offers several advantages over the other types of waste treatment systems. The thermophilic system at the University of British Columbia differs from most other high-temperature systems in that no external heat source is provided. Experiments were carried out which show that the heat necessary to maintain the temperature in the thermophilic range comes solely from microbial activity. The actions of agitation and aeration do not provide any input of heat into the fermenter. The foam which forms on the top of the liquid during a fermentation was shown to be a good insulator. Feeding trials conducted with the liquid product from thermophilic fermentation demonstrated that this liquid can be substituted for water in the diet of pigs older than twenty-eight days of age with no harmful effects. It is possible that pigs older than fifty-six days of age will be able to utilize the nutrients in the liquid more efficiently and increase their rate of gain without increasing the amount of feed consumed. Experiments with larger sized fermenters resulted in a commercial design for a thermophilic waste treatment system with a total capacity of six thousand gallons. Finally, preliminary trials utilizing lignocellulose as a substrate for thermophilic bacteria indicated that these bateria are able to utilize cellulose as a nutrient source.

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