Preliminary cost estimates for commercial fermentation of straw as animal feed

Abstract

AbstractA preliminary cost estimate was made for two fermentation processes that increase the feed value of grass straw. In one method, straw hydrolyzed with dilute sulfuric acid is fermented by yeast. In the second method, the straw is treated with alkali, then inoculated with cellulolytic bacteria. Both processes increase the digestibility, protein content, and fat content of straw. Production costs estimated for plants processing 100 tons of straw/day by the two methods, were 80 to 88 dollars/ton. Capital costs were estimated at 5.2 million dollars for the acidhydrolysis yeast‐fermentation process and at 3.1 million dollars for the alkalicellulolytic bacteria process. Labor, capital, and energy were significant cost factors for both processes. Caustic costs were important in the alkaline‐treatment cellulolytic bacteria process.