Also, a broad spectrum of microbial pathogens can be destroyed by anaerobic digestion. This may have particular significance for animal health in recycle flush systems. The ability of the fixed- film digester to provide recyclable water for barn flushing is especially valuable as water becomes an increasingly precious limited resource. The primary benefit of separation of solids from liquids is the production of two fractions that are inherently more manageable than the original slurry. The benefits in terms of ease of materials handling, production of a highfiber by-product, and reduction in digester volume requirements are substantial.
Fibrous solids have potential use for bedding, refeeding and horticultural applications.
The financial attractiveness of on-farm anaerobic digestion is likely to improve considerably as environmental concerns assume greater importance. A complete assessment of economic feasibility must take account of all avoided costs and the value of intangible environmental externals, such as odor control and reduction of volatile emissions. Environmentally sound, sustainable practices are essential for staying in business over the long run. The alternative may be to relocate the enterprise, or cease operations entirely. The fixed-film anaerobic digester offers an innovative technology option for waste management without limiting the enterprise.