摘要 |
An anaerobic fermentation assembly (1) has a pre-acidification stage (2) and a fermentation stage (3a, 3b) linked by a transfer system (5a-e, 10-12, 14, 21), where the transfer system especially selectively transfers ingredients (A, B) to fermentation after they have been adequately acidified. Also claimed is a commensurate process in which methane and carbon dioxide are generated from liquid and solid organic residues arising from the production of beer and fruit juice. Methane is recovered for use as fuel. The selection process exploits the properties of the raw materials e.g. yeast and spent grain, which are separated by sedimentation and sieving, ensuring that inadequately acidified substances are held back from the fermentation stage until acidification has been completed. Liquid and softened substances pass these stages unhindered. Mechanical mixing devices maintain solids in suspension thereby promoting acidification. Discharge of such solids is facilitated only during mixer rest periods. Solids are further maintained in suspension by rising gas bubbles, promoting selection of acidified components by weight. |