GB687296A - Process and apparatus for the anaerobic fermentation of vegetable products and more particularly for producing manure and gas - Google Patents

Abstract

In the anaerolbic fermentation of solid vegetable products suspended in liquid animal manure, the liquid suspension is fed to the lower part of a vat, the gases formed during the fermentation are allowed to raise the fermented solid above the surface of the liquid and the fermentation gases, liquid manure and fermented vegetable product are evacuated separately from the vat. As shown in Fig. 1, liquid manure such as liquid horse manure, is supplied from pipe 7 to a mixer 1 where it is mixed with finely-divided dry animal manure and straw. The resulting suspension is passed via line 8 to the bottom of vat 31. The liquid is withdrawn through outlets 34 and is recycled to the mixers by line 321, annular space 33 and pipe 4. Solid floating on the liquid is removed by blades on a rotating air-tight top 95 and conveyer 12. Gas is withdrawn by pipes 19 and 20 and may be used in part to reheat the recycled liquid. In Fig. 3, the suspension from a mixer 30 is injected tangentially at the base of a vessel 23. Floating solid is withdrawn through shoot 43 under the action of rotating paddle-wheels 39 and gas is withdrawn at 42. The liquid is <PICT:0687296/IV (b)/1> <PICT:0687296/IV (b)/2> <PICT:0687296/IV (b)/3> removed from quiescent areas 25 and is recirculated through pipe 26, a heater 28 and pipe 29 to the mixer 30. In a further modification (Fig. 5), the suspension enters the vessel at 13a, the liquid is withdrawn at 17a, the gas at 17b, and the solid through the swan-neck 22a. The solid vegetable products may have undergone a prior aerobic fermentation, assisted by bacteria, before being fed to the anaerobic fermentation vessel.