| 摘要 |
<p>A process for treating solid waste material comprises: a) preparing a slurry comprising particles of the solid waste material in a liquid carrier, the particles having sizes less than a predetermined maximum size; b) subjecting a decomposable fraction of the solid waste material to a fermentation process in a solids digestion vessel to produce a compostable 10 material and a fermentation gas comprising mainly carbon dioxide; c) before the fermentation gas from the slurry contains as much as 1% of methane by volume, removing liquid from the solids digestion vessel to leave a compostable fermented solid waste material; d) removing at least some of the compostable solid waste material from the solids digestion vessel; e) feeding at least some of the liquid from step (c) to a liquid digestion vessel; and f) subjecting the liquid in the liquid digestion vessel to anaerobic bacterial digestion to produce a liquid fraction containing active anaerobic bacteria and a methane-rich gas fraction. Also claimed is an apparatus for digesting a solids waste material comprising a mixing vessel, a solids digestion vessel, and a liquid digestion vessel. The mixing vessel is connected to the solids digestion vessel by a slurry pump. The pump may be a chopper pump, a self-cleaning pump or a macerating pump. As, little or no methane-producing anaerobic digestion occurs in the solid digestion vessel, there is no danger that of an explosive mixture being formed in the event that air is drawn into the solid digestion vessel.</p> |
