| 摘要 |
<p>1491501 Anaerobic digestion of water polluting waste material BIOMECHANICS Ltd 22 May 1975 [24 May 1974] 23467/74 Heading ClC A method of treating biodegradable waste material by anaerobic digestion comprises the steps of (a) agitating liquid containing waste material within a closed tank and digesting the waste material anaerobically, (b) ceasing agitation of the liquid containing the waste material and allowing solids in the liquid containing waste material to settle for a predetermined period of time, (c) withdrawing from the tank an upper layer of liquid having a solids concentration which is substantially less than the average concentration of the solids in the liquid containing the waste material, and (d) further agitating the liquid containing the waste material within the tank together with a further volume of liquid containing waste material substantially equal in volume to the upper layer of liquid which is withdrawn from the tank. The waste material may be water polluting material. The solids on which the gas bubbles have accumulated may be physically prevented from floating into the upper layer of liquid by a packing material which floats, e.g. plastic Raschig rings, or by a metal grid. Inert particulate material having a density greater than the density of the waste material and a particle size similar to the size of the bacteria (e.g. fly ash or digested sewage) may be added at the digestion stage to assist settling.</p> |
