| 摘要 |
<p>1491502 Anaerobic digestion of water polluting waste material BIOMECHANICS Ltd 22 May 1975 [24 May 1974] 22390/75 Divided out of 1491501 Heading ClC A method of treating biodegradable waste material comprises the steps of submitting the waste material to anaerobic digestion to provide a treated liquid, subjecting the treated liquid to a thermal shock which is effected by a reduction in temperature of the treated liquid, which reduction in temperature is of such magnitude and is effected at such a rate of cooling that the gas-producing activity of anaerobic bacteria in the treated liquid is substantially inhibited, allowing the cooled treated liquid to settle, whereby bacteria in the cooled treated liquid sink in the liquid to leave a layer of sludge above which is a relatively clear liquid, and separately removing the sludge and the relatively clear liquid before the bacteria in the sludge regain sufficient gas producing activity to raise substantial quantities of solids in the sludge into the relatively clear liquid. The thermal shock preferably effects a reduction in temperature of the treated liquid of at least 8‹ C. in a period not exceeding ten minutes. The upper layer may be separated from the sludge by a region containing packing material which is capable of causing solids to be stripped from gas bubbles, such as Raschig rings made of a plastics material. A gas lift pump may be used to pass the treated liquid through the cooler. Effluents from factories operating the wheat starch/gluten/dextrose process, abbatoirs, confectionery factories, and creameries; single cell protein processes, wine making, domestic sewage, breweries, distilleries, meat processing, milk or dairy products, paper processing, sugar refining and textile processing are among the other sources of effluent mentioned.</p> |
