| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the generation of excess sludge and to use energy efficiently in a biotreatment system in which anaerobic biotreatment is followed by aerobic biotreatment. SOLUTION: Aerobic biotreatment water is separated into solid and liquid 4, and separated sludge is heated 5 and separated into solid and liquid 6. The separated liquid is returned to an anaerobic biotreatment process 2. Methane gas generated in the process 2 is used for heating. Since the dewatering property of sludge is improved by heating, the water content of the sludge obtained by the solid-liquid separation of heated sludge is low with its volume decreased remarkably. Part of organic substances in sludge is solubilized through hydrolysis etc., by heating. The solubilized organic substances are treated aerobically to reduce the volume of the sludge further. Methane gas in an anaerobic tank is uses as a heat source for heating sludge to accomplish the efficient use of energy. The separated sludge of low water content is heated to obtain improved heating efficiency. Liquid of high temperature is returned to the anaerobic tank to be heated to use heat efficiently.</p> |
