FIELD TREATMENT OF LAKE OR SWAMP-BOTTOM SLUDGE BY METHANE FERMENTATION SCARCELY CAUSING WATER CONTAMINATION

摘要

PURPOSE:To purify sludge, while inhibiting water contamination, by covering bottom sludge with a plastic sheet or the like, further covering the sludge with low-BOD sand or the like, and then fixing a gas-extracting pipe into the sludge layer. CONSTITUTION:Sand 3, optionally in company with a flocculant and phosphorus and nitrogen-removing agents, is settled on a sludge layer. One or more plastic film sheets 4 are put thereon. Thereafter, sand, mountain soil, cement or these mixutre 5 containing little of BOD components is applied to the said film 4 by mortar spray or the like, to firmly hold the film 4 down on the sludge layer. In this state, a pipe 6 is straightly or inclinedly thrust into the sludge layer through the film 4 from above. The top end of the pipe 6 is exposed to the air beyond the water surface. Under this condition, methane fermentation is accelerated.