PURPOSE: To economize auxiliary fuel costs in the incineration stage considerably and to prevent escaping of sludge in the secondary dehydrating stage by dehydrating sewage sludge of high water contents with a primary dehydrator then dehydrating the primarily dehydrated sludge with a secondary dehydrator.
CONSTITUTION: Sewage sludge is concd. with a concentrator and after the sewage is mixed with a flocculating agent in a mixing tank, the mixture is charged into a tank 2 of a primary dehydrator 1. When the drum 3 of the primary dehydrator is rotated in an arrow (b) direction and a vaccum pump is operated, the water contained in the sewage sludge A passes through a filter cloth 4 and is sucked into the drum 3, from which the water is discharged to the outside of the tank 2 and recovered. The primary dehydrated sludge A1 of 70W 80% water content scraped by a scraper 23 is charged into the box 15 of a secondary dehydrator 7, and is sandwiched by an upper pressing plate 11 and a lower pressing plate 11 which are pressed downward via respective supporting rollers 17 by cylinder devices, whereby the sludge is dehydrated to 50W60%.
KANBAYASHI IKUO
FUJITA HIROSHI
SAKATA YUUJI
