| 摘要 |
PCT No. PCT/SE93/01112 Sec. 371 Date Jun. 7, 1995 Sec. 102(e) Date Jun. 7, 1995 PCT Filed Dec. 29, 1993 PCT Pub. No. WO94/14730 PCT Pub. Date Jul. 7, 1994A method and an apparatus for producing plant nutritive pellets from raw sludge produced by wastewater treatment plants. The raw sludge has a water content normally in the region of 70-80%. Powder is used to stabilize the pellets and prevent their sticking together. The powder is added in connection with the sludge being formed into at least one pellet string or immediately after formation when the string has been cut into pellets. An air stream in which the powder has become entrained is used to douse the pellet string or the cut-off pellets, whereafter drying is readily peformed to provide a moisture content of about 10-15%, adequate for storage. The device according to the invention comprises an extruder for forming at least one pellet string, which by cutting-off means is cut into separate pellets, at least one blowing nozzle for lime powder intended to be doused over the pellets, a rotatable tumbler and a drying kiln, in which the pellets are dried to a moisture content adequate for storage. |
