| 摘要 |
<p>The invention relates to a method and an apparatus for producing plant nutritive pellets from wastewater treatment plants, so-called raw sludge, with a water content normally in the region of 70-80 %, where a powder (9) is used to stabilize the pellets (6) and prevent their sticking together. The powder (9) 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 (6), an air stream (7), in which the powder (9) has become entrained being used to douse the pellet string or the cut-off pellets, whereafter drying is readily performed to provide a predetermined moisture content of about 10-15 % (90-85 %, DS) adequate for storage. The device according to the invention comprises an extruder (1) to form at least one pellet string (5), which by cutting-off means (29) is cut into separate pellets (6), at least one blowing nozzle (14) for lime powder (9) intended to be doused over the pellets, a rotatable tumbler (12) and a drying kiln, in which the pellets (6) are dried to said moisture content adequate for storage.</p> |
