Method and an apparatus for producing plant nutritive pellets from wastewater sludge

A method of producing plant nutritive pellets from raw sludge produced by wastewater treatment plants, the raw sludge having a water content in the region of 70-80%, where pelletization takes place without further dewatering of the sludge and where a powder is used to stabilize the pellets and prevent their sticking together, the powder being added in connection with the sludge being formed into at least one pellet string and after formation of the pellet string when the string is eventually cut into pellets, the method comprising the steps of:

• forming the sludge into a pellet string;
• cutting the pellet string into pellets;
• supplying an air stream in which the powder has become entrained to douse the pellet string and/or the cut-off pellets so as to give the pellet string and/or the cut-off pellets strength, and to prevent the formation of aggregates during subsequent collection of the pellet string and/or cut-off pellets;
• and
• drying the pellet string and/or cut-off pellets to provide a moisture content of about 10-15% adequate for storage of the pellets.