To provide a recycling method of an organic sludge generated by the treatment of waste water of food industry, pulp industry, etc., by a biological method such as active sludge treatment and free from harmful metals or the organic sludge subjected to the separation and removal of harmful metals to effectively utilize the sludge as a feed or a feed raw material.

Organic sludge generated by waste-water treatment is subjected to drying, heating or pressing treatment by heating, exposure to the sun evacuation or freezing to obtain a feed or a feed raw material for domestic animals, poultry or pets.