Method for dehydrating and conditioning sludge and preparing raw materials of slow-release fertilizer

The invention relates to a method for preparing a slow-release fertilizer, in particular provides a method for dehydrating and conditioning sludge and preparing raw materials of the slow-release fertilizer. The method particularly comprises the following steps of: adding water-absorbing clay minerals, a mixture of water-absorbing macromolecular compounds and plant residues to dehydrated sludge ineach cubic meter, composting and fermenting for 10-15 days according to a conventional method, sequentially adding compounds formed by phosphoric acid radicals and ammonium ions and magnesium-containing alkaline substances in fermentation products, and mixing uniformly to obtain the raw materials for producing a slow-release type organic-inorganic compound fertilizer. The method for dehydrating and conditioning the sludge and preparing raw materials of the slow-release fertilizer, disclosed by the invention, is suitable for large-scale sludge dehydration treatment and also provides high-nutrient raw materials for the manufacturing of the slow-release fertilizer.