To provide a flocculating, separating and recovering method by using a zeolite-compounded treating agent with which ammonia-state nitrogen, nitrite- state nitrogen and nitrate-state nitrogen in the water to be treated can be treated at a low cost, and at the same time, nitrogen and phosphorus which cause eutrophication can be removed with high efficiency, and moreover, various kinds of heavy metal ions can be removed.

A treating agent prepared by compounding a natural zeolite fine powder having high cation exchange capacity and a compound salt of alkaline earth metal is added to the water to be treated containing a nitrogen component, phosphorus component or heavy metals so as to adsorb the contaminant component. After adsorption, the contaminant is not desorbed but flocculated, separated and recovered. The natural zeolite is clinoptilolite or mordenite and the natural zeolite has ≥80 meq/100 g cation exchange capacity. The treating agent preferably contains clay mineral such as bentonite, and the compounding ratio of the treating agent is preferably 100 pts.wt. natural zeolite, 1 to 50 pts.wt. clay mineral and 1 to 15 pts.wt. compound salt of alkaline earth metal.