The recovery of aqueous phosphate from a model solution consisting of NH₄⁺, NO₂^- and NO₃^-, which are contained in a surplus that phosphate in rivers in Tokushima Prefecture, Japan, using boehmite together with the elution behaviors of phosphate from dephosphorization slag using various eluates were examined. The recovery of aqueous phosphate using boehmite was not influenced by the coexistence of those nitrogen-containing contaminants under various pH conditions. For the elution behaviors of phosphate from dephosphorization slag, it was found that aqueous HNO₃ among various acidic and basic solutions was a suitable solution as an eluate. Present study suggests that the employment of the unused resources such as aqueous phosphate in rivers and phosphate in the dephosphorization slag can be used as a possible candidate as a new raw material for rare phosphate.