REACTOR, TREATMENT EQUIPMENT, AND TREATMENT METHOD

PROBLEM TO BE SOLVED: To provide a reactor capable of conveniently and efficiently removing fluorine in wastewater, securing permeability for a long period of time, and further conveniently and efficiently recovering a reagent after used.SOLUTION: A reactor for removing fluorine from a treatment objective water containing the fluorine houses sand and a reagent, the sand and the reagent constitute a first sand layer, a reaction reagent layer, and a second sand layer from the top of the reactor in the order, the reagent contains calcium hydrogenphosphate dihydrate (A) and a particle (B), the calcium hydrogenphosphate dihydrate (A) is supported on the particle (B), the first sand layer comprises a first sand whose effective diameter is smaller than that of the particle (B), and the second sand layer comprises a second sand whose effective diameter is also smaller than that of the particle (B).