To provide a method which enables the cheap and efficient treatment of an antifreeze for spraying, mainly having propylene glycol, such as an ice prevention agent and an ice removal agent for an aircraft and an antifreezing agent and a snow-melting agent for a runway, wherein this method reduces the viscosity and effectively reuses it as a pulverizing agent of cement clinker.

The treatment method of the antifreeze for spraying has a first step which recovers the antifreeze for spraying, consisting mainly of propylene glycol, as a waste antifreeze after being used, a second step which agglomeration precipitate polyacrylic acid in propylene glycol, a third step for filtering out its agglomeration precipitate, and a fourth step for measuring the viscosity of the waste antifreeze after being filtered out.