Unlike most other chemicals, the purpose of a peroxide is to decompose. In doing so it generates useful radicals that can initiate polymerization to make polymers, modify polymers by grafting or visbreaking, or crosslink polymers to create a thermoset. When used for these purposes, the peroxide is highly diluted, so the heat generated by the exothermic decomposition is safely absorbed by the surrounding medium (e.g. Vynyl Ester resin).
Basically that means after the reaction has taken place and a solid film has formed no organic peroxide is present !! Therefore the organic peroxide is never exposed to waste water !