40 CFR § 265.406
Special requirements for incompatible wastes
June 9, 2020
(a) Incompatible wastes, or incompatible wastes and materials, (see appendix V for examples) must not be placed in the same treatment process or equipment, unless §265.17(b) is complied with.
(b) Hazardous waste must not be placed in unwashed treatment equipment which previously held an incompatible waste or material, unless §265.17(b) is complied with.