Abstract: A disposal assembly (10) includes a base (14) and four walls (20) extending perpendicularly out therefrom defining a hollow interior (22) partially filled with a plurality of layers. The bottom-most layer (38) is fabricated of styrofoam which, along with the tapered cylinders (28) and hydrostatic pressure, secures the medical instruments (12) therein. A layer of dry disinfectant (36) covers the styrofoam (38). A layer of sponge (34) directly covers the dry disinfectant (36). When fluid is injected into the dry disinfectant (36) to create a disinfectant solution, the sponge (34) absorbs the solution and distributes it across the entire cross section of the disposal assembly (10). A semi-viscous material (40) seals the disinfectant solution and the infected portions (26) of the medical instruments (12) in an anaerobic environment.