Treatment of infectious wastes

Abstract

There is disclosed the sterilization of infectious hospital waste to generating a residue which is suitable for disposal. The invention comprises a first step of digestion at elevated temperatures and under highly alkaline condition for one to three hours. This step is combined with the necessary comminution, e.g., grinding, pulverizing and the like, to ensure substantially complete liquefaction of the wastes. The liquid reaction products from the first step are neutralized to a slightly alkaline pH, e.g., 7.5-9.5, and the waste is then subjected to enzymatic digestion with a suitable proteolytic enzyme for a short period of time. Preferably this proteinase treatment is combined with further comminution to further reduce any oversized particles that may remain in the waste following the first treatment. The enzymatic treatment is continued for a period from 30 to 90 minutes at temperatures most suitable for the selected enzyme and results in substantially complete hydrolysis of the proteins in the waste. Finally, the treated waste from the second step of enzymatic digestion is inoculated with from 8 to 20 percent of a sterilant, preferably sodium hypochlorite and the pH is reduced to an acidic pH from about 3 to about 6, and the inoculated residue is held for an extended period of time, from about 30 to about 120 minutes at an elevated temperature to ensure essentially complete sterilization of the liquid which can be concentrated or dried for disposal.