Continuous biowaste sterilization process, the operability of which is ensured in such a way that during process startup, extreme conditions possibly coming into question during operation are simulated, i.e. the greatest possible flow rate and the lowest temperature of the feed flow. In the startup stage, a liquid to be sterlized is circulated in the apparatus, until the capacity has been ascertained, whereafter the discharge stream can be conducted to a sewer system. The apparatus according to the invention comprises, in the flow direction of the biowaste-containing liquid, a storage tank, at least one feed pump capable of delivering a constant flow, at least one heating unit, at least one cooling unit, and a circulation circuit for circulating the biowaste-containing liquid through the heating unit, as well as connecting piping and valves. By means of specific piping and valve arrangements it is also ensured that all parts of the apparatus can be sterilized for maintenance purposes.