Bio-waste sterilizers are described. In one implementation an exemplary system has waste transport vessels that can be intermittently heated and pressurized, for example, with steam, and are interconnected to provide multiple sterilization pathways for waste as the waste is transported. Selected sterilization pathways may depend on attributes of the waste. Sterilization factors, such as mechanical shredding, application of steam, application of pressure, maintenance of temperature, separation of liquid, etc., are integrated into the waste transport features of the system, which can be made compact to save space while processing relatively large bulk amounts of materials, such as medical wastes. The system maintains safe isolation of bio-hazardous components in the waste from the external environment. A system controller provides parameters management, smart sterilization cycle control, quality assurance, safety management, diagnostics, and reporting over a network.