An apparatus and method for cleaning carcasses is described and illustrated, as is a device for mixing a cleaning substance that can be used in such applications. In some embodiments, the apparatus and method utilize a multi-phase cleaning substance spraying procedure in which the cleaning substance has desired levels of chlorine dioxide and is delivered to the carcasses at desired flow rates, both of which can vary between phases of the procedure and/or at different locations of the carcasses being cleaned.