The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor (MFR) which utilizes two-phase flow in the monolith channels. A perforated plate was used to disperse the gas into the liquid, allowing for precise control of the distribution parameters. These distribution parameters controlled the size of the gas bubbles at the entrance to the monolith. In turn, the bubble size at the monolith entrance was the key parameter in determining the performance of the MFR. Important control parameters include the ease in which the bubbles enter the monolith channels, uniform coverage of the monolith entrance by gas bubbles, and the resulting gas-liquid flow patterns that are developed within the channels of the monolith. The observed results are described in terms of detailed flow phenomena that have previously been determined and reported. Based on the experimental observations and the theoretical analysis of the results, we have determined that optimal performance of the MFR occurs when a maximum number of channels are operating in bubble-train flow.