Honeycomb ceramic for RTO Regenerative Thermal Oxidizer Applications Organic compounds can be removed from waste gases by treatment through a regenerative thermal oxidizer (RTO). An RTO contains a ceramic heat exchanger bed that is utilized for the preheating and cooling of the waste gases before the gases enter and exit the combustion chamber, respectively. Honeycomb monoliths provide a more efficient alternative to other ceramic media, such as saddles or balls, that have conventionally been used in RTOs.