The major difference between the Rohr and CBI processes is in the ceramic drying and firing steps. The energy draw is 80,000 Btu per hour, approximately that of a domestic water heater. After four hours in the thermal processor unit at temperatures reaching I 1000 C, metals in the sludge become so firmly locked into the clay matrix that even when the pellets are crushed and hot nitric acid is poured on them, the metals stay bound up. Toxic air emissions from the thermal processor appear to be very low. After the air passes through the driest pellets on the bottom, the particles it picks up are to a great extent scrubbed from it as it passes through the closely packed wet pellets in the top of the chamber.
Exact costs depend on sludge characteristics, and the type of pretreatment it receives.
Fired pellets from the CBI process are designed to be used as a lightweight high strength construction aggregate. Both of these features raise the market value of the product. To receive more information on CBI's services and on the appropriate regulatory requirements governing waste conversion, contact the company directly. The resulting slag can be crushed and sold as aggregate to concrete block manufacturers. Rostoker, Inc. of Burnham, Illinois has developed a novel process which utilizes custom designed slagging systems for the needs of the particular shop.