Apparatus and process for forming uniform, pelletizable sludge product

摘要

An automated, non-polluting process and apparatus for mechanically dewatering and heat drying liquid sewage sludge of widely varying solids content to form a pelletizable, dried sludge of predetermined uniform solids content without requiring recycling of previously heat processed sludge. Prior to being dried, the sludge is mixed with flocculation and coagulation promoting chemicals and is dewatered in a belt-type press. Drying takes place within an indirect heat dryer including an enclosed housing for capturing all gases and particles entrained in the gas driven off during the drying process. The gases and particles are advanced by means of a fan first through a cyclone separator for removing dust particles and next through a water jet scrubber prior to being exhausted or burned in order to control odor. The dust removed by the cyclone separator is recombined with the output from the indirect dryer prior to being pelletized. An automated start-up and shut-down control circuit is disclosed for producing the maximum degree of automation of the overall system and process.