RADIOLOGICAL MONITORING ACTIVITIES AT THE METROPOLITAN WATER RECLAMATION DISTRICT OF GREATER CHICAGO

Radioactivity may enter the sanitary sewer system through a variety of sources including manmade and natural sources. The raw sewage is treated at the water reclamation plant (WRP) to remove contaminants. The radioactivity removed from the raw sewage by the wastewater treatment process is concentrated in biosolids. There have been several reported cases of radioactive contamination in wastewater treatment plants in the United States over the last twenty years.This study was conducted to measure the radioactivity concentration in raw sewage, final effluent, sludge, and biosolids at the facilities owned and operated by the Metropolitan Water Reclamation District of Greater Chicago (District). The radiological monitoring data helps to assure adequate effluent water quality at the District's seven WRPs. It also helps to minimize the build-up of radioactivity in landfills, and assures that the biosolids are suitable for land application as fertilizer. The data provides information to determine if the treatment plant workers and the public are exposed to radioactivity in biosolids that are above normal background levels.