The removal of radioactive cobalt, cesium, and iodine in a conventional municipal wastewater treatment plant
A radiotracer study was conducted to determine removal efficiencies for cobalt, cesium, and iodine in a conventional municipal wastewater treatment plant. The study was conducted in a full-scale facility that provides primary treatment through physical settling and secondary treatment using activated sludge. The radiotracers, 58Co and 134Cs as chlorides, and 131I as Nal, were equilibrated in raw wastewater and introduced to the treatment system as a pulse in the incoming raw wastewater. Samples of wastewater and sludge were collected and analyzed to quantify primary treatment, secondary treatment, and overall removal efficiencies. Selected samples were filtered to determine the partitioning of the tracers between the solid and liquid phases of the wastewater and sludge throughout the treatment process. In the incoming wastewater, approximately 10% of the 58Co, 7% of the 134Cs, and 3% of the I31I were associated with suspended solids. The suspended tracer fractions decreased across the treatment plant. Primary treatment resulted in the partial removal of the incoming suspended fraction with observed removal efficiencies of 8.1% and 3.0% for 58Co and 134Cs, respectively, and an estimated removal of 2% for 131I. Approximately 80% of the radiotracers in the primary treatment sludge were associated with the sludge solids. The affinity of the radiotracers for the activated sludge solids was in the following order: 58Co > 134Cs > 131I. Secondary treatment removal efficiencies of 25% and 9.4% were observed for 58Co and 134Cs, respectively. The secondary treatment removal efficiency for 131I was estimated to be 2-3%. Overall removal efficiencies were 31%, 12%, and 3-5% for 58Co, 134Cs, and 131I, respectively. The remaining fractions of the radiotracers remained within the soluble phase of the wastewater and were discharged in the treatment plant effluent.
Document Type: Research Article
Publication date: 1993-07-01
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- Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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