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Levels of 131I and Six Natural Radionuclides in Sludge from the Sewage Treatment Plant of Valladolid, Spain

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The levels of 131I and six natural radionuclides (238U, 226Ra, 210Pb, 228Ra, 224Ra, and 40K) were determined in sewage sludge samples obtained from an urban wastewater treatment plant that services a medium-sized town in Spain. Secondary treatment of wastewater consisting of anaerobic, anoxic, and oxic stages is collectively called A2O processing. Radio analytical determinations were performed by gamma spectrometry using a high-purity germanium detector. This technique has proven useful in identifying local radioactive pollution. This type of pollution was consistently detected throughout the year, with several increases associated with authorized discharges from hospitals. Finally, we examined the radiation dose that workers are exposed to due to the presence of 131I in the sludge. We found inhalation risk to be negligible, with external radiation as the main source of exposure to 131I.

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We are grateful to the staff of the Urban Sewage Treatment Plant of Valladolid, Spain, the Municipal Energy Agency from the Council of Valladolid (AEMVA), and the Nuclear Medicine Service at the Hospital Clinic of Salamanca.

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Correspondence to Luis Debán.

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Jiménez, F., Debán, L., Pardo, R. et al. Levels of 131I and Six Natural Radionuclides in Sludge from the Sewage Treatment Plant of Valladolid, Spain. Water Air Soil Pollut 217, 515–521 (2011). https://doi.org/10.1007/s11270-010-0605-8

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  • 131I
  • Gamma spectrometry
  • Sewage sludge
  • Radioactive exposition
  • A2O process