Gross alpha and gross beta particle activity in recycled water for augmentation of drinking water supplies

An assessment of potential health impacts of radioactive compounds in recycled water to augment drinking water supplies was conducted. Gross alpha and gross beta particle activity was selected for the screening of radioactive species. Samples both pre- and post-reverse osmosis treatment of secondary effluent in Perth, Australia were examined in both a full-scale and in a pilot water reclamation plant. Risk quotients (RQs) were estimated by expressing the mean (RQ mean) and the maximum concentration (RQ max) at each sampling point as a function of the recommended Australian screening levels of 0.5 Bq/L. The results indicate that reverse osmosis (RO) is able to reduce the concentration of gross alpha particle activity (average removal of almost 80%) and gross beta particle activity (average removal of 95%) and produce water of high quality. Maximum gross alpha particle activity in the recycled water was 0.023 Bq/L and maximum gross beta (excluding ⁴⁰K) particle activity was 0.03 Bq/L, which correspond to an RQ max of 0.07 for gross alpha and 0.06 for gross beta particle activity, respectively. No increased human radiological risk is anticipated if recycled water is used to augment drinking water supplies in Perth.