Radionuclides in Drinking Water
Decision Narrative 3: Selecting Treatment Options
For Water Systems with Radionuclides above the MCL
Community water systems (CWSs) that use source water containing radium-226 (Ra-226), radium-228 (Ra-228), gross alpha particle activity, beta particle and photon radioactivity, or uranium must comply with the Radionuclides Rule (see www.epa.gov/safewater/radionuc.html). This document provides general information to CWSs on: the available treatment technologies for the removal of radium, uranium, and gross alpha particle activity; the residuals produced by each technology; disposal options; and, the regulations governing these options. The applicable regulatory requirements are described here in summary form only and there may be additional federal or State laws or regulations that apply to you beyond those described in this document. You need to consult the statutory and regulatory provisions that apply to the waste you generate or manage in order to determine the requirements with which you must comply. This document also provides additional recommendations and information on possible options; these are not regulatory requirements and are provided for your information only. This document does not cover residuals from treatment of beta particle or photon radioactivity. Information on those radionuclides can be obtained from your primacy agency. EPA will continue to review and update this guidance as necessary and appropriate.
In the Radionuclides Rule, EPA has listed Best Available Technologies (BATs) and Small System Compliance Technologies (SSCTs) for radionuclide treatment based on their efficiency at removing radionuclides from drinking water, taking cost into consideration. You are not required to use a listed BAT or a SSCT. Any technology that is accepted by your primacy agency and achieves compliance with the maximum contaminant level (MCL) is allowed.
The EPA Radionuclides Rule lists Best Available Technology (BAT) for radium as reverse osmosis (RO), ion exchange, and lime softening. For uranium removal, BATs consist of RO, ion exchange, coagulation/filtration, and lime softening. Other non-BAT technologies, such as iron/manganese removal, preformed hydrous manganese oxide (HMO) addition with filtration, adsorptive media (such as activated alumina) and electrodialysis/electrodialysis reversal (ED/EDR) are also capable of removing either radium or uranium. The removal efficiency of all of the processes will vary with the source water quality and the technology.
All technologies, whether they are BAT or non-BAT, produce a residual (waste) containing radium or uranium or both that requires appropriate disposal. The residual(s) can be a liquid, a solid, or both. Liquid residuals include brine, backwash water, reject water, acid neutralization water, caustic regenerant, and rinse water. The most common methods for liquid residual disposal is discharge to a sewer. Some water systems may also be able to dispose of liquid residuals (after receiving appropriate regulatory approvals) by direct discharge to a water body, in underground injection wells, in on-site wastewater treatment systems, or hauling the liquid residuals to a wastewater treatment plant. If liquid residual disposal options are limited or unavailable, consider switching to treatment units that do not generate significant quantities of liquid residuals. Solid residuals may include aged/ineffective media which typically refers to media that has been used and/or regenerated so many times that it is no longer effective at removing the contaminant(s) of concern; exhausted media which refers to the one-use throw-away media or media that has adsorbed all the contaminant(s) that it can handle and therefore contains a high concentration of the contaminant(s); and spent/used membranes that no longer effectively remove the contaminant(s) of concern. Because these solid residuals contain radionuclides, disposal can be a major consideration. Consequently, the very first step in the technology evaluation and selection process should be the identification of the disposal options available to the utility for these radionuclide wastes. Local landfills and wastewater treatment plants (WWTPs) have requirements that vary widely for accepting liquid and solid residuals containing radionuclides. You should consult with local landfill and WWTP professionals as well as your state drinking water primacy agency to determine if residuals containing radionuclides can be accepted, and at what concentrations.
Knowing the concentration of radionuclides in the residuals will likely be needed when determining the disposal options available. You may need to consult with the treatment process manufacturer and perhaps run pilot tests to determine concentrations. Residuals disposal.
Can you dispose of wastes containing radionuclides locally?