= Solution
\b[<evaporation>] transfers water to a vapour stream and retains mainly nonvolatile solutes in a concentrate. It can give substantial volume reduction and works across many dissolved-solute compositions. Its disadvantages are heat demand, scaling and <corrosion>; <aerosols>, entrainment or volatile radioactive species can contaminate the condensate. Condensate must therefore be sampled or monitored rather than assumed releasable, while the concentrate requires <radioactive waste conditioning>. A demister limits droplet carryover but does not remove a genuinely volatile contaminant.
\b[<ion exchange>] transfers dissolved radioactive <ions> to an exchanger, often an <ion-exchange resin>. It is useful for polishing relatively dilute aqueous streams and can provide selective removal without evaporating the bulk water. Competing inactive <ions> consume capacity, suspended particles foul the bed, and a neutral or poorly retained species may pass through. Breakthrough measurements determine when the exchanger ceases to meet its target; exhausted resin or regeneration liquors become secondary <radioactive waste>. Separation performance must be established for the actual feed chemistry, not inferred from the name of the radionuclide alone.
\b[Chemical <precipitation (chemistry)> with solid–liquid separation] uses <precipitation (chemistry)>, <coprecipitation> and <adsorption> to carry contaminants into solids, followed by settling or <filtration (chemistry)>. It can treat substantial volumes and complex feeds at moderate equipment cost. Its disadvantages are a relatively bulky sludge, incomplete removal of soluble species, and sensitivity to <pH>, <complexation> and competing <ions>. The sludge must be dewatered and conditioned, and the clarified liquid checked for residual <radioactive activity>. Polishing by another method may still be needed.
In each case, measure both the treated stream and the residue so that the radioactive inventory balance can be checked. Treatment transfers or concentrates <radioactive activity>; \b[only <radioactive decay> reduces the number of radioactive parent nuclei]. These methods and the distinction between treatment and conditioning are set out in the institutional waste-management framework.<Predisposal Management of Radioactive Waste from Nuclear Power Plants and Research Reactors by the International Atomic Energy Agency>[SSG-40, section 6, especially paragraph 6.42 and the liquid-waste treatment discussion]{ref}
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