Objective <p>The rapid global expansion of targeted radionuclide therapy using ¹⁷⁷Lu-labeled radiopharmaceuticals has increased the need for effective and regulatory-compliant management of radioactive wastewater. However, long-lived impurities, such as ^177mLu, which emit high-energy γ-ray emissions complicate wastewater treatment and compliance with discharge regulations. This study aimed to determine an optimal method to treat wastewater contaminated with ¹⁷⁷Lu and ^177mLu.</p> Methods <p>Radioactive wastewater samples were collected from a storage tank in a targeted radionuclide therapy ward. The adsorption efficiency of various adsorbents, including Chelex resin, Bondesil-C18 and granular activated carbon, was assessed using both batch and column methods. Adsorption efficiency was measured as counts at 208&#xa0;keV using a high-purity germanium detector.</p> Results <p>The adsorption efficiency of Chelex resin and Bondesil-C18 in 100&#xa0;mL of radioactive wastewater, was below 25%, whereas that of granular activated carbon was 85.9%. The adsorption efficiency of batch and column methods increased with adsorbent mass and processing time. The column method with small amounts of granular activated carbon achieved 60%–70% adsorption efficiency within ~ 7&#xa0;min in a single-pass operation.</p> Conclusion <p>Adsorption treatment using granular activated carbon was effective for the removal of ¹⁷⁷Lu and ^177mLu from radioactive wastewater. Column method may support the management of radioactive wastewater contaminated with ¹⁷⁷Lu and other radionuclides in clinical settings.</p>