Reverse osmosis concentrate (ROC), a hyper-saline byproduct of domestic RO systems, contains elevated ionic and heavy metal content, posing environmental risks. This study developed a decentralized treatment system using a fluidized-bed column packed with chitosan-impregnated zinc-oxide nanocomposite (CS@ZnO) and acid-treated resin (ATR) beads. ROC samples were collected from residential RO units in groundwater (GW) and surface water (SW) dependent regions in Gujarat, India. Physicochemical analysis revealed elevated total dissolved solids (TDS: ≥3241 mg L−1), electrical conductivity (EC: ≥5440 μS cm−1), anions, cations and heavy metals exceeding regulatory limits. A negative correlation between pH and EC/TDS revealed acidification linked to ion accumulation, informing sorbent optimization. The hybrid column, operated in upward flow (570 mL min−1), demonstrated effective stabilization of pH and removal of TDS (25.9 %) and EC (39.5 %) up to 60 L. Significant contaminant removal efficiencies included: Ca2+ (73.2 %), Mg2+ (62.4 %), Na+ (31.3 %), F− (76.6 %), Cl− (46.2 %), SO₄2− (99.7 %), NO₃− (92.1 %), Mn (100 %), Zn (65.3 %), Ni (42.5 %), Co (16.7 %), and Cd (54.5 %). The adsorption mechanism combined CS’s chelation, ATR’s ion-exchange, and ZnO’s surface reactivity. Although Pb and Cr exceeded safe limits post-treatment, the effluent complied with standards for non-potable reuse. This column offers a scalable, low-cost method for ROC valorization, promoting sustainable water reuse and environmental protection in water-stressed areas.