The current disposal of waterworks sludge (WS) by landfill or discharge into water body results in land consumption and environment pollution. To solve the problem, alum-based waterworks sludge (AWS) was reclaimed and reused to develop adsorbent for aqueous tetracycline hydrochloride (TCH) removal. WS was modified using HCl solution and Fe²+/Fe³⁺ coprecipitation to get acidized and magnetized waterworks sludge (Fe₃O₄@HAWS) for the improvement of its adsorption capacity and separation efficiency. Fe₃O₄@HAWS was used as adsorbent to test its static TC adsorption performance. The results suggested that the TCH adsorption was a pH dependent process, and the maximum TCH adsorption by Fe₃O₄@HAWS was achieved at pH 5 at 25ºC in the pH range of 3-10. Among the three kinetic models, the pseudo-second-order equation best characterized the adsorption process, while the Freundlich equation best described the adsorption process. The thermodynamic study indicated that the adsorption process was spontaneous and exothermic. The investigation demonstrated that the composite was successful for aqueous TCH adsorption and spent adsorbent separation, providing not only a unique notion for the sustainable and environmentally friendly treatment and disposal of WS, but also a novel solution for TCH-containing wastewater treatment.