Although Al-based coagulation and adsorption processes have been proved highly efficient for fluoride (F) removal, the two processes both generate large amount of Al(OH)3 solid waste containing F (Al(OH)3-F). This study aimed to investigate the feasibility of utilizing Al(OH)3-F generated in Al(OH)3 adsorption (Al(OH)3-Fads) and coagulation (Al(OH)3-Fcoag) for the adsorption of cadmium ion (Cd(II)). The adsorption capacity of Al(OH)3-Fads and Al(OH)3-Fcoag for Cd(II) was similar as that of pristine aluminum hydroxide (Al(OH)3), being of 24.39 and 19.90 mg·g-1, respectively. The adsorption of Cd(II) onto Al(OH)3-Fads and Al(OH)3-Fcoag was identified to be dominated by ion-exchange with sodium ion (Na+) or hydrogen ion (H+), surface microprecitation, and electrostatic attraction. The maximum concentration of the leached fluoride from Al(OH)3-Fads and Al(OH)3-Fcoag is below the Chinese Class-I Industrial Wastewater Discharge Standard for fluoride (<10 mg·L-1). This study demonstrates that the Al(OH)3 solid wastes generated in fluoride removal process could be potentially utilized as a adsorbent for Cd(II) removal. |