Simultaneous phosphorus removal and adsorbents recovery with Ca-PAC assisted adsorption dynamic membrane system: Removal performance and influencing factors

Ca(OH)2 treated powdered activated carbon (Ca-PAC) assisted adsorption dynamic membrane system was proposed for simultaneous phosphorus adsorption and micrometer scale adsorbent recovery. In Ca-PAC assisted adsorption dynamic membrane system, adsorption and dynamic membrane separation acted as the key roles for pollutants removal. At first, the effect of Ca(OH)2 concentration in Ca-PAC preparation was evaluated. Phos-phorus removal rate increased from 3.79% to 98.01% when added Ca(OH)2 concentration was increased from 0 to 2 M in PAC treatment. Effect of initial phosphorus concentration, reaction temperature, and solution pH on phosphorus removal with Ca-PAC was explored in this study. And then, adsorption isotherms, adsorption ki-netics, SEM, XRD, and FTIR were conducted to explain the phosphorus adsorption. Ligand exchange between hydroxyl on Ca-PAC and phosphate was confirmed to be the main phosphorus removal mechanism, with little Ca-P precipitation verified in X-ray diffraction (XRD) analysis. At last, integrated adsorption dynamic membrane system was operated with Ca-PAC, showing more than 90% phosphorus adsorbed in 1 min and 63.25%-87.65% micrometer scale Ca-PAC recovered. Overall, adsorption-dynamic membrane system presents to be stable and applicable in deep phosphorus removal and micrometer scale adsorbent recovery, which presents a new route for micrometer scale adsorbent application and recovery in actual surface water and wastewater treatment.

Automated summary

In this study, a Ca(OH)2 treated powdered activated carbon (Ca-PAC) assisted adsorption dynamic membrane system was proposed for simultaneous phosphorus adsorption and micrometer scale adsorbent recovery. The effect of Ca(OH)2 concentration on phosphorus removal rate was evaluated and the main phosphorus removal mechanism was determined to be ligand exchange between hydroxyl on Ca-PAC and phosphate. The integrated adsorption dynamic membrane system using Ca-PAC showed effective phosphorus adsorption and considerable micrometer scale adsorbent recovery.