Phosphorus removal from wastewater using Ca-modified attapulgite: Fixed-bed column performance and breakthrough curves analysis

The adsorbent calcium-modified attapulgite (Ca-GAT) prepared by calcium chloride modification and high temperature treatment (700 degrees C) has proved to remove phosphorus in low-concentration phosphorus wastewater in batch adsorption experiments. Dynamic adsorption performance and industrial application potential still need further determination. This study explored the effects of various parameters on the dynamic phosphorus adsorption, including initial phosphate concentration (2-10 mg/L), flow rate (1-3 mL/min) and adsorption bed height (2-6 cm). Phosphorus adsorption ability improved and the breakthrough time increased with the increase of bed height, flow rate, and a decrease in initial phosphorus concentration. Breakthrough curves fitted four models, the Adams-Bohart, Thomas, Yoon-Nelson and Bed depth service time (BDST). The maximum adsorption amount determined by the Thomas model obtained 13.477 mg/g. The saturated fixed-bed column were regen-erated with NaOH, NaOH + NaCl and HCl, among which 0.5 mol/L NaOH had the best regeneration effect. During the utilization of a large fixed-bed to treat the actual membrane bioreactor (MBR) effluent, the break-through point (0.5 mg/L) was obtained after 177 h. These results implied that Ca-GAT had an application po-tential for the treatment of low-concentration phosphorus wastewater (2 mg/L).

Automated summary

The study investigated the adsorption of phosphorus in low-concentration phosphorus wastewater using a modified calcium-modified attapulgite (Ca-GAT). The study explored the effects of various parameters on dynamic phosphorus adsorption and found that the adsorption ability improved with increased bed height and flow rate, and decreased initial phosphorus concentration. Breakthrough curves were fitted using four models, with the Thomas model determining a maximum adsorption amount of 13.477 mg/g. The study also found that NaOH regeneration had the best effect, and the breakthrough point was achieved after 177 hours in treating actual MBR effluent. These findings suggest that Ca-GAT has potential for the treatment of low-concentration phosphorus wastewater.