Study on Leaching of Phosphate from Municipal Wastewater Treatment Plant’s Sewage Sludge and Followed by Adsorption on Mg‐Al Layered Double Hydroxide

Sewage sludge from municipal wastewater treatment plant was a rich phosphorus resource. In this study, HCl, H2SO4, and HNO3 were investigated as leaching acids for extraction of phosphate from the sludge to recover this value nutrient by adsorption using layered double hydroxide (LDH) nanomaterial. Mg-Al LDH was synthesized by coprecipitation at room temperature and at a constant pH of 10 (±0.5) with Mg/Al molar ratio of 2.0. The material was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), and Fourier transform infrared spectroscopy (FTIR) and then was used to adsorb phosphate leaching from the sewage sludge. Adsorption experiments were carried out as a function of adsorbent dose, phosphate initial concentrations, and pH. The adsorption isotherm data fitted the Langmuir model perfectly. The high adsorption capacity of Mg-Al LDH and slowly released phosphate of the post-adsorption LDH suggested that this material was an excellent adsorbent for phosphate recovery and could be considered as a potential phosphate release fertilizer.