Abstract
Nitrogen (N) and phosphorus (P) are primary pollutants contributing to water quality degradation and eutrophication but are also indispensable resources for agricultural production. In this study, we synthesized porous MgO/Mg(OH)2-modified starch gels (SC-M/SC-OM) to facilitate the simultaneous removal of N and P from wastewater and address the challenges associated with separating and recycling powdered materials. By immobilizing magnesium powder within the matrix of starch gel, with the addition of 1.7 % w/w of MgO and 2.4 % w/w of Mg(OH)₂, the adsorbent can be efficiently recovered from the liquid phase, minimizing material loss. Due to their inherent pH-regulating capabilities, the modified starch gels exhibited excellent removal performance over a wide pH range. At the appropriate adsorbent dose, the maximum recovery of SC-M was 70.072 mg/g P and 25.517 mg/g N, whereas SC-OM was marginally inferior to SC-M. The pseudo-first kinetic model more accurately represented the adsorption of the two materials, showing that N and P concentrations mainly affected the adsorption efficiency, which benefits nutrient recovery at higher concentrations. Starch gels function as carriers for powdered magnesium and contribute to the synergistic removal of N and P, particularly enhancing P removal. SC-OM primarily facilitates the recovery of N and P by forming struvite. At the same time, the adsorption during the hydration process of MgO also plays a crucial role in the recovery with SC-M. Finally, the pot experiment confirmed the feasibility of using the recovered SC as a sustained release fertilizer. This study reveals the significant potential of SC-M/SC-OM for environmentally friendly nutrient removal and recovery, providing a promising approach for wastewater treatment and nutrient recycling.
Published Version
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