Abstract
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.
Highlights
Phosphorus (P) is an essential nutrient for plant growth
According to data of the Vietnam Water Supply and Sewerage Association by the end of 2016, out of 35 centralized wastewater treatment systems operating in the country, only 7 biological treatment plants combine nitrogen and phosphate treatment thoroughly [4]
Sludge was obtained from Truc Bach municipal wastewater treatment plant (MWTP) in Hanoi, Vietnam
Summary
Phosphorus (P) is an essential nutrient for plant growth. In the form of phosphate, it was used to produce fertilizers in order to increase yields in agriculture. The over-use of fertilizers, as well as phosphate-containing products causes a large amount of phosphate to accumulate in the soil or be washed out into rivers, streams, ponds, lakes, and present in wastewater contributes to significant phosphate pollution [2]. In the face of such phosphate pollution, the treatment and control of phosphates in wastewater is a big challenge. According to data of the Vietnam Water Supply and Sewerage Association by the end of 2016, out of 35 centralized wastewater treatment systems operating in the country, only 7 biological treatment plants combine nitrogen and phosphate treatment thoroughly [4]. Because of the irreplaceable role of phosphate in fertilizer production, the objective of phosphate treatment should change from removal to recovery
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