The Freundlich and Langmuir adsorption models were used for the mathematical description of adsorption equilibrium and it was found that P removal was best described by Langmuir model. The maximum adsorption capacity of the adsorbent based on sludge of Quang Te DWTP was mg/g. The adsorption process followed pseudo-second-order kinetics (R2 ≥ ). These findings suggest that MS has potential applications as a low-cost adsorbent for P treatment. | Vietnam Journal of Science and Technology 56 (2C) (2018) 43-49 PHOSPHATE REMOVAL FROM AQUEOUS SOLUTION BY USING MODIFIED SLUDGE FROM WATER TREATMENT PLANT Dang-Thi Thanh-Loc1, *, Le-Van Tuan1, Hidenori Harada2 1 2 Department of Environmental Science, Hue University of Sciences, Hue University, 77 Nguyen Hue street, Hue city, Viet Nam Graduate School of Global Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan * Email: dangthithanhloc@ Received: 10 May 2018; Accepted for publication: 20 August 2018 ABSTRACT Heat and humic acid modified sludge (MS) from drinking water treatment plant (DWTP) is used as an adsorbent for removal of phosphate (P) from aqueous solution. The MS was characterized by XRD and SEM observation. The effects of pH, adsorbent dosage, initial P concentration, and exposure time on the P removal were studied. Under identical treatment conditions (MS dosage = 10 g/L, initial P concentration = 10 mg/L, pH 7, 120 rpm, and room temperature), a removal efficiency of 91 % was obtained within 240 min. The Freundlich and Langmuir adsorption models were used for the mathematical description of adsorption equilibrium and it was found that P removal was best described by Langmuir model. The maximum adsorption capacity of the adsorbent based on sludge of Quang Te DWTP was mg/g. The adsorption process followed pseudo-second-order kinetics (R2 ≥ ). These findings suggest that MS has potential applications as a low-cost adsorbent for P treatment. Keywords: adsorption, modified sludge, phosphate removal, drinking water treatment sludge. 1. INTRODUCTION Phosphorus (P) plays a significant role in the growth of plants but is now widely recognized as a serious environmental issue because of the water eutrophication through wastewater discharge. The P concentration in water medium above mg/L can lead to eutrophication, reducing water quality and threatening aquatic ecosystems [1]. To avoid these .
