Abstract

The use of coal fly ash for nutrient recovery in wastewater treatment offers a potential win-win scenario as it simultaneously utilizes and re-channels two wastes - coal fly ash and wastewater. This study investigated the adsorptive recovery of urea from synthetic urine using fly ash. Equilibrium experiments revealed that 1.5 g ash loading, initial urea concentration of 13.5 g L-1, urine pH = 6.0, sorption temperature = 30 degrees C and 150 rpm shaker speed were the optimal process parameters and maximum adsorption capacity was 410 mg g(-1). Proof of concept to the use of synthetic urine was conducted by performing adsorption with real human urine which validated the experimental findings. Comparative analysis and non-linear optimization of nine isotherm models through comprehensive error analysis revealed that Flory-Huggins and Redlich-Peterson equations best described the adsorption. Process thermodynamics suggested that Van der Waal's and electrostatic interactions occur between urea molecules and the surface of fly ash particles; besides, the sorption was found to be exothermic, spontaneous and physical in nature. Kinetic studies pointed toward a pseudo-second-order kinetic fit with contributions from intra-particle diffusion. Further, the rate of mass transfer was seen to be controlled and limited by film diffusion of urea which featured stronger than its pore diffusion. To design a multistage batch adsorber, a mathematical model unique to the sorption system was derived that minimized the total amount of fly ash required for 90% removal of urea from different volumes of influent synthetic urine solutions. (C) 2016 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.

Keywords

Resource recovery; Wastewater treatment; Urine; Sustainable waste management; Isotherm analysis; Process design

Published in

Arabian Journal of Chemistry
2019, Volume: 12, number: 8, pages: 5049-5061
Publisher: ELSEVIER

SLU Authors

• Simha, Prithvi

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • University of Manchester

Sustainable Development Goals

SDG6 Ensure availability and sustainable management of water and sanitation for all
SDG12 Ensure sustainable consumption and production patterns


UKÄ Subject classification

Water Treatment
Water Treatment


Publication identifier

DOI: https://doi.org/10.1016/j.arabjc.2016.11.013

Permanent link to this page (URI)

https://res.slu.se/id/publ/103839