The Fate of Fluorine Post Per- and Polyfluoroalkyl Substances Destruction during the Thermal Treatment of Biosolids: A Thermodynamic Study
Savankumar Patel,
Pobitra Halder,
Ibrahim Gbolahan Hakeem,
Ekaterina Selezneva,
Manoj Kumar Jena,
Ganesh Veluswamy,
Nimesha Rathnayake,
Abhishek Sharma,
Anithadevi Kenday Sivaram,
Aravind Surapaneni,
Ravi Naidu,
Mallavarapu Megharaj,
Arun K. Vuppaladadiyam,
Kalpit Shah
Affiliations
Savankumar Patel
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Pobitra Halder
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Ibrahim Gbolahan Hakeem
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Ekaterina Selezneva
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Manoj Kumar Jena
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Ganesh Veluswamy
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Nimesha Rathnayake
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Abhishek Sharma
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Anithadevi Kenday Sivaram
Global Centre for Environmental Remediation, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
Aravind Surapaneni
ARC Training Centre on Advance Transformation of Australia’s Biosolids Resource, RMIT University, Bundoora, VIC 3083, Australia
Ravi Naidu
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
Mallavarapu Megharaj
Global Centre for Environmental Remediation, College of Engineering, Science and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
Arun K. Vuppaladadiyam
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Kalpit Shah
Chemical & Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated synthetic chemicals that are highly recalcitrant, toxic, and bio-accumulative and have been detected in biosolids worldwide, posing potential risks to humans and the environment. Recent studies suggest that the organic C-F bond in PFAS can be destructed and potentially mineralised into inorganic fluorides during thermal treatment. This study focuses on thermodynamic equilibrium investigations and the fate of fluorine compounds post-PFAS destruction during biosolid thermal treatment. The results indicate that gas-phase fluorine compounds are mainly hydrogen fluoride (HF) and alkali fluorides, whereas solid-phase fluorine compounds include alkaline earth fluorides and their spinels. High moisture and oxygen content in the volatiles increased the concentration of HF in the gas phase. However, adding minerals reduced the emission of HF in the gas phase significantly and enhanced the capture of fluorine as CaF2 spinel in the solid phase. This study also investigates the effect of feedstock composition on the fate of fluorine. High ash content and low volatile matter in the feedstock reduced HF gas emissions and increased fluorine capture in the solid product. The findings of this work are useful in designing thermal systems with optimised operating conditions for minimising the release of fluorinated species during the thermal treatment of PFAS-containing biosolids.
