Speaker
Description
The high temperatures and reactive radicals generated during irradiation by electron beam can degrade or remove challenging contaminants such as petroleum hydrocarbons and per- and polyfluoroalkyl substances (PFAS). Reductions in hydrocarbon concentrations of up to 98.4% were observed for field soils using a 10 MeV, 18 kW accelerator; hydrocarbons of all weights were reduced, suggesting both thermal and non-thermal mechanisms of hydrocarbon decomposition and removal. Total petroleum hydrocarbon (TPH) reduction was also achieved at higher power densities using a 90 kW, 3 MeV accelerator (up to 96% reduced), showing promise for process scalability. Temperature-programmed oxidation and desorption characterization suggested the production of a form of non-desorbable carbon resembling biochar, a byproduct of pyrolysis that may improve soil health parameters when applied to soil. Additionally, qualitative characterization of process condensate shows a mixture hydrocarbons, carboxylic acids, and alcohols, which may have value as fuel or chemical feedstocks. During a comparative assessment of EBeam and thermal remediation methods, energy requirements for EBeam irradiation were shown to fall between indirect and direct thermal desorption for comparable reductions, with the added benefit of an electrical, potentially carbon-neutral power source. Reductions in concentration were also observed for PFAS compounds following irradiation with doses up to 2000 kGy, with perfluoroalkyl sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) reduced by 99.9% and 86.5%, respectively. Subsequent experiments have focused on upscaling of treatment. Design work has been performed to develop a mobile treatment facility, including simulation using the PUFFIn and PENELOPE Monte Carlo software packages for process optimization.
