Theoretical evaluation of chemical and physical feasibility of an in situ ultrasonic reactor for remediation of groundwater contaminated with per‐ and polyfluoroalkyl substances

Abstract

Per-and polyfluoroalkyl substances (PFAS) have been found in air, water, and soil globally. Groundwater is used as a drinking water supply in many locations and PFAS detections in groundwater occur frequently. Cavitation occurs when ultrasound is applied to liquids and has been shown to be effective for PFAS degradation. Sonolysis is often used to describe the cavity collapse that occurs after cavity expansion. An ideal scenario implements sonolysis in a horizontal well, which allows passive capture of contaminated water while reducing the costs and hazards associated with ex situ remediation. Four PFAS-contaminated site groundwaters were treated in the sonolytic reactor in the laboratory. Data from those experiments were used in a series of hypothetical case studies to evaluate the influence of chemical and physical properties on feasibility of installation of a novel in situ sonolytic reactor. When PFAS precursor species and perfluorobutanoic acid were included in the remediation goals they were found to drive the hydraulic retention times necessary for effective treatment compared to longer-chain PFAS. Improved implementation efficiency occurred when the target treatment area was restricted to a concentrated source zone, rather than less concentrated areas of the downgradient plume.

A Review of PFAS Destruction Technologies

“…Theoretical in-situ : To address the need for in-situ contaminated groundwater treatment, a theoretical system of ultrasonic reactors applied in a horizontal well, assuming two sonolytic reactors of 1.5 ft in length each, was presented with more details in the reference [ 114 ]. In this feasibility study, four groundwater-contaminated site samples were investigated and used to determine treatment time for the baseline at 70 ppt for each PFAS present.…”

Editor's perspective—Highlights of recent remediation technology innovations published in Remediation

“…Researchers at Clarkson University conducted a study that first tested the use of a laboratory‐scale sonolysis reactor and then applied the laboratory results to a theoretical site application using horizontal wells (Laramay & Crimi, 2021). The goal of the theoretical site study was to assess what chemical and physical conditions may be appropriate for implementing the sonolysis reactor in horizontal wells.…”