Stephen D. Richardson

Effects of Mass Transfer Limitations on PFAS Breakthrough in Colloidal Activated Carbon Groundwater Barriers

Zijie Zheng, Dayna M. Cline, Chun-Yu Shih, Stephen D. Richardson et autres

Per- and polyfluoroalkyl substances (PFAS) persist in groundwater and are difficult to remove. Colloidal activated carbon (CAC) is increasingly used in porous barriers to slow PFAS migration in groundwater, but it is unclear when grain-scale mass transfer limitations reduce the barrier performance. …

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Child Refugee to Wartime Scientist: a German Jewish Refugee’s Search for a British Identity

Rob David, Stephen D. Richardson

This chapter examines the wartime scientific work of Werner David, a German Jewish child refugee who arrived in Britain in 1933, and suggests that the contribution he was able to make to the British war effort played a pivotal role in his …

Investigation of PFAS rejection by closed-circuit reverse osmosis and nanofiltration and sorption to treatment materials during groundwater treatment: a pilot demonstration

Nicole A. Masters, Brian A. Marron, Adria Lau, Stephen D. Richardson et autres

The rejection of a broad range of per- and polyfluoroalkyl substances (PFAS) by reverse osmosis (RO) and nanofiltration (NF) was evaluated using a pilot closed-circuit membrane system operating at three recoveries (80, 85, 90 %) treating aqueous film-forming foam (AFFF) impaired groundwater …

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Removal, Concentration, and Destruction of Per- and Polyfluoroalkyl Substances Using Foam Fractionation Coupled with Enhanced Contact Plasma

Dung Nguyen, John Stults, Stephen D. Richardson, Peter Murphy et autres

Per- and polyfluoroalkyl substances (PFAS) can occur in groundwater at elevated concentrations due to use in numerous commercial and industrial applications. Foam fractionation, which utilizes the surfactant properties of air–water interfacial adsorption and foaming to recover surfactants from the aqueous phase, has …

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Tool and Database for Estimating Potential Longevity of Colloidal Activated Carbon Barriers for PFAS in Groundwater

Charles J. Newell, Wayne H. Smith, Kade Kearney, Hassan Javed et autres

ABSTRACT This study presents a planning‐level graphical tool and a regression equation model for estimating the longevity of Colloidal Activated Carbon (CAC) barriers for treating per‐ and polyfluoroalkyl substances (PFAS) in groundwater. The tool development incorporated information from field‐scale CAC barriers, including …

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Neuron-Level Language Tag Injection Improves Zero-Shot Translation Performance

Jay Orten, Ammon Shurtz, Nancy Fulda, Stephen D. Richardson

Language tagging, a method whereby source and target inputs are prefixed with a unique language token, has become the de facto standard for conditioning Multilingual Neural Machine Translation (MNMT) models on specific language directions.This conditioning can manifest effective zero-shot translation abilities in …

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Semitic Root Encoding: Tokenization Based on the Templatic Morphology of Semitic Languages in NMT

Brendan T. Hatch, Stephen D. Richardson

The morphological structure of Semitic languages, such as Arabic, is based on nonconcatenative roots and templates.This complex word structure used by humans is obscured to neural models that employ traditional tokenization algorithms, such as byte-pair encoding (BPE) (Sennrich et al., 2016;Gage, 1994).In …

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The Effects of Pretraining in Video-Guided Machine Translation

Ammon Shurtz, Lawry Sorenson, Stephen D. Richardson

Available and emerging liquid treatment technologies for PFASs

William H. DiGuiseppi, Charles J. Newell, Grant R. Carey, Poonam R. Kulkarni et autres

Abstract Per‐ and polyfluoroalkyl substances (PFASs) are present at a wide range of private sector facilities and United States (US) government installations, including those operated by the Department of Defense, the Department of Energy, the National Aeronauts and Space Administration, and other …

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Demonstration of a Principal Component Analysis Trajectory Method to Assess Bioremediation Progress at a TCE ‐Impacted Site

Matan Freedman, Kevin G. Mumford, Anthony S. Danko, Dylan Hart et autres

Abstract In‐situ bioremediation (ISB) is a popular remediation technology for the treatment of a range of compounds, including chlorinated solvents such as tetrachloroethene and trichloroethene (TCE). Large amounts of data are collected before, during, and after ISB applications to determine amendment approaches, …

A novel application of a geotechnical soil stabilization technology for improved delivery of remedial amendments

Stephen D. Richardson, Joshua M. Kolz, Dylan Hart, Justin A. Long et autres

Abstract Accelerating the remediation of contaminants that have diffused into low‐permeability (low‐k) geologic units such as silts and clays is a key need for the groundwater remediation industry. Injection‐based remedial technologies are often ineffective because the injected amendments are more likely to …

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Field Demonstration of a Sonolysis Reactor for Treatment of PFAS-Contaminated Groundwater

Poonam R. Kulkarni, Stephen D. Richardson, Blossom N. Nzeribe, David T. Adamson et autres

A mobile treatment system equipped with a custom-built sonolysis reactor was deployed at a site in California to treat groundwater impacted with per- and polyfluoroalkyl substances (PFAS). Extracted groundwater was treated in a 700-kHz sonolysis reactor for batch treatment under different power …

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