Tool and Database for Estimating Potential Longevity of Colloidal Activated Carbon Barriers for PFAS in Groundwater
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
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 design data from 17 sites and performance monitoring results from a total of 26 sites. The tool consists of both graphical and mathematical frameworks for estimating barrier longevity based on site‐specific parameters, including barrier dimensions, groundwater Darcy velocity, CAC loading, and influent PFAS concentrations. Application of the tool to 17 field sites yields barrier longevities ranging from 4 to over 100,000 years, with median values of 870, 150, and 180 years for PFOS, PFOA, and PFHxS, respectively. The wide variation in longevities is partly due to the significant variability in PFAS mass flux entering the barriers, as shown by the five‐order‐of‐magnitude difference in PFOA mass flux, ranging from 4 × 10 −8 to 1 × 10 −3 kg m −2 year −1 . The systematic decrease in barrier longevity from PFOS to PFOA/PFHxS aligns with known sorption behavior of these compounds onto CAC media. Key uncertainties in longevity estimation include spatial and temporal variability of PFAS and CAC, hydrogeologic heterogeneity, sorption isotherm selection, competitive sorption effects, and limited long‐term performance data. The tool provides a standardized approach for preliminary barrier design using site‐specific data while emphasizing the importance of applying appropriate safety factors and implementing long‐term monitoring strategies.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it