Conventional pollutants must be controlled alongside trace emerging contaminants, including per- and polyfluoroalkyl substances (PFAS) and antibiotics, yet the existing infrastructure at such plants cannot adequately manage this combination. Most previous work on emerging-contaminant removal has concentrated either on urban water treatment plants or on single contaminant classes tested under laboratory conditions, leaving a gap in evidence for small rural systems operating with constrained budgets and technical capacity. The research team quantified the simultaneous removal of five PFAS compounds and nine antibiotics across the treatment train, before and after the plant upgrade.

Effluent turbidity fell to 0.22 plus or minus 0.03 NTU, while total PFAS concentrations in the finished water dropped from 10.8 to 11.3 ng/L before the upgrade to 3.06 plus or minus 0.60 ng/L afterwards. That corresponds to 72.9 percent removal of total PFAS, a marked improvement over the 10.7 percent removal achieved by the conventional process. The chemistry of the individual PFAS compounds mattered considerably.

Long-chain PFAS were removed more effectively, with removal efficiencies exceeding 83 percent, whereas short-chain compounds reached only 53 to 60 percent removal. The upgrade combined powdered activated carbon with ultrafiltration, the treatment elements highlighted among the study's keywords. Antibiotics responded even more strongly to the intensified process.

Total antibiotic removal improved from 23.4 percent under the conventional configuration to 82.6 percent after the upgrade, a near-quadrupling of removal efficiency at a small rural plant. Beyond documenting removal performance, the researchers explored whether routine organic indicators could serve as surrogates for the hard-to-measure emerging contaminants. After the upgrade, total concentrations of PFAS and antibiotics showed positive correlations with ultraviolet absorbance at 254 nanometers, dissolved organic carbon, and the permanganate index along the treatment train.

The surrogate finding is exploratory rather than definitive. The correlations were observed at a single plant along one treatment train, and the authors state that their results provide preliminary, site-specific evidence. Broader validation across multiple sites and seasons is warranted before such surrogate relationships can be generalized to other rural water supply scenarios, where source water chemistry, contaminant mixtures and operational conditions may differ.

Even with those caveats, the study offers a reference for a widespread problem. The findings give engineers and regulators in similar settings a quantified benchmark for what cost-appropriate intensification achieved at this site. The work also reflects a shift in research perspective.

By adopting a rural-systems view and evaluating performance at full scale rather than in bench-top experiments, the study captures real-world interactions between co-occurring contaminants, treatment processes and operational constraints.

Subject of Research: Full-scale before-after evaluation of a rural water treatment plant upgrade for simultaneous removal of PFAS, antibiotics and conventional pollutants in northeastern Chongqing

Article Title: Addressing conventional and emerging contamination in resource-limited rural water supplies: a full-scale before-after evaluation of a process upgrade and exploratory surrogate analysis of PFAS and antibiotic removal

Article References: Li, W., Xu, W., Li, J., Shao, T., Ran, L., Xiang, Q., & Tian, Y. (2026). Addressing conventional and emerging contamination in resource-limited rural water supplies: a full-scale before-after evaluation of a process upgrade and exploratory surrogate analysis of PFAS and antibiotic removal. Frontiers in Environmental Science, 14, Article 1989300. https://doi.org/10.3389/fenvs.2026.1989300

Image Credits: AI Generated

DOI: 10.3389/fenvs.2026.1989300

Keywords: PFAS, antibiotics, rural drinking water, powdered activated carbon, ultrafiltration, emerging contaminants, surrogate monitoring, water treatment, Chongqing, UV254 absorbance, dissolved organic carbon, Addressing