Per‐ and polyfluoroalkyl substances (PFAS) are a recalcitrant group of chemicals and can be found throughout the environment. They often collect in wastewater systems with virtually no degradation prior to environmental discharge. Some PFAS partitions to solids captured in wastewater treatment which require further processing. Of all the commonly applied solids treatment technologies, incineration offers the only possibility to completely destroy PFAS. Little is known about the fate of PFAS through incineration, in particular, for the systems employed in water resource recovery facilities (WRRF). This review covers available research on the fate of PFAS through incineration systems with a focus on sewage sludge incinerators. This research indicates that at least some PFAS destruction will occur with incineration approaches used at WRRFs. Furthermore, PFAS in flue gas, ash, or water streams used for incinerator pollution control may be undetectable. Future research involving full‐scale fate studies will provide insight on the efficacy of PFAS destruction through incineration and whether other compounds of concern are generated. Practitioner points Thermal processing is the only commercial approach available to destroy PFAS. Thermal degradation conditions required for destruction of PFAS during incineration processes are discussed. Fate of PFAS through water resource recovery facility incineration technologies remains unclear. Other thermal technologies such as smoldering combustion, pyrolysis, gasification, and hydrothermal liquefaction provide promise but are in developmental phases.

The photosynthetic inhibitory effect of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl amino‐1,3,5‐triazine) and three of its major metabolites (deethylated, deisopropylated, and hydroxyatrazine) were determined for four species of submerged macrophytes: Potamogeton perfoliatus L., Ruppia maritima L., Myriophyllum spicatum L., and Zannichellia palustris L. The four species showed a similar response to varied dosages of the parent atrazine compound with an average I1 (concentration at which photosynthesis is inhibited by 1%) for the four species of 20 µg/L and an average I50 (concentration at which photosynthesis is inhibited by 50%) for the four species of 95 µg/L. The three major degradation metabolites of atrazine produced varying degrees of photosynthetic inhibition in the four species, but generally the order of toxicity was deethylated > deisopropylated > hydroxyatrazine with hydroxyatrazine causing an apparent stimulation of photosynthesis in several species. Of four species tested, Myriophyllum spicatum L. was the most resistant to atrazine and its metabolites. The magnitude of the actual uptake of the compounds [µg compound/grams dry wt (gdw) plant] by the plants correlated closely with the photosynthetic inhibitory response, i.e., at the same concentration the uptake of atrazine > deethylated > deisopropylated > hydroxyatrazine. Considering that an extremely high environmental concentration (0.5 mg/L) of deethylated atrazine for an estuary only produced a photosynthetic inhibition of from 20 to 40% in four major species of submerged macrophytes, it is concluded that the degradation products of atrazine tested did not play a major role in the disappearance of the submerged vascular plants from the Chesapeake Bay.

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Wastewater treatment generates solids requiring subsequent processing. Costs and contaminant concerns (e.g., per‐ and polyfluoroalkyl substances [PFAS]) are challenging widely used landfilling and land application practices. These circumstances are partly driving the re‐emergence of pyrolysis and gasification technologies along with beneficial reuse prospects of the char solid residual. Previously, technologies experienced operational challenges leading to revised configurations, such as directly coupling a thermal oxidizer to the reactor to destroy tar forming compounds. This paper provides an overview of pyrolysis and gasification technologies, characteristics of the char product, air emission considerations, and potential fate of PFAS and other pollutants through the systems. Results from a survey of viable suppliers illustrate differences in commercially available options. Additional research is required to validate performance over the long‐term operation and confirm contaminant fate, which will help determine whether resurging interest in pyrolysis and gasification warrants widespread adoption. Practitioner Points Pyrolysis and gasification systems are re‐emerging in the wastewater industry. Direct coupling of thermal oxidizers and other modifications offered by contemporary systems aim to overcome past failures. Process conditions when coupled with a thermal oxidizer will likely destroy most organic contaminants, including PFAS, but requires additional research. Three full‐scale facilities recently operated, several in construction or design that will provide operating experience for widespread technology adoption consideration.