The Emerging Role of Peroxyacetic Acid in Water and Wastewater Treatment: Degradation of Pharmaceuticals, Microplastics, and Other Micropollutants.

Conventional wastewater treatment systems cannot effectively eliminate micropollutants such as contaminants of emerging concern (CECs). These compounds, even at trace levels, are persistent or pseudo-persistent, bioaccumulative, and potentially harmful to ecosystems and human health. Advanced oxidation processes (AOPs), based on the in situ generation of highly reactive oxygen species, have emerged as promising solutions. Peroxyacetic acid (PAA) has gained attention due to its strong oxidizing capacity, broad antimicrobial activity, environmentally benign by-products, and compatibility with different activation methods. This review provides an updated and integrated synthesis of recent advances in PAA-based AOPs for the degradation of major CEC groups, including pharmaceuticals, personal care products, pesticides, and industrial chemicals, as well as for the oxidative modification of microplastics (MPs). The review discusses several strategies for PAA activation and critically discusses removal efficiency, underlying mechanisms, and current limitations, emphasizing the gap between pollutant transformation and complete mineralization. Furthermore, the article highlights a key research need, which is the assessment of the toxicity of transformation products and their validation under realistic conditions. Overall, this review provides insight into the potential and challenges of PAA-based AOPs for sustainable water treatment.