Importance and challenges of bromate analysis in wastewater: a systematic review

Abstract The increasing prevalence of anthropogenic trace substances and organic micropollutants in wastewater necessitates advanced treatment stages in wastewater treatment plants (WWTP) to effectively remove these pollutants. Ozonation has proven to be an effective method for this purpose but poses the risk of generating toxic by-products like bromate, especially when treating bromide-containing wastewater at high ozone dosages. Bromate is classified as a possible human carcinogen (IARC Group 2B) and presents both acute and chronic health risks, along with various ecotoxic effects. With the new European Union Urban Wastewater Directive (2024/3019) mandating advanced treatment for micropollutant removal, the occurrence and monitoring of bromate will gain increasing relevance. Although no threshold value for bromate in wastewater has yet been established, the proposed environmental quality standard indicates ongoing regulatory efforts, resulting in the need to monitor bromate concentrations in WWTPs effluents to safeguard public health and the environment. This review systematically examines the toxicological and ecological relevance of bromate and evaluates existing analytical approaches for its detection in wastewater. Methods developed for drinking and surface waters, such as ion chromatography (IC) with conductivity (CD) or post-column reaction and ultraviolet detection (PCR-UV), as well as mass spectrometry (MS)-based techniques, have been applied to wastewater matrices with varying levels of success. Reported quantification limits range from 70 µg/L using IC-CD to as low as 0.1 µg/L using IC-MS/MS. Wastewater presents a significantly more complex matrix than drinking water, introducing interferences from dissolved organic matter, anions, and fluctuating compositions. These challenges reduce accuracy, reliability, and reproducibility of results. However, none of these methods have been standardized by ISO, ASTM, or CEN or validated through interlaboratory trials for wastewater analysis. Among the evaluated methods, IC-PCR-UV as well as IC-MS-based approaches appear most suitable to provide the required sensitivity and robustness. Developing a harmonized methodology tailored to wastewater matrices is essential for regulatory compliance, environmental protection, and safeguarding public health.