Two seasonal sampling campaigns of raw and finished waters from 28 water treatment plants were conducted to investigate the occurrence and removal of dissolved organic nitrogen (DON). A new dialysis pretreatment technique was applied for accurate DON determination. The average DON concentration was 0.186 mg/L nitrogen (N) in raw waters and 0.148 mg/L N in finished waters. On average, total dissolved nitrogen in the raw waters consist of 10% DON and 90% dissolved inorganic nitrogen. The dissolved organic carbon (DOC)‐to‐DON ratio of raw waters averaged 18 mg DOC to 1 mg DON. DON removal during water treatment closely mirrored that of DOC removal. The molecular weight distribution of DON roughly parallels that of DOC, and higher‐molecular‐weight fractions (> 10,000 D) of both DON and DOC were preferentially removed across the full‐scale water treatment plants.

a b s t r a c tIn this study, we investigated the occurrence and removal of contaminants of emerging concern including 10 pharmaceuticals and personal care products (PPCPs) and 3 endocrine disrupting compounds in 6 water reclamation facilities (WRFs) in Korea for better understanding of the fate of those contaminants through the water reuse system. The sampling campaigns were performed six times at each WRF from influent, and after biological, coagulation and ultraviolet disinfection processes. Concentrations of the monitored compounds in WRFs (A, B and C), which were located in industrial and urban areas, were relatively higher compared with other WRFs. Concentrations of caffeine and ibuprofen in influents were relatively higher than other PPCPs. Biological processes in the WRFs removed most of the PPCPs except carbamazepine and primidone. Carbamazepine was not readily removed by coagulation and filtration processes, which were followed by biological processes in the WRFs. Continuous monitoring and management for carbamazepine and primidone may be required to reduce or eliminate the potential adverse impact of those contaminants to ecosystems and downstream utilities.