PCB congeners occurrence in sewage sludge from municipal wastewater treatment plants in Romania

Abstract

Sewage sludges originating from waste water treatment plants (WWTP) act as a sink for various contaminants including polychlorinated biphenyls (PCBs). The fate of organochlorine compounds in sewage sludge is shaped by their physical-chemical properties and by environmental conditions. The high persistence of polychlorobiphenyls (PCBs) in sewage sludge is given by an extremely reduced degradation rate which varies from months to years (the half-life of PCB 28 is 10.9 years, and PCB 52, 11.2 years). Due to their increased hydrophobicity, these carcinogenic compounds can be easily uptake by plants and transferred to the food chain. The present study investigated the occurrence of these seven PCB congeners in sewage sludge sampled from municipal waste water treatment plants from different geographical areas in Romania for a two-year period (2018 and 2019). For the analyzed PCB congeners a database was created concerning their occurrence levels in sewage sludge from these WWTPs. A total number of 62 sewage sludge samples were collected from different WWTPs between 2018-2019 and analyzed for PCB congener content using a validated GC-ECD method according to SR EN 16167/2013. In all the samples that were analyzed in this study the sum of PCB congeners was situated below the maximum allowable concentration (MAC = 0.8 mg/kg d.w.) stated by the Order 708/2004.