Evaluation of the Removal Efficiency of PCBs from Five Wastewater Treatment Plants in Jordan

Abstract

The levels of persistent organic pollutants, polychlorinated biphenyls (PCBs), were investigated in influent, effluent, and sludge of five wastewater treatment plants (WWTPs) in Jordan. Concentrations of 12 dioxin-like PCBs were determined. The extraction of PCBs from wastewater samples was done by solvent extraction using dichloromethane/hexane 1:1 mixture. The concentrated extracts were sequentially subjected to multilayer silica gel, basic alumina, and florisil chromatography columns for further cleanup. Sludge samples were extracted in a Soxhlet apparatus, using petroleum ether. PCB determination has been completed using gas chromatography equipped with mass spectrometry detector. The total concentrations of PCBs in influent samples ranged from 34.65 to 228.3 ng L−1, in effluent samples from 16.1 to 123.88 ng L−1, and in the sludge samples from 51.1 to 223.85 ng kg−1. In three of the investigated wastewater treatment plants, the amount of PCBs in sludge exceeded the limit proposed by European Union legislation. The total removal efficiencies of the total PCBs were evaluated and ranged from 34.8 to 88.1% for Aqaba and Abu-Nsair WWTP, respectively. The values of incremental lifetime cancer risk due to exposure to PCBs in sludge samples were also estimated in this study, and they ranged from 2.415 × 10−7 to 1.193 × 10−6 for adults. The number of people suspected to have cancer due to the exposure to the sludge of the WWTPs in Jordan is between 4 and 20 out of ten million.