Prioritization of the treatment and disposal methods of wastes containing polychlorinated biphenyl by fuzzy multi-criteria decision-making and risk assessment.

A total of 209 different types of polychlorinated biphenyls (PCBs) with various properties have been produced from 1930 to 1970s in which they have been banned due to their toxic effects. Total produced PCBs in the world are around 15 to 20 million tons, and up to now, 5.4 million tons of PCB-containing or PCB-contaminated equipment/materials has been eliminated. The remaining 10-15 million tons still needs to be removed or managed. Moreover, PCBs are pollutants still being unintentionally formed. These pollutants can be treated or disposed of various methods. However, there is a lack of knowledge about the selection of the treatment and disposal methods and their environmental, technological, cost, and social/ergonomic evaluation perspectives and the risk assessment during method selection. In this study, a projection was presented for the management of PCBs with an integrated multi-criteria decision-making (MCDM)-risk analysis focusing on these questions. Treatment (physical, chemical, biological) and disposal (incineration, landfill, supercritical water oxidation/gasification (SCWO/G), and pyrolysis/gasification) methods for the management of PCB-containing waste have been prioritized by fuzzy-analytical hierarchy process (F-AHP) in terms of environmental, technology, cost, and social/ergonomic criteria. Risk analysis was also made in terms of these criteria for considered alternatives, and compliance with risk and MCDM was evaluated. As a result of the study, priority methods among alternatives were determined as chemical treatment and SCWO/G. It has been determined that the weight values of the main criteria of environmental, technology, cost, and social/ergonomics were close to each other, but the emission criterion of the sub-criteria was determined to be of higher priority. In the risk analysis, chemical treatment and SCWO/G methods have been found to carry a more acceptable risk. Thus, it has been evaluated that these methods provide more superiority than other methods.