Case study: Electrochemical Geo-Oxidation (ECGO) treatment of Massachusetts New Bedford Harbor sediment PCBs

An electrochemical remediation technology, referred to as Electrochemical Geo-Oxidation (ECGO) was tested in field to assess its potential to treat polychlorinated biphenyls (PCBs) contaminated sediments from New Bedford Harbor (NBH), Massachusetts. The primary objective was to evaluate the effectiveness of ECGO for reducing PCB levels under the anaerobic conditions typical of saturated and submerged sediments. The ECGO treatment of aerated and un-aerated (anaerobic) samples of the NBH sediments began on November, 2003 and lasted over four-years until early July, 2008. During 2003–2006 seven sampling events occurred, and the last sampling was done on March, 2010, about 20 months after the treatment power was turned off on July 12, 2008. Full PCB congener analyses (EPA 22 1668A) and partial PCB scans (EPA Method 8082) were performed on samples collected from the ECGO test cells and the control cell. At the end of the first 30-month period, the sample analyses indicated about 30% reduction in total PCB levels in un-aerated ECGO test cell compared to the control. The eighth and final sampling in March 2010 showed that total PCBs had been greatly reduced in the un-aerated test cell, from about 40,000 μg/kg (ppb) to 200 μg/kg (ppb). Conversely, PCB levels in sediments contained in the aerated ECGO test cell remained relatively unchanged compared to the pre-test level and control. This represented a greater than 90% reduction in total PCBs relative to the 2003 starting levels and the control sample average. The final results indicated that ECGO was effective at degrading PCBs in a reducing environment.