Pilot and full-scale treatment of PAHs in waters from MGP sites, using the GAC-FBR process

Successful pilot-scale studies were conducted to test the applicability of an innovative biological treatment process to treating groundwaters, contaminated with polynuclear aromatic hydrocarbons (PAHs) at former manufactured gas plant (MGP) sites. Subsequently, the Granular Activated Carbon - Fluidized Bed Reactor (GAC-FBR) system has been used in treatment trains at three former MGP sites, to test the effectiveness of the biological process at the field scale. Pilot studies were conducted using a synthetic feed of contaminated MGP Groundwater, a fingerprint containing eight PAHs and major phenolic compounds. hive steady-state periods were tested over a three month period, at organic loading rates ranging from 1.6 to 4.6 Kg-COD/M{sup 3}-day. Removal of PAHs ranged from >99.9% for Naphthalene and 97.8 % for 3-4 ring PAHs to 62-80% for 5-6 ring PAHs, adding up to total PAH removals ranging from 97.9 to 99.7 percent. Batch kinetic tests conducted with biomass from the pilot reactor yielded naphthalene degradation rates of 0.9-3.3 g-COD/ g TSS-day. Vertical profiles of PAHs and dissolved oxygen in the GAC-FBR indicated that most of this removal was accomplished in the bottom half of the reactor. The first field application was initiated at a superfund site, treating excess groundwater produced from amore » subsurface DNAPL extraction (CROW{trademark}) process. The GAC-FBR was used to treat a 10- 15 GPM aqueous stream from the oil-water separator and the effluent discharged to surface waters. The second field trial at another MGP site was on groundwaters pumped from subsurface exposed to acid purifier wastes, containing elevated concentrations of Fe[II] ({approximately}100 mg/L). The GAC-FBR was used to treat PAHs after chemical oxidation of the Fe[II]. The third field trial was to test PAH removal from MGP waters containing varying amounts of LNAPL and DNAPL, under dynamic loading conditions.« less