Performance of a Sequential Reactive Barrier for Bioremediation of Coal Tar Contaminated Groundwater

Abstract

Following a thorough site investigation, a biological Sequential Reactive Barrier (SEREBAR), designed to remove Polycyclic Aromatic Hydrocarbons (PAHs) and BTEX compounds, was installed at a Former Manufactured Gas Plant (FMGP) site. The novel design of the barrier comprises, in series, an interceptor and six reactive chambers. The first four chambers (2 nonaerated-2 aerated) were filled with sand to encourage microbial colonization. Sorbant Granular Activated Carbon (GAC) was present in the final two chambers in order to remove any recalcitrant compounds. The SEREBAR has been in continuous operation for 2 years at different operational flow rates (ranging from 320 L/d to 4000 L/d, with corresponding residence times in each chamber of 19 days and 1.5 days, respectively). Under low flow rate conditions (320−520 L/d) the majority of contaminant removal (>93%) occurred biotically within the interceptor and the aerated chambers. Under high flow rates (1000−4000 L/d) and following the installation of a new interceptor to prevent passive aeration, the majority of contaminant removal (>80%) again occurred biotically within the aerated chambers. The sorption zone (GAC) proved to be an effective polishing step, removing any remaining contaminants to acceptable concentrations before discharge down-gradient of the SEREBAR (overall removals >95%).

Resolving Genetic Functions within Microbial Populations: In Situ Analyses Using rRNA and mRNA Stable Isotope Probing Coupled with Single-Cell Raman-Fluorescence In Situ Hybridization

“…Figure 5C highlights the disproportionate incorporation of the 13 C label into the Acidovorax sp., compared with incorporation by the Pseudomonas sp., in groundwater pulsed with 3.8 M [ Ecologically, the naphthalene concentration in the field is often highly variable over space and time. Ambient concentrations of naphthalene throughout the site are around 3.8 M, but pockets of high naphthalene concentrations also exist (10,11). This heterogeneity, in the light of these data, has given rise to the evolution of a diverse community of naphthalene degraders.…”

“…A sequential reactive barrier (SEREBAR) was installed to aerobically treat the complex polycyclic aromatic hydrocarbon mixture plume within the groundwater, and this study addressed the microbial population at the inlet to the SEREBAR (10). Groundwater used in this study was sampled from the inlet to the SEREBAR in presterilized, nitrogen-filled bottles (10,11). The samples were taken from groundwater that converged at the inlet before entering the SEREBAR barrier.…”

“…The samples were collected in bottles without headspace and were immediately sealed and stored at 4°C before use; although they were not anaerobic, their condition was the nearest approximation to the in situ condition. The primary groundwater contaminant throughout the site was naphthalene, with an average concentration of 3.8 M. The groundwater temperature was consistently 14 Ϯ 2°C (10,11).…”

Processes in Pathogenic Biocolloidal Contaminants Transport in Saturated and Unsaturated Porous Media: A Review

“…In recent years, bioremediation has become a viable option in the restoration of contaminated aquifers (Gibert et al 2007;Wang and Ford 2009). However, the process is technologically challenging because of the difficulty in delivering the microbial population to the target locations.…”

Electro-assisted groundwater bioremediation: Fundamentals, challenges and future perspectives

“…In order to promote the local microbial activity, biological permeable reactive barrier (Bio-PRB) is commonly emplaced in the groundwater flow path to intercept contaminant plumes and encourage microbial colonization by creating favorable redox potential and grow conditions (Gibert et al, 2007). Bio-PRB relies on suitable carrier materials and injected nutrients to support the immobilized microorganisms for degrading contaminants that pass through the barrier, and has been demonstrated to be an effective strategy to enhance groundwater bioremediation .…”