The use of slurry phase bioreactor technology for the remediation of coal tars

Abstract

AbstractSecondSite Property (now National Grid Property), commissioned Parsons Brinckerhoff Ltd. (PB) to project manage a trial of a slurry phase bioreactor at a former gasworks in the Northwest of England. The trial was designed to demonstrate the effectiveness of slurry phase bioremediation at remediat-ing coal tar contaminated soils at the field scale, through the CL:AIRE (Contaminated Land: Applica-tions in Real Environments) technology demonstration programme. Slurry phase bioremediation is one of the most intensive forms of biological treatment available for the degradation of organic com-pounds. Three trials were completed, though technical difficulties were encountered throughout the project, due to inefficient mixing within the reactor. The results of the second trial, however, showed significant contaminant degradation, especially with respect to PAHs. Low molecular weight PAHs were degraded by up to 95% and high molecular weight PAHs such as benzo(a)pyrene were also degraded by 68%. Trials 1 and 3 recorded similar pa tterns of degradation, but not to the same extent as Trial 2. Microbial analysis of the trials showed that although some microorganisms predominated, the population was not stable, and a wide range of unidentified potentially unique organisms were detected. These results indicate that slurry phase bioremediation can be utilized to treat compounds associated with gasworks normally reca lcitrant to biodegradation in a relatively short timeframe. With process improvements in mixing and robustness, a viable cost-effective system could be developed to operate in a commercially viable manner.Key words: benzo(a)pyrene, bioreactor, bioremediation, coal tar, polycyclic aromatic hydrocarbons, remediation, slurry-phase