The removal of fuel oil compounds from groundwater for potable supply
This study was a joint project between the Environmental Engineering Group of the Department of Civil and Environmental Engineering - University College London and Anglian Water. The project was funded by an EPSRC CASE studentship (award No. 00800074) with Anglian Water. Cases of fuel oil contamination of groundwater are common throughout the world. The leakage of above and below-ground fuel storage tanks pose a significant threat to groundwater and in some cases potable water supply (PWS) boreholes. Although in-situ remediation methods are fundamental to a remediation strategy and can remove large amounts of hydrocarbon contamination, practical steps must sometimes be taken at PWS boreholes down- gradient of the contamination source to protect the supply. This study details the optimisation of a modular post-abstraction remediation system incorporating air-stripping and granular activated carbon (GAC) technologies. Emphasis throughout the experimental phase of the study is placed on methyl-tertiary-butyl-ether (MTBE) and benzene, toluene, ethylbenzene and xylene (BTEX) compounds. MTBE and BTEX compounds represent those most likely to reach the borehole after a contamination event, and also those which pose the greatest risk to human health. Stringent remedial targets were implemented, based upon world-wide drinking water standards. For benzene the remedial target was 1 ig/L and for MTBE the remedial target was 5pg/L. Utilising high performance stainless steel structured packing with air-to-water ratios ranging from 9 - 86, air-stripping removal efficiencies for MTBE ranged from 20 - 89%, whilst removal efficiencies for benzene ranged from 52 - 90%. The results of the study suggested that the removal efficiency of MTBE was dependent upon the air-to-water ratio, whilst the removal efficiency of benzene was independent of the air-to-water ratio. Utilising F400 GAC, the total adsorptive capacity for MTBE was 3.45 mg/g, whilst the adsorptive capacity for benzene was 2.72 mg/g. However, the general results suggested that benzene was adsorbed much more readily than MTBE. Utilising F600 GAC, the total adsorptive capacity for MTBE was 1.45 mg/g, whilst the adsorptive capacity for benzene was 1.96 mg/g.