Application Guide for Bioslurping Principles and Practices of Bioslurping Addendum: Use of Pre-Pump Separation for Improved Bioslurper System Operation

Abstract

Abstract : The purpose of the document is to provide remedial project managers and operators of multiphase extraction systems the ability to design and operate prepump separation systems to improve the operation of their recovery systems. Prepump separation systems remove the light non-aqueous phase liquid (LNAPL) from the process stream before the stream enters the extraction pump, thus eliminating the mixing of the LNAPL, groundwater, and air as the process stream moves through the pump. Information regarding the use of prepump separation systems was produced during demonstrations of the technologies funded by the Environmental Security Technology Certification Program (ESTCP). Two types of prepump separation systems were tested during the demonstrations. The dual drop tube system removes the LNAPL from the process stream inside the extraction well and the knockout tank removes the LNAPL from the stream just before it enters the extraction pump. This user s guide was produced as an addendum to the Navy s Application Guide. As such, the majority of background information on general bioslurping can be found in the Application Guide. Bioslurping is a demonstrated technology for cost-effectively removing LNAPL from contaminated aquifers. Bioslurping combines vacuum-assisted LNAPL recovery with bioventing and soil vapor extraction (SVE) to simultaneously recover LNAPL from the water table and accentuate bioremediation of the vadose zone by promoting the influx of air. A conventional bioslurper system withdraws groundwater, soil gas, and free-phase LNAPL from the water table as a single process stream, through a single vacuum drop tube situated in each extraction well, most often using the vacuum created by an aboveground liquid ring pump. The recovered LNAPL is separated from the groundwater and soil vapor and may be recycled. The recovered groundwater and soil vapor usually are treated and discharged.