Field Push-Pull Test Protocol for Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbons

摘要

A major problem limiting the widespread use of aerobic cometabolism for treating chlorinated aliphatic hydrocarbons (CAHs) contamination in groundwater is the need for site-specific data for use in feasibility assessment and remedial design. Currently, the approach used to obtain this information consists of preliminary laboratory microcosm tests performed on core samples followed by pilot-scale well-to-well recirculation tests (Semprini et al., 1992). Although this approach has been successfully applied in a limited number of field demonstrations, it has several disadvantages that limit its routine use. For example, sediment samples are difficult to obtain and samples obtained by coring may be too small to provide representative information on subsurface conditions. Well-to-well recirculation tests interrogate a larger volume of the subsurface and thus have the potential to provide more representative information but are expensive and logistically complicated. This protocol describes a newly developed field technology for evaluating the feasibility of using in situ aerobic cometabolic processes to treat groundwater contaminated with chlorinated solvent mixtures. The technology is called the single-well push-pull test. Push-pull tests have been previously used to obtain quantitative information on a variety of aquifer physical, chemical, and microbiological characteristics (Istok et al., 1997; Schroth et al., 1998; Istok et al., 1999; Schroth et al. 2001; Hageman et al., 2001), but have not previously been used to investigate aerobic cometabolic processes. This protocol describes the use of push-pull tests to evaluate the potential for aerobic cometabolism of CAHs using gaseous cometabolic substrates such as propane and soluble substrates, such as toluene. The protocol consists of 8 Sections. Sections 1 and 2 describe the overview of the protocol and introduction to the field test methodology. Section 3 describes how field push-pull tests are performed.