Caption title. "EPA/600-S2-90-017." "July 1990."

"Research to better assess the capabilities and limitations of fixed-film bioreactors for removing selected organic contaminants from ground water or from contaminated vapor streams produced by air stripping of polluted ground water and by soil venting operations is described. Work was focused on volatile chlorinated aliphatic hydrocarbons and light aromatic constituents of distilled petroleum products, two groups of compounds which have been identified in polluted ground water more frequently and usually in higher concentrations than other organic pollutants. Laboratory scale fixed-film bioreactors containing soil or diatomaceous earth materials were employed to study the cometabolic removal of trichloroethylene and related compounds from aqueous and vapor streams by biofilms sustained on primary substrates consisting of gaseous aliphatic hydrocarbons. Additionally, the removal of alkylbenzenes from air streams by biofilms using these compounds as primary substrates was examined in laboratory scale soil bioreactors. The biodegradation processes involved and the effects of bioreactor operating parameters and systems configurations on contaminant removal were evaluated. Results obtained indicate a significant potential for utilization of fixed-film bioreactors in systems for above ground treatment of contaminated ground water and vadose zone gases."