Biodegradation of mono- and poly aromatic hydrocarbons in a contaminated aquifer originating from a former Pintsch gas factory site

Abstract

The objectives of this research were to gain a better chemical and microbial understanding of natural processes at tar contaminated sites, containing a large extension of DNAPL in the source zone and Pintsch gas tar in specific. The following research questions were addressed: • How the composition of Pintsch gas tar differs from known coal tars composition and this effects partition to water characteristics? • What is the effect of nitrate presence on biodegradation in the aquifer on Pintsch gas tar compounds and benzene in specific? • Does biodegradation occur at source zone conditions and can it be enhanced? 1.8 Thesis Outline This thesis is organized in six chapters, with four chapters (chapter 2-5) as stand-alone manuscripts. Chapter 1: An introduction to the problem of liquid tar as dense non aqueous phase liquid (DNAPL) and Pintsch gas tar in specific in the saturated zone, biodegradation of tar constituent in the subsurface and enhanced bioremediation complications. Chapter 2: presents the composition and water-soluble characteristics of Pintsch gas tar. This chapter shows how Pintsch gas tar is different to coal tars by looking at density, viscosity, primary components and amount of light molecular aromatic hydrocarbons. Additionally, it is described how metabolites originating from the tar indicate biodegradation in the vicinity of the DNAPL in the subsurface and a novel anaerobic biodegradation pathway through carboxylation for indene is proposed. Chapter 3: demonstrates the potential for enhanced bioremediation in source zones by indigenous species to the contaminated aquifer. Long term microcosm

Field investigations and reactive transport modelling of biodegrading coal tar compounds at a complex former manufactured gas plant

“…The concentrations were determined using a combination of DIONEX ion-exchange chromatography and inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The method has been described by van Leeuwen et al [294]. Additionally, soil samples were analysed to determine the concentrations of electron acceptors to provide insights into the mass of electron acceptor available for biodegradation in the subsurface.…”