Journal of Hazardous Materials B89 (2002) 241–252 A pilot study for the selection of a bioreactor for remediation of groundwater from a coal tar contaminated site Turlough F. Guerin ∗ Shell Engineering Pty Ltd., NSW State Office, P.O. Box 26, Granville 2142 NSW, Australia Received 28 February 2001; received in revised form 23 July 2001; accepted 24 July 2001 Abstract Coal tars in soil at a gasworks site in South Eastern Australia led to groundwater contamination with polycyclic aromatic hydrocarbons (PAHs), mono-aromatic compounds (BTEX) and phenols. The scope of the study included testwork in laboratory scale bioreactors and evaluation of avail- able commercial groundwater treatment units. Two bioreactor configurations, a submerged fixed film reactor (SFFR) and a fluidized bed bioreactor (FBR) were effective, with high efficiencies of contaminant removal (typically >90%) over a range of hydraulic retention times (HRT) (3–29h). Specifically, concentrations of total PAH, naphthalene, pyrene and total phenols in the feedstock and effluent of the SFFR were 123, 60, 51, 1.38 and 0.004, 0.001, 0.004, 0.1 mg/l, respectively. The FBR was only marginally less effective than the SFFR for the same groundwater contaminants. Discharge to sewer was the most appropriate end use for the effluent. SFFRs are regarded as being simpler in design and operation, and a commercially available unit has been identified which would be suitable for treating small volumes (<10 m 3 per day) of contaminated water collected at an interception trench at the site. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Pilot-scale; Bioremediation; Coal tar; Groundwater; Treatment; Contamination; Bioreactors; Gasworks; PAH 1. Introduction 1.1. Soil and groundwater contamination from gasworks sites Former gasworks (or manufactured gas plant (MGP)) sites typically have soil and ground- water contaminated with various petroleum hydrocarbons [1–4]. Contaminants typically ∗ Tel.: +61-2-9556-1840. E-mail address: turlough.guerin@shell.com.au (T.F. Guerin). 0304-3894/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0304-3894(01)00313-2