In situ bioremediation of cyanide, PAHs and organic compounds using an engineered SEquenced REactive BARrier (SEREBAR)

Jamie Robinson, Russell Thomas, Steve Wallace, Paddy Daly and Robert Kalin

Abstract

Remedial action at former Manufactured Gas Plants is complicated if the sites are still operational gas distribution depots. The constraints posed by above and below ground structures prevent the use of many commonly used remediation strategies. PB has been the consultant for the investigation and remediation of such a site in Southwest England owned by National Grid Property. After an options appraisal it was decided that a Permeable Reactive Barrier (PRB) was the best remediation option for the site. A unique type of Permeable Reactive Barrier called a SEquential REactive BARrier (SEREBAR) has now been successfully completed. This is currently treating groundwater (1m³/day) contaminated with typical gasworks contaminants, which includes cyanide, polycyclic aromatic hydrocarbons and petroleum hydrocarbons. The system comprises of a 200-metre long impermeable bentonite slurry barrier, installed across active gas mains to intercept contaminated groundwater and direct it into the capture zone of the SEREBAR system. Groundwater flows into the system through an interceptor and six treatment canisters, which remediate contaminated groundwater using sequential anaerobic and aerobic treatments populated by indigenous bacteria, with a backup system of granular activated carbon, should the biological system fail. A collaborative approach was formed between the industrial partners NG, PB and the Environmental Engineering Research Centre (EERC) of Queens University Belfast (QUB) led by Prof. Bob Kalin. Groundwater modelling was updated continually onsite during the investigation, providing real time data to support the groundwater risk assessment. There was a large research aspect to the project; the research work was funded through the Biotechnological and Biological Science Research Council LINK Bioremediation Programme, with the industrial partner NG funding a large proportion of the work. The research was undertaken by QUB, University of Oxford, CEH and Surrey University. Monitoring undertaken since commissioning has shown that the contaminants in the discharge are significantly lower than the negotiated consent.

Key words:aerobic, anaerobic, bacteria, cyanide, innovation, permeable reactive barrier, polyaromatic hydrocarbons, sequential reactor, treatment

© 2007 EPP Publications Ltd

To purchase the full article as a pdf (price £14.00), please click on 'buy now'. Payment can be made by PayPal or credit card for immediate download.

Article code 755