Testing of In Situ and Ex Situ Bioremediation Approaches for an Oil-Contaminated Peat Bog Following a Pipeline Break

Abstract

A biotreatability test was performed on oil-contaminated sphagnum peat moss from a 1985 pipeline spill of light Pembina Cardium crude oil at a bog near Violet Grove in central Alberta. Four tests were designed to simulate several field treatment approaches and to collect critical data on toxicity and leachability of this material. These tests included a bioslurry test, a soil microcosm test, an aerated water saturated peat column test, and a standard toxicity characteristic leachate potential (TCLP) test.</jats:p> <jats:p>In the saturated peat column tests, two nutrient amendment rates and a surfactant were tested to quantify biostimulation effects from an in-situ treatment design. An innovative aeration technology called the GLR (Gas-Liquid Reactor) was used to create a constant supply of hyperoxygenated water prior to column injection. The GLR continuously produces air bubbles of less than 50 microns in diameter, thereby maximizing air surface area and thereby increasing gas transfer rates. Crude oil biodegradation was quantified by the reduction in both extractable hydrocarbons and toxicity of the peat solids.</jats:p> <jats:p>The results confirmed that bioremediation of the residual crude oil to non-toxic levels in the peat bog at Violet Grove will be successful. All three tests — bioslurry, soil microcosm, and soil columns — gave similar results of at least 74% biodegradation of the residual crude oil on the peat solids.</jats:p> <jats:p>In situ bioremediation using the GLR aerated water injection system or an ex situ landfarming or biopile approach should achieve the 1000 mg/kg total petroleum hydrocarbon criteria. Neither fertilizer nor surfactant amendments were necessary to enhance oil biodegradation in the in situ column tests. The TCLP test indicated that ex situ treatment would require an impermeable liner for leachate collection.</jats:p> <jats:p>The time required to achieve the final remediation goals will depend on climatic variable such as temperature and rainfall during active summer season bioremediation. It is anticipated that an in situ approach using recirculated aerated water would achieve the cleanup up criteria within one full field treatment season.