Comparison of Ex Situ and in Situ Bioremediation of Unsaturated Soils Contaminated by Petroleum

Abstract

The most feasible bioremediation technologies of unsaturated soils contaminated by Petroleum are (1) the on-site controlled remediation of the excavated contaminated plume in the contained system; and (2) the in situ sub-surface, highly controlled process in which nutrients and microbes or air are injected into the plume volume via a grid of wells and reversing the direction of the pumping. The detailed results of ex situ (controlled aerobic bioremediation) of ten sites with differing petroleum contamination and four in situ cases are reported and compared. It is concluded, that bioremediation of petroleum contaminated soil is an effective, safe and economically feasible remediation technique for the remediation of such contaminated sites, contingent on the providing of the site-specific appropriate conditions. However, the biodegradation rate of the NAPL is more variable in the in situ than in the ex situ aerobic process, correlating best in the latter with the molecular weight of the petroleum contaminants.

Just Add Water and Salt: the Optimisation of Petrogenic Hydrocarbon Biodegradation in Soils from Semi-arid Barrow Island, Western Australia

“…Several factors can influence the amount of N and P to be added to hydrocarbon-impacted soils , including indexation against the levels of C present in contaminated soils (Riser-Roberts 1998). Optimal nutrient dosages, however, vary with soil properties and environmental conditions and the concentration and nature of the hydrocarbon pollutant (Wrenn et al 1994;Carberry and Wik 2001;Walworth et al 1997).…”

A general model for bioremediation processes of contaminated soils

“…For such cases a different approach has been proposed (see [11] for instance) which includes dynamical effects expressed by a differential equation linking θ and ψ. If we confine to the case of slowly varying flows we may use equations (1), (3).…”

“…There I. Borsi · A. Fasano Dipartimento di Matematica "U. Dini", Università degli Studi di Firenze, Viale Morgagni 67/A, 50134 Firenze, Italy E-mail: borsi@math.unifi.it; fasano@math.unifi.it are two main types of bioremediation the ex situ implementation, when the contaminated plume can be excavated and remediated in a contained system, and the in situ remediation process, in which microbes are injected into the contaminated subsurface via a grid of wells (see [3]). …”

In-Situ Remediation Approaches for the Management of Contaminated Sites: A Comprehensive Overview

“…In -situ remediation is a good option, since excavation involving higher transport costs is not an option when the treatment site is large and/or of greater depth in the soil. However, due to the soil heterogeneity, it is quite challenging to achieve uniform remediation throughout the treatment area (Carberry and Wik 2001 ).…”