Title: Numerical investigations on feasibility of surfactant enhanced remediation of polycyclic aromatic hydrocarbons in an unsaturated subsurface system beneath an onshore surface spill site

Authors: M. Berlin; M. Vasudevan; S. Mohanasundaram; G. Suresh Kumar; Indumathi M. Nambi

Addresses: Department of Civil Engineering, National Institute of Technology, Arunachal Pradesh, India ' Department of Civil Engineering, Bannari Amman Institute of Technology, Sathyamangalam, Erode, India ' EWRE Division, Department of Civil Engineering, Indian Institute of Technology Madras, India ' Petroleum Engineering Programme, Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai – 36, India ' EWRE Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai – 36, India

Abstract: The adaptability of in situ remediation techniques for low soluble fractions in petroleum products such as polycyclic aromatic hydrocarbon (PAH) is generally constrained due to their limited bio-availability owing to hydrophobicity. In the present study, a numerical model is developed to evaluate the effect of unsaturated hydraulic properties, equilibrium chemical partitioning as well as coupled reactions on the fate and transport of a typical PAH (phenanthrene) originating from a surface spill. Simulation of surfactant enhanced remediation using a non-ionic surfactant (Triton N-101) resulted in significant modifications in unsaturated hydraulic properties. The presence of natural organic matter (adsorption partitioning coefficient of 8.97 × 10−4 L/mg) as well as viable bacterial consortium (specific growth rate > 3.06 × 10−7 /sec) in the soil is found to be favouring the biodegradation in order to limit the reach of phenanthrene up to a depth of 200 cm. The results suggest that selection of surfactant type and dosage affected the extent of solubility enhancement of phenanthrene (from 1.27 to 11.5 mg/L); however, ultimately the typical bio-geochemical features of the subsurface seemed to control the success of remediation.

Keywords: contaminant transport; numerical model; polycyclic aromatic hydrocarbon; PAH; surfactant enhanced remediation; unsaturated subsurface; onshore surface spill; environmental technology; in situ remediation; adsorption; biodegradation.

DOI: 10.1504/IJETM.2017.091293

International Journal of Environmental Technology and Management, 2017 Vol.20 No.5/6, pp.321 - 346

Received: 09 Dec 2016
Accepted: 15 Nov 2017

Published online: 16 Apr 2018 *

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