Impact of Magnetic Fields on the Efficiency of Dense Non-Aqueous Phase Liquid Removal from Unsaturated Zones Using Steam Injection

Abstract

Unsaturated zone is of great importance in providing water and nutrients that are vital to the biosphere and the main factor controlling water movement from the land surface to the aquifer. Contamination of unsaturated zone by Dense Non-Aqueous Phase Liquids (NAPLs) has becoming major threat to human environment as a result of increasing concern with industrialization. The use of steam injection for remediation of porous media which are contaminated by DNAPLs has not given the desire recovery efficiency, hence the need for improvement in recovery efficiency has been a subject of continuous study. This study investigated the effect of magnetic field on the removal of DNAPL from unsaturated zone using steam injection. An unsaturated zone of a sand box of interior dimensions 110 x 74 x 8.5 cm was polluted at different periods with 200 ml of Carbon tetrachloride. Steam injection experiment with flow rate of 0.01 m3/s was performed to determine the recovery efficiencies of Carbon tetrachloride in an unsaturated zone containing sand of porosity 0.42 and permeability of 0.001163779 cm/s. Magnetic field in step of 1 Tesla (T) was introduced from 1-3 Tesla (T) into experiment. The effects of magnetic field on removal of DNAPL from unsaturated zone using steam injection only and steam injection with magnetic field were compared using descriptive statistic. The recovery efficiency of Carbon tetrachloride using steam injection only was 82.05 %, while that with varying magnetic field at 1T, 2T and 3T were 89.45%, 94.95% and 95.35% respectively. The recovery efficiency of steam injection with varying magnetic field at 1T, 2T and 3T were 9.02, 15.72, 16.21% higher than the result of steam injection only for Carbon tetrachloride. The result demonstrated the ability of steam injection to recover contaminants from the subsurface. The application of magnetic field as an aid to facilitate system activities has been signifi-cantly effective due to its ability to overcome the constraints of conventional treatment processes. A combined application of steam injection with magnetic field appreciably enhances the removal of Non Aqueous phase liquids from Unsaturated Zone.