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Mitigation of water repellency in the treatment of contaminated muds using the chemical–biological stabilization process
Guzmán-Osorio, F. J. & Adams, R. H.
Abstract
The soil–water relationship was used to
evaluate the efficacy of a novel remediation technology,
the chemical–biological stabilization process, which
focuses principally on soil fertility restoration in agricultural
sites. This process was evaluated for the treatment
of 150 m3 of bentonitic drilling muds from a
closed sulfur mine which contained 70 % fines
(<0.05 mm), and which had been contaminated with
very weathered hydrocarbons, containing 31 % asphaltenes.
This material was monitored for two and a
half years, for in situ moisture content, field capacity,
and soil water repellency. Additionally, critical soil
moisture content for water drop penetration times of <5
and <60 s was monitored. Field capacity increased
46.6 % with respect to initial values and a vigorous
vegetative growth was established. Concurrently, water
repellency values for molarity ethanol droplet and water
drop penetration times were reduced from 5.1 to 3.9 M
and 106 to 0.12 h, respectively. Soil in situ moisture
content during the driest part of the year (20.3 %
humidity) remained above critical values (15.1 %
humidity and 19.5 % humidity) to avoid a water repellency
of <5 and <60 s, respectively, and water repellency
was not observed in the field. Thus, complete
mitigation of water repellency was achieved. These
findings indicate that the soil–water relationship should
be evaluated to achieve an integral soil remediation and
that water repellency as a remediation criterion should
be complemented with determinations of critical moisture
content and actual site information on soil in situ
moisture content during the annual cycle.
Keywords
Critical moisture content; Fertility restoration; Field capacity; Hydrophobicity
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