BIOLOGICAL
Phytoremediation † the removal of contaminants by plants which
will absorb harmful chemicals from the ground. The plants are
subsequently harvested and destroyed. A variant uses fungal
degradation of the contaminants.Bioremediation † stimulating the growth of naturally occurring
microbes. Microbes consume petrochemicals and oils, converting
them to water and carbon dioxide. Conditions must be right, i.e. a
temperature of at least 10°C with an adequate supply of nutrients
and oxygen. Untreated soil can be excavated and placed over
perforated piping, through which air is pumped to enhance the
process prior to the soil being replaced.CHEMICAL
Oxidation † sub-soil boreholes are used for the pumped distribution
of liquid hydrogen peroxide or potassium permanganate. Chemicals
and fuel deposits convert to water and carbon dioxide.Solvent extraction † the sub-soil is excavated and mixed with a
solvent to break down oils, grease and chemicals that do not
dissolve in water.THERMAL
Thermal treatment (off site) † an incineration process involving the
use of a large heating container/oven. Soil is excavated, dried and
crushed prior to heating to 2500°C, where harmful chemicals are
removed by evaporation or fusion.Thermal treatment (in-situ) † steam, hot water or hot air is
pressure-injected through the soil. Variations include electric
currents and radio waves to heat water in the ground to become
steam. Evaporates chemicals.Ref. Building Regulations, Approved Document, C1: Site preparation
and resistance to contaminants. Section 1: Clearance or treatment
of unsuitable material. Section 2: Resistance to contaminants.Biological, Chemical and Thermal Treatment of Contaminated Sub-soil