Various physico-chemical and biological remedial
technologies have been developed over the last three
decades and selection of each technology is site specific
[4–6]. Biochemical processes such as bioleaching involving
Thiobacillus spp. bacteria and Aspergillus niger
fungus, biosorption of low concentrations of metals in
water by algal or bio-oxidation or bioreduction
of metal contaminants by Bacillus subtilis and
sulphate reducing bacteria, and biomethylation of
metals such as arsenic, cadmium, mercury or lead, have
shown some promises and could be used for soil
sediment treatments [4]. Several technologies exist for
in situ chemically enhanced soil flushing by extracting
solutions such as organic and inorganic acids, and
complexation agents have also been proposed for
remediation [7]. All these methods in many cases are
expensive, labour intensive, and result in extensive
changes to the physical, chemical, and biological
characteristics of the treated soil. Physical and chemical
methods of remediation of contaminated soils are
mainly applicable to relatively small areas and are
unsuitable for very large areas such as a typical
mining site or industrially/agrochemically contaminated
soils. bacterial cells