The microbial ecology of remediating industrially contaminated land: sorting out the bugs in the system - Ecology of Industrial Pollution - page 246

Identifying and alleviating constraints

Remediation possible

High

Biosensing

Soil samples Toxicity Light output

Identification of constraint

Low

Sample manipulation

Air sparging Charcoal ZVI XAD-4

Removal of VOCs Removal of non VOCs Removal of chlonnated HCs Removal of PAHs

Light
output

Light
output

Light
output

Light
output

high

high high low high low low

low

Non VOCs
constraints

Inorganic
constraints

Chloriasted HC
constraints

PSM PAM

constraints

PSM

VOCs constraints

FSM

Remediation possible through alleviation of constraints

Figure 12.4. A sample manipulation protocol coupled to a biosensor assay to identify
constraints to microbial degradation in the soils, sediments and groundwater of a BTEX
contaminated site. An example of the kind of results obtained from this type of
screening is provided in Fig. 12.5 (adapted from Sousa et al., 1998).

To do this, and since the main risk contaminants were the BTEX which require
aerobic conditions for their rapid degradation (Fritsche & Hofrichter 2005 ),
it was first necessary to identify key constraints to the aerobic BTEX minera-
lising bacterial population and investigate the scope to alleviate these con-
straints. Biosensor technology was deployed to understand the bioavailability
and toxicity of the contaminants to the indigenous microbial population and
to identify key constraints to BTEX mineralisation resulting from other spe-
cific, bioavailability contaminants (Paton et al. 1995 ). Bacterial biosensors are
now routinely used for screening of contaminated soil (Killham & Paton 2003 )
as a complementary tool to standard, chemical analysis. It is the capacity of
microbial biosensors to address contaminant bioavailability that so effectively
complements chemical analysis, as well as to screen (using toxicity biosensors)
all toxic contaminants and to identify otherwise unknown problems that
the highly specified, analytical approach may miss (Killham & Paton 2003 ).
The use of biosensors to assess contaminant bioavailability involves integration
of the many physical, chemical and biological factors that influence this
availability.
A scheme of sample manipulation coupled to a biosensor assay was
developed ( Fig. 12.4 ) so that the remediative potential of this part of the soil