NATO/CCMS Pilot Study Evaluation of Demonstrated and ... - CLU-IN

NATO/CCMS Pilot Project on Contaminated Land and Groundwater (Phase III) January 2001
- determination of the maximum potential biodegradability of the contamination present
In order to determine the maximum degradability of the pollutants, column tests with lysimeters are
being executed. Therefore optimal conditions for microbial growth and degradation are created by
means of addition of water, nutrients, air, microorganisms and other additives. During the column
tests the pollutant concentration, the use of oxygen and the CO2 production are continuously
monitored in order to obtain an accurate image of the biodegradability of the pollutants.
The preparatory stages will result in a first indication of the potential applicability of bioremediation as a
decontamination technique for loamy soils that were contaminated with hydrocarbons.
Based on the results and conclusions of the preparatory stages a number of decontamination concepts and
configurations will be tested on a lab scale. Regarding the in-situ decontamination techniques, this is only
executed with the help of column studies based on soil column lysimeters. Regarding the ex-situ
decontamination techniques, mainly bioreactor tests will be executed.
Soil column lysimeters are simple but efficient means to verify the possibilities to what extent the soil can
be in-situ decontaminated with the help of bioremediation techniques. In Figure 6 a schematic
representation of the test setting is given. Different soil columns are being equipped as represented in
Figure 6. In the test setting fluid solutions can be put in with the help of a time-directed system that is
established on top of each column. Furthermore, air fumes can be added in each column. Before entering
the column, the fumes are lead through a shaft filled with glass pearls to enable a uniform separation.
Different column tests will be performed simultaneously to monitor the microbial activity and the
evolution of the contaminants under different circumstances and feedings. The liquid solutions will
mainly consist of nutrient mixtures containing nitrogen sources, phosphates and oligo-elements. For each
column the effluent is collected and analysed on pH, conductivity and nutrient concentrations. In order to
measure microbial activity in the column, the production of CO2 produced is determined. On the columns
following treatments will be performed: control setting without specific treatment; only addition of water,
addition of water and nutrients, addition of water + nutrients + microorganisms; addition of water + air +
nutrients; addition of water + microorganisms + air + nutrients.
Such soil column lysimeters are extremely well equipped to verify whether contaminated sites can be
decontaminated in-situ with the help of bioremediation techniques. In addition, the column tests will be
used for the evaluation of ex-situ decontamination techniques, during which the contaminated soil will be
submitted to different preliminary treatments (e.g., mixing with compost). Different compost formulas
and relationships in the process will be tested.
Based on the results of the experiments on a lab scale, the most appropriate concepts will be tested on a
larger scale, in order to obtain a more realistic idea. Therefore the ex-situ decontamination techniques will
be tested in the soil-recycling centre. Regarding the in-situ decontamination techniques, the different
contaminated zones in different sites will be isolated civil-technically in order to prevent a horizontal
spreading of the contamination. The volume of isolated cells will amount to approximately 50m³. In order
to prevent spreading towards the ground water, a pump and injection system are established around
different cells. If possible slots will be dug to the depth of 2 to 3 m around the cells. From these slots
horizontal perforated tubes will be installed under the cells to enable monitoring of the groundwater as
well as of the soil vapour. With this sampling system the heterogeneity of the soil can be optimally
studied.
This decontamination experiments will be conducted on the future soil-recycling centre of s.a. Ecoterres
in Brussels. This centre will be built on the van Oss site, owned by the G.O.M.B. Figure 7 gives an
impression of the future soil-recycling centre.
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