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Decontamination
of Hydrocarbon Polluted Military Sites to Decrease Environmental Risks Low - Cost Cyclodextrin
Technology (SfP-973720) ACTIVITIES |
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Phase 1.
Preliminary screening on artificially contaminated soils
In this phase, the influence of
CDs on the biodegradation of different hydrocarbon mixtures in defined soils
will be determined by analyzing the pollutant disappearance and the ecotoxicity
depletion in artificially contaminated soils treated in fixed- and slurry-phase
conditions (scale: 50-500 g). Several chemical and biological analytical
procedures will be developed and jointly used at the beginning and at the end
of the experiments to assess and quantify the occurrence of the soil
detoxification and remediation in the different treatment conditions.
The CDs will be used in the concentration range: 0.1 to 5 %
of dry soil.
Four different complex mixtures of organic compounds will be
applied: Diesel oil, transformer oil, PAHs and PCBs. These groups of hydrocarbons
highly differ from each other in biodegradability and in toxicity. Their
concentrations will follow their usual occurrence at military sites.
- Diesel oil 10
000–50 000 ppm -
PAHs 10–5 000 ppm
- Transformer oil 5 000–30 000 ppm - PCBs 100–1 000 ppm
Parallel experiments are planned to perform by using a
CD-contaminant complex. These experiments will allow us to understand the
possible action-mechanism of CDs.
This preliminary study will allow us to screen the potential
role of CDs in the biological restoration of the military area chosen in this
project and the influence of the main soil and treatment parameters that can
affect their activity.
The experiments will be carried out by using three different
types of soil (loamy, sandy and humic) to study the effect of soil
characteristics on the CDs activity. Consistence of the soil according to the
technology may be slurry or solid. Inoculation with the appropriate microflora
may be useful to increase biodegradation or can be necessary for PCBs biodegradation.
Two possibilities will be evaluated: indigenous, adapted microflora or
commercially available mixture of bacterial strains. The optimal nutrient
supply may vary depending on contaminant and CD concentration. The experiments
will be carried out in batch aerobic reactors: in solid phase or in mixed
slurry.
Phase 2. Laboratory experiments
After assessment of the site, laboratory experiments (scale:
100-1000 g) directed to evaluate the effects of RAMEB on the bioremediation and
detoxification of actual site contaminated soil samples in fixed- and
slurry-phase conditions will be performed. Aim of Phase 2 is to evaluate the
effect of the concentration of CDs, and in their presence, the influence of
temperature (20oC and 30oC), nutrients (N, P and microelements)
and microbial inocula on the soil decontamination. Two consistencies will be
applied: solid and slurry. Evaluation (analysis) will be carried out at the
beginning and at the end of the experiments. Shaken and static aerated glass
vessels will be used as batch reactors for the slurry and solid phase soil
treatment.
Phase 3. Laboratory scale
technological experiments
After the determination of optimal nutrient concentration and
inoculation, we investigate the effect of two different CD concentrations, and
the use-pattern of CD, as well as the effect of aeration on the decontamination
process. In order to be able to identify the best technology for the next phase
experiment we will evaluate these parameters both in slurry and in solid phase
conditions.
Aim of the technological experiments (Scale: 500 - 1000 g)
is not only to select the best (optimal) conditions for scaling up but also to
develop reactors which are able to model the ex situ and in situ soil
remediation technologies.
In this phase 1-2 liter of volume reactors will be applied
with aeration. In case of slurry phase mixing will be applied, whereas in case
of soil phase, packed columns or storage vessels will be used.
Phase 4. Pilot-scale experiments
Complex analysis to control and manage the technology on the
basis of the continuous measuring of respiration and biological conditions of
the soil originating from the contaminated site. Aims of these experiments
(Scale: 20 kg) are to support the design and keeping the field experiments, to
compare the homogenous ex situ system
with the heterogeneous in situ system,
and to get more information about the inside of the black box, i.e. the
interactions between the soil, i.e. the CD, the contaminant and the microflora.
In this phase special interest is given for the effect of a randomly methylated
ß-cyclodextrin (RAMEB), which is currently the cheapest CD derivative on the
market.
20 dm3 volume self-designed glass and plastic reactors
will be used. The reactors are supplied with aeration, with an injection and
sampling system. For modeling the in situ
technology, a solid-phase reactor will be used in order to treat the soil in an
undisturbed system. For modeling the ex
situ technology, rotated plastic vessels will be applied. These more
advanced reactors are equipped with a control system for O2
consumption, CO2 production and temperature
Phase 5. Application of the technology
Phase 5 has four further tasks: assessment of the site,
design of the technologies and their field application in 30 and 70 m3.
After completion of the remediation a monitoring system will be established and
maintain.
Phase
5.1. Assessment of the contaminated
site (see the map in Annex 2)
Two or three sites indicated in the map as contaminated
sites will be selected on the basis of the contamination degree (which will be
estimated on the basis of the uncomplete evaluation made available by Hungarian
environmental authorities which characterized this military area in 1991) and
location (accessibility); and 96 samples taken from different depths of each
area will be subjected to an extensive characterization by using chemical,
biological and ecotoxicological analyses. On the bases of the results we can
select the most suitable site for the field experiments.
Phase
5.2. Design of the technology
Planning of the technology will be performed on the basis of
the results of Phase 5.1., Phase2, Phase 3 and Phase 4. An ex situ and an in situ
technology will be designed.
Phase
5.3. Field experiments (Scale:
100 m3)
Field experiments will be based on the results of the former
small and medium size technological experiments. Two different remediation
technologies will be investigated.
As ex situ bioremediation
process 30 m3 of excavated and homogenized soil will be treated. Ex situ treatment is a controlled
solid-phase biotechnology. The excavated soil will be supplemented with
amendments and placed into a close reactor equipped with systems for leachate
collection, and for air and nutrient addition.
CD, nutrients and microbes will be added according to the
optimal schedule.
About 70 m3 of non-excavated contaminated soil
will be treated by an in situ
biological process. During the in situ bioremediation
undisturbed soil will be aerated (regulated by CO2 production or O2
consumption) through vertical bore hole system supplied with perforated plastic
tubes. Bioventing means a slow airflow within the soil matrix ensured a low
capacity ventilator. Exhausted gas will be collected and treated. CDs and other
additives will be applied to keep an optimal concentration.
The information from the completely homogeneous, ex situ system will be compared with the
undisturbed in situ system, where all
the parameters have a gradient or other kind of tendentious change according to
the place and time. Differences and similarities in the two systems will give
important basic information about the processes in the soil.
100 samples (10 times 10). To clear up the
arising technological problems, additional small scale experiments will be
carried out in the labs. Phase 5 experiments will be performed by TDT-3R, TUB,
RISSAC and CYL. Biological investigations will be carried out by TUB,
chemical-physical characterization of the soil by the RISSAC, the evaluation of
the experiments by chemical analysis will be done by CYL and by BU.
Phase 5.4. Monitoring of the remedied site
Design and settlement of soil and ground water monitoring
system to control of remedied site will be performed.
Phase 6. Demonstration and
dissemination of the results
Demonstration and dissemination of the project result to the universities and scientific community through publications and conference presentations.
A complex methodology is applied to follow and
evaluate the experiments:
- Extraction: Soxhlet and/or ultrasonic extraction
- Biological investigations: cell number of aerobic
heterotrophic bacteria, oil-degrading bacteria and aerobic PCB- and chlorobenzoic
acid-degrading bacteria, CO2 production and O2
consumption, ATP content in connection with biological activity of soil
- Ecotoxicological methods: Photobacterium phosphoreum bioluminescence inhibition test, Sinapis alba and Lepidum sativum germination and root elongation test, Azotobacter agile dehydrogenase enzyme
activity test and/or Folsomia candida
(Collembola) mortality test
- Chemical-physical investigations: physical
characteristics of the soil, nutrient supply (for plants) of the soil, two and
three phase water transport, pore-size distribution and humus content
- Chemical analysis: oil content
measured and PAH content measured by GC-FID and/or by CE and GC-MS, PCBs
content measured by GC-ECD, chlorobenzoic acids and chloride ions produced by
the PCBs break-down measured by HPLC-DAD and a CSE, respectively.