Within the framework of this special programme the Technical University of
Hamburg-Harburg and the University of Hamburg are investigating basic
methods for the treatment of contaminated soils in 16 projects.
The first two research periods ran from Jan. 1st 1989 to Dec. 31st 1994. The
third, and current, research period will end on Dec. 31st 1997.
In March 1985 the German government declared soil protection a crucial
issue. After a phase of ascertaining and evaluating toxic legacies, this issue
has now entered a new phase where the emphasis is on the necessity to
develop concrete measures for decontaminating soil.
Since the German reunification the number of contaminated sites in Germany
has increased. In the NFL (New Federal
Lands) there are numerous sites where the risk potential (type,
concentration and possible synergistic effect of the contamination) is
particularly high. Apart from the Bitterfeld site, which is heavily contaminated
with both organic and inorganic contaminants, there are areas in Sachsen-
Anhalt with particularly high levels of heavy metals. Although many remedial
projects have been carried out in the former FRG, the decrease in the number
of contaminated sites has been insignificant; this is mainly due to the fact that
many new sites have had to classified as requiring treatment.
There are four basic options for treating contaminated soils:
Decontamination of the soil is the only viable, long-term option. It is the only
solution which ensures that the contamination is actually removed and not
merely transferred to a different location. Furthermore, the soil can be restored
to a state in which reutilization and recultivation become possible. In present
decontamination practice mechanical, thermal and biological methods are used.
There are a variety of different, competing methods being used, all of which were
developed on a purely empirical basis. The fact that no precise emission
standards have been set and that the analytical procedures vary makes it difficult
to compare the decontamination efficiency of the various methods.
It is the aim of this research centre to establish the scientific basis of each
decontamination method. This data will enable the methods to be perfected, and,
at the same time, a range of procedures, methodical steps and apparatus
allowing a wide variety of different contaminations to be dealt effectively can be
developed. The main focus is on biological methods combined with chemo-
physical methods.
Technical soil protection has developed into an independent scientific discipline
in which the experience and knowledge of different specialist disciplines can help
find solutions and answers to the problems posed by contaminants. Within the
special research project civil engineers, process engineers, chemists,
microbiologists, soil scientists, geologists and environmental planners are
cooperating in the development of this new field of work.
Potential recultivation and revitalization of treated soil is to be investigated in the
current phase of the project.
Throughout the development of new or modified methods for soil
decontamination the focus will be on the development of biological methods. The
soil is either directly treated in bioreactors or exposed to biological breakdown
processes after chemo-physical pretreatment.
During chemo-physical treatment supercritical water is used to break down
substances with a high molecular structure where biological degradation is either
impossible or difficult. Rapid and complete degradation is then ensured in
subsequent biological treatment. As this method is especially suitable for highly
concentrated contaminations, soil fractions with a high level of contamination are
first separated by means of mechanical processing methods. The use of flotation
methods for microsubstances is being investigated.
The primary objective of all these projects is the clarification and description of
mechanisms which either result in decontamination or prevent decontamination.
The following mechanisms are of particular interest:
The investigation of biological soil decontamination processes requires the
efficiency of the microflora to be evaluated. Steps must be taken to increase the
efficiency of the biological degradation processes which occur; microbiological
screening in conjunction with strain development techniques is also required.
Process technological and assessment oriented research is being carried out in
cooperation with scientific projects investigating soil chemistry, soil physics and
chemical analytics. These projects evaluate results and establish decisive criteria
for planning and realization of the techniques used here.
For the first time it is planned to investigate the treatment of soils contaminated
with heavy metals within the framework of the SFB 188 (Projects A5 and A8).
The practicality of mechanically pre-upgrading the fraction containing heavy
metals by classification and particle flotation will be examined. The heavy metals
will then be removed and recovered from the soil using a new, ecologically
compatible process consisting of extraction with organic acids, electrolysis and
foam separation.
The question of the behaviour and reutilization of treated soils, which was one of
the key issues in the previous SFB 188 assessment report, has so far only been
investigated by advancing biological test methods. The results of the
investigations indicate the potential and boundaries of these processing methods.
During the next phase research shall therefore be extended to include
chemical/physical treatment steps, meaning that these treatment methods have
developed into a key area within the SFB 188. Chemical/physical treatment prior
to biological treatment is already familiar from the treatment of industrial waste
waters. Compared to the alternatives, i.e. thermal treatment, it is a process that
requires less energy and is thus one that will be significant in the future.
The biological treatment of contaminations under extremely thermophilic
conditions (> 65 Grad C) is a new, promising process (SFB 188, Project
B6).
In addition to targeting the new key fields described above, the research
programme will continue to deal with the existing questions in greater depth in
order to yield satisfactory and definite findings on the basis of the existing
preliminary results. The main emphasis will be on the explanation of structures
as well as the behaviour of non-bioavailable and thus non-degradable
substances: the bound residues.
The structure of SFB 188 has not been changed considerably; the new projects
have been integrated into the existing structure.
As contaminations with oil occur frequently it was decided to use a model oil as
a soil contaminant. The biological degradability of the most important main
components is ensured, so that the basics of a decontamination/cleanup method
can be developed. However, oils contain minor components that are degraded
only with difficulty or not at all (according to latest research), meaning that it
becomes necessary either to pretreat the contamination chemo-physically or to
train specialists in the use of biological methods.
Typical mineral oil soil pollution figures lie between 0.5 and 1.5% by weight. The
research centre therefore elected to use a 1% diesel fuel and lubricating oil
contamination.
The model oils used are a genuine diesel fuel, a lubricating oil, and a synthetic
mixture of 8 selected oil components which represents all the main constituents
of oil in proportion. This mixture has the advantage of allowing the degradation
of individual substances and the analytic registration of degradation products to
be observed in detail. For certain projects the investigation of problematic trace
substances in the oil is of particular interest. These projects will concentrate on
the investigation of lubricating oil.
At the start of this research programme genuinely contaminated soils were used
in various projects. These projects were primarily concerned with the
investigation of the inhomogeneity of the soil structure and the dissolution of the
bonds between contaminants and soil particles (mechanical processes). It is also
necessary to use genuinely contaminated soil when investigating the adaptation
of microflora in contaminated sites. In the current research period the main soil
contaminants which will be investigated are PAH and hydrocarbons (partly
chlorinated).
These were the main issues that were investigated on an interdisciplinary basis.
The results of these and other questions investigated by the SFB 188 have a
direct practical application. For example, testing methods, to be applied before
and after remedial and corrective action is taken, were developed. The positive
effect of the addition of biocompost with a low contaminant content is of great
practical relevance. This also holds true for the development of expert
systems.
These examples demonstrate the positive development of the SFB 188
throughout the second research period; we are confident that this development
will be continued in the third, and current, period.
Project Area A comprises the projects which deal with concrete process steps to
reclaim highly contaminated soils. The scheduled research projects will
investigate fundamental mechanical and physical-chemical principles. One long-
term basis it is anticipated that this will result in the development of effective and
economic processes for the treatment of highly contaminated soils. In
comparison to the first two research periods, the scope of the investigations - in
particular regarding the type of soils examined, the contaminations and the
concrete processing steps - will be extended. The individual projects in Area A
will continue to cooperate in many ways with other projects. This applies mainly
to the groups working on or with measuring techniques, since the process steps
examined here can only be evaluated and the results quantified with the help of
customized analytics. However, the work groups investigating soil characteristics
before and after treatment will also be actively involved in all aspects of the
project work.
The investigations into direct biological soil treatment, on the analytics of the
original contaminants and of the metabolites formed during biological treatment
which took place in the second research period will be extended to more
complex systems: systems in which several contaminant classes are
simultaneously present and real mixed-type contaminations. One main working
objective is to establish more detailed information on the interactions in the
humus-contaminant complex. Special attention will be paid to the effect of the
compost materials often added in biological treatment, as well as to the
mechanisms of contaminant incorporation which take place during humidification
processes. Essential insights are expected to be gained from the investigations
on nuclear magnetic resonance which the SFB 188 will carry out. For the first
time the ability of thermophilic microorganisms to degrade organic contaminants
will be characterized in the new B6 project.
The following presents the objectives of the individual projects in brief. As in
previous research periods, the investigations scheduled for Project Area B
supplement those of Areas A, C and D in many aspects. For example, process
waste waters and fractions with high contaminant concentrations from the
process engineering work groups will be further treated in the Area B projects,
and the synergetic and antagonistic interactions of coexisting contaminant
classes are to be described in close cooperation with the analytical sub-projects.
An important aspect is the joint elucidation of the structure of the bonds within a
humus/contaminant system. In connection with this, further investigations on the
effect of compost materials (B3), experiments with 13C- and 14C-labelled
compounds (B1, D6), as well as the required measurements by means of high-
resolution- (D5) and solid body-NMR (B4) have been scheduled. These joint
projects are presented only as examples; the other interproject cooperations that
have been planned are stated in the application paper of each individual
project.
The projects of Area C aim to prepare decision criteria for processes, to evaluate
the results, and to draw conclusions regarding the potential and boundaries of
soil treatment processes. Project C1 will concentrate on the investigation of the
ecological effects of contaminations on soil organisms in order to derive
standardized evaluations for practical application. Project C3 will concentrate on
the investigation of the behaviour of these substances and their degradation
products in deeper soil layers. Project C6 will evaluate aims and techniques of
reclamation within regional and urban planning schemes.
Research in Projects D4 and D5 focuses mainly on organics and analyses, while
D7 looks closely at problems related to soil science. In addition to the projects of
Area D cooperating closely with the Area A-C projects working on process
development - especially on sub-project level - the projects comprised in Area D
will also make independent contributions to the development of methods and to
the characterization of standard parameters relevant to remedial action. Project
D4 is responsible for the development of swift and reliable methods of analysis
for recording organic substances. Project D5 will be concentrating on
microanalytical approaches and the elucidation of the structure of unknown
substances (contaminants and metabolites). D6 is working on the particularly
important subject of the binding of contaminants in the humus matrix (bound
residues). In the field of analytics D6 is interlinked with D5; on the subject of the
remobilization of contaminants there are close links with Project D7, whose key-
area this is. In addition, Project D5 is working on the electrochemical
dehalogenization of chlorinated aromatic compounds aiming - in cooperation with
A1 - at processes for industrial application.
The work groups form the basic units for the intensive cooperation between the
individual projects; each scientist participated in at least one work group (most
in several) so that contact was made at intervals of 2-3 months. The results of
the teamwork were documented and can be reconstructed. Intensive discussions
stimulated the cooperation between the individual projects mentioned above.
Plenary sessions in which information was exchanged and research results set
out were attended by both the project leaders and the scientific assistants. The
project results were also discussed outside the SFB 188. The platforms for these
discussions were the weekly Friday seminars and both national and international
congresses. In addition to cooperation within the SFB, the projects also
collaborated with institutes outside the SFB. One of these institutes is the
Graduierten Kolleg Biotechnologie, which is researching the disposal of bio-
products by means of cells or enzymes in bioreactors.