256
Discussion
concrete bottom will be plastic-lined to render them as smooth as possible and eliminate seams. Thus,
settlement of flora will be difficult and cleaning facilitated. The design of the pumping station will
permit any conceivable mixing to be made and controlled. It will be possible, for example, to have
water circulate within the individual channels or pass it in a defined sequence. The total running length
for one passage will be 4 km.
As a diluent for the different types of sewage, ground water will be available. In a water conditioning unit its chemical composition may be adjusted, for example as to its iron content, to
correspond to a natural water say from a river. In an additional channel which surrounds the main one,
such water may be adjusted to the state of a river water biochemically, by dosage of nutrients and
"inoculation" of sewage. It should be added that this special channel will permit a velocity of flow of
1 m/s while in the main channel, the maximal value will be about 0.25 m/s.
In the vicinity of the simulating channel will be eight ponds having a surface of approximately 150
m each and a depth of water of about 1 m. They may be passed in sequence as well as in parallel (in
groups of two or four), with variable times of passage. The test field will also include a lysimeter unit
for seepage experiments and a laboratory building with a minor hall for experiments.
Finally, a wide open area where the necessary utilities are located will be of special importance. It
would be possible to operate for example pilot plants for a chemical-physical treatment or elimination
of nutrients, the effluents from which might be passed to the simulated receiving water or the ponds
mentioned. Also experimental plants for the treatment of sewage and effluents from the simulated
receiving water or the ponds and if required also from waters having undergone a brief soil passage, to
yield industrial or even drinking water, could be operated there.
The capital costs required for the whole complex of test field plus laboratory building will be
about 7 million DM. It is expected that these funds will be allocated before long. When discussing
these costs, it should be taken into account that one of the main objectives of this test field will mean
a contribution to a specific problem of West Berlin. In the south of West Berlin, a canal has to take up
the effluents from two major sewage treatment plants and a number of power stations either now or
within a few years. The construction of plants which had been planned for elimination of phosphate
and - as it was initially believed to be necessary on the basis of corresponding laboratory experiments
- for a reduction of nitrogen as far as possible, would have involved many times the sum needed for
building the test field without the assurance of adequate success and with sufficient certainty. So, for
the time being, the canal is artificially aerated at the sites and times necessary, and the question of a
final re-establishment of satisfactory conditions within this body of water will be answered with
adequate certainty after having completed corresponding carefully performed studies over a number of
years. Considering that there is a preponderant participation of the Federal Republic in such major
investments of capital in West Berlin, it is in the legitimate interest of the Federal Government to
verify by corresponding studies whether the measures planned would in fact yield success as expected.
So it was obvious that this problem should be coupled with the construction of a technical test field
for the Institute of Water, Soil, and Air Hygiene. Beyond this, however, the experimental results
achieved in the course of time will also supply useful information on all questions related to the
treament of municipal sewage, its influence upon stagnant and flowing bodies of water and utilization
of the latter for drinking water supply and also for recreational purposes. If viewed from this angle,
the simulated water as the centre of this test field will not mean an alternative to the U.S. simulator
but rather a necessary complementary test with a technological application.
J. Blok, Netherlands.
J. Blok observed that the experimenter still knows very little about natural ecosystems.
K. Wuhrmann, Switzerland.
The response of a once established biocenosis to new conditions is very slow and one has always to
deal with transient biological conditions even under highly constant conditions of seemingly all
pertinent ecological factors. An essential point in such experiments is the producer-predator relationship, which includes also the higher trophic levels. How will this factor be introduced in the enclosed
systems and how will the seasonal variations of predators be emphasized? Light-energy flux is of great
importance; how does the artificial illumination compare with energy flux outdoor, e.g. in
cal/m /time? I think that the most essential counterpart to the admirable installation will be the skill
in the formulation of experimental questions which can be really and efficiently answered.
Author's Comments on the Edited Discussion by K. Wuhrmann, Switzerland.
The question raised concerning higher trophic levels and producer-predator relationships is an
important one. It should be noted that the ecosystem simulator under discussion was primarily
Discussion
concrete bottom will be plastic-lined to render them as smooth as possible and eliminate seams. Thus,
settlement of flora will be difficult and cleaning facilitated. The design of the pumping station will
permit any conceivable mixing to be made and controlled. It will be possible, for example, to have
water circulate within the individual channels or pass it in a defined sequence. The total running length
for one passage will be 4 km.
As a diluent for the different types of sewage, ground water will be available. In a water conditioning unit its chemical composition may be adjusted, for example as to its iron content, to
correspond to a natural water say from a river. In an additional channel which surrounds the main one,
such water may be adjusted to the state of a river water biochemically, by dosage of nutrients and
"inoculation" of sewage. It should be added that this special channel will permit a velocity of flow of
1 m/s while in the main channel, the maximal value will be about 0.25 m/s.
In the vicinity of the simulating channel will be eight ponds having a surface of approximately 150
m each and a depth of water of about 1 m. They may be passed in sequence as well as in parallel (in
groups of two or four), with variable times of passage. The test field will also include a lysimeter unit
for seepage experiments and a laboratory building with a minor hall for experiments.
Finally, a wide open area where the necessary utilities are located will be of special importance. It
would be possible to operate for example pilot plants for a chemical-physical treatment or elimination
of nutrients, the effluents from which might be passed to the simulated receiving water or the ponds
mentioned. Also experimental plants for the treatment of sewage and effluents from the simulated
receiving water or the ponds and if required also from waters having undergone a brief soil passage, to
yield industrial or even drinking water, could be operated there.
The capital costs required for the whole complex of test field plus laboratory building will be
about 7 million DM. It is expected that these funds will be allocated before long. When discussing
these costs, it should be taken into account that one of the main objectives of this test field will mean
a contribution to a specific problem of West Berlin. In the south of West Berlin, a canal has to take up
the effluents from two major sewage treatment plants and a number of power stations either now or
within a few years. The construction of plants which had been planned for elimination of phosphate
and - as it was initially believed to be necessary on the basis of corresponding laboratory experiments
- for a reduction of nitrogen as far as possible, would have involved many times the sum needed for
building the test field without the assurance of adequate success and with sufficient certainty. So, for
the time being, the canal is artificially aerated at the sites and times necessary, and the question of a
final re-establishment of satisfactory conditions within this body of water will be answered with
adequate certainty after having completed corresponding carefully performed studies over a number of
years. Considering that there is a preponderant participation of the Federal Republic in such major
investments of capital in West Berlin, it is in the legitimate interest of the Federal Government to
verify by corresponding studies whether the measures planned would in fact yield success as expected.
So it was obvious that this problem should be coupled with the construction of a technical test field
for the Institute of Water, Soil, and Air Hygiene. Beyond this, however, the experimental results
achieved in the course of time will also supply useful information on all questions related to the
treament of municipal sewage, its influence upon stagnant and flowing bodies of water and utilization
of the latter for drinking water supply and also for recreational purposes. If viewed from this angle,
the simulated water as the centre of this test field will not mean an alternative to the U.S. simulator
but rather a necessary complementary test with a technological application.
J. Blok, Netherlands.
J. Blok observed that the experimenter still knows very little about natural ecosystems.
K. Wuhrmann, Switzerland.
The response of a once established biocenosis to new conditions is very slow and one has always to
deal with transient biological conditions even under highly constant conditions of seemingly all
pertinent ecological factors. An essential point in such experiments is the producer-predator relationship, which includes also the higher trophic levels. How will this factor be introduced in the enclosed
systems and how will the seasonal variations of predators be emphasized? Light-energy flux is of great
importance; how does the artificial illumination compare with energy flux outdoor, e.g. in
cal/m /time? I think that the most essential counterpart to the admirable installation will be the skill
in the formulation of experimental questions which can be really and efficiently answered.
Author's Comments on the Edited Discussion by K. Wuhrmann, Switzerland.
The question raised concerning higher trophic levels and producer-predator relationships is an
important one. It should be noted that the ecosystem simulator under discussion was primarily