productive (a forest is replaced by a grassland with a recreational area). The term
ecological reconstruction may overlap with any of the terms’ restoration, rehabilitation, and replacement. Ecological rebuilding means an active and guided (engineering) replacement of the original ecosystem with another for a well-defined purpose.
Mining waste presents specific rehabilitation problems. Mining waste dumps are
often naturally colonized by vegetation. This depends very much on the material
from which the heap was built. Many mining waste dumps have no limitations on
plant growth, except for the absence of nitrogen and possibly phosphorus. It is easy
to install vegetation that includes obligatory nitrogen fixation plants. For such
dumps, a wide range of uses from forests to agricultural fields can be considered.
Many mining waste dumps contain pyrite, and H 2 SO 4 is formed by oxidation.
These dumps have restrictions for both the natural vegetation installation and for
a number of other uses. When the pyrite content is low, there is a chance of slow
planting of a flora composed of plants tolerant to acidity. Installation of vegetation
should be aided by lime treatments. Such land cannot be used for agriculture because
rehabilitation costs would be too high and their agricultural efficiency would be
reduced.
Nonferrous and pyrite-containing holes are more difficult. Here, acidity also
carries heavy metal ions that are toxic to vegetation and to microorganisms.
Old holes from nonferrous ores have often high metal content due to the poor
efficiency of metal extraction techniques used in those times. These waste dumps
remain uncolonized by vegetation and are exposed to erosion and sliding phenomena, constituting a permanent and real danger to the environment. Any public use of
these lands requires coating with an inert material to isolate the area of toxicity,
which is quite costly. After such treatment, the huts can be used for recreational areas
(Gay-des-Combes et al. 2017).
4.10.1.1 Treatments in Ecological Reconstruction Technologies
of Degraded or Industrially Polluted Sites
The treatment of a site is supposed to be two components. Immediate treatment to
improve the physical, chemical, topographic, toxicity, and site stability features
provides conditions for long-term treatment. Long-term treatment consists of
installing and maintaining vegetation on the site, etc. To improve the physical
structure of the field, immediate treatment is done: scarification or discussion, if
the structure is too compact; compaction and finishing, if the structure is loose;
stabilization works by treatments with various stabilizing materials; drainage works;
and humidification to improve stability and humidity.
Other treatment works can be carried out in order to ensure the conditions
required for the efficient installation of the vegetation: fertilization works (fertilizer
additions and amendments), pH lime correction can be carried out; works to
neutralize and fix toxic substances (HMs). The purpose of rehabilitation is to create
an ecosystem with robust self-maintenance. The installation of vegetation and its
maintenance is a decisive step in this action, and it depends on the success of the
whole rehabilitation action. Biological recultivation is important; the successful
realization of the self-sustaining ecosystem necessarily requires that all problems
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
111
ecological reconstruction may overlap with any of the terms’ restoration, rehabilitation, and replacement. Ecological rebuilding means an active and guided (engineering) replacement of the original ecosystem with another for a well-defined purpose.
Mining waste presents specific rehabilitation problems. Mining waste dumps are
often naturally colonized by vegetation. This depends very much on the material
from which the heap was built. Many mining waste dumps have no limitations on
plant growth, except for the absence of nitrogen and possibly phosphorus. It is easy
to install vegetation that includes obligatory nitrogen fixation plants. For such
dumps, a wide range of uses from forests to agricultural fields can be considered.
Many mining waste dumps contain pyrite, and H 2 SO 4 is formed by oxidation.
These dumps have restrictions for both the natural vegetation installation and for
a number of other uses. When the pyrite content is low, there is a chance of slow
planting of a flora composed of plants tolerant to acidity. Installation of vegetation
should be aided by lime treatments. Such land cannot be used for agriculture because
rehabilitation costs would be too high and their agricultural efficiency would be
reduced.
Nonferrous and pyrite-containing holes are more difficult. Here, acidity also
carries heavy metal ions that are toxic to vegetation and to microorganisms.
Old holes from nonferrous ores have often high metal content due to the poor
efficiency of metal extraction techniques used in those times. These waste dumps
remain uncolonized by vegetation and are exposed to erosion and sliding phenomena, constituting a permanent and real danger to the environment. Any public use of
these lands requires coating with an inert material to isolate the area of toxicity,
which is quite costly. After such treatment, the huts can be used for recreational areas
(Gay-des-Combes et al. 2017).
4.10.1.1 Treatments in Ecological Reconstruction Technologies
of Degraded or Industrially Polluted Sites
The treatment of a site is supposed to be two components. Immediate treatment to
improve the physical, chemical, topographic, toxicity, and site stability features
provides conditions for long-term treatment. Long-term treatment consists of
installing and maintaining vegetation on the site, etc. To improve the physical
structure of the field, immediate treatment is done: scarification or discussion, if
the structure is too compact; compaction and finishing, if the structure is loose;
stabilization works by treatments with various stabilizing materials; drainage works;
and humidification to improve stability and humidity.
Other treatment works can be carried out in order to ensure the conditions
required for the efficient installation of the vegetation: fertilization works (fertilizer
additions and amendments), pH lime correction can be carried out; works to
neutralize and fix toxic substances (HMs). The purpose of rehabilitation is to create
an ecosystem with robust self-maintenance. The installation of vegetation and its
maintenance is a decisive step in this action, and it depends on the success of the
whole rehabilitation action. Biological recultivation is important; the successful
realization of the self-sustaining ecosystem necessarily requires that all problems
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
111