However, experience shows that different leguminous species could be installed
and stabilized in the vegetal carpet on the mining tailings dumps and made the
nitrogen fixation. Sowing techniques can be ordinary farming or water sowing.
Growth is helped if larger amounts of phosphate are added to the usual fertilization
than usual (it fixes some metals that become so unavailable). If grazing is intended, it
is necessary to track the metal content of the plants. Grass may be unusable (Różyło
et al. 2016).
Surface Coatings In toxic dumps, one of the alternatives is to improve the surface
with sufficient material such as sewage sludge or household waste or plant soil so as
to ensure plant growth. OM has the ability to complex soluble metals and make them
unavailable for plants and at the same time is a long-term source of nutrients for
plants.
At Lower Swansea Valley, vegetation has been successfully stabilized on various
metallic wastes using a layer of at least 10 cm of coating material. It was also used in
Anaconda (Montana–USA) and in England. At some sites (e.g., Broken Hill),
household wastewater was pumped to the tailings pond dike, resulting in a good
increase in common species. The problem is whether this vegetation lasts after
stopping the water supply.
Sometimes the toxicity of metallic waste can be so great that it is preferable to
achieve complete isolation, especially where the land is to be farmed and the
vegetation must not contain high levels of metals. It would seem that the most useful
solution would be the use of vegetal soil cover, but this is also not ideal. Plant soil is
difficult to obtain in large quantities, and a substantial thickness layer is required.
The soil’s ability to retain soluble ions is a disadvantage.
During the dry period, the evaporation will carry upward the toxic ions that will
be retained in the soil. If a porous material (zeolites) with a low ion exchange
capacity is used, toxic ions will be recirculated again after the drought, and toxicity
will not occur at the surface. There are good arguments for the use of coarse
inorganic materials.
They will be relatively easy to obtain, often being produced even by mining
operations (sterile rock from works outside the deposit); termino heat ash can be
used. The surface covered with inert material will be improved by fertilization and
using nitrogen fixation legumes. In order to install the trees on such dumps, it will
require a layer of inert material of a consistent depth (2 m) for the trees to roots well
and grow satisfactorily for many years. Maintenance of vegetation is particularly
important, no matter what the landfills were.
Except when covered with a thick layer of inert material, there will be no question
of agricultural use that would require a high nutrient intake. To maintain growth after
the initial installation period, it is sufficient to administer 25–30 kg/year N, P, and
K. This maintenance should last for 6 years. After that, the recycling of nutrients will
begin to run alone, and there may be no need for other nutrient additions (Dold et al.
2011).
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
119
and stabilized in the vegetal carpet on the mining tailings dumps and made the
nitrogen fixation. Sowing techniques can be ordinary farming or water sowing.
Growth is helped if larger amounts of phosphate are added to the usual fertilization
than usual (it fixes some metals that become so unavailable). If grazing is intended, it
is necessary to track the metal content of the plants. Grass may be unusable (Różyło
et al. 2016).
Surface Coatings In toxic dumps, one of the alternatives is to improve the surface
with sufficient material such as sewage sludge or household waste or plant soil so as
to ensure plant growth. OM has the ability to complex soluble metals and make them
unavailable for plants and at the same time is a long-term source of nutrients for
plants.
At Lower Swansea Valley, vegetation has been successfully stabilized on various
metallic wastes using a layer of at least 10 cm of coating material. It was also used in
Anaconda (Montana–USA) and in England. At some sites (e.g., Broken Hill),
household wastewater was pumped to the tailings pond dike, resulting in a good
increase in common species. The problem is whether this vegetation lasts after
stopping the water supply.
Sometimes the toxicity of metallic waste can be so great that it is preferable to
achieve complete isolation, especially where the land is to be farmed and the
vegetation must not contain high levels of metals. It would seem that the most useful
solution would be the use of vegetal soil cover, but this is also not ideal. Plant soil is
difficult to obtain in large quantities, and a substantial thickness layer is required.
The soil’s ability to retain soluble ions is a disadvantage.
During the dry period, the evaporation will carry upward the toxic ions that will
be retained in the soil. If a porous material (zeolites) with a low ion exchange
capacity is used, toxic ions will be recirculated again after the drought, and toxicity
will not occur at the surface. There are good arguments for the use of coarse
inorganic materials.
They will be relatively easy to obtain, often being produced even by mining
operations (sterile rock from works outside the deposit); termino heat ash can be
used. The surface covered with inert material will be improved by fertilization and
using nitrogen fixation legumes. In order to install the trees on such dumps, it will
require a layer of inert material of a consistent depth (2 m) for the trees to roots well
and grow satisfactorily for many years. Maintenance of vegetation is particularly
important, no matter what the landfills were.
Except when covered with a thick layer of inert material, there will be no question
of agricultural use that would require a high nutrient intake. To maintain growth after
the initial installation period, it is sufficient to administer 25–30 kg/year N, P, and
K. This maintenance should last for 6 years. After that, the recycling of nutrients will
begin to run alone, and there may be no need for other nutrient additions (Dold et al.
2011).
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
119