Different acid-thermophilic MOs from soil, sludge and water from polluted
environments from metallurgical industries were isolated for use in the bioremediation of toxic HMs.
The tolerance of these MOs to high concentrations of Ag, As, Bi, Cd, Cr, Co, Cu,
Hg, Li, Mo, Pb, Sn, and Zn was improved. Isolation and adaptation of MOs to large
concentrations of metals were done by growing them on autotrophic bacteria media
under different incubation conditions: pH, 2–4.5; temperature, 40–65
C; and metal
concentrations in culture media, 10
À3
À10
À7 M (Jonasson and Afshari 2018).
4.5.5 In Situ Bioremediation of Soils Contaminated with Heavy
Metals
For bioremediation of technogenic soils, tailings dumps resulting from mining
operations of Pb, Zn and Fe, bioremediation of Pb and Zn tailings dumps, and Fe,
on some tailings, dumps were installed experimental plots, subject to a different
treatment and seeded with Lolium perenne and Trifolium pratense. Later on, the
slopes of the heap were planted H. rhamnoides. Applied biotechnologies have led to
the formation of favorable conditions for the development of MOs, for plant growth,
and for intense and sustainable enzyme activity.
The best technology for tailing bioremediation containing Pb and Zn impurities
was to cover a 10 cm layer of natural soil in the vicinity of the heap, NPK mineral
fertilization, and seedling with a mixture of herbaceous plants or plants from the
spontaneous flora of the region. The ascending evolution of the microbial and EAs of
the soils of the experimental parcels has been remarkable from year to year. The
crops and the juvenile or extended plantations, so that after many years, the tailings
heap, initially with a serene appearance, with no trace of vegetation, especially on the
upper terraces, covered the vegetation totally.
Technogenic soil is being transformed; it already records an enzymatic and
microbial potential comparable to natural soils. On the terraces and the slopes of
the Fe, mine tailings were planted trees and shrubs, most of them H. rhamnoides.
Experimental parcels were cultivated with the following herbaceous species:
Festuca rubra, Festuca arundinacea, Dactylis glomerata, L. perenne (Poaceae
family), Onobrychis viciifolia, Trifolium repens, T. pratense, Lotus corniculatus,
and Medicago sativa (Fabaceae family). Both parcels and planting seedlings have
undergone differentiated treatments. The evolution of the vegetation and of the
microbial and EAs of the soil of the experimental plots was followed. The assessment of microbial potential was based on the values of soil quality bacterial
indicators, calculated taking into account the number of aerobic, ammonifier,
denitrifying, reducing, and desulfurization in mesophilic heterotrophic bacteria.
The EAs were assessed on the basis of the values of enzymatic soil quality
indicators, calculated on the basis of the following EAs: catalase, sucrase, phosphatase, and actual and potential dehydrogenase. The results obtained demonstrated the
efficiency of applied technologies. After only 1 year of vegetation, a remarkable
biological potential has developed in the soils of the experimental plots. The
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
101
environments from metallurgical industries were isolated for use in the bioremediation of toxic HMs.
The tolerance of these MOs to high concentrations of Ag, As, Bi, Cd, Cr, Co, Cu,
Hg, Li, Mo, Pb, Sn, and Zn was improved. Isolation and adaptation of MOs to large
concentrations of metals were done by growing them on autotrophic bacteria media
under different incubation conditions: pH, 2–4.5; temperature, 40–65
C; and metal
concentrations in culture media, 10
À3
À10
À7 M (Jonasson and Afshari 2018).
4.5.5 In Situ Bioremediation of Soils Contaminated with Heavy
Metals
For bioremediation of technogenic soils, tailings dumps resulting from mining
operations of Pb, Zn and Fe, bioremediation of Pb and Zn tailings dumps, and Fe,
on some tailings, dumps were installed experimental plots, subject to a different
treatment and seeded with Lolium perenne and Trifolium pratense. Later on, the
slopes of the heap were planted H. rhamnoides. Applied biotechnologies have led to
the formation of favorable conditions for the development of MOs, for plant growth,
and for intense and sustainable enzyme activity.
The best technology for tailing bioremediation containing Pb and Zn impurities
was to cover a 10 cm layer of natural soil in the vicinity of the heap, NPK mineral
fertilization, and seedling with a mixture of herbaceous plants or plants from the
spontaneous flora of the region. The ascending evolution of the microbial and EAs of
the soils of the experimental parcels has been remarkable from year to year. The
crops and the juvenile or extended plantations, so that after many years, the tailings
heap, initially with a serene appearance, with no trace of vegetation, especially on the
upper terraces, covered the vegetation totally.
Technogenic soil is being transformed; it already records an enzymatic and
microbial potential comparable to natural soils. On the terraces and the slopes of
the Fe, mine tailings were planted trees and shrubs, most of them H. rhamnoides.
Experimental parcels were cultivated with the following herbaceous species:
Festuca rubra, Festuca arundinacea, Dactylis glomerata, L. perenne (Poaceae
family), Onobrychis viciifolia, Trifolium repens, T. pratense, Lotus corniculatus,
and Medicago sativa (Fabaceae family). Both parcels and planting seedlings have
undergone differentiated treatments. The evolution of the vegetation and of the
microbial and EAs of the soil of the experimental plots was followed. The assessment of microbial potential was based on the values of soil quality bacterial
indicators, calculated taking into account the number of aerobic, ammonifier,
denitrifying, reducing, and desulfurization in mesophilic heterotrophic bacteria.
The EAs were assessed on the basis of the values of enzymatic soil quality
indicators, calculated on the basis of the following EAs: catalase, sucrase, phosphatase, and actual and potential dehydrogenase. The results obtained demonstrated the
efficiency of applied technologies. After only 1 year of vegetation, a remarkable
biological potential has developed in the soils of the experimental plots. The
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
101