Chapter 2
Advances in Bioremediation of Toxic Heavy
Metals and Radionuclides in Contaminated
Soil and Aquatic Systems
Evans M. Nkhalambayausi-Chirwa, Pulane Elsie Molokwane,
Tshilidzi Bridget Lutsinge, Tony Ebuka Igboamalu, and Zainab S. Birungi
Abstract Metals are used in several products essential to humans. However,
processes for extraction of the metals generate effluents containing chemical
by-products many of which are toxic to living organisms and are disruptive to
ecosystems. Processes used in the creation of useful products from the metals
leave a legacy of pollution that may take generations to clear. Metals such as
mercury, cadmium, lead, chromium, and uranium, and a range of metalloids such
as arsenic and selenium, are widely known for their acute toxicity at high doses
and carcinogenicity at low doses. Several technologies for treatment of land and
water that have been contaminated with toxic heavy metals have been proposed.
Other metallic elements, although possessing no significant chemical toxicity to
organisms, occur as radioactive isotopes that impart oxidative stress on organisms
leading to increased incidence of mutations and carcinomas in animal tissue. The
main difficulty in the treatment of metals is that the metals cannot be degraded or
mineralized as is the case with organic pollutants. Metallic elements can only be
oxidized or reduced to forms that are less mobile and easier to extract from the
environment. This chapter is compiled from information from projects in which
metals were either oxidized or reduced to less mobile and less toxic states using
pure or consortium cultures of bacteria followed by immobilization or extraction
using physical or biological media. The uptake of metals for reuse was attempted
using bioengineered molecular adsorbents on cell surfaces. The latter process was
developed to facilitate selective uptake of different metallic species as a low
energy biorefinery.
E. M. Nkhalambayausi-Chirwa (*) · T. B. Lutsinge · T. E. Igboamalu · Z. S. Birungi
Water Utilization and Environmental Engineering Division, Department of Chemical
Engineering, University of Pretoria, Pretoria, Gauteng, South Africa
e-mail: evans.chirwa@up.ac.za
P. E. Molokwane
Water Utilization and Environmental Engineering Division, Department of Chemical
Engineering, University of Pretoria, Pretoria, Gauteng, South Africa
Oloenviron Consultancy, Johannesburg, South Africa
© Springer Nature Singapore Pte Ltd. 2020
R. N. Bharagava, G. Saxena (eds.), Bioremediation of Industrial Waste for
Environmental Safety, https://doi.org/10.1007/978-981-13-3426-9_2
21
Advances in Bioremediation of Toxic Heavy
Metals and Radionuclides in Contaminated
Soil and Aquatic Systems
Evans M. Nkhalambayausi-Chirwa, Pulane Elsie Molokwane,
Tshilidzi Bridget Lutsinge, Tony Ebuka Igboamalu, and Zainab S. Birungi
Abstract Metals are used in several products essential to humans. However,
processes for extraction of the metals generate effluents containing chemical
by-products many of which are toxic to living organisms and are disruptive to
ecosystems. Processes used in the creation of useful products from the metals
leave a legacy of pollution that may take generations to clear. Metals such as
mercury, cadmium, lead, chromium, and uranium, and a range of metalloids such
as arsenic and selenium, are widely known for their acute toxicity at high doses
and carcinogenicity at low doses. Several technologies for treatment of land and
water that have been contaminated with toxic heavy metals have been proposed.
Other metallic elements, although possessing no significant chemical toxicity to
organisms, occur as radioactive isotopes that impart oxidative stress on organisms
leading to increased incidence of mutations and carcinomas in animal tissue. The
main difficulty in the treatment of metals is that the metals cannot be degraded or
mineralized as is the case with organic pollutants. Metallic elements can only be
oxidized or reduced to forms that are less mobile and easier to extract from the
environment. This chapter is compiled from information from projects in which
metals were either oxidized or reduced to less mobile and less toxic states using
pure or consortium cultures of bacteria followed by immobilization or extraction
using physical or biological media. The uptake of metals for reuse was attempted
using bioengineered molecular adsorbents on cell surfaces. The latter process was
developed to facilitate selective uptake of different metallic species as a low
energy biorefinery.
E. M. Nkhalambayausi-Chirwa (*) · T. B. Lutsinge · T. E. Igboamalu · Z. S. Birungi
Water Utilization and Environmental Engineering Division, Department of Chemical
Engineering, University of Pretoria, Pretoria, Gauteng, South Africa
e-mail: evans.chirwa@up.ac.za
P. E. Molokwane
Water Utilization and Environmental Engineering Division, Department of Chemical
Engineering, University of Pretoria, Pretoria, Gauteng, South Africa
Oloenviron Consultancy, Johannesburg, South Africa
© Springer Nature Singapore Pte Ltd. 2020
R. N. Bharagava, G. Saxena (eds.), Bioremediation of Industrial Waste for
Environmental Safety, https://doi.org/10.1007/978-981-13-3426-9_2
21