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Bioreduction of Selenite and Tellurite by Phanerochaete Chrysosporium

Selenium (Se) and tellurium (Te) are metalloids of commercial interest due to their physicochemical properties. The water soluble oxyanions of these elements (selenite, selenate, tellurite and tellurate) exhibit high toxicities; hence, their release in the environment is of great concern. Les mer
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Vår pris: 2279,-

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Leveringstid: Sendes innen 21 dager
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Om boka

Selenium (Se) and tellurium (Te) are metalloids of commercial interest due to their physicochemical properties. The water soluble oxyanions of these elements (selenite, selenate, tellurite and tellurate) exhibit high toxicities; hence, their release in the environment is of great concern.
This study demonstrates the potential use of fungi as Se- and Te-reducing organisms. The response of Phanerochaete chrysosporium to the presence of selenite and tellurite was evaluated, as well as its potential application in wastewater treatment and production of nanoparticles. Growth stress and morphological changes were induced in P. chrysosoporium when exposed to selenite and tellurite. Synthesis of Se0 and Te0 nanoparticles entrapped in the fungal biomass was observed, as well as the formation of unique Se0-Te0 nanocomposites when the fungus was cultivated concurrently with Se and Te. The response of P. chrysosporium to selenite exposure was investigated in different modes of fungal growth (pellets and biofilm). A bioprocess for selenite removal and Se0 nanoparticles recovery using an up-flow fungal pelleted reactor was developed. 70% selenite removal (10 mg Se L-1 d-1) was achieved under continuous mode. The use of Se0 nanoparticles immobilized in P. chrysosporium pellets as a new sorbent material for the removal of heavy metals from wastewater was demonstrated.

Fakta

Innholdsfortegnelse

1 General introduction
1.1 Background
1.2 Problem statement
1.3 Research objectives
1.4 Structure of the thesis
1.5 References


2 Literature review
2.1 Introduction
2.2 Fungal pellets
2.2.1 Fungal pellets: formation and growth
2.2.2 Factors influencing the characteristics and formation of pellets
2.2.3 Fungal pellets in bioreactors
2.3 Fungal pelleted bioreactors for wastewater treatment
2.3.1 Potential applications and challenges
2.3.2 Reactor configurations
2.3.3 Reactor design for fungal pelleted reactors
2.3.4 Sterile versus non-sterile conditions
2.3.5 Biomass recycle in fungal pelleted reactors
2.4 Removal of organic and inorganic pollutants
2.4.1 Removal of organic pollutants
2.4.2 Removal of inorganic pollutants
2.5 Scope for further research
2.6 Conclusions
2.7 References


3 Effects of selenium oxyanions on the fungus Phanerochaete chrysosporium
3.1 Introduction
3.2 Materials and methods
3.2.1 Fungal culture and medium composition
3.2.2 Batch experiments
3.2.3 Transmission electron microscopy (TEM) and electron-energy loss spectroscopy (EELS) analysis
3.2.4 Analytical methods
3.3 Results
3.3.1 Fungal interaction with selenium oxyanions
3.3.2 Effect of glucose concentration
3.3.3 Effect of pH
3.3.4 Effects of selenium concentration
3.4 Discussion
3.4.1 Inhibition of fungal growth induced by selenium oxyanions
3.4.2 Morphological effects induced by selenium oxyanions
3.4.3 Removal of selenium oxyanions by P. chrysosporium
3.4.4 Production of Se0 by P. chrysosporium
3.4.5 Potential applications
3.5 References


4 Removal of selenite from wastewater in a Phanerochaete chrysosporium pellet based fungal bioreactor
4.1 Introduction
4.2 Materials and methods
4.2.1 Strain, medium composition and pre-cultivation of fungal cultures
4.2.2 Bioreactor configuration and operating conditions
4.2.3 Analytical methods
4.2.4 Statistical analysis
4.3 Results
4.3.1 Bioreactor operation in batch mode
4.3.2 Continuous bioreactor operation at constant selenium concentrations
4.3.3 Bioreactor response to spikes of selenium concentration
4.3.4 Evolution and growth of the fungal biomass
4.4 Discussion
4.4.1 Removal of selenite in a fungal pelleted bioreactor
4.4.2 Response of the system to selenium spikes
4.4.3 Fungal morphology in the bioreactor
4.4.4 Operational advantages of fungal pelleted reactors
4.4.5 Longevity of reactor operation
4.5 Conclusions
4.6 References


5 Sorption of zinc onto elemental selenium nanoparticles immobilized in Phanerochaete chrysosporium pellets
5.1 Introduction
5.2 Experimental
5.2.1 Biosorbent prepara

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