Bioremediation of Heavy Metals by using the Microalga Desmodesmus Subspicatus
Hajdu-Rahkama, Réka (2014)
Hajdu-Rahkama, Réka
Tampereen ammattikorkeakoulu
2014
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2014101914822
https://urn.fi/URN:NBN:fi:amk-2014101914822
Tiivistelmä
All around the world natural water bodies are contaminated with heavy metals from previous and recent mining activities. These contaminants not just can reach our drinking water supplies but endanger aquatic ecosystems and also other organisms. The recent technologies used for the removal of heavy metals are expensive and also causing harm to the nature. To avoid the negative impacts caused through the removal of contaminants, environmentally friendly methods, bioremediation should be applied. Using microbial processes for the removal of contaminants is still not widely used and enough studied. The objective of this work was to investigate the bioremediation properties and behavior in different environmental conditions of the microalga Desmodesmus subspicatus.
The heavy metal (300µg/l Pb, 30µg/l As, Cd, Hg) solution chosen was similar with the values found in the River Oker, which originate from previous mining site of the Harz Mountain in Lower Saxony, Germany. The heavy metal uptake by Desmodesmus subspicatus biomass was not efficient at pH 5 since the final uptakes were (4.5±0.67) µg/l As, (21.1±2.89) µg/l Pb, (7.33±1.96) µg/l Cd and (6.25±1.28) µg/l Hg (15% As, 7% Pb, 24% Cd, 21% Hg). However, its initial biosorption showed good results with Pb (<79%) and Hg (<63%).
In the conditions applied the Desmodesmus subspicatus can be used only for initial biosorption of Pb and Hg. Making changes like adjustment of different pH levels; applying multi culture mix, adding immobilization material, increasing the population and pretreating the cells could increase the efficiency. Also the immediate uptake of Hg and Pb by biosorption is an interesting feature as it could be used with biomass filtering not with growing cultures and lead to immediate results. The bioremediation property of Desmodesmus subspicatus in an environment with one or several of the previously mentioned methods applied should be further investigated.
The heavy metal (300µg/l Pb, 30µg/l As, Cd, Hg) solution chosen was similar with the values found in the River Oker, which originate from previous mining site of the Harz Mountain in Lower Saxony, Germany. The heavy metal uptake by Desmodesmus subspicatus biomass was not efficient at pH 5 since the final uptakes were (4.5±0.67) µg/l As, (21.1±2.89) µg/l Pb, (7.33±1.96) µg/l Cd and (6.25±1.28) µg/l Hg (15% As, 7% Pb, 24% Cd, 21% Hg). However, its initial biosorption showed good results with Pb (<79%) and Hg (<63%).
In the conditions applied the Desmodesmus subspicatus can be used only for initial biosorption of Pb and Hg. Making changes like adjustment of different pH levels; applying multi culture mix, adding immobilization material, increasing the population and pretreating the cells could increase the efficiency. Also the immediate uptake of Hg and Pb by biosorption is an interesting feature as it could be used with biomass filtering not with growing cultures and lead to immediate results. The bioremediation property of Desmodesmus subspicatus in an environment with one or several of the previously mentioned methods applied should be further investigated.