Biosorption of zinc and copper from aqueous solutions by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus.
OBJECTIVE
The objective of this study was to determine the removal of zinc and copper by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus and to investigate changes of algal ultrastructure and photosynthetic pigment.


METHODS
Algal cells were exposed for 8 days to different initial zinc or copper concentrations. Heavy metal concentrations were detected by an atomic absorption spectrophotometer. Algal growth, ultrastructure, and photosynthetic pigment were analyzed by a microplate reader, transmission electron microscope, and spectrophotometer, respectively.


RESULTS
Low zinc and copper concentrations induced increase in algal growth, whereas application of high zinc and copper concentrations suppressed the growth of both algae. High metal concentrations also decreased the photosynthetic pigments and destroyed algal cell ultrastructure. The zinc removal efficiency by both algae increased rapidly during the first day and thereafter remained nearly constant throughout the experiment. The copper removal efficiency by both algae increased slowly during the whole experimental periods. In all cultures, the quantity of both metals removed intracellularly was much lower than the adsorbed quantity on the cell surface.


CONCLUSIONS
Both strains of the microalgae had proven effective in removing zinc and copper from aqueous solutions, with the highest removal efficiency being near 100%. In addition, C. pyrenoidosa appeared to be more efficient than S. obliquus for removing copper ions. On the contrary, S. obliquus appeared to be more efficient than C. pyrenoidosa for removing zinc ions.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, People's Republic of China.
Guang-Jie
GJ
Zhou
Fu-Qiang
FQ
Peng
Li-Juan
LJ
Zhang
Guang-Guo
GG
Ying
D001673:Biodegradation, Environmental; D002708:Chlorella / Q000378:metabolism* / Q000648:ultrastructure; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D044444:Scenedesmus / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
D008670:Metals; D014874:Water Pollutants, Chemical; D014867:Water; D003300:Copper; D015032:Zinc