Transcript Slide 1
Removal of Cadmium from Controlled Water Systems using Spirulina platensis
Carmen Cowo and Jim Bidlack
Department of Biology, University of Central Oklahoma, Edmond, OK 73034
RESULTS AND DISCUSSION
The amount of microalgae biomass will affect the amount of cadmium that can be
adsorbed from the water systems. A constant accumulation during exposure time is
expected. Results should conclude that a low biomass of Spirulina platenis will remove
more cadmium than a high biomass. However, that is also dependent on the
concentration of cadmium that S. platensis is exposed to. The maximum sorption
capacity will be calculated (Rangsayatorn et al. 2002). To determine the effective uptake
for each exposed sample, biological concentration factors (BCF) will be calculated. This
is determined by dividing the concentration of metal in the microalgae tissue by the
initial concentration of the metal added to the water tanks (Lu. et al. 2004). To ensure
the variability of data retrieved, two- way analysis of variance tests (ANOVA) will be
used. Significant differences will be determined as well.
Figure 2: Atomic absorption spectrophotometer used in cadmium concentration analysis in Spirulina and “waste water.”
Figure 1: Photo of Spirulina platensis provided by UTEX Culture Collection of Algae.
INTRODUCTION
Water pollution is clearly detrimental to the stability of ecosystems. There are
numerous contributors to pollution (i.e. urbanization and industrialization).
Human populations are rising and pollution control is an area of study that must
be persistently addressed and refined. Waters can become contaminated by
organic and inorganic substances in a variety of ways. The heavy metal
cadmium is carcinogenic to human cells as shown in Figure 3 (Waisberg et al.
2003). One way cadmium can be introduced to environments is by the improper
disposal of batteries.
MATERIALS AND METHODS
LITERATURE CITED
After receiving shipments of Spirulina platensis from UTEX Culture Collection of Algae, culturing and
acclimation to the simulated water system will need to take place. S. platensis will be easy to maintain within
these systems in that it is an easily adaptable species. An algae- growth medium will be added along with to
deionized water to fill the tanks to 6-L. Water levels will be maintained (pH at 7.5) every day in that water loss
will likely occur due to evaporation, sampling, and transpiration. The environmental chamber, which will house
the tanks, will remain at a constant optimal temperature and humidity. Water oxygenation will be maintained
by two air pumps which will supply all five tanks with oxygen using split- airline tubing.
Ahmad, A., Grufran, R., and Z. Wahid. 2010. Cd, As, Cu, and Zn Transfer through Dry
to Rehydrated Biomass of Spirulina platensis from Wastewater. Polish Journal of
Environmental Studies. 19; 887- 893.
Preliminary experiments will determine the optimal biomass at which Spirulina platensis will be able to remove
cadmium from the experimental tanks without becoming nonviable. Once an optimal biomass has been
determined, that amount will be cultured within each tank. Before cadmium addition, all five tanks will hold
the same amount of algal biomass (will be weighed). Various concentrations of cadmium will be added to four of
the tanks. The fifth tank will have no addition of cadmium and serve as a control. The concentrations of
cadmium added will include the following: 1.0 mg/ mL, 1.5 mg/ mL, 2.0 mg/ mL and 2.5 mg/ mL. The cadmium
used will be provided by a mixture of CdCl2 and H20. S. platensis will be exposed for 20 days with four
replications.
Upon completion of the 20 day period, the biomass will be removed from all tanks by a filtration process and the
use of Millipore membrane filters. Biomass will be weighed once again to determine final fresh weight. Water
samples will be taken from each tank for metal content analysis. Concentration of cadmium present in the
water after exposure period and concentration of cadmium accumulated within the Spirulina platensis biomass
will be determined using atomic absorption spectrophotometry (Figure 2).
Phytoremediation describes the use of living plants to bio absorb organic and
inorganic pollutants from contaminated environmental sites, such as soil or
water, and remain viable (Ahmad et al. 2010). Phytoremediation is a more
environmentally friendly method for pollution clean- up. Another benefit it
provides is that it is normally a low- cost process.
S. platensis is a microalgae, and more specifically, a cyanobacteria (blue- green
algae). The surface of cells in cyanobacteriums are composed of various
polysaccharides, proteins, and lipids. These molecules contain the functional
groups necessary for heavy metals to bind with. S. platensis thrives worldwide.
It is easy to culture and is known to withstand harsh environmental conditions. It
has also been shown that even dried biomass of S. platensis can be rehydrated
and still remain able to remove cadmium from simulated water systems and
actual waste water (Ahmad et al. 2010). S. platensis is a worthy candidate for
phytoremediation involving heavy metal contaminants (Rangsayatorn et al.
2002). Because it has been shown in literature that Spirulina platensis can remove
cadmium from water systems and remain viable, it is my organism of choice for
this project. Cultures of S. platensis will be obtained from the University of Texas
Culture Collection of Algae (Figure 1). Cultures will be grown and inspected
before experimentation begins.
The results of these experiments will provide further knowledge on the uptake capacity
of Spirulina platensis for cadmium and its optimal tolerance to the metal. These efficient
methods can be introduced to expand development in phytoremediation strategies
involving this species for projects of a larger scale.
Figure 3: The molecular effects in cells in conjunction with cadmium exposure (Waisberg et al. 2003).
Lu, X. et al. 2004. Removal of Cadmium and Zinc by Water Hyacinth Eichhornia
crassipes. Science Asia. 30: 93- 103.
Rangsayatorn, N. et al. 2002. Phytoremediation potential of Spirulina (Arthospira)
platensis: biosorption and toxicity studies of cadmium. Environmental Pollution.
119: 45- 53.
Solosio, C. et al. 2008. Bioresource Technology. 99: 5933-5937.
Waisbrg, M. et al. 2003. Molecular and cellular mechanisms of cadmium carcinogenesis.
Toxicology. 192: 95-117.
ACKNOWLEDGEMENTS
Funding for this project was provided by Office of Research & Grants at the University
of Central Oklahoma (UCO). Many thanks to Jim Bidlack, Jocelyn Bidlack and Dr.
Bidlack’s research group. The biology and chemistry department at UCO are also
appreciated in providing materials and equipment during experimental processes.