This study examined the growth of Spirulina algae when exposed to copper and acetaldehyde in two culturing methods: airlift loop bioreactors (ALBs) and flasks. Spirulina was able to acclimate to increasing copper concentrations in the ALBs but not flasks, possibly due to higher toxicity in flasks. Growth rates were higher in ALBs due to better gas exchange. Results from testing different concentrations of copper and acetaldehyde on Spirulina growth were analyzed to determine acclimation ranges.

1. Chemical &
Biological
Engineering.
Algal Screening: Spirulina
Student Name :
Christine Ho
cssho1@sheffield.ac.uk
Supervisor Names : 2014
Prof. Will Zimmerman
Dr. James Hanotu
Mr. Yuzhen Shi
Introduction
Microalgae are known for its industrial application in carbon abatement, biofuels and
heavy metal removal. Spirulina is known for its high protein content and being consumed
as food supplements. It is a freshwater blue-green algae.
The aim of this project is to study the growth of Spirulina when added with copper as
heavy metal and acetaldehyde as organic pollutant. The algal growth between and
culturing method were compared between ALB and flask culturing.
Spirulina was tested with different concentrations of copper and acetaldehyde and its
growth was monitored to determine whether it was able to acclimatised to the following
concentrations.
Results
Figure 3: Comparison of Spirulina growth in ALB and flask
Figure 1: The growth of Spirulina in ALBs
Figure 4: Growth of control and added acetaldehyde in flask
Figure 2: The specific growth rate of Spirulina in ALBs Figure 5: Growth of control and added copper concentrations
in flask
Picture of Apparatus
Experimental set-up Design of ALB (Ying et al. 2011)
Conclusions
• Spirulina was able to acclimatised when added with copper in ALB but not in the flask cultures due to
copper toxicity. The acetaldehyde concentration used were within the acclimatised range for Spirulina,
expect when 200 µl was added into ALB.
• The Spirulina growth rate is higher when cultured in ALB as to compare in flask due to the high mass
transfer rate of bubbles (600 µm) in and the bubbling mechanism that enables O2 stripping within algal
cells. Photoinhibition occurred when algal cells reached above saturated point.
References
1. Ying et al. 2011 xxx
2. Vonshak 1997 xxx
Description of Methods
1. The Spirulina were supplied with enriched CO2 supply for 30 minutes everyday in the airlift
loop bioreactors (ALB) as feedstock for algal growth. The light exposure is constant for
continuous photosynthesis to occur.
2. A lower concentration of copper and acetaldehyde concentration were added initially and
were gradually increased.
3. By taking samples from the Spirulina medium, the optical density was measured using a
spectrophotometer to monitor growth rate. Medium was well mixed before sampling.
4. The specific growth rate was calculated using the equation,
0"
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0" 2" 4" 6" 8" 10" 12"
Op#cal'density'(Abs)'at'595'nm'
Time'(days)'
Flask"
Control"1"
Control"2"
0"
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Op#cal'density'(Abs)'at'595'nm'
Time'(Days)'
Control"
5"mg/L"
2"mg/L"
2"mg/L"
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