Date

5-2009

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Rex B. Demafelis

Co-adviser

June Owen O. Nacorda

Committee Member

Amelia E. Parao, Ma. Cristina V. Mahilum

Abstract

The green microalga Ankistrodesmus falcatus was cultured with BG- 11 medium in polyethylene bottles under varying cultivation parameters. This study was done to determine the effect of (a) reactor diameter, (b) aeration rate and (c) light intensity to the biomass cultivation of the microalgae. The culture was allowed to grow in 2.75, 3.75, and 6.75 in. photobioreactors and aerated with 0.60 and 0.93 vvm. The culture was operated under 1.59, 1.86, and 2.04 klux of light and sampling was done every 12 hours. Calibration of the optical density of the culture at 625 nm and its biomass concentration was done to determine the corresponding cell density per unit time. A linear relationship was generated giving a high correlation coefficient of 0.991 and an equation of y = 2.961x where biomass concentration in g/L is given by y and x is the optical density at 625 nm. Growth curves were generated from the computed biomass concentrations of the cultures. It was observed that on the average, the culture undergone lag phase from the inoculation period until day 3. Exponential phase started from day 4 to day 8 and the curve achieved steady state at day 9. Varied diameter of the photobioreactor showed insignificant differences in the biomass concentrations. However, increasing light intensity showed that the yield for biomass also increases. Varied air flowrate also varied the cell density significantly. Other parameters were also used to determine relationship of the cultivation parameters to the cultivation of Ankistrodesmus falcatus. Specific growth rate and doubling time were used as a gauge to determine the effect on the culture. Highest doubling time occurred in the smallest reactor with the highest aeration and light intensity. Its doubling time is at 1.369 day. This recorded highest because of the evaporation that undergone on the container. Water leaving the container made the culture denser giving a higher optical density reading. Three-way ANOVA was used to determine if the treatments done were significant in the study. Statistical analysis showed that the diameter of the reactor is insignificant on the biomass production of Ankistrodesmus falcatus. Moreover, light intensity and aeration rate proved to be significant treatments for the biomass cultivation. Lastly, after optimizing the data collected. Statistics showed that biomass cultivation can be optimized by using the 6.75 in. reactor diameter under 0.93 vvm aeration rate and 2.04 klux of light.

Language

English

LC Subject

Biomass chemicals, Algae--Philippines--Identification.

Call Number

LG 993 2009 E62 D42

Document Type

Thesis

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