Growth rate measurements of Chlorella vulgaris in a photobioreactor by Neubauer-improved counting chamber and densitometer

Abstract

The depletion of fossil fuel sources and increased CO2 emissions has triggered intensive research to discover renewable energy sources. With the Low Carbon Scenario, the role of renewable energy will increase to 58% in 2050. As a renewable energy source, bioethanol is environmentally friendly which can substitute gasoline. Currently, the third-generation bioethanol production technology from microalgae is still being developed. Chlorella vulgaris is one of the microalgae types with high carbohydrate content and is easy and fast to cultivate. This study aims to evaluate the growth rate of C. vulgaris cultivated in a bubble column photobioreactor using artificial seawater aerated with pure CO2. Two LED tube lights were used with 12 h light and 12 dark cycles for 12 – 13 days. Microalgae culture population was measured every 24 h using a Neubauer-improved counting chamber and a microscope equipped with a digital camera. The results showed that the maximum specific growth rate, μmax, was found to be 0.344 d-1, and the highest concentration of 1.88 ×107 cells mL-1 occurred on day 7. Moreover, the microalgae populations were also measured using a densitometer. Since the calculation of the cell population used secondary data from the literature, the results were less accurate than those of the counting chamber.