Development of an Arduino-based photobioreactor to investigate algae growth rate and CO₂ removal efficiency

Abstract

<span style="font-size: 11.0pt; line-height: 107%; font-family: 'Calibri','sans-serif'; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA; mso-bidi-font-style: italic;">Global carbon dioxide (CO₂) emissions are rising, and microalgae have been a primary focus for alleviating the negative impacts of increasing CO₂ levels. CO₂ sequestration is influenced by pH level, temperature, light, nutrient levels, and aeration. This study adapted a 2-chamber system with a 6-Liter vertical-column photobioreactor. It was constructed to remove CO₂ from the air using microalgae. Arduino sensors, namely temperature, pH, and CO₂ gas, were incorporated to monitor microalgal growth. Two 7-day trials, with an initial algae mass of 15 g, were implemented to investigate the growth and CO₂ removal rates. The results showed that trial 1 yielded 21.5 g with a growth rate of 0.56 gxin-2 x day-1, and trial 2, a final sample of 19.7 g with a growth rate of 0.51 gxin-2 x day-1. The CO₂ removal rate for trial 1 increased from 10.17% to 22.04%. However, the CO₂ removal rate for trial 2 decreased from 15.66% to 3.55%. In terms of relative percent error, the Arduino sensors' accuracy was also determined to be low, ranging from 0.85 to 1.94. With accurate readings, the findings show that the CO₂ removal efficiency rate and algae growth rate are directly proportional to each other.</span>