Trend Analysis of Chlorella sp. Immobilization Versus Capacitance Measurements

This study investigated the immobilization of Chlorella sp. in a nylon matrix to analyze its retention behavior and monitor biomass adhesion. Image capture and processing techniques were combined with capacitance measurements over time, using a Python-based data analysis code. The experiment was carried out in a 2 L photobioreactor under controlled conditions (24 °C, continuous aeration at 9.31 L/min, and light intensity of 71 μmol m⁻² s⁻¹). The methodology allowed for quantification of biomass distribution on the matrix surface, as well as changes in the capacitance and optical density of the microalgal culture. The results indicated maximum growth around day 15, showing a strong correlation between optical density (absorbance at 686 nm), image analysis of the matrix, and capacitance records. At this point, absorbance reached 3.913, coverage of 24.56% on the nylon matrix, and capacitance of 375.9 μF. Capacitance measurement proved to be a useful indirect tool to estimate biomass adhesion, while image analysis provided spatial distribution. The observed upward trend in process variables highlights the potential of electrical parameters, such as capacitance, for monitoring microalgal immobilization in suspended systems without altering biofilm structure. This approach supports future applications in scaling processes for bioactive compound production or environmental treatment systems.