An Image Processing Technique to Recover the Biomass Concentration in Algae Biofilm Photobioreactors

This paper reports a simple technique based on multispectral image processing that can be used to recover the biomass concentration of an algal biofilm photobioreactor. Monitoring the biomass concentration of a culture is critical in achieving successful algae cultivation for biofuel or food supplement production. In particular, non-invasive and rapid detection techniques that can provide estimates of the biomass concentration can significantly aid in providing delay-free process control feedback in large scale cultivation platforms. In this technique, the digital images of the biofilms of the cyanobacteria Anabaena variabilis were obtained under consistent lighting conditions and analyzed as a function of their biomass content. The image analysis was carried out using a custom Matlab code where the red, green and blue content of the images were correlated with the biomass concentration. The obtained correlation was consistent across biofilms generated from different stock cultures of varying culture age. Challenges facing application of the image processing technique for scaled up outdoor photobioreactors under various lighting conditions and color backgrounds were discussed.