Surface attached cultivation and filtration of microalgal biofilm in a ceramic substrate photobioreactaor

Abstract

In this research, a capillary ceramic membrane was used as the substrate for surface attached cultivation of microalgae. A photobioreactor was constructed and tested for cultivation of Chlorella vulgaris adhered to this substrate. Optimum biomass productivity of 4.65 ± 0.42 g/m2/d was obtained during 8 days of cultivation by using the light intensity of 17,000 lx and BG-11 medium flow rate of 14 mL/d. The moisture content of the produced biofilm was around 80% which is comparable with the moisture content obtained from centrifugation of suspended algal cultures. It was shown that further dewatering is possible by applying vacuum to the ceramic membrane. According to these results, moisture content was reduced to 59% under the vacuum of 0.6 bar. It was also illustrated that after scrapping the biofilm, the remaining cells on the ceramic membrane can be used as an inoculum for the re-culture of the algal biofilm. According to the current results, the biomass productivity of the re-cultured biofilm was very close to the initially cultured biofilm, which indicates the applicability of the proposed system for long term cultivation of algal biofilm. Comparing the results obtained in this study with similar surface attached cultivation systems demonstrated the promissing performance of the designed photobioreactor with a lower culture medium consumption rate.