Sustainable harvesting of Chlorella vulgaris using bioflocculants from Camellia oleifera cake-based medium

Abstract

Camellia oleifera cake (COC) is a by-product of the Camellia oleifera oil collection process, which is rich in nutrients such as polysaccharide and protein. This study represents the first use of COC as a microbial medium substitute and its potential for producing bioflocculants. The COC was used to culture Paenibacillus polymyxa GA1, and its colony counts was more than one order of magnitude higher than that in the traditional fermentation medium, increasing from $0.6\times {10}^7$ CFU/mL to $1.8\times {10}^8$ CFU/mL. The bioflocculant produced by GA1 had a flocculation efficiency of 98.9 ± 0.4 % on kaolin suspension, which remained unchanged when the volume of acetone used in extracting the bioflocculant was reduced by 75 %. Chlorella vulgaris was harvested with the bioflocculant and the harvesting efficiency reached 95.6 ± 0.3 %, even without improving the pH. The above results demonstrate the potential of COC as an alternative medium.