In order to utilize the excess sludge and reduce the cost of algal cultivation, Chlorella vulgaris was cultivated in increasing proportions of sludge extracts for simultaneous nutrients removal and algal utilization. Results showed that C. vulgaris cultivated in the 100% sludge extract gained the highest total biomass (33.98 ± 0.30 × 106 cells/mL) and showed good results in TOC (absolute value 175 mg/L) and nutrients (TN: 77.1%; TP: 95.0%) removals. According to the Excitation-emission matrix spectra (EEMs) analysis, the 8th day was suggested as the optimal time for biomass harvesting. Although the lipid contents showed a negative correlation with the proportion of sludge extract, the FAME analysis showed that the saturated fatty acids (SFA) contents decreased and the unsaturated fatty acids (UFA) content increased as the concentration of sludge extract increased. The 100% sludge extract could be a desirable alternative medium for the algae cultivation.
Bibliographical noteFunding Information:
This work was supported by the Shanghai Pujiang Program in China [Grant No. 13PJD009 ]; the Natural Science Foundation of China [Grant No. 51378207 ] and the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2014ZX07202-011-002 ). We also would like to express our great appreciation to University of Minnesota Center for Biorefining and China Scholarship Council ( CSC ).
- Algal utilization
- Chlorella vulgaris
- Low-cost cultivation
- Nutrient removal
- Sludge extracts