Cultivation of Chlorella vulgaris on anaerobically digested swine manure with daily recycling of the post-harvest culture broth

- A cultivation system with daily recycling of post-harvest culture broth was set up.
- The system was firstly used for microalgae cultivation on pretreated swine manure.
- Chlorella vulgaris grow very well in this system with moderate recycling ratios.
- Chemical compositions in this alga varied with the change of recycling ratios.
- The algal biomass grown in this system could be used as a biodiesel feedstock.

In this work, a cultivation system with daily recycling of the post-harvest culture broth was set up and performed in order to reuse the water and nutrients in pretreated anaerobically digested swine manure, which was used as media to cultivate Chlorella vulgaris (UTEX 2714) at different recycling ratios. Results showed that the alga grew well in the system with an accumulative algal biomass and productivity of 1.68-3.47 g/L and 234.1-532.2 mg/L/d, respectively, at the end of the cultivation. Additionally, chemical compositions in this alga varied with the change of recycling ratios, and the highest productivities of carbohydrate, protein and lipids (76.4, 257.2 and 183.7 mg/L/d, respectively) were obtained in the system with a recycling ratio of 1/4 or 1/6. Fatty acid profiles indicated that this alga could be used as a good-quality biodiesel feedstock with a biodiesel productivity of 9.65-40.1 mg/L/d.