Piggery wastewater is a potent nutr

Piggery wastewater is a potent nutrient source for microalgal lipid production. Wastewater has been
usually sterilized when used for microalgal cultivation. This is uneconomical in large-scale applications.
Therefore, lipid productivity of Chlorella vulgaris CY5 using sterilized and non-sterilized diluted
anaerobically pretreated piggery wastewater was studied in batch reactors. The maximum average lipid
productivity was obtained after 12 days of incubation and it was higher with the sterilized wastewater
than with the non-sterilized one (117 g/L/d vs. 91.3 g/L/d), due to the higher biomass concentration.
Because of the unexpected increase of dissolved organic carbon (DOC) in the cultures, second experiment
was conducted to characterize the composition of produced DOC in non-sterilized wastewater.
Carbohydrate content increased in the liquid phase but decreased in the biomass after nitrogen had been
exhausted. After 12 days of incubation, soluble chemical oxygen demand (CODs) was 414 ± 56 mg/L,
biomass production was 2.8 ± 0.15 g/L, and lipid content was 30.3 ± 1.2 wt%. Average lipid productivity
from day zero to day 12 was 70.5 ± 1.1 g/L/d. C. vulgaris removed nutrients from the non-sterilized
wastewater and produced oleaginous biomass, although the lipid productivity was higher with sterilized
wastewater.
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