Nutrient removal from swine wastewater using a thermotolerant strain of Chlorella sp. grown under outdoor conditions

• Published in: Journal of chemical technology and biotechnology (1986) Vol. 95; no. 4; pp. 1243 - 1249
• Main Authors: Gracida‐Valdepeña, Miriam L, Navarro‐Aguirre, Fernanda, Herrera‐Acosta, Karla, Ulloa‐Mercado, Gabriela, Meza‐Escalante, Edna, Plascencia‐Jatomea, Rigoberto, González‐Meza, Georgia, Serrano‐Palacios, Denisse
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-04-2020; Wiley Subscription Services, Inc
• Subjects: Agricultural wastes; Algae; Ammonium; Anaerobic digestion; Anaerobic treatment; Animal wastes; Batch culture; Biochemical composition; Biomass; Carbohydrates; Cell culture; Chlorella; Chlorella sp; Cultivation; Culture media; Effluent treatment; Farms; Fatty acids; Inorganic compounds; Livestock; microalgae; Nitrates; Nutrient removal; Nutrients; outdoor culture; Phosphates; Reactors; Swine; Wastewater; Wastewater treatment; Weight
• ISSN: 0268-2575; 1097-4660
• DOI: 10.1002/jctb.6313

BACKGROUND
Recently, wastewater effluents from animal farms have been treated using microalgae for the removal of organic and inorganic compounds. Swine wastewater (SW) and wastewater treated by anaerobic digestion (TW) were used as culture media for a wild strain of microalga, Chlorella sp. (Chlorophyta), previously isolated for our research group. This was cultivated under laboratory conditions in a batch culture, and then inoculated in a cascade thin‐layer reactor under outdoor conditions. The kinetic behavior, nutrient removal (COD, NH4+‐N, NO3−‐N and PO34−‐P) efficiency and biochemical composition of the microalga biomass were evaluated.
RESULTS
SW supported the highest growth (339 × 106 cells mL−1 and μ = 0.42 d−1) and the maximal removal of COD (91%), nitrates (87%), ammonium (45%) and phosphate (70%) in a batch culture. Whereas, in continuous cultivation, an adequate operation was achieved at temperatures up to 42 °C, with removals greater than 80% of COD, 70% of nitrates, 90% of ammonium and 60% of phosphates. Also, the produced biomass achieved the highest content of proteins (386 mg g−1 dry weight), carbohydrates (291.49 mg g−1 dry weight) and saturated and monounsaturated fatty acids, reaching 74.76% of total fatty acids.
CONCLUSIONS
The SW medium showed greater growth of Chlorella than TW using the outdoor thin‐layer cascade reactor. This is an opportunity to use wastewater as nutrient to obtain biomass enriched in compounds with various possibilities for application. © 2019 Society of Chemical Industry