Abstract
IntroductionThe decline in fishery resources from the wild has led to an ever increasing focus on aquaculture in recent years. With increasing aquaculture of animal species, there is an increasing need for suitable microalgae in the production of these animals. However, cultivation of microalgae in expensive pure chemical media is one of the major challenges facing large-scale cultivation of microalgae.PurposeThe present study investigated the suitability of aquaculture wastewater (AWW) supplemented with NPK (nitrogen:phosphorus:potassium) fertilizer as a cheap source of nutrient to cultivate a microalga Chlorella vulgaris (C. vulgaris).MethodsC. vulgaris with an initial cell density of 0.8 × 106 cells/mL was batch cultured in AWW supplemented with NPK at 0.1, 0.5, 1.0 g/L and BBM for 20 days under laboratory conditions using 2000 mL Erlenmeyer flasks. The proximate composition, chlorophyll, minerals, and vitamins analysis of C. vulgaris biomass were done using standard analytical methods.ResultsThe highest values in optical density (4.872 ± 0.025), dry cell weight (2.858 ± 0.015 g/L), specific growth rate (0.2097 ± 0.0038 day–1), and biomass productivity (0.1701 ± 0.0007 g/L/day) were obtained in C. vulgaris grown in AWW + 1.0 NPK medium. The total chlorophyll, protein, lipid, and carbohydrate content of the microalgae biomass were in the range of 0.05–0.862%, 44.062–57.089%, 17.064–23.260%, and 15.217–21.896%, respectively. Furthermore, microalgae grown in AWW + 1.0 NPK showed good vitamin and mineral content compared to BBM grown alga.ConclusionThese findings indicated that the AWW + 0.1 NPK, AWW + 0.5 NPK, and AWW + 1.0 NPK are potential growth media for C. vulgaris cultivation and can replace the BBM medium, which is very expensive and less accessible to users.
Highlights
The decline in fishery resources from the wild has led to an ever increasing focus on aquaculture in recent years
Microalgae grown in aquaculture wastewater (AWW) + 1.0 NPK showed good vitamin and mineral content compared to Bold’s Basal Medium (BBM) grown alga
These findings indicated that the AWW + 0.1 NPK, AWW + 0.5 NPK, and AWW + 1.0 NPK are potential growth media for C. vulgaris cultivation and can replace the BBM medium, which is very expensive and less accessible to users
Summary
The decline in fishery resources from the wild has led to an ever increasing focus on aquaculture in recent years. Apart from aquaculture, C. vulgaris has become a good candidate for biofuel production due to its rapid growth rate and high lipid content (Koller et al 2014) It is used as a healthy food, and nutrition supplements for animals and human consumption, because of the quality of proteins that they produce (Ramaraj et al 2015). Besides the high levels of protein (51–58%), carbohydrates (12– 17%), lipids (14–22%), and nucleic acids (4–5%), C. vulgaris contains appreciable amounts of valuable vitamins and minerals (Kim et al 2010; Mata et al 2010) This microalga can accumulate pigments such as chlorophyll a and b, β-carotene, and xanthophylls which are used for enhancement of the pigmentation in fish and as a colorant for foods, drugs, and cosmetics (Guedes et al 2011)
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