Cultivation of Chlorella vulgaris in aquaculture wastewater as alternative nutrient source and better treatment process

Abstract

Together with the fastest growing of aquaculture production, aquaculture industry also produces a large amount of wastewater that results in not only eutrophication of waterbody but also increases the aquaculture cost and threatening global sustainability. To overcome those barriers in the aquaculture industry, application of microalgae for wastewater remediation, biomass production to produce value added products, and water quality control have been devoted as microalgae assimilate nutrients in a eutrophic water body and a good way for wastewater remediation. The objective of this study was to determine the growth and nutritional profile of Chlorella vulgaris culture in different percentage of aquaculture wastewater (ww) in combination with Conway media. For the experiment, C. vulgaris was cultivated in different wastewater concentration such as 25% ww + 75% Conway media (T2); 50% ww + 50% Conway media (T3); 75% ww + 25% Conway media (T4); 100% ww (T5) and 100% Conway media, considered as control (T1). The results of this study showed that the growth of C. vulgaris, in terms of cell density and optical density were maximum at day 5 in T3 (50% wastewater) and was significantly (p > 0.05) higher (4.33x106 cellsml-1 ) (0.400 Abs) compared to the other treatments. Highest amount of protein content was found in Conway media (T1) (42.69 % dry weight) whereas lipid content was highest in 100 % ww (17 % dry weight) and then in 75 % ww treatment (16 % dry weight) and carbohydrate content was maximum in T3 treatment (24 % dry weight) which were significantly higher (p > 0.05) then the other treatments. The study indicates that media enriched with aquaculture wastewater can enhance the cell growth and nutrient values of C. vulgaris which is a cost effective and environment friendly approach to minimize aquaculture waste loading in water body.