Valorization of nutrients from fruit residues for the growth and lipid production of Chlorella sp.: A vision of the circular economy in Peru

The supplementation of nutrients from agro-industrial residues is a sustainable strategy to improve cost-benefit microalgae production; nonetheless, developing the appropriate supplementation of residue for each microalgal strain is necessary. In this study, a supply strategy of fruit residue (such as mango, banana, apple, tomato, plum, melon, orange, tangerine, grape, strawberry, cherimoya, pear, pineapple, peach and cucumber) was developed to enhance Chlorella sp. CM18 growth and lipid production in a 5-L photo-bioreactor and simultaneously maximize the efficiencies of nutrient removal processes (chemical oxygen demand [COD], NO3-, PO43-, and SO42-) by this alga. This study demonstrates that the microalga attained the highest removal efficiencies when this residue was diluted at 10% (v/v) with MN medium, attaining 89.07 +/- 0.31% (COD), 91.55 +/- 0.94% (NO3-), 93.82 +/- 0.61% (PO43-), and 76.01 +/- 0.68% (SO42-). Under this condition, the highest growth rate of Chlorella sp. was 1.35 +/- 0.004 day(-1) with a lipid production of 15.60 +/- 3.17 mg L-1, demonstrating the feasibility of the culture process with Chlorella sp. CM18 to obtain an effluent possessing characteristics that were below the regulatory limits for the concerned parameters and emphasizing the concept of the sustainable circular economy. Overall, this study establishes a method to valorize the nutrients of fruit residues with the aim of producing biomass and lipids through the cultivation of the microalga Chlorella sp. CM18.