CHLORELLA VULGARIS CULTIVATED IN HYDROPONIC WASTEWATER

Abstract

Alternative culture media, such as industrial and agricultural wastewaters, have been evaluated for cultivating microalgae. This use makes residue recycling possible by bioconverting wastewater in a rich nutritive biomass that can be used as feeding supplement in aquaculture and several other areas. This experiment aimed to verify the hydroponic wastewater as a potential alternative culture media for Chlorella vulgaris growth, and to evaluate the content and composition of proteic biomass obtained and the bioremoval of nitrogen and phosphorus by microalgae cultivated in the residual solutions. A volume of 180 ml with a cell density of 2.5 × 10 6 cell/ml of Chlorella vulgaris in Bold's Basal Medium (BBM) was inoculated in inverted conic photobioreactors, containing 3.7 L of four different cultivation media: BBM (reference cultivation), hydroponic wastewater (HW), diluted hydroponic wastewater 1:1 (50% residue and 50% deionized water) labeled as HW50 and diluted hydroponic wastewater 1:3 (25% residue ad 75% deionized water) labeled as HW25. Results of the present work suggest that Chlorella vulgaris cultivated in hydroponic wastewater solution has potential to obtain single cell protein of good quality, due to its composition and balanced amino acid distribution, as well as high protein content that presented values of 52.40, 50.51, 43.96 and 39.98 g/100 g for BBM, HW, HW50 and HW25, respectively. Good results were also obtained in bioremoval of N and P from the hydroponic wastewater solution, reaching a rate of removal of 204.07 mg/L in HW, 109.41 mg/L in HW50 and 78.65 mg/L in HW25 of total inorganic nitrogen. The removal of the total phosphorus average was 18.18 mg/L in HW, 9.01 mg/L in HW50 and 4.05 mg/L in HW25. Additionally, the results showed that Chlorella vulgaris efficiently removes nitrogen and phosphorus from hydroponic wastewater, making recycling this wastewater possible.