Treatment of different dairy wastewater with Chlorella sorokiniana: removal of pollutants and biomass characterization

Abstract BACKGROUND There is a continuous need for the development of novel processes for the sustainable management of dairy wastewater. The use of microalgae for wastewater decontamination and production of valuable biomass seems a promising alternative; however, limited information currently exists on the chemical characteristics of the biomass cultivated in effluents from the dairy industry. In this paper, experiments were carried out with the microalga Chlorella sorokiniana and different types of dairy effluents (raw dairy wastewater, anaerobically treated dairy wastewater, cheese whey). The collected biomass was characterized for the existence of proteins, starch, lipids, lutein, β‐carotene, polyphenolic compounds and amino acids. RESULTS The removal of chemical oxygen demand and NH 4 ‐N was higher than 91% and 80%, respectively, for all types of dairy effluents, while the removal of total phosphorus ranged between 20% and 84%. The protein, starch and lipid contents of the microalgal biomass ranged between 28.6% and 52.8%, 10.5% and 13.3%, and 36.8% and 40.2%, respectively. The concentration of lutein increased after treatment, reaching values up to 508 mg kg −1 , whereas amino acid concentrations were decreased due to nitrogen inefficiency. The biomass cultivated in anaerobically treated dairy wastewater was characterized by the higher total phenolic content; tyrosol concentration reached 20.2 mg kg −1 . CONCLUSION Chlorella sorokiniana can efficiently remove the major pollutants from effluents of dairy industry, while the produced biomass is a source of proteins, carbohydrates and lipids. Additionally, it contains important amounts of pigments, phenolic compounds and amino acids. Further research is required for the conditions that achieve optimal biochemical characteristics of the produced biomass. © 2022 Society of Chemical Industry (SCI).