Batch cultivation of Chlorella vulgaris and simultaneous treatment of restaurant wastewater

• Conditions were optimized for the cultivation of Chlorella vulgaris with RWW. • Autotrophic mode at 25 °C, aeration of 3 L/min with 3 % CO 2 (v/v), and light intensity of 80–150 μmol/m 2 / sec . • Maximum specific growth rate and biomass productivity were 0.14 day -1 and 42 mg/l/d, respectively. • The maximum pollutant removal efficiency was 98 % for COD , 98.5 % for BOD, and 96.8 % for FOG . • This contributes to an overall environmentally sustainable and economically viable treatment of RWW. The rapid growth of restaurants due to the changing lifestyle has imposed unnecessary impacts on environmental sustainability following an increased generation of restaurant wastewater (RWW). RWW contains alarming concentrations of fats, oils, and greases (FOG), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and nutrients, including nitrogen and phosphorus. Microalgae are known to be able to treat wastewater and provide simultaneous production of biomass and other valuable metabolites (e.g., lipids, proteins, and carotenoids). Numerous studies have been reported on treating various types of wastewater using microalgae. However, studies still need to be reported on treating RWW using microalgae collected from grease traps. This research aims to determine the potential of the freshwater microalgae Chlorella vulgaris ( Chlorella vulgaris ) in treating RWW-containing pollutants (COD, BOD, FOG) and nutrients (TN, TP, AN, K) via optimal autotrophic cultivation conditions (i.e., pH, temperature, light intensity, and aeration). The conditions for the batch scale cultivation of Chlorella vulgaris opted as an autotrophic mode with a temperature of 25 °C, aeration of 3 litres per minute supplemented with 3 % CO 2 (v/v), and an irradiance range of 80–150 μmol/m 2 / sec . Maximum specific growth rate and biomass productivity achieved were 0.14 day -1 and 42 mg/l/d, respectively. The maximum pollutant removal efficiency was 98 % for COD, 98.5 % for BOD, 96.8 % for FOG. While the nutrient uptake achieved was 99.7 % for total nitrogen (TN), 99.9 % for ammoniacal nitrogen (AN), 99.9 % for total phosphorus (TP), and 97.8 % for potassium (K). Therefore, this study shall provide an alternative potential solution by proposing treatment using microalgae and cultivating it with RWW. No study has been reported to date using freshwater microalgae Chlorella vulgaris to evaluate its potential in removing pollutants, nutrients, and FOG in RWW collected from GGI. The removal efficiencies indicated that the RWW acclimatised well with Chlorella vulgaris, thus providing an environmentally sustainable and economically viable treatment method.