Efficient pollutant and nutrient removal from restaurant wastewater using Chlorella vulgaris in a bubble column photobioreactor

The rapid growth of restaurants due to people's changing lifestyles has been implicated in negative impacts on environmental sustainability made by restaurant wastewater (RWW). To overcome this challenge, this work cultivated Chlorella vulgaris with RWW in the Bubble Column Photobioreactor (BCPBR) to investigate the efficiency of removing pollutants and nutrients in this type of wastewater. Biomass productivity, chlorophyll, and lipid content were also determined. Fatty acid methyl esters (FAME) were extracted and analyzed by GC/MS. Maximum growth rate (0.18 day⁻¹) and productivity (88.7 mg/L/d) were achieved in autotrophic mode at 150 μmol/m²/sec (12:12 light-dark cycle). The highest pollutant removal efficiency from RWW was recorded at 130 μmol/m²/sec (16:8 light-dark cycle) with COD: 96.4% | BOD: 98.2% | FOG: 97.1% | TN: 99.7% | AN: 99.9% | TP: 99.9% | K: 98.3%. Chlorella vulgaris exhibited high lipid content (51.5%) and lipid productivity (2 mg/L/d) at 150 μmol/m²/sec (12:12 light-dark cycle), supporting its biofuel applications. Maximum chlorophyll content (42 μg/mL) was achieved during autotrophic growth at 100 μmol/m²/sec (24:0 light-dark cycle), highlighting its potential for high-value bioactive compounds. The FAME analysis results showed that long-chain saturated fatty acid (SFA) concentration increased when cultivated in RWW, enhancing biofuel quality. The fatty acid profile was composed of SFA (45–49%), MUFA (37–41%), and PUFA (9–12%), making it a suitable feedstock for sustainable biodiesel production. The treatment contributes to the circular economy concept by reducing the cost of nutrients and water required for microalgal cultivation, making the process economically viable and environmentally sustainable. • Chlorella vulgaris cultivated in RWW achieved about 98 % removal of pollutants and nutrients. • Specific growth rate - 0.18 d −1 , biomass productivity - 88.75 mg/L/d, and lipid content was 51.27 %. • Chlorella cultivation led to increased saturated and monounsaturated fatty acids. • Chlorella cultivation led to decreased polyunsaturated fatty acids. • The study supports the circular economy and environmental sustainability.