Sustainable treatment of sugarcane vinasse using Chlorella sp. in scalable airlift flat-panel photobioreactors: nutrient removal and biomass valorization
摘要
The global production of sugarcane ethanol generates vast amounts of vinasse, a liquid waste by-product requiring treatment to mitigate environmental impacts. Using vinasse as a feedstock for microalgae cultivation offers a sustainable alternative. This study evaluates the performance of the native strain Chlorella sp. MC18 in internal-loop airlift flat-panel photobioreactors (PBR) for treating industrial raw sugarcane vinasse (SCV) while producing biomass. Cultures were grown in diluted, centrifugation-pretreated SCV (5–25% v/v) as the sole nutrient source, with CO2 supplied by aeration. The best results were obtained with 10% SCV. Nutrient removal efficiencies reached up to 99% for nitrates and 90% for phosphates, with reduction in chemical oxygen demand (COD) exceeding 75% at 5–10% SCV. The highest specific growth rate (0.711 day–1) and biomass productivity (116 mg L–1 day–1) occurred at 10% SCV, maintaining stable pH control (8.2–8.5). The PBR design enabled scalable, reproducible growth kinetics while minimising biofouling. Biomass from 10% SCV holds significant potential for energy recovery (20.24 kJ g–1) and production of high-value product pools (lipids, carbohydrates, proteins, and carotenoids). These results demonstrate the feasibility of scaling up the PBR design for integrated vinasse treatment with Chlorella and biomass valorisation, reinforcing the concept of an agro-industrial sector biorefinery.