Fed-Batch Cultivation of Microalgae Using Effluent from the Anaerobic Digestion of Cattle Waste and Cultivation Scale-Up in 100 L Raceways

The search for sustainable development has led several production processes to adopt biorefineries. We evaluated the cultivation of Spirulina platensis and Scenedesmus obliquus in consortium (50/50%), with the addition of effluent of the anaerobic digestion (AD) of cattle waste, in fed-batch mode, to obtain biomass in 10 L raceways. Subsequently, cultivation was carried out at pilot scale in a 100 L raceway. Zarrouk medium (20%) was used, with the addition of 10% (v/v) of effluent in the fed-batch process. The biomasses were characterized to evaluate their application. In 10 L raceways, higher biomass concentrations were obtained in the cultivation of Spirulina with the addition of effluent, or with the microalgae consortia without the addition of effluent (around 1 g/L). The addition of the effluent reduced the carbohydrate content and increased the protein content during the cultivation. Scale-up (100 L raceways) with Spirulina showed similar results to those obtained in the 10 L raceways, with removals of 48%, 88% and 11% for COD, nitrogen and total phosphorus, respectively. The cultivation of microalgae in consortium and Spirulina can be used in the post-treatment of effluent of AD, allowing the production of biomass for different applications.