Microalgae cultivation for municipal and piggery wastewater treatment in Brazil

Microalgae are a source of high-valuable products covering a wide range of applications. However, costs incurred by cultivating them make it an expensive process. The combination of wastewater treatment and microalgae cultivation is a viable option to reduce expenses related to cultivation. However, municipal wastewater from the centralized Brazilian sanitation system is highly diluted, and it is technically and economically impractical to use it for microalgae cultivation. As an alternative, diluted effluent can be mixed with a different kind of wastewater, aiming to increase the nutrient concentration (carbon, nitrogen and phosphorus) for microalgae cultivation. In this study, microalgae cultivation and wastewater mixture (municipal and piggery wastewater) treatment were monitored for four weeks. The pilot treatment system consisted of UASB as pretreatment and Chlorella sorokiniana cultivation in three flat panel photobioreactors. High UASB efficiency was obtained in organic matter removal (> 90%), even with a large variability of initial mixture characteristics. C. sorokiniana production reached about 1 g L-1, with an average removal of dissolved inorganic carbon, orthophosphate and ammonia around 46 to 56%, 40 to 60% and 100%, respectively. Possible solutions to improve the microalgae growth and the system treatment are discussed.