Culture operational strategies for the production of methane and algal oil using ethanol vinasse effluent

Brazilian ethanol production generates approximately 351 billion liters yearly of vinasse that is mostly used for fertigation, but with significant environmental impact. This research aims at comparing the growth of Chlorella vulgaris on three different media preparation using raw vinasse, diluted vinasse, and vinasse treated by anaerobic digestion; all under four distinct treatments or supplementations (antibiotic, nitrogen and phosphorous). The results show that C vulgaris grows poorly on raw vinasse alone or after supplementation. However, 11–13 mg L −1 day −1 of algal oil can be produced with diluted or anaerobically treated vinasse. The first would require antibiotic, nitrogen and phosphorous supplementation and the later only antibiotic supplementation. Whilst using diluted vinasse may reduce work input, it requires significant amounts of clean water. The use of anaerobically treated vinasse requires some additional work and investment, but it can generate 122 mL CH 4 g −1 COD vinasse (10–26.4 m 3 of biogas from 1m 3 of vinasse). Thus, the association of methane and algal oil production from vinasse is an effective approach for removing inorganic nutrients and potentially toxic organics from this effluent before discharge. The quality of the algal oil produced is affected by culturing conditions and anaerobically treated vinasse produced the best results in this area according to the estimated parameters of the biodiesel.