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The production of ethanol from sugarcane or molasses generates vinasse, a residue rich in organic matter and minerals. Vinasse is often used in fertilization and irrigation practices, which may be linked to negative environmental outcomes if excess is applied. Herein, we introduce a novel alternative to the treatment of vinasse promoting the reduction in Chemical Oxygen Demand (COD) levels, phenolic compounds, and its mineral content through the coupling of ozone treatment, anaerobic digestion, and the aerobic growth of fungi. The ozone treatment is able to remove about 30% of the total COD, and deplete the concentration of phenolic compounds, while anaerobic digestion produces biogas and generates vinasse digestate, which is less biorecalcitrant than raw vinasse. The aerobic fungal growth generates oleaginous fungal biomass and promotes over 80% of Kjeldahl-Nitrogen in the vinasse. If vinasse were treated following the sequence of anaerobic digestion, aerobic fungal growth, and ozone treatment, the effluent would have about 95% of the COD decreased, complete removal of phenolic compounds, and over 80% of Kjeldahl-Nitrogen.

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BACKGROUND: The utilization of vinasse as a feasible culture medium for fungi is hindered by the presence of inhibitory compounds, such as phenols and other recalcitrant structures. This work analyzes the effect of different homogeneous advanced oxidation processes (AOP) to lower the concentration of inhibitory phenolic compounds in vinasse, and to test the effects of the pre-treatment on the growth of an oleaginous fungal strain. Vinasse was treated using a batch system with the addition of ferrous ion (Fe 2+) (Fenton), in the presence of UV, and with the addition of hydrogen peroxide (H 2 O 2). RESULTS: All of the reaction systems were able to partially degrade the chemical oxygen demand, ranging from 18.4% up to 54.1% in the factorial results. The pre-treated vinasse samples were assayed for the growth performance of Mucor circinelloides, demonstrating that the control value of 3.54 g L −1 was increased to values as high as 4.84 g L −1 , also followed by an increase of ≈73% in terms of lipid productivity. CONCLUSION: Different AOP were tested to degrade phenolic compounds present in vinasse, demonstrating that the optimum condition (Fe 2+ /UV at alkaline pH) provided a culture medium for M. circinelloides that increased the biomass accumulation by ≈35% and the lipid productivity by >70% when compared to the control.