Hazardous impact of vinasse from distilled winemaking by-products in terrestrial plants and aquatic organisms

Vinasses obtained from the distillation of winemaking by-products (WDV) are complex effluents with variable physicochemical properties. Frequently, WDVs are used to irrigate agricultural soil, and/or discharged into aquatic bodies, which may result in serious environmental pollution, due to the presence of organic acids and recalcitrant compounds (polyphenols, tannins and metals). The present study aimed to evaluate the toxicity impact of an untreated WDV on terrestrial and aquatic organisms, at different levels of biological organization. The effluent was collected at the distillation column exit and characterized according to several physicochemical properties. The WDV potential phytotoxicity was assessed by germination inhibition assays on six agricultural crops, and its acute toxicity was assessed on Aliivibrio fisheri (microtox assay), Daphnia magna neonates (freshwater crustacean), and zebrafish Danio rerio (fish embryo toxicity test, FET). The WDV presented a low pH (3.88), high levels of electrical conductivity, ECond (6.36 dS m^-1) and salinity (3.3 ppt), besides high level of potassium (2.1 g L^-1) and organic compounds (TOC = 17.7 g L^-1), namely polyphenols (1.7 g L^-1). The diluted WDV displayed variable inhibitory effects on the plant endpoints (percentage of inhibition of germination and radicle elongation and germination index). Overall, plants' susceptibility to increasing concentrations of WDV were differential (onion ≈ garden cress ≥ tomato > lettuce > maize > green beans) and the germination index EC₅₀ varied from 10.9 to 64.4% v/v. Also, the acute negative effects toward aquatic organisms were determined, decreasing from the more complex organism to the simpler one: zebrafish embryos (96 h-LC₅₀ = 0.34% v/v)>D. magna (48 h-LC₅₀ = 4.8% v/v)>A. fisheri (30min-EC₅₀ = 7.0% v/v). In conclusion, the findings suggest that WDVs might have a high toxicological impact on both terrestrial plants and aquatic organisms, even at high dilution levels, reinforcing the need for appropriate treatments before considering its discharge or reuse.