The potential application of an autochthonous fungus from the northwest of Argentina for treatment of sugarcane vinasse

Vinasse odyssey: sugarcane vinasse remediation and laccase production by Trametes sp. immobilized in polyurethane foam

Vinasse is a high pollutant liquid residue from bioethanol production. Due to its toxicity, most vinasse is used not disposed of in water bodies but employed for the fertigation of sugarcane crops, potentially leading to soil salinization or heavy metal deposition. The anaerobic digestion of vinasse for energy production is the main alternative to fertigation, but the process cannot eliminate colored compounds such as melanoidins, caramels, or phenolic compounds. The treatment of raw vinasse with white-rot fungi could remove colored and persistent toxic compounds, but is generally considered cost-ineffective. We report the treatment of vinasse by an autochthonous Trametes sp. strain immobilized in polyurethane foam and the concomitant production of high titers of laccase, a high value-added product that could improve the viability of the process. The reuse of the immobilized biomass and the discoloration of raw vinasse, the concentration of phenolic compounds, BOD and COD, and the phytotoxicity of the treated vinasse were measured to assess the viability of the process and the potential use of treated vinasse in fertigation or as a complementary treatment to anaerobic digestion. Under optimal conditions (vinasse 0.25X, 30 °C, 21 days incubation, 2% glucose added in the implantation stage), immobilized Trametes sp. causes a decrease of 75% in vinasse color and total phenolic compounds, reaching 1082 U L^-1 of laccase. The fungi could be used to treat 0.50X vinasse (BOD 44,400 mg O₂ L^-1), causing a 26% decolorization and a 30% removal of phenolic compounds after 21 days of treatment with maximum laccase titers of 112 U L^-1, while reducing COD and BOD from 103,290 to 42,500 mg O₂ L^-1 (59%) and from 44,440 to 21,230 mg O₂ L^-1 (52%), respectively. The re-utilization of immobilized biomass to treat 0.50X vinasse proved to be successful, leading to the production of 361 U L^-1 of laccase with 77% decolorization, 61% degradation of phenolic compounds, and the reduction of COD and BOD by 75% and 80%, respectively. Trametes sp. also reduced vinasse phytotoxicity to Lactuca sativa seedlings. The obtained results show that the aerobic treatment of vinasse by immobilized Trametes sp. is an interesting technology that could be employed as a sole treatment for the bioremediation of vinasse, with the concomitant the production of laccase. Alternatively, the methodology could be used in combination with anaerobic digestion to achieve greater decolorization and reduction of phenolic compounds, melanoidins, and organic load.

Evaluation of Filamentous Fungi and Yeasts for the Biodegradation of Sugarcane Distillery Wastewater

Sugarcane Distillery Spent Wash (DSW) is among the most pollutant industrial effluents, generally characterized by high Chemical Oxygen Demand (COD), high mineral matters and acidic pH, causing strong environmental impacts. Bioremediation is considered to be a good and cheap alternative to DSW treatment. In this study, 37 strains of yeasts and filamentous fungi were performed to assess their potential to significantly reduce four parameters characterizing the organic load of vinasses (COD, pH, minerals and OD_475nm). In all cases, a pH increase (until a final pH higher than 8.5, being an increase superior to 3.5 units, as compared to initial pH) and a COD and minerals removal could be observed, respectively (until 76.53% using Aspergillus terreus var. africanus and 77.57% using Aspergillus niger). Depending on the microorganism, the OD_475nm could decrease (generally when filamentous fungi were used) or increase (generally when yeasts were used). Among the strains tested, the species from Aspergillus and Trametes genus offered the best results in the depollution of DSW. Concomitant with the pollutant load removal, fungal biomass, with yields exceeding 20 g·L^-1, was produced.

Efficacy of polyextremophilic Aeribacillus pallidus on bioprocessing of beet vinasse derived from ethanol industries

This work aimed to evaluate the applicability of Aeribacillus pallidus for the aerobic treatment of the concentrated beet vinasse with high chemical oxygen demand (COD 685 g.L^-1) that is defined as an environmental pollutant. This bacterium is a polyextremophilic strain and grow aerobically up to 7.5% vinasse at high temperature (50 °C). In the bioreactor and under controlled conditions, A. pallidus reduced the soluble COD content of 5% vinasse up to 27% during 48 h and utilized glucose and glycerol, completely. Furthermore, a reduction of manganese, copper, aluminum, and nickel concentrations was observed in the treated vinasse with A. pallidus. The obtained results make this strain as an appropriate alternative to be used for the aerobic bioprocessing of the vinasse.

Ultrasound and heterogeneous photocatalysis for the treatment of vinasse from pisco production

Production of the distilled alcohol pisco results in vinasse, dark brown wastewater with high polyphenols contents and chemical oxygen demand (COD). No prior research exists on the efficiency of advanced oxidations processes (AOPs) in treating pisco vinasse. Therefore, the purpose of this study was to assess the efficiency of ultraviolet (UV), ultrasound (US), US + UV, heterogeneous photocatalysis (HP), and HP + US treatments. Polyphenols, COD, and color removal, as well as oxidation-reduction potential, were monitored over a 60-minute treatment period. Energy consumption levels and synergies were also calculated. The HP + US treatment achieved the best removal ratios for polyphenols (68%), COD (70%), and color (48%). While the HP treatment was the second most efficient in terms of polyphenols (62%), COD (58%), and color (40%) removal, this AOP comparatively required the least amount of energy. Considering the energy efficiency and relatively high pollutant-removal rates of the HP treatment, this AOP is recommended as a practical alternative for treating pisco vinasse.