Tequila vinasses is a mixture made from up to six still distillation two-stage process residual effluents. First stage fractions: residual must (60%), heads (0.9%) and tails (20.0%); second stage fractions: non-evaporated (8.0%), heads (0.1%) and tails (1.0%); the result is a more complex effluent for its treatment or biorefining. The objectives of this study were to: (a) characterize the five still distillation volatile streams in the Tequila 100% Agave processing; compounds: methanol, ethanol, acetaldehyde, ethyl acetate, sec-butanol, n-propanol, iso-butanol, n-butanol, iso-amyl, n-amyl, and ethyl lactate were detected by gas chromatography; calculated chemical oxygen demand from chemical composition had very high values (53,760–1,239,220 mg/L); measurement of pH (3.24–4.80), color (38.6 UC Pt-Co max), turbidity (46.1 max), electrical conductivity (3.30–172.20 μS/cm), and solid content (0 mg/L) was also made; (b) report an energy analysis (2.02 × 10⁹ KWh) and CO₂ production (429 × 10⁶ kg) in the Tequila industry during 2019; (c) up to date residues (365.2 × 10⁶ kg agave bagasse, 1146.1 × 10⁶ kg agave leaves and 3300.0 × 10⁶ L agave vinasse) in 2019; (d) economic analysis, current tequila vinasses treatment price is 16.00 USD/m³ but could reach a considerable fraction value if is bio-refined, a break down component analysis reach for five volatile streams $51.23–$140.00 USD/m³.

The tequila industry faces several environmental challenges due to its high yields of contaminants, especially tequila distillation stillage or tequila vinasses, with ten to twelve liters produced per liter of tequila. All treatments aim to shorten retention times to avoid the need for large equipment or new facilities and the saturation of residues within tequila distilleries. The complexity of tequila vinasses has led to treatments with several stages, whereby most of the organic matter content is reduced, but the treatment range results are insufficient. This study aimed to evaluate a fourth-stage tequila vinasse treatment using an electrocoagulation system that uses inexpensive electrodes (SS cathodes and iron anodes), has a low electrical consumption, and applies low voltages in order to meet safety, economic, and environmental criteria so as to comply with Mexican norm NOM-001-SEMARNAT-2021. Three sets of voltage–amperage controllable power source, a 4 mm cylindrical 304 stainless-steel cathode, and a 9 mm iron anode with 200 mL samples in 250 mL beakers were used; three replicas (R1, R2, and R3) underwent 2 h treatment at 1–6 volts to evaluate the voltage effect and 1–6 h of 5-volt treatment to assess the time effect. All samples were filtered with 8 μm and 0.25 μm meshes. Chemical oxygen demand, pH, electrical conductivity, turbidity, and color measurements (SAC for λ 436, 525, and 620 nm) were taken. The experiments determined the optimal voltage and time, considering a hydraulic retention time below 6 h. The results show that electrocoagulation of pretreated tequila vinasses effectively helps in the final removal of organic matter measured as COD, reaching values below 150 COD mg/L at 5–6 h with 5 V treatments and color reduction with 5 V, 1 h treatment. This leads to final polishing that complies with the Mexican wastewater discharge norm criteria.

Tequila production occurs in Mexico's designated area of origin, principally in the Jalisco State. Its residues are a challenge in treatment and tracking due to a lack of technology, non-economic treatments available, low environmental consciousness and incipient control from authorities. In 2021, average production was close to 1.5 million tequila litres per day with an estimated residue yield of 10-12 litres of stillage (tequila vinasses) per tequila litre produced, including volatile fractions. This research aims to reduce organic matter by electrooxidation (EO) from 5 distillation volatile residual effluents (two-stage still distillation) from three tequila distilleries, first and second-stage heads and heads and tails and second-stage non-evaporated fraction. Round 3 mm titanium (grade-1) electrodes (one anode and one cathode) were used, with fixed voltage to a value of 30 VDC at 0, 3, 6, 9 and 12 hours with 75 experiments. Gas chromatography was used to analyze methanol, ethanol, acetaldehyde, ethyl acetate, n-propanol, sec-butanol, iso-butanol, n-butanol, iso-amyl, n-amyl, and ethyl lactate content. Treatment shows positive results, reducing organic matter content in all effluents in a Chemical Oxygen Demand COD range of 580-1880 mg/L.h, particularly useful in the second-stage non-evaporated fraction for water recovery. GRAPHICAL ABSTRACT

La industria tequilera es de una de las más prósperas del país, aporta el 18.6% del Producto Interno Bruto nacional en el apartado de bebidas alcohólicas, junto con el mezcal con exportaciones que rebasan los 1874 millones de dólares en 2019. Se estima que 70,000 familias dependen de la industria tequilera de manera directa. Su desempeño ha sido ascendente y no se ha visto afectada a nivel producción por la pandemia de COVID-19. El año de 2020 rompió la marca de producción: más de un millón de litros de tequila diariamente, presentando además 7 años de crecimiento consecutivo. El presente documento tiene como objetivo analizar la percepción de sustentabilidad social, económica y ambiental de la industria tequilera y sus áreas de oportunidad. Se utilizó una revisión documental de tipo cualitativo-descriptivo. Dentro de los apartados de sustentabilidad se encuentra que el apartado económico está en muy buen nivel, no obstante existen retos, por ejemplo, promover un consumo responsable, mejorar los métodos de cultivo de agave, evitar la deforestación y la desertificación, desarrollar tecnologías de tratamiento de residuos que sean eficientes, rápidas y económicas para alcanzar un escenario de cero residuos y evitar la contaminación ambiental que generan la gran mayoría de las empresas del sector.