## 1 Introduction  
Water pollution is a critical challenge at a global level, affecting both developed and developing countries. This is especially true in the agri-food industry, such as with wine and pisco production [1]. The wine and pisco industry is one of Chile's most important, representing 20% of agricultural exports and 0.5% of the gross domestic product (GDP) [2]. Pisco is made through wine distillation, and the annual production of these spirits is 44.4 ML [3] and 1103 ML [4], respectively. However, their production generates liquid industrial waste (LIW), specifically vinasse (VZ), which represents 70% of the total liquor [5]. These industries generate LIW, with a high organic load characterized as Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD\({}_{5}\)) [6]. This load mainly consists of high concentrations of difficult-to-degrade phenolic compounds [7]. For example, if discharged without adequate treatment, VZ's composition represents a significant risk to the soil, surface, and underground water bodies, as well as to human health [6, 8, 9]. For these reasons, phenolic compounds such as gallic acid, caffeic acid, and gentisic acid must be removed from wastewater before it is discharged into the environment [10]. Among the pollutants mentioned, caffeic acid is one of the most refractory phenolic compounds due to its high toxicity and antimicrobial activity [9; 11]. In the last decade, emphasis has been placed on developing innovative technologies to remove pollutants from water efficiently. Among these, Advanced Oxidation Processes (AOPs) have emerged as a promising option for treating wastewater with difficult-to-degrade organic compounds due to their high oxidizing capacity [12; 13]. Heterogeneous photocatalysis, one of the most effective AOPs [14], stands out for its ability to degrade recalcitrant pollutants quickly, efficiently, and at a lower cost than conventional methods using solar radiation [15; 16; 17]. The development of advanced photocatalytic heterostructures, such as the BiOI semiconductor coupled to magnetite (Fe\({}_{3}\)O\({}_{4}\)), has proven highly effective in degrading persistent organic compounds under solar irradiation [18; 19; 20; 21; 22]. The solvothermal synthesis technique is particularly effective for manufacturing these materials, providing an accurate control over their structure and composition [23]. This technique takes advantage of high-temperature conditions above the solvent's boiling point, and pressure to induce unique reaction pathways, resulting in nanomaterials with synergistic photocatalytic and magnetic properties [24; 25]. The use of BiOI as a semiconductor is attractive due to its 1.9 eV bandgap, which can absorb 95% of sunlight within the visible range [26; 27]. However, BiOI's micrometric size, like other powdered photocatalysts, limits its recovery and separation in post-treatment. To overcome these limitations, the coupling of BiOI with magnetite provides magnetic properties that facilitate the separation and recovery of the photocatalyst, addressing a current problem for the applicability and sustainability of this technology on a large scale [28]. The potential applications of these nanomaterials are vast and range from wastewater treatment to improving industrial processes that require the removal of persistent and emerging pollutants [29]. Given the complexity of conventional and current systems, water treatment by solar photocatalysis is a process with high sustainability prospects, capable of degrading recalcitrant pollutants [30]. However, as far as we know, no studies guarantee this technology's viability and sustainability using BiOI/Fe\({}_{3}\)O\({}_{4}\) at a TRL higher than the validation under controlled laboratory conditions. Although photocatalysis offers significant advantages as a wastewater remediation method, its widespread adoption has faced obstacles, and studies often focus on the treatment's technical success at a laboratory scale without evaluating its future scalability [31].