Fly Ash as a Catalyst for the Heterogenous Fenton Process in a Hybrid Oxidation Membrane Reactor: Optimization of Wastewater Treatment in the Winery Industry

The growing global population has increased energy and food demand, leading to a higher production of waste streams such as fly ash from the energy sector and wastewater from food and beverage industries. Without proper treatment, these wastes pose significant environmental concerns. One promising strategy is to repurpose industrial byproducts for wastewater treatment. Winery wastewater, for instance, contains acidic organic compounds and alcohol that are difficult to remove using conventional methods, while large amounts of fly ash remain underutilized. This study, therefore, examines a hybrid system that combines fly ash-assisted Fenton oxidation with membrane filtration for winery wastewater treatment. The process involved sequential Fenton pre-treatment followed by lab-scale nanofiltration using a 1 kg/mol ceramic membrane (13.1 cm2). A Design of Experiments approach was applied to evaluate system performance under varying H2O2 dosages (10–30 mL/L), fly ash loadings (1–3 g/L), and membrane fluxes (40–80 LMH). Filtration was performed through multiple constant-flux cycles, with energy requirements ranging from 400 to 800 kWh/m3 for the flux variations calculated from the lab-scale pump operating at a constant power supply. The hybrid method showed strong performance, achieving 70% TOC removal and 90% reduction of color and iron. However, considerable membrane fouling was observed, likely due to increased retention and deposition of organic matter, iron, and fly ash during filtration.