BIOLOGICAL TREATMENT OF WASTE WATER FROM FAST FOOD OUTLETS USING TRICKLING BED FILTER

Fast-food outlets generate wastewater containing substantial concentrations of biodegradable organic matter, suspended solids, dissolved solids and nutrients, which may pose environmental risks when discharged without adequate treatment. This study investigated the biological treatment of wastewater from a fast-food outlet in Uyo, Akwa Ibom State, Nigeria, using a laboratory-scale trickling bed filter packed with locally sourced granite media. The effects of hydraulic loading rate, filter-bed height and biofilm-support particle size on treatment performance were investigated. The filter was operated with granite media of different particle sizes and bed heights, while wastewater was recirculated through the system under aerobic conditions. Biological and physicochemical characteristics of the wastewater were determined using standard analytical procedures. The biodegradability assessment gave a BOD/COD ratio of 0.79, indicating a substantial biodegradable fraction and suitability for biological treatment. The simulated treatment results showed BOD removal efficiencies of 86.40–90.33% and COD removal efficiencies of 83.99–86.95% across the investigated operating conditions. Removal performance generally improved with increasing bed height and decreased with increasing hydraulic loading rate and media particle size. Reductions were also observed in TDS, TSS and nitrate concentrations. Regression models developed for BOD and COD removal gave coefficients of determination (R²) of 0.8187 and 0.8779, respectively, indicating useful predictive capability within the experimental range. The study demonstrates the potential of locally available granite media in trickling bed filtration for biological treatment of fast-food wastewater and provides a basis for further pilot-scale investigation and process optimization.