Pilot scale application of a hybrid process based on ozone and BAF process: Performance evaluation for livestock wastewater treatment in a real environment

Environmental pollution was generated continuously because of the slack standard of effluent from livestock wastewater treatment even though the specific treatment process was applied. Despite the continuous ecological pollution caused by livestock wastewater effluent, a comprehensive treatment process for livestock wastewater effluent has not been investigated. This study utilized an ozone-biological aerated filter (BAF) hybrid process at a pilot scale (1st ozone–BAF–2nd ozone), with a 1 m³/day capacity for real-livestock wastewater treatment. Compared with each process configuration, the single-ozone process showed effective performance in removing chromaticity, but the removal ratio of suspended solids, organic matter (OM), and trace-organic compounds (TrOCs) was insufficient, even at high ozone concentrations. The ozone–BAF hybrid process improved the removal ratios of suspended solids and biochemical oxygen demand (BOD) by 61.61 and 17.70 %, respectively, due to aeration and filtration by the BAF; however, TrOC removal ratios remained low, at <75 %. The removal ratios of TrOCs of the 1st ozone–2nd ozone hybrid process were better than those of the ozone–BAF hybrid process (by 28.2–77.9 %) owing to enhanced oxidation from increased ozone exposure to livestock wastewater. Nevertheless, the removal ratios of suspended solids and BOD were below 40 %. Owing to the complementarity between the BAF and 2nd ozone process, the removal ratios of chromaticity, suspended solids, and TrOCs reached 98, 95, and 92 %, respectively, by the optimized 1st ozone–BAF–2nd ozone hybrid process. Our results highlight the necessity of developing a new hybrid process based on ozone and BAF for treating livestock wastewater, and provide guidelines for livestock wastewater treatment.