An in-situ strategy of modified biochar–activated persulfate for low-temperature livestock wastewater treatment: Dynamic reaction kinetics and computational fluid dynamics-based multi-unit structure reactor design

Livestock wastewater treatment in cold regions is hampered by low temperatures, small scale, and dispersed wastewater. Our research group previously synthesized δ-MnO₂/biochar (BC) material for early-stage wastewater treatment, which has good low-temperature application prospects. Static experiments show that the critical temperature to ensure efficient composite pollution removal is 15 °C. Herein, δ-MnO₂/BC/persulfate was adopted as the core technology, the key parameters of wastewater treatment were explored through large-capacity continuous dynamic experiments, and a unit internal circulation reactor was designed and optimized. The kinetic experiment showed that the overall removal rate of antibiotics could reach 65.27 % ∼ 72.57 % under the optimal reaction condition and 15 °C. The removal rate of trace heavy metal Cd could reach 100 %. Combined with fluent simulations via computational fluid dynamics modeling and technology verification, an industrial dynamic continuous unit reactor was designed with a volume of 40 m³. After optimization, the designed multiunit reactor effectively ensured an internal water temperature of >15 °C, stable operation at external temperatures from −25 °C to −20 °C, and could withstand an extremely low outside temperature of −35 °C. This research describes an effective industrial treatment strategy for livestock wastewater in cold regions and provides a practical application of advanced oxidation technology based on catalytic materials.