Effectiveness and mechanism of in situ sludge biochar carrier enhancing salt-tolerant bacteria for pyrazolone degradation in high-salinity pharmaceutical wastewater

High-salt organic industrial wastewater severely impairs microbial activity due to high osmotic pressure, limiting treatment efficiency. Additionally, waste sludge from wastewater is considered harmful solid waste, incurring high disposal costs for treatment plants. Existing bioaugmentation methods relying on salt-tolerant bacteria often fail due to low biomass maintenance without proper carriers. This study proposes using in situ waste sludge to prepare biochar carriers, creating a synergistic system with salt-tolerant bacteria for treating high-salt pyrazolone wastewater. Sequential batch experiments showed that under 5 % salinity, the system achieved complete degradation in 6 days. In reactors with combined high PMP (500 mg/L) and salinity stress, the biochar carrier group reached 85 % degradation in 4 days at 3 % salinity. This approach offers an efficient, low-carbon solution for high-salt organic wastewater treatment, promoting both waste resource recovery and pollution control.