Effect of abscisic acid concentration on nutrient and antibiotics removal performance by different microalgae-based system treating bullfrog aquaculture wastewater

This study systematically evaluated the performance of diverse microalgae-based systems supplemented with abscisic acid (ABA) in treating bullfrog aquaculture wastewater, focusing on nutrient (COD, TN, TP) and antibiotic removal. Four experimental setups were established: single culture of Chlorella vulgaris (Treatment 1), co-cultures of Chlorella vulgaris with Rhodopseudomonas sphaeroides (Treatment 2) or Curvularia moringae J-26 (Treatment 3), and a tri-culture system combining all three microorganisms (Treatment 4), each treated with ABA concentrations of 0, 0.01, 0.05, and 0.1 mg L⁻¹. Results revealed that the Treatment 4 system with 0.05 mg L⁻¹ ABA demonstrated superior efficiency, achieving removal rates of 90.51 % for chemical oxygen demand (COD), 88.72 % for total nitrogen (TN), and 92.51 % for total phosphorus (TP) over a 10-day treatment period. For six target antibiotics—including enrofloxacin (ENR), ciprofloxacin (CIP), sulfadiazine (SDZ), sulfamethoxazole (SMX), florfenicol (FFC), and doxycycline hydrochloride (DOX)—removal efficiencies ranged from 79.69 % (ENR) to 98.64 % (DOX), with photosensitive antibiotics like DOX showing the highest degradation. This study provides empirical evidence for the synergistic efficacy of ABA-regulated microalgae-bacteria-fungi systems, offering a sustainable and efficient strategy to address the complex pollution challenges in bullfrog aquaculture wastewater and facilitating the development of eco-friendly wastewater treatment technologies for the aquaculture industry.