Nano zero-valent iron mediated optimization of microalgae-based systems for efficient nutrient and antibiotics removal from aquaculture wastewater

Abstract

This study was dedicated to investigating the influence of nano zero-valent iron (NZVI) on microalgae-based systems in eliminating nutrients and antibiotics from aquaculture wastewater. The aquaculture industry's fast expansion has caused severe pollution issues, as its wastewater is rich in nutrients and antibiotics. Microalgae-based treatment technologies hold promise, yet the effects of NZVI on their performance remain unclear. Four systems were established with different NZVI concentrations (0 mg L⁻¹, 5 mg L⁻¹, 10 mg L⁻¹,20 mg L⁻¹). Results showed that 10 mg L⁻¹ of NZVI best promoted microalgae growth, and Treatment 2 (Chlorella vulgaris + endophytic bacteria + Clonostachys rosea) performed best. Its removal efficiencies of COD, TN, TP, and tetracycline reached 87.29 ± 8.04 %, 87.76 ± 8.32 %, 88.12 ± 8.45 %, and 99.17 ± 0.52 % respectively. This research identified the optimal technology and NZVI concentration, providing crucial theoretical support for the application of microalgae in aquaculture wastewater treatment. However, it should be noted that real-scale validation is still required to fully confirm its effectiveness.