Enhancement of multiple antibiotics removal performance of different microalgae-based system by agricultural phytohormone and carboxylated multi-walled carbon nanotubes induction

Novel microalgae-based technologies for eight antibiotics removal are developed and characterized in the present study based upon the screened dominant strains Scenedesmus quadricauda (S. quadricauda), Chlorella ellipsoidea (C. ellipsoidea), exogenous supplementation of the agricultural multi-phytohormone composed of 0.135 % gibberellin acid, 0.00052 % indole-3-acetic acid as well as 0.00031 % brassinolide (GIB) and carboxylated multiwalled carbon nanotubes (MWCNT-COOH). Four microalgae-based systems were constructed by using S. quadricauda, C. ellipsoidea, endophytic bacterium (S395-2) and the saprophytic filamentous fungus Clonostachys rosea (C. rosea). The results demonstrated that C. ellipsoidea-S395-2- C. rosea symbiont under 10 mg L- 1 GIB treatment had greatest growth rate, mean daily production, Chlorophyll a contents and highest antibiotics removal efficiencies of 99.05 f 0.43 %, 95.45 f 3.51 %, 99.61 f 0.18 %, 76.07 f 6.41 %, 74.09 f 6.25 %, 77.53 f 7.12 %, 81.13 f 7.45 % and 75.43 f 6.74 % for tetracycline hydrochloride (TC), oxytetracycline hydrochloride (OTC), chlorotetracycline (CTC), ciprofloxacin (CPFX), norfloxacin (NFX), sulfadiazine (SMZ), sulfamethazine (SMX) and sulfamethoxazole (SMM), respectively. Collectively, this work demonstrates that exogenously supplementing 10 mg L- 1 GIB and 2 mg L- 1 MWCNT-COOH can optimally and maximally enhance the biomass production, photosynthetic activity and multiple antibiotics removal rate of C. ellipsoidea-S395-2C. rosea symbiotic culture, which provides the foundation for complex treatment of antibiotics-containing swine wastewater by three-phase symbiont supplemented with both agricultural multi-hormone and MWCNT-COOH.