Removal of Sulfamethoxazole Using Fe-Mn Biochar Filtration Columns: Influence of Co-existing Polystyrene...

Area of Science:

• Environmental Science
• Water Treatment Technology
• Materials Science

Background:

• Emerging contaminants like antibiotics and microplastics (MPs) pose significant environmental and wastewater treatment challenges.
• Sulfamethoxazole (SMX) is a common antibiotic contaminant, and polystyrene microplastics (PS-MPs) are prevalent in aquatic environments.
• Biochar-based materials are explored for contaminant removal, but their efficacy in the presence of co-contaminants like MPs needs investigation.

Purpose of the Study:

• To evaluate the removal efficiency of sulfamethoxazole (SMX) using Fe-Mn modified biochar (BFM) in fixed-bed filtration systems.
• To investigate the impact of polystyrene microplastics (PS-MPs) on SMX removal efficiency under varying pH conditions (water and wastewater).
• To elucidate the mechanisms governing SMX and PS-MP interactions and their implications for wastewater treatment.

Main Methods:

• Batch sorption experiments were conducted to determine SMX removal by BFM.
• Fixed-bed column filtration studies were performed to assess SMX and PS-MP removal.
• The Bed Depth Service Time and Yan models were applied to analyze column performance and adsorption mechanisms.
• Experiments were carried out in synthetic water (pH≈5.6) and simulated wastewater (pH≈8) with varying concentrations of SMX and PS-MPs.

Main Results:

• BFM demonstrated complete removal of 10 mg/L SMX in batch tests.
• The Yan model indicated external mass transfer and intraparticle diffusion as dominant SMX adsorption mechanisms.
• The presence of PS-MPs significantly reduced SMX retention in synthetic water due to competitive sorption, particularly at neutral pH.
• At pH 3.2, electrostatic interactions facilitated PS-MP sorption, reducing competition with SMX.
• Elevated pH intensified sorption competition between PS-MPs and SMX.
• In wastewater, PS-MPs slightly inhibited SMX filtration but were effectively removed themselves due to high ionic strength and alkaline pH.

Conclusions:

• Fe-Mn modified biochar is a promising material for SMX removal in continuous flow systems.
• Microplastics significantly interfere with antibiotic removal in filtration systems, with pH being a critical factor influencing these interactions.
• Understanding these interactions is crucial for optimizing biochar-based wastewater treatment strategies to address co-occurring contaminants.