Biosorption of sub-micron-sized polystyrene microplastics using bacterial biofilms

Area of Science:

• Environmental Microbiology
• Environmental Chemistry
• Materials Science

Background:

• Microplastics pose significant ecological and toxicological risks.
• Effective removal of microplastics from aquatic environments is crucial.
• Bacterial biofilms are explored as a sustainable solution for microplastic remediation.

Purpose of the Study:

• To evaluate the efficacy of bacterial biofilms in biosorptive removal of sub-micron-sized polystyrene (PS) microplastics.
• To compare the performance of different bacterial biofilms (Pseudomonas aeruginosa, Bacillus subtilis, Acinetobacter sp.) for microplastic removal.
• To investigate the adsorption kinetics, isotherm models, and influencing environmental factors for microplastic biosorption.

Main Methods:

• Formation of bacterial biofilms using three distinct strains.
• Batch experiments to test microplastic removal efficiency.
• Analysis using Fourier transform infrared spectroscopy (FTIR) to understand biosorption mechanisms.
• Investigation of environmental parameters (temperature, pH, coexisting ions) and pre-incubation effects.

Main Results:

• Acinetobacter sp. biofilm exhibited superior removal performance for 430 nm PS microplastics compared to other strains.
• High removal capacity of 715.5 mg/g was achieved by Acinetobacter sp. biofilm within 20 minutes.
• Biosorption followed pseudo-second-order kinetics and Freundlich isotherm models, indicating chemisorption.
• Environmental factors had minimal impact, but pre-incubation in freshwater reduced biosorption capacity.

Conclusions:

• Acinetobacter sp. biofilms are highly effective for the biosorptive removal of sub-micron PS microplastics.
• Chemisorption is the primary mechanism for microplastic uptake by the biofilms.
• Bacterial biofilms present a viable biological approach for mitigating microplastic pollution in aquatic systems.