Improving the performance of coupled solid carbon source biofilm carriers through pore-forming methods

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Coupled solid carbon source biofilm carriers (CCBs) are used to improve wastewater treatment efficiency, especially for low carbon/nitrogen (C/N) ratios.
• Existing CCBs suffer from limited carbon release due to poor mass transfer within their structure.

Purpose of the Study:

• To develop modified CCBs with enhanced carbon release capacity using pore-forming methods.
• To evaluate the performance of these novel CCBs in treating low C/N wastewater within sequencing batch moving bed biofilm reactors (SBMBBRs).

Main Methods:

• Orthogonal selection of pore-forming methods to optimize CCB modification.
• Preparation of porous CCBs using circulating freezing (CCB2) and ammonium bicarbonate (CCB3) methods.
• Application of modified CCBs in SBMBBRs for wastewater treatment and analysis of total nitrogen (TN) removal efficiency.

Main Results:

• The circulating freezing method (CCB2) improved CCB mechanical strength and carbon source release rate compared to non-porous CCBs (CCB1).
• CCB2 significantly enhanced TN removal efficiency in SBMBBRs, attributed to increased biofilm accumulation and a higher simultaneous nitrification and denitrification (SND) rate.
• Microbial analysis revealed enrichment of specific bacteria (Proteobacteria, Actinobacteriota, Nitrospirota) and stimulated key metabolic pathways in CCB2 and CCB3.

Conclusions:

• Porous CCBs, particularly those prepared by the circulating freezing method, offer more sites for carbon release and microbial attachment.
• These enhanced CCBs effectively improve nitrogen removal in low C/N wastewater treatment.
• The circulating freezing method presents a cost-effective and highly applicable approach for developing advanced biofilm carriers.