Pilot-scale sulfur-fed vibrating membrane bioreactor for efficient mainstream autotrophic nitrogen removal

Area of Science:

• Environmental Engineering
• Microbiology
• Water Treatment Technologies

Background:

• Sulfur autotrophic denitrification (SADN) is a promising wastewater treatment method for low carbon to nitrogen (C/N) ratios.
• Existing SADN methods face challenges with anoxic membrane fouling and sulfur powder deposition, hindering large-scale application.
• Membrane bioreactors offer potential for efficient nutrient removal but require effective fouling control.

Purpose of the Study:

• To develop and evaluate a pilot-scale sulfur-fed vibrating membrane bioreactor (S-VMBR) for enhanced wastewater treatment.
• To investigate strategies for improving denitrification efficiency and controlling membrane fouling in SADN systems.
• To understand the microbial community dynamics and syntrophic interactions within the S-VMBR.

Main Methods:

• Development of a pilot-scale S-VMBR system.
• Implementation of operational strategies including intermittent recirculation, elevated sludge concentration, and extended hydraulic retention time (HRT).
• Analysis of microbial community composition using 16S rRNA gene sequencing and assessment of nitrogen removal rates and membrane flux.

Main Results:

• The S-VMBR achieved a maximum nitrogen removal rate of 0.32 kg N m⁻³ d⁻¹, limited by membrane flux.
• Microbial analysis revealed enrichment of sulfur-oxidizing bacteria (Thiobacillus, Sulfurimonas) and evidence of sulfur utilization.
• Long-term operation demonstrated community differentiation, with distinct autotrophic denitrification and cross-feeding communities exhibiting stable syntrophy.

Conclusions:

• The developed S-VMBR presents a scalable and energy-efficient strategy for autotrophic denitrification in low C/N wastewater.
• Microbial syntrophy between autotrophic and heterotrophic communities is crucial for stable S-VMBR performance.
• This study provides valuable insights into microbial ecology and process optimization for advanced wastewater treatment.