Integrated simultaneous desulfurization and denitrification (ISDD) process at various COD/sulfate ratios

Area of Science:

• Environmental Science
• Microbiology
• Chemical Engineering

Background:

• High-sulfate and high-nitrate wastewaters pose significant environmental challenges.
• Integrated Simultaneous Desulfurization and Denitrification (ISDD) is a novel process for treating such effluents.
• Understanding microbial interactions is crucial for optimizing ISDD performance.

Purpose of the Study:

• To investigate the impact of the chemical oxygen demand to sulfate ratio (COD/SO4(2-)) on ISDD performance.
• To analyze the complex interplay between sulfate-reducing bacteria (SRB), heterotrophic denitrifiers (hNRB), and autotrophic denitrifiers (aNRB).
• To identify optimal conditions for high pollutant removal and elemental sulfur recovery.

Main Methods:

• Experimental study of the ISDD process under varying COD/SO4(2-) ratios.
• Monitoring of sulfate, nitrate, and elemental sulfur concentrations.
• Microbial community analysis using advanced techniques.
• Correlation of microbial shifts with process performance.

Main Results:

• An optimal COD/SO4(2-) ratio of 1.5:1 was identified for maximum efficiency.
• 100% removal of both sulfate (SO4(2-)) and nitrate (NO3(-)) was achieved at the optimal ratio.
• Elemental sulfur (S(0)) recovery reached 42.6% under optimal conditions.
• The optimal ratio promoted the formation of well-retained microbial granules.
• Microbial community analysis revealed significant shifts in SRB, hNRB, and aNRB populations correlating with performance.

Conclusions:

• The COD/SO4(2-) ratio is a critical factor in optimizing the ISDD process.
• The identified optimal ratio enhances pollutant removal and valuable byproduct recovery.
• Microbial community structure and interactions play a key role in ISDD efficiency.
• Further strategies can be developed to enhance ISDD performance based on these findings.