Sulfide removal by simultaneous autotrophic and heterotrophic desulfurization-denitrification process

Area of Science:

• Environmental Engineering
• Microbial Ecology
• Wastewater Treatment

Background:

• Sulfide and organic carbon in wastewater pose significant environmental challenges.
• Conventional treatment methods may be inefficient or costly.
• Nitrate and nitrite can serve as electron acceptors in bioremediation processes.

Purpose of the Study:

• To investigate the efficacy of an anaerobic attached-growth bioreactor (AAGBR) for simultaneous desulfurization and organic carbon removal.
• To evaluate the role of nitrate and nitrite as electron acceptors in this process.
• To assess the performance under varying operational conditions.

Main Methods:

• Operation of a 3.52 L AAGBR for 510 days.
• Introduction of nitrate and nitrite as electron acceptors.
• Manipulation of influent sulfide, organic carbon, and hydraulic retention time.
• Monitoring of pollutant removal rates and denitrification processes.

Main Results:

• Achieved 99.9% sulfide removal and 91.8% organic carbon removal at high loading rates.
• Simultaneously removed 99.9% nitrate and 99.9% nitrite.
• Identified both autotrophic and heterotrophic denitrification pathways within the bioreactor.
• Demonstrated significant contribution of heterotrophic denitrification to electron acceptor consumption.

Conclusions:

• The AAGBR process is highly effective for simultaneous sulfide and organic carbon removal.
• Nitrate and nitrite are efficient electron acceptors for this combined treatment.
• The process supports both autotrophic and heterotrophic microbial communities for desulfurization and denitrification.