Multifunctional role of the biological sulfur cycle in wastewater treatment: Sulfur oxidation, sulfur reduction, and sulfur disproportionation

The biological sulfur cycle, a crucial biogeochemical process in nature, demonstrate significant engineering potential in pollutant removal and resource recovery. In recent years, research on the three major biological processes of sulfur oxidation, sulfur reduction, and sulfur disproportionation in wastewater treatment has deepened, driving the development of multifunctional technologies. This paper systematically reviews the metabolic mechanisms of sulfur-oxidizing bacteria, sulfur-reducing bacteria, and sulfur-disproportionating bacteria, as well as their engineering applications in wastewater treatment. Emphasis is placed on the role of core microorganisms in the sulfur cycle and their synergistic functions in pollutant removal and resource recovery. These insights provide solutions for municipal wastewater nitrogen removal, heavy metal removal from industrial effluents, and resource utilization from complex wastewater streams. Future research should focus on optimizing microbial metabolic mechanisms and integrating multifunctional processes to enhance the efficiency and stability of sulfur cycle technologies in wastewater treatment, providing a theoretical basis and technical support for large-scale application.