Research progress on sulfur-based composite filler applied to denitrification of wastewater

Sulfur autotrophic denitrification technology has been widely concerned in advanced denitrification of wastewater treatment due to its lower cost, less sludge production and without secondary pollution. Pure sulfur has a series of disadvantages, such as flammability, soft quality, weak resistance to hydraulic shock, low solubility and strong acid-producing ability, thereby inhibiting its engineering application for denitrification. To solve the aforementioned problems, numerous studies on preparing sulfur-based composite filler particles via sulfur and alkaline materials are reported recently, which has broadened the practical application market of sulfur autotrophic denitrification technology. The study reviewed the biochemical mechanism of sulfur autotrophic denitrification, and summarized the manufacture and characteristics of sulfur-based composite filler(including metal-induced and nonmetal-induced) comprehensively on the basis of sulfur-limestone autotrophic denitrification mixed fillers, along with sulfur-based composite filler induced experiments, pilots and practical applications. Considering the wear rate of fillers and formation of high concentration of sulfate, the mechanism of functional microorganism and the application of multiple coupling processes should be conducted in the future to promote the practical application of sulfur autotrophic denitrification technology.