Influence of microbial spatial distribution and activity in an EGSB reactor under high- and low-loading denitrification desulfurization

To characterize the impact of reactor configuration and influent loading on elemental sulphur (S-0) recovery during denitrification desulfurization, a laboratory-scale expanded granular sludge bed (EGSB) reactor was established under two influent acetate/nitrate/sulphide loadings; the water flow velocity, microbial community, and functional genes at different heights were investigated. There was no S-0 generated when acetate/nitrate/sulphide loadings were set to 0.95/0.60/1.05 kg/m(3).d (low-loading). Furthermore, there were no typical denitrifying sulphide oxidizing bacteria under this condition, and Syntrophobacter, Anaerolineaceae genera were predominant in the reactor. As the influent loading was doubled (high-loading), S-0 recovery increased to 87%; the bacterial distribution was relatively homogeneous with sulphide oxidation genera (Thauera) being predominant. Neither nirK nor sqr genes were detected in the low-loading sample at a height of 50 cm. The sqr/sox ratios of low-loading stage were 2.50 (10 cm), 0.94 (30 cm), and 0 (50 cm), and the ratios of the high-loading stage were 1.38 (10 cm), 1.33 (30 cm), and 1.08 (50 cm). A hydrodynamics analysis indicated that the water flow velocity was homogenous throughout the reactor. Appropriate reactor configuration and operation parameters play an important role in the efficient regulation of S-0 recovery during denitrification desulfurization.

Automated summary

The research investigated the impact of reactor configuration and influent loading on S-0 recovery during denitrification desulfurization. It found that under low-loading conditions, S-0 was not generated, and the dominant microbial genera were Syntrophobacter and Anaerolineaceae. However, under high-loading conditions, S-0 recovery increased to 87%, with Thauera genus being predominant and a relatively homogeneous bacterial distribution. The study emphasized the importance of appropriate reactor configuration and operation parameters for efficient regulation of S-0 recovery.