A sulfur-limestone bioretention system for stormwater treatment: Nitrogen removal performance and microbial community

A lab-scale sulfur-limestone based bioretention system with a submerged zone was used to remove nitrate-nitrogen (NO3--N) from stormwater. The results indicated that denitrification mainly occurred during the first 5 d of drying period. With the NO3--N concentration in the influent increasing from 20 to 50 mg/L, after 5 d of drying period 93.99-97.26% NO3--N was removed, and the effluent sulfate (SO42-) concentration ranged from 170.28 to 359.87 mg/L. When the NO3--N content in the influent was lower than 30 mg/L, the effluent SO42- concentration met the Chinese Quality Standard for Ground Water (GB/T 14848-2017). Compared with the woodchips bioretention, there was no organic matter leakage problem. Sulfur autotrophic denitrification process followed first-order kinetic model, and the reaction kinetic parameters (k) were 0.7392-1.1472 d(-1). The dominant genera in the submerged zone were Thiobacillus and Halothiobacillus (> 63.69%) which participated in the sulfur autotrophic denitrification process.

Automated summary

A lab-scale sulfur-limestone based bioretention system with a submerged zone was used to remove nitrate-nitrogen from stormwater. The study found that denitrification mainly occurred during the first 5 days of drying period. The system effectively removed nitrate-nitrogen and met the Chinese Quality Standard for Ground Water when the influent concentration was below 30 mg/L. The sulfur autotrophic denitrification process followed a first-order kinetic model, and the dominant bacteria in the submerged zone were Thiobacillus and Halothiobacillus.