Effect of phosphorus on the performance of sulfur autotrophic denitrification

Autotrophic denitrification, recognized as a biological denitrification method, has garnered increasing interest in the field of ecological water environment denitrification technology. This study focuses on the utilization of the sulfur autotrophic denitrification process for the deep denitrification treatment of wastewater. Furthermore, it investigates the impact of phosphorus on nitrogen removal efficiency and bacterial community structure of sulfur autotrophic denitrification. In the experiment, a column containing an autotrophic denitrification filter with a carbon-sulfur filler was constructed. This study aimed to examine the impact of phosphorus on the initiation and denitrification efficiency of the autotrophic denitrification filter column. High-throughput sequencing was used to examine alterations in the structure of the bacterial community. The experimental findings indicated that the absence of phosphorus in the influent considerably extended the initiation period of the autotrophic denitrification filter column. The average Total Inorganic Nitrogen (TIN) removal rate was determined to be 80.26%, while the effluent exhibited an accumulation concentration of NO2−-N ranging from 7 to 11 mg/L. After the addition of phosphate, the removal rate of NO3−-N in the autotrophic denitrification process increased to more than 97%, with no2−-N accumulation. As the influent phosphorus concentration increased, the ability of the sulfur autotrophic denitrification filter column to resist hydraulic impact load improved. At a NO3−-N concentration of 30 mg/L and Hydraulic Retention Time (HRT) = 2 h, the mean NO3−-N removal rate increased from 73.22% to 81.71%. The concentration of phosphorus affected the quantity and variety of primary bacteria in the sulfur autotrophic denitrification system, as their domination changed from Pseudomonas to Ferritrophicum and Thiobacillus, and from a mixed culture to complete autotrophy.