Optimized start-up strategies for elemental sulfur packing bioreactor achieving effective autotrophic denitrification

• Published in: The Science of the total environment 2024-01, Vol.907, p.168036-168036, Article 168036
• Main Authors: Sun, Yi-Lu, Zhang, Jing-Zhe, Ngo, Huu Hao, Shao, Chen-Yang, Wei, Wei, Zhang, Xue-Ning, Guo, Wen-Shan, Cheng, Hao-Yi, Wang, Ai-Jie
• Format: Article
• Language: English
• Subjects: Backwashing; Empty bed contact time; Inoculation; Start-up; Sulfur autotrophic denitrification
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.168036

The start-up efficiency of the elemental sulfur packing bioreactor (S0PB) is constrained by the slow growth kinetics of autotrophic microorganisms, which is essentially optimized. This study aims to optimize start-up procedures and offer scientific guidance for the practical applications of S0PB. Through comparing the start-up efficiencies under various conditions related to inoculation, backwashing, and EBCT, it was found that these conditions did not significantly influence start-up time, but they did impact denitrification performance in detail. Using activated sludge as the inoculum was not recommended as the 2.5 ± 0.2 mg-N/L higher nitrite accumulation and 26.0 ± 5.1 % lower TN removal rate, compared to self-enrichment. Starting with a long-to-short EBCT (1 → 0.33 h) achieved higher nitrate removal of 11.5 ± 0.6 mg-N/L and eliminated nitrite accumulation compared to constantly short EBCT (0.33 h) conditions. Daily and postponed backwashing were suggested for long-to-short EBCT and constantly short EBCT start-up, respectively. Enrichment of Sulfurimonas was beneficial for the effective nitrite reduction process. [Display omitted] •Inoculating activated sludge led to 3.8 mg-N/L higher nitrite accumulation.•Postponed backwashing was required for short empty bed contact time (EBCT) start-up.•Daily backwashing was recommended for long-to-short EBCT (1 → 0.33 h) start-up.•Sulfurimonas was closely associated with the nitrite reduction efficiency.