Enhancing the treatment performance of partial denitrification/Anammox process at high nitrogen load: Effects of immobilized strain HFQ8C/N on the sludge characteristics

A novel strategy based on quorum sense (QS) was proposed to improve the treatment performance of the partial denitrification/Anammox (PD/A) process at high loads by adding immobilized Pseudomonas sp. HFQ8C/N, which could release high concentrations of N-butyryl-DL-homoserine lactone (C4-HSL), N-octanoyl-DL- homoserine lactone (C8-HSL) and N-decanoyl-DL-homoserine lactone (C10-HSL). The results showed that adding immobilized HFQ8C/ N improved the sludge activity and settleability, contributing to higher nitrogen removal efficiency at the high nitrogen loading rate (NLR). It was proved that C4-HSL promoted the abundances of Thauera and Candidatus Kuenenia at NLR 1.68-2.52 kg N/(m(3).d), while C10-HSL promoted the abundance of Candidatus Brocadia. Besides, C8-HSL and C10-HSL played different regulation roles in the production of protein (PN) in tightly bound extracellular polymeric substances (TB-EPS) at different loads, improving the sludge settleability. This study provided a new way to improve the treatment performance of high-load PD/A processes.

Automated summary

A novel strategy based on quorum sense was proposed to improve the treatment performance of the partial denitrification/Anammox process at high loads by adding immobilized Pseudomonas sp. HFQ8C/N, which released high concentrations of specific compounds. The results showed enhanced sludge activity and settleability, leading to higher nitrogen removal efficiency at high nitrogen loading rates. Different HSL compounds played specific roles in regulating microbial abundances and protein production, ultimately improving sludge settleability under different loads.