LAUSR

Nitrogen removal from wastewater is often deteriorated under high salinity and low temperature. Solid-phase denitrification (SPD) might improve total nitrogen removal efficiency (TNRE) by stably supplying carbon resources under adverse conditions. In this study, an SPD biofilm reactor was successfully established by inoculating halophilic sludge and filling poly (butanediol succinate) (PBS) granules, and achieved over 96% TNRE at low temperature. More extracellular polysaccharides were produced at low temperature. Microbial network analysis evidenced dominant heterotrophic denitrifiers (Marinicella, Fusibacter, Saccharicrinis and Vitellibacter) at 25 °C were replaced by genera Melioribacter, Marinobacter, Desulfatitalea and Thiomicrospira at 15 °C. At low temperature, genes nirS and narG might be mainly responsible for denitrification. Fluorescence spectrum coupled with fluorescence regional integration and parallel factor analysis revealed low temperature increased the proportion of proteins of soluble microbial products. This study provides guidance for the practical application of SPD in the treatment of high salinity and low-temperature wastewater.