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• Single 50 µg L−1 SMX or TMP improved the denitrification rate in CC-SPD, while mixed ones had no significant inhibitory effect on denitrification. • Dominant denitrifiers and fermentation bacteria verified the denitrification performance in CC-SPD with different antibiotics. • Single SMX or TMP achieved relatively higher denitrification gene and enzyme abundance. • SMX and TMP were mainly removed by biodegradation. • Niveibacterium and Bradyrhizobium were the ARGs potential hosts and promoted the horizontal transmission of ARGs. Solid-phase denitrification (SPD) has been used in wastewater treatment plant effluent to enhance nitrate removal, and antibiotics co-existing in the effluent is a common environmental problem. In this study, it was systematically investigated the effect of single trace sulfamethoxazole (SMX)/trimethoprim (TMP) and their mixture on microbial denitrification performance, the antibiotics removal, and antibiotics resistance genes (ARGs) in corncob supported SPD system. The average denitrification rate was improved by 46.90% or 61.09% with single 50 µg/L SMX or TMP, while there was no significant inhibition with mixed SMX and TMP. The abundance of dominant denitrifiers (Comamonadaceae family and Azospia) and fermentation bacteria (Ancalomicrobium) were consistent with the denitrification performance of different antibiotics groups. Single SMX and TMP achieved relatively higher denitrification gene and enzyme abundance. Mixed SMX and TMP improved the denitrification gene copies, but they reduced the key denitrification enzymes except for EC 1.7.7.2. Additionally, the removal efficiency of TMP (56.70% ± 3.18%) was higher than that of SMX (25.44% ± 2.62%) in single antibiotic group, and the existence of other antibiotics (i.e. SMX or TMP) had no significant impact on the TMP or SMX removal performance. Biodegradation was the main removal mechanism of SMX and TMP, while sludge and corncob adsorption contributed a little to their removal. SMX had the risk of sulfanilamide resistance genes (SRGs) dissemination. Furthermore, network analysis indicated that Niveibacterium and Bradyrhizobium were the potential hosts of SRGs, which promoted the horizontal transmission of ARGs. [Display omitted] [ABSTRACT FROM AUTHOR]

MFC anodic denitrification is more suitable for the coexistence of organic matter and nitrate in actual sewage, but the traditional carbon source has some problems such as high cost and difficulty of dosage control in MFC. Herein, corncob and polycaprolactone (PCL) were mechanically pulverized and mixed in the system of polyvinyl alcohol and sodium alginate, and cross-linked to prepare slow-release carbon source fillers (CPSP), which were added to the MFC anolyte to realize the coupling of solid-phase denitrification and anodic denitrification. Results showed the start-up period of MFC experimental group (MFC-C) with CPSP was slightly longer than the control group (MFC-0), but MFC-C's maximum output voltage (648.4 mV) and power density (2738 mW/m3) could be increased by 5% and 15% higher than that of MFC-0 (P < 0.05). The degradation process of MFC substrate in unit cycle was mainly divided into nitrogen removal stage (0–8 h) and electricity generation stage (8–48 h). The NO 3 −-N and COD degradation and power generation kinetic processes of MFC conformed to the Han-Levenspiel model. Kinetics experiments showed CPSP can improve the affinity and tolerance of MFC to NO 3 −-N, also it can alleviate the pressure of electron competition in anolyte and improve coulombic efficiency. In addition, microbial communities were significantly changed under the effect of CPSP (P < 0.001). Meanwhile, CPSP can promote the synthesis of denitrification functional genes. This study provides a new strategy to improve the performance of MFC by the addition of novel denitrification carbon source. [Display omitted] • The addition of CPSP increased the power density of the anodic denitrification MFC. • The NO 3 −-N and COD degradation and power generation kinetic processes of MFC conformed to the Han-Levenspiel model. • Microbial communities in sludge and anodic biofilms were significantly changed by CPSP. • CPSP promoted the increase of denitrification gene in MFC anode suspended sludge. [ABSTRACT FROM AUTHOR]