In this study, the performance of shortcut nitrification–denitrification (SCND) at different TC and SD stress conditions (0 μg/L, 1–97 days; 100 μg/L, 98–138 days; 500 μg/L, 139–175 days) was investigated. Higher level antibiotic stress (500 μg/L) led to the serious deterioration of nitrogen removal, and denitrification was more sensitive to antibiotic stress than nitrification. The dynamics of antibiotic resistance genes (ARGs) and microbial community were revealed by quantitative real-time PCR and 16S rDNA high-throughput sequencing, respectively. Tet-genes (tetA, tetQ, tetW), sul-genes (sulI, sulII), and mobile genetic element (intI1) in activated sludge increased by 1.2?~?2.5 logs with long-term exposure of antibiotic stress, and sulI, tetA, tetQ, and tetW were significantly positively correlated with intI1. Long-term antibiotics stress caused the decrease of most denitrifiers, and five genera were identified as the potential host of ARGs. The key impact factors of SCND drove the dynamics of ARGs and microbial community. Except for sulII gene, DO and FA were significantly positively correlated with ARGs, while FNA, NAR, and NO2?-N showed opposite effects to ARGs. Overall, maintaining relative lower DO, higher FNA, NAR, and NO2?-N conditions are not only benefit to the stable operation of SCND, but may also conducive to the control of ARG dissemination. This study provides theoretical basis on the control of ARGs in the SCND process.
In this paper, based on symbiotic network of Eco-agricultural Park (EAP), value flows of different industrial chains are studied, and input–output efficiencies of industrial chain and individual enterprise accounted independently are compared in the case of Huaning EAP. The results indicate: (1) the total profit of industrial chain of feedstuff processing, breeder duck breeding, laying-hen breeding, farm garden, dairy farm and milk processing is more than the sum of profits of individual enterprises independently accounted, with a difference of 950,800 RMB yuan. Input–output efficiency of this industrial chain is 1.30 times higher than the average that of individual enterprises accounted independently. (2) The total profit of industrial chain of feedstuff processing, dairy farm, grass farm, laying-hen breeding and milk processing is more than the sum of profits of individual enterprises accounted independently, with a difference of 3,258,800 RMB yuan. Input–output efficiency of this industrial chain is 1.45 times higher than the average that of individual enterprises accounted independently. (3) Through collaboration among enterprises in the industrial system, the benefits of the industrial chain are much higher than the sum of those obtained by individual enterprises, which is benefited from the performance of resource and by-product exchange network among enterprises in the EAP. 相似文献