Biodegradable carrier are vital for the solid-phase denitrification (SPD) systems for treating nitrate-rich water. Two solid-phase denitrification reactors were developed with both 200 g L⁻¹ of single (polycaprolactone, PCL) (R1) and hybrid solid carbon sources (PCL/polylactic acid (PLA) /polyhydroxyalkanoates (PHA)) (R2) to examine the denitrification performance, denitrifying community and functional genes to various oxytetracycline (OTC) exposure in this study, respectively. Complete denitrification performance was achieved in the both SPD systems at low stress of OTC (1 mg L⁻¹), but then dramatically reduced to less than 20% of nitrate reduction efficiency after one-month high OTC stress (10 mg L⁻¹), and rapidly recovered to stable nitrate removal rates of 76.77 ± 5.48% (R1) and 40.68 ± 4.40% (R2) after the next day of no OTC stress. However, the reactor R1 with single PCL carriers acquired more efficient nitrate removal rate than that of reactor R2 at the high OTC stress and recovery phase with OTC stress, mainly due to the more organics availability from the single PCL carriers. The richness and diversity of nirK and nirS deintrifiers significantly declined at high OTC stress, and much more of those occurred in biofilm R1 with more organics availability. Besides, biofilm R1 achieved much more abundant periplasmic nitrate reductase, nitrite reductase genes and tetracycline resistance genes after high OTC stress, which explained the potential resistance to OTC and rapid recovery efficiency after no stress of OTC. Thus, the organics availability played an important role in assuring SPD system to be efficient under high OTC stress.

可生物降解的载体对于用于处理富含硝酸盐的水的固相反硝化（SPD）系统至关重要。开发了两个固相反硝化反应器，分别使用200 g L ^-1的单一（聚己内酯，PCL）（R1）和混合固体碳源（PCL /聚乳酸（PLA）/聚羟基链烷酸酯（PHA））（R2）进行检测在这项研究中，分别对各种土霉素的反硝化性能，反硝化群落和功能基因进行了研究。在低OTC（1 mg L ^-1）压力下，两个SPD系统均实现了完全的反硝化性能，但在一个月高OTC压力（10 mg L ^-1）下，硝酸盐还原效率却显着降低至硝酸盐还原效率的20％以下），并在第二天无OTC胁迫后迅速恢复至稳定的硝酸盐去除率，分别为76.77±5.48％（R1）和40.68±4.40％（R2）。但是，在高OTC应力和带有OTC应力的回收阶段，具有单个PCL载体的反应器R1获得的硝酸盐去除率比反应器R2更高。在高的OTC胁迫下，nirK和nirS解灭剂的丰富性和多样性显着下降，其中更多发生在生物膜R1中，有机物的利用率更高。此外，生物膜R1在高OTC胁迫后获得了更丰富的周质硝酸还原酶，亚硝酸还原酶基因和四环素抗性基因，这解释了在无OTC胁迫下对OTC的潜在抗性和快速恢复效率。从而，