The concept of improving in-situ nitrate removal was demonstrated in a CdS nanoparticles (NPs)-assisted periphyton bioelectrochemical system (PCdS-BES). Compared to the control (periphyton bioelectrochemical system, P-BES), nitrate reduction to nitrogen gas by the PCdS-BES was enhanced by 1.5 times on day 7 under stimulated sunlight irradiation (20 W m⁻²), avoiding nitrous oxide emission. The presence of CdS NPs optimized the community structure of periphyton, enhanced its activities (represented by ATPase), stimulated more extracellular polymeric substance (EPS) production and increased the relative abundance of electroactive bacteria strains (e.g. Family Xanthomonadaceae, Hyphomonadaceae and Sphingobacteriales). The enhancement of nitrate reduction under irradiation was primarily attributed to the synergistic effect of EPS, electroactive bacteria strains and CdS NPs. Specifically, CdS NPs provided photoexcited electrons under light irradiation. The EPS facilitated the stability of CdS NPs in the periphyton matrix and separation of photo-induced electron-hole on the surface of CdS NPs. EPS served as extracellular electron transfer mediators for electron transfer from CdS NPs to microorganisms. The electroactive bacteria were beneficial to the acquisition of electrons produced by CdS NPs under irradiation, promoting catalytic nitrate reduction. This study gives an insight into the mechanism of nitrate reduction via the synergistic action of photoexcited electrons, EPS and electroactive bacteria. The successful combination of photocatalyst (i.e. CdS NP) and microbial community in BES also provides a promising approach for nitrate removal.

在CdS纳米颗粒（NPs）辅助的浮游生物生物电化学系统（PCdS-BES）中证明了改善原位硝酸盐去除的概念。与对照（附生生物化学系统，P-BES）相比，PCdS-BES在刺激的阳光照射下（20 W m ^-2）在第7天将硝酸盐还原成氮气的速率提高了1.5倍，避免了氧化亚氮的排放。CdS NPs的存在优化了附生植物的群落结构，增强了其周围植物的活性（以ATPase表示），刺激了更多的细胞外聚合物质（EPS）的产生，并增加了电活性细菌菌株（例如黄单胞菌科，次单藻科和鞘氨醇杆菌）的相对丰度。）。辐射下硝酸盐还原的增强主要归因于EPS，电活性细菌菌株和CdS NP的协同作用。具体而言，CdS NP在光照射下提供了光激发电子。EPS促进了CdS NPs在浮游生物基质中的稳定性以及CdS NPs表面光致电子空穴的分离。EPS用作细胞外电子转移介质，可将电子从CdS NP转移至微生物。电活性细菌有利于CdS NPs在辐射下获取电子，促进硝酸盐催化还原。这项研究深入了解了通过光激发电子，EPS和电活性细菌的协同作用而使硝酸盐还原的机理。光催化剂的成功组合（即