Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China.
College of Civil Engineering, Fuzhou University, Fuzhou, Fujian, 350116, PR China.
Chemosphere. 2022 Aug;301:134762. doi: 10.1016/j.chemosphere.2022.134762. Epub 2022 Apr 28.
Aiming at the problems of lack of carbon sources for nitrogen removal and low phosphorus removal efficiency of constructed wetlands (CWs) in treating wastewater treatment plant (WWTP) effluent, an electrolysis assisted constructed wetland (E-CW) with coconut fiber as substrate and solid carbon sources was constructed. The synthetic secondary effluent was used as the influent of the E-CW with a wastewater treatment capacity of 140 L d. The total nitrogen (TN) and the total phosphorus (TP) removal efficiency of the E-CW with coconut fiber treating WWTP effluent were 69.4% and 93.3%, respectively, which were 54.3% and 88.2% higher than those of CW with coconut fiber and no electrolysis. The removal efficiency of TN was 39.9% higher than that of E-CW with gravel. The current intensity had significant effect on nitrogen removal efficiency and the release of carbon sources from coconut fiber. When current intensity increased from 0.25 A to 1.00 A, the TN removal efficiency and nitrate removal rate increased by 21.1% and 0.21 mg L h, respectively, and the volatile fatty acids (VFAs) released from coconut fiber increased by 57.7 mg L. The 16S rRNA high-throughput sequencing results indicated that the main functional nitrogen-removing microbes were Hydrogenophaga, Thauera, Rhodanobacteraceae_norank, Xanthobacteraceae_norank, etc. Multiple paths including autotrophic denitrification with hydrogen and Fe as electron donors and heterotrophic denitrification were achieved in the system. Meanwhile, the main functional lignocellulose degradation microbes were enriched in the system, including Cytophaga_xylanolytica_group, and Caldilineaceae. Because electrolysis created a favorable environment for them to release carbon sources from coconut fiber. This study provided a new perspective for advanced nutrients removal of WWTP effluent in CWs.
针对污水处理厂（WWTP）出水中人工湿地（CWs）缺乏碳源和除磷效率低的问题，构建了以椰纤维为基质和固体碳源的电解辅助人工湿地（E-CW）。以合成二级出水为 E-CW 的进水，处理能力为 140 L/d。椰纤维处理 WWTP 出水的 E-CW 对总氮（TN）和总磷（TP）的去除效率分别为 69.4%和 93.3%，分别比无电解的椰纤维 CW 高 54.3%和 88.2%。E-CW 对 TN 的去除效率比砾石 E-CW 高 39.9%。电流强度对氮去除效率和椰纤维中碳源的释放有显著影响。当电流强度从 0.25 A 增加到 1.00 A 时，TN 去除效率和硝酸盐去除率分别提高了 21.1%和 0.21 mg L h，而椰纤维释放的挥发性脂肪酸（VFAs）增加了 57.7 mg L。16S rRNA 高通量测序结果表明，主要的功能氮去除微生物是氢噬菌属、陶厄氏菌属、Rhodanobacteraceae_norank、黄杆菌科等。该系统实现了包括以氢和 Fe 为电子供体的自养反硝化和异养反硝化在内的多种脱氮途径。同时，系统中富集了主要的木质纤维素降解微生物，包括纤维弧菌属和 Caldilineaceae。因为电解为它们从椰纤维中释放碳源创造了有利的环境。本研究为 CWs 中 WWTP 出水的高级营养物去除提供了新的视角。
