Keystone Species and Niche Differentiation Promote Microbial N, P, and COD Removal in Pilot Scale Constructed Wetlands Treating Domestic Sewage

• Published in: Environmental science & technology Vol. 55; no. 18; pp. 12652 - 12663
• Main Authors: Zeng, Luping, Dai, Yunv, Zhang, Xiaomeng, Man, Ying, Tai, Yiping, Yang, Yang, Tao, Ran
• Format: Journal Article
• Language: English
• Published: Easton American Chemical Society 21.09.2021
• Subjects: Artificial wetlands; Bacteria; Chemical oxygen demand; Denitrification; Dephosphorizing; Differentiation; Dissolved oxygen; Household wastes; Keystone species; Microorganisms; Niche overlap; Niches; Nitrification; Nitrogen; Nutrient removal; Oxidation; Phosphorus; Redundancy; Sewage; Storm seepage; Surface flow; Treatment and Resource Recovery; Vertical flow; Wastewater treatment; Wetlands; chemical oxygen demand metabolism; nitrogen and phosphorus removal; keystone species; bacterial niche; pilot scale constructed wetlands
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.1c03880

The microbial characteristics related to nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) removal were investigated in three pilot scale constructed wetlands (CWs). Compared to horizontal subsurface flow (HSSF) and surface flow (SF) CWs, the aerobic vertical flow (VF) CW enriched more functional bacteria carrying genes for nitrification (nxrA, amoA), denitrification (nosZ), dephosphorization (phoD), and methane oxidation (mmoX), while the removal of COD, total P, and total N increased by 33.28%, 255.28%, and 299.06%, respectively. The co-occurrence network of functional bacteria in the HSSF CW was complex, with equivalent bacterial cooperation and competition. Both the VF and SF CWs exhibited a simple functional topological structure. The VF CW reduced functional redundancy by forming niche differentiation, which filtered out keystone species that were closely related to each other, thus achieving effective sewage purification. Alternatively, bacterial niche overlap protected a single function in the SF CW. Compared with the construction type, temperature, and plants had less effect on nutrient removal in the CWs from this subtropical region. Partial least-squares path modeling (PLS–PM) suggests that high dissolved oxygen and oxidation–reduction potential promoted a diverse bacterial community and that the nonkeystone bacteria reduced external stress for functional bacteria, thereby indirectly promoting nutrient removal.