Details

Autor(en) / Beteiligte

• Wang, Xiaoning
• Wang, Jie
• Chen, Jingyi
• Chen, Jieyu
• Lv, Yabing
• Chen, Ruiya
• Xu, Juchen
• Li, Dapeng
• He, Xugang
• Hou, Jie

Titel

Formation of microorganism-derived dissolved organic nitrogen in intermittent aeration constructed wetland and its stimulating effect on phytoplankton production: Implications for nitrogen mitigation

Ist Teil von

• Water research (Oxford), 2023-02, Vol.230, p.119563-119563, Article 119563

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2023

Quelle

MEDLINE

Beschreibungen/Notizen

• •Effluent DON features in aeration constructed wetlands were investigated.•Intermittent aeration reduced DIN but lead larger amounts of DON and ABDON.•Release protein-like substances during post-aerobic step contributed to high ABDON.•DON has a greater potential to stimulate algal biomass than DIN. To control eutrophication in aquatic ecosystems, enhancing nitrogen removal in the constructed wetland (CW) by upgrading conventional CW to aeration CW is commonplace. However, regulatory efforts have only focused on reducing dissolved inorganic nitrogen (DIN) discharge and disregarding dissolved organic nitrogen (DON). Here, we used experimental mesocosms to investigate the effect of aeration mode on the characteristics of effluent DON in CW. The results showed that intermittent aeration is prone to introduce large amounts of DON and bioavailable DON (ABDON) in the effluents, although it greatly decreases effluent total nitrogen (TN). Analysis of DON fluorescent components and molecular characteristics indicated that suddenly shifting the environment from anoxic condition to aerobic condition in the intermittent aeration CW (IACW) would stimulate microorganisms to release tryptophan and simple aromatic proteins-like substances, which does not occur in the limited continuous aeration CW (CACW). Consequently, the abundance of DON resembling lipids, proteins/amino sugars, and carbohydrates-like molecules in IACW were about 2.1 times higher than that in CACW. Bioassay results showed that Selenastrum capricornutum and Microcystis aeruginosa incubated with effluent from IACW both generate larger phytoplankton biomass than that with CACW effluent, even though IACW effluent contains less TN than its counterpart. Moreover, Microcystis aeruginosa can simultaneously utilize DON and DIN, while Selenastrum capricornutum seem to utilize the DON only when DIN was not available. This result implies that increasing DON discharge may also influence phytoplankton composition and stimulate harmful phytoplankton species. Overall, this study indicates that upgrading CW solely depending on DIN removal level cannot ensure a mitigation of nitrogen-related eutrophication, and more efforts should be paid to curb DON discharge. [Display omitted]