This study assessed the feasibility of achieving phosphorus removal through enhanced biological phosphorus removal (EBPR) in an intermittent aeration constructed wetland (CW). The results showed that within just 3 weeks, a polyphosphate-accumulating organisms (PAOs)-enriched biofilm was successfully established in the CW by integrating a pre-anaerobic stage, intermittent aeration and periodic PO43--P release strategies. This strategy enabled a high PO43--P removal efficiency of 92.68% using normal gravel as a substrate. Moreover, simultaneous nitrification-endogenous denitrification (SNED) was found to be the main nitrogen removal pathway in the EBPR-CW without specific control. SNED significantly reduces the demand for oxygen and organic carbon compared with classical nitrification-denitrification, and allowed the system to reach 96.21% total nitrogen (TN) removal even under carbon limiting conditions. With control experiment, EBPR combined with SNED in CWs improved the phosphorus and nitrogen removal by about 73% and 48%, respectively, compared with normal nitrification-denitrification and media storage-based nitrogen and phosphorus removal processes. Based on stoichiometric analysis, 71.25% of PO43--P was removed by aerobic PAOs (APAOs), with 27.50% removed by DPAONi (denitrifying PAOs using nitrite as electron acceptor) and 1.25% removed by DPAONa (denitrifying PAOs using nitrate as electron acceptor). DGAOs were the main organisms providing nitrite to DPAOs. Overall, our results demonstrate a novel approach to combine SNED with EBPR for advanced nitrogen and phosphorus removal in CWs.
- Constructed wetlands
- Nitrogen and phosphorus removal
- Simultaneous nitrification-endogenous denitrification
ASJC Scopus subject areas
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering