A novel aerated surface flow constructed wetland using exhaust gas from biological wastewater treatment: Performance and mechanisms

Abstract

In this study, a novel aerated surface flow constructed wetland (SFCW) using exhaust gas from biological wastewater treatment was investigated. Compared with un-aerated SFCW, the introduction of exhaust gas into SFCW significantly improved NH-N, TN and COD removal efficiencies by 68.30 ± 2.06%, 24.92 ± 1.13% and 73.92 ± 2.36%, respectively. The pollutants removal mechanism was related to the microbial abundance and the highest microbial abundance was observed in the SFCW with exhaust gas because of the introduction of exhaust gas from sequencing batch reactor (SBR), and thereby optimizing nitrogen transformation processes. Moreover, SFCW would significantly mitigate the risk of exhaust gas pollution. SFCW removed 20.00 ± 1.23%, 34.78 ± 1.39%, and 59.50 ± 2.33% of HS, NH and NO in the exhaust gas, respectively. And 31.32 ± 2.23% and 32.02 ± 2.86% of bacterial and fungal aerosols in exhaust gas were also removed through passing SFCW, respectively.

Removal behaviour of residual pollutants from biologically treated palm oil mill effluent by Pennisetum purpureum in constructed wetland

“… COD (%) TSS (%) Tannin and lignin (%) Colour (%) NH 4 + -N (%) Types of wetland Types of wastewater Types of plant Refs. 56.2 – – – 67.2 HSF-CW a Modified river water Common reeds 42 64.0 68.0 – – – VSF-CW b Secondary sewage P. purpureum 14 66.7 – – 84.5 – HSF-CW Domestic sewage Reed grass 43 65.9 – – – 30.5 HSF-CW Wastewater from livestock Potamogeton crispus 44 49.72 – – – 42.8 VF-CW c Secondary wastewater Sweet flag 45 42.0 85.0 – – 39.0 HSF-CW ...…”

“…The Proteobacteria and Firmicutes phyla can live together in harsh environments, and have been shown to have the potential to remove a broad-spectrum of heavy metals 58 . Proteobacteria are copiotrophic and root-associated bacteria that influence NO 3 − -N and NH 4 + -N in the soil 45 . Proteobacteria do not show a consistent change in depth 59 , 60 .…”

Wetlands for wastewater treatment

“…The results indicated that the introduction of waste gas improved NH + 4 − N and TN removal efficiencies by 128.48 ± 3.13% and 59.09 ± 2.26%, respectively, and the waste gas was strippedoff of H 2 S (77.78 ± 3.46%), NH 3 (52.17 ± 2.53%), and N 2 O (87.40 ± 3.89%) along with removal of bacterial and fungal aerosols with removal efficiencies of 42.72 ± 3.21% and 47.89 ± 2.82%, respectively . Similarly, Zhang, Hu, Zhang, Fan, et al (2018) studied the effect of exhaust gases from the wastewater treatment in a SFCWs, revealing that the exhaust gas significantly improved NH + 4 − N, TN, and COD removal efficiencies by 68.3 ± 2.1%, 24.9 ± 1.1%, and 73.9 ± 2.4%, respectively, and the SFCW's mitigation potential of exhaust gas pollution in terms of removal of H 2 S (20.0 ± 1.2%), NH 3 (34.8 ± 1.4%), and N 2 O (59.5 ± 2.33%) along with bacteria (31.32 ± 2.23%) and fungal (32.02 ± 2.86%) aerosol removal.…”

High denitrification potential but low nitrous oxide emission in a constructed wetland treating nitrate-polluted agricultural run-off

“…Excess nutrients in freshwaters can be reduced efficiently by buffer zones and natural or constructed wetlands (CW; Verhoeven et al, 2006;Cheng et al, 2020). Nitrogen (N) is removed from the water via the following processes: (i) temporary direct plant uptake of inorganic N and sedimentation (Brix, 1997;Abe et al, 2014;Li et al, 2015); (ii) microbial N transformation into gaseous dinitrogen (N 2 ) via denitrification and anammox (Erler et al, 2008;Ligi et al, 2015;Wang et al, 2018;Ma et al, 2019), and (iii) nitrous oxide (N 2 O) from denitrification (Erler et al, 2008;Jia et al, 2011;Batson et al, 2012), nitrification (Jia et al, 2011;Zhang et al, 2018) or DNRA (Jahangir et al, 2017;Wang et al, 2018). Although wetlands play a larger role in climate change mitigation through the carbon cycle, N removal may also contribute significantly through N 2 O emissions, especially at higher N loading rates.…”