Intermittently aerated up-flow constructed wetland for improved wastewater treatment and footprint

Constructed wetlands are widely applied for wastewater treatment; however, their practical implementation is often constrained by large land requirements. The present study investigates improvements in wastewater treatment using an Intermittently Aerated Up-flow Constructed Wetland (IA-UCW). Two identical lab-scale UCW reactors were designed and operated, with one as a control and the other incorporating intermittent aeration. Experimental results revealed that the IA-UCW achieved enhanced wastewater treatment and supported similar plant growth to the control. Specifically, the aerated system achieved 78 ± 8% removal of TSS, 81 ± 4% of COD, 78 ± 12% of TN, and 64 ± 15% of TP, as compared to 59 ± 18%, 58 ± 13%, 17 ± 9%, and 26 ± 9% removal, respectively, in the control reactor. Dissolved oxygen showed a significant increase in the aerated system, with average Dissolved Oxygen (DO) values of 1.6 mg/L at 50 cm depth and 2.9 mg/L at 10 cm depth. Improved oxygen facilitated microbial activity and organic degradation, while promoting zones for nitrification-denitrification under intermittent on-off aeration. Plant growth study in both reactors enables harvest scheduling. Further, an intermittent aeration facilitated a reduction in footprint from 2.8 m²/PE to 0.9-2.1 m²/PE based on removal of organics and nutrients. These findings demonstrate the potential of IA-UCW as a wetland intensification strategy for land-constrained urban wastewater treatment.