Enhancement of the performance of constructed wetlands for wastewater treatment in winter: the effect of Tubifex tubifex

Abstract

Constructed wetlands (CWs) have recently been studied as a promising technology to achieve nutrient removal. However, the sustainable operation of CWs has shown low-efficiency wastewater treatment in winter. This study presented an improved constructed wetland (CW) with the addition of Tubifex tubifex in winter using laboratory batch systems. It was found that the reduction of nitrate (NO₃–N) was significantly enhanced in wastewater in which water celery (Oenanthe javanica (Blume) DC) and Tubifex tubifex coexisted, with a removal efficiency of up to 97.58%. This system could also achieve high removal efficiencies for total nitrogen (TN, 85.10%) and ammonium nitrogen (NH₄–N, 56.93%) associated with sediment stored. The organic carbon in both the wastewater and sediment was higher with the effect of Tubifex tubifex on mineralization, which could provide a carbon source sufficient for biological denitrification. The bioturbation by Tubifex tubifex could greatly stimulate the absolute abundance of anaerobic microbes. The outcomes of this study indicate that the potential utility of Tubifex tubifex could improve the ecosystem and water purification by CWs in winter.