Inorganic nutrient removal efficiency of a constructed wetland before discharging into an urban eutrophic estuary.

Mar Pollut Bull

Botany Department and the DSI/NRF Research Chair in Shallow Water Ecosystems, Nelson Mandela University, Gqeberha 6031, South Africa; Institute for Coastal and Marine Research (CMR), Nelson Mandela University, PO Box 77000, Gqeberha 6031, South Africa. Electronic address:

Published: June 2022

AI Article Synopsis

  • * The CW showed poor efficiency in removing dissolved inorganic nitrogen (DIN), only absorbing 5%, while significantly adding dissolved inorganic phosphorus (DIP) at a rate of 68%.
  • * To better manage the increased flow (10-fold since 2016) and improve nutrient removal, the CW's size would need to expand from 0.8 hectares to 46 hectares, along with better maintenance practices.

Article Abstract

This study investigated the nutrient removal efficiency of a constructed wetland (CW) piloted to treat urban runoff before entering an estuary. Physico-chemical, dissolved inorganic nutrient (DIN and DIP), and stormwater inflow volume data were measured. The CW removal efficiency of DIN was negligible (5% uptake), while it acted as a consistent source of DIP (68% efflux) to the receiving estuarine waters. There was low water residency within the small CW (0.8 ha) that has been compounded by a 10-fold increase in flow volume since 2016. The surface area of the CW would need to be increased to 46 ha to cope with current daily inputs (ca. 6300 m d). The lack of maintenance (e.g., macrophyte harvesting, sediment desludging) has reduced nutrient uptake and increased autochthonous inputs. The conversion of an abandoned saltpan into an extension of the CW has been considered to manage the high flow volume and remove nutrients.

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Source
http://dx.doi.org/10.1016/j.marpolbul.2022.113727DOI Listing

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