Composite iron-carbon constructed wetland combined with photocatalytic film to restore eutrophic water body and the hydraulic performance of constructed wetland

Eutrophication is a globally faced environmental issue against which water resources need to be protected as it impairs water quality, threatens the safety of drinking water, and hinders the sustainable development of the regional economy. Given severe environmental impacts and risks of eutrophication, there is an urgent need for an effective method to restore eutrophic surface water bodies. This study proposed an effective technical program for a composite iron‑carbon constructed wetland combined with a photocatalytic film (WIC&PF) to restore eutrophic water. The removal efficiencies of WIC&PF were estimated at 81.77 ± 6.98 % for ammonia nitrogen (NH4+-N), 79.18 ± 5.58 % for total nitrogen (TN), 80.45 ± 5.55 % total phosphorus (TP), 80.12 ± 5.87 % for chemical oxygen demand (COD) and 93.96 ± 4.68 % for chlorophyll a. According to the experimental results, compared with the pre-treatment water quality, the post-treatment water quality improved significantly. A large number of microalgae growing on WIC&PF exerted a significant reoxygenation effect on the treated water, improving the self-purification capacity of the receiving water body. Boosting the pollutant removal efficiency via enhancing the hydraulic performance of constructed wetlands as well as the activity of photocatalytic films may serve to improve the remediation of eutrophic water bodies.