Mesocosm constructed wetlands to remove micropollutants from wastewater treatment plant effluent: Effect of matrices and pre-treatments

The contamination of the aquatic environment by micropollutants (MPs) brings risks for the ecosystem and human health. Constructed wetlands (CWs) were an eco-friendly technology to remove MPs from wastewater treatment plant effluent. In this study, the removal of MPs was evaluated in seven vertical flow mesocosm CWs with different configurations, including different support matrices (sand and a combination of bark-biochar), light pre-treatments (UVC and sunlight) or bioaugmentation in support matrices (activated sludge). The CWs with bark-biochar as support matrix significantly enhanced the removal of irbesartan and carbamazepine (>40 %), compared to the CW filled with the conventional support matrix sand. UVC irradiation as pre-treatment was more efficient in removing MPs than sunlight irradiation. After INC pre-treatment, less MPs accumulated in the plants in the subsequent CW unit compared to the CW unit without any pre-treatment. Moreover, in the INC combined CW system, less sulfamethoxazole, fumsemide, mecoprop and diclofenac were accumulated in the plants (<0.5 pg) than other MPs (>3 mu g). The addition of 0.5 % activated sludge combined with the aeration of influent did not improve MP removal in the CW. Considering the application, a bark-biochar based MN combined with UVC pre-treatment will result in more MP removal than a conventional sand CW.

Automated summary

This study evaluated the removal of micropollutants in constructed wetlands with different configurations. The use of bark-biochar as a support matrix significantly enhanced the removal of irbesartan and carbamazepine. UVC irradiation as a pre-treatment was more effective in removing micropollutants than sunlight irradiation. After INC pre-treatment, less micropollutants accumulated in the plants in the subsequent wetland unit. The addition of activated sludge and aeration did not improve micropollutant removal. A bark-biochar based system combined with UVC pre-treatment showed better micropollutant removal than a conventional sand wetland.