Recent Advances in the Application, Design, and Operations & Maintenance of Aerated Treatment Wetlands

This paper outlines recent advances in the design, application, and operations and maintenance (O&M) of aerated treatment wetland systems as well as current research trends. We provide the first-ever comprehensive estimate of the number and geographical distribution of aerated treatment wetlands worldwide and review new developments in aerated wetland design and application. This paper also presents and discusses first-hand experiences and challenges with the O&M of full-scale aerated treatment wetland systems, which is an important aspect that is currently not well reported in the literature. Knowledge gaps and suggestions for future research on aerated treatment wetlands are provided.

Nitrate Removal by Floating Treatment Wetlands Amended with Spent Coffee: A Mesocosm-Scale Evaluation

HighlightsA floating treatment wetland design was evaluated for water quality improvements.Nitrate-N removal rates were quantified using spent coffee grounds as a carbon source.Nitrate-N removal rates increased throughout the growing season Abstract. The Midwestern U.S. is vulnerable to eutrophic conditions from high nutrient concentrations. Floating treatment wetlands (FTWs) are an innovative wetland design for nutrient removal from nonpoint sources and provide a unique treatment. The objectives of this project were to quantify nitrate removal in traditional and carbon-amended FTWs planted with Midwestern plant species during the establishment year. Three greenhouse experiments were conducted throughout the growing season using 18 mesocosms. Two vegetation designs were evaluated: rush species ( and ) and diverse species (, , , , , and ). Spent coffee grounds were applied to 9 of the 18 mesocosms as a carbon amendment. Nitrate-N removal increased during the establishment growing season in the FTW systems (Spring: 15.0% to 17.3%, Summer 1: 82.8% to 92.6%, Summer 2: 86.4% to 94.7%). Nitrate-N removal was also impacted by carbon amendments (FTW without amendment: 82.8% to 94.7%, FTW with amendment: 88.4% to 96.1%). Carbon additions were found to enhance denitrifying conditions even in the absence of FTWs (decreased dissolved oxygen, increased available organic carbon). Significant differences in nitrate-N removal were not observed between FTW vegetation designs. This study provides new insight on the impacts of the growing season, plant species, and carbon amendments on FTW nitrate-N removal performance during the establishment year. Keywords: Best management practices, Carbon amendment, Floating treatment wetlands, Nitrogen removal, Spent coffee grounds