Intermittent aeration to improve wastewater treatment efficiency in pilot-scale constructed wetland

• Published in: The Science of the total environment 2016-07, Vol.559, p.212-217
• Main Authors: Uggetti, Enrica, Hughes-Riley, Theodore, Morris, Robert H., Newton, Michael I., Trabi, Christophe L., Hawes, Patrick, Puigagut, Jaume, García, Joan
• Format: Article
• Language: English
• Subjects: Ammonium removal; Constructed wetlands; Desenvolupament humà i sostenible; Enginyeria ambiental; Enginyeria civil; Enginyeria hidràulica, marítima i sanitària; Enginyeria sanitària; Horizontal sub-surface flow; Intermittent aeration; Nitrification/denitrification; Tractament de l'aigua; Zones humides artificials; Àrees temàtiques de la UPC
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.03.195

Forced aeration of horizontal subsurface flow constructed wetlands (HSSF CWs) is nowadays a recognized method to improve treatment efficiency, mainly in terms of ammonium removal. While numerous investigations have been reported testing constant aeration, scarce information can be found about the efficiency of intermittent aeration. This study aims at comparing continuous and intermittent aeration, establishing if there is an optimal regime that will increase treatment efficiency of HSSF CWs whilst minimizing the energy requirement. Full and intermittent aeration were tested in a pilot plant of three HSSF CWs (2.64m2 each) fed with primary treated wastewater. One unit was fully aerated; one intermittently aerated (i.e. by setting a limit of 0.5mg/L dissolved oxygen within the bed) with the remaining unit not aerated as a control. Results indicated that intermittent aeration was the most successful operating method. Indeed, the coexistence of aerobic and anoxic conditions promoted by the intermittent aeration resulted in the highest COD (66%), ammonium (99%) and total nitrogen (79%) removals. On the other hand, continuous aeration promotes ammonium removal (99%), but resulted in nitrate concentrations in the effluent of up to 27mg/L. This study demonstrates the high potential of the intermittent aeration to increase wastewater treatment efficiency of CWs providing an extreme benefit in terms of the energy consumption. [Display omitted] •This study tests intermittent and full aeration to improve wastewater treatment.•Intermittent aeration reached better COD, ammonium and total nitrogen removals.•Full aeration promotes ammonium removal, but with higher nitrates in the effluent.•Intermittent aeration is an energy efficient solution to improve wastewater quality.