Nutrient levels in a constructed wetland system Gložan (Vojvodina Province)

Abstract

The constructed wetland system (CWS) located near the village of Gložan is the first system for wastewater treatment built in the Vojvodina Province (Serbia). The CWS at Gložan has been designed to treat municipal wastewater. The CWS uses the reed (Phragmites australis (Cav.) Trina. Ex Steud.) as a biofilter, the plant species that had grown naturally at the site prior to the construction of the CWS. In the study period, the Gložan CWS proved to be capable of effectively removing nutrients from wastewater. Removal rates for nitrogen compounds ranged from 47.3% for nitrates, 47.5% for ammonium, to 78.3% for nitrites, while the phosphorus removal rate was 29.1%. The efficiency of the system is clearly a result of a combined action of microbes and the reed residing in the CWS. The analysis of the chemical composition of the reed confirmed that it acted as a biofilter, i.e., nutrients were found to accumulate in its parts. Reed leaves accumulated largest amounts of nitrogen (up to 42.7 g kg -1 DM), while the inflorescence accumulated largest amounts of phosphorus (up to 2.1 g kg -1 DM). The Gložan CWS retained on average 292 kg P year -1 and 2920 kg N year -1.