Removal of conventional water quality parameters, emerging contaminants and fluorescing organic matter in a hybrid constructed wetland system

Abstract

Constructed wetlands (CWs) are nature-based wastewater treatment systems, which are often implemented in decentralized areas and small communities. In recent decades, the CW technology has rapidly evolved through the use of various designs and operational modes or other intensifications so as to improve effluent water quality with respect to various pollutants from wastewater. In the present study, the removal of conventional water quality parameters, emerging organic contaminants (EOCs) and fluorescence signature was investigated in a hybrid constructed wetland system comprising different CW configurations: (i) unsaturated vertical subsurface flow (VF), (ii) partial saturated vertical subsurface flow (VF sat), (iii) saturated horizontal flow (HF) and (iv) free water surface (FWS) wetlands. The obtained results showed higher removal of BOD5, COD and fluorescing organic matter in the aerobic VF reactor, whereas the anoxic HF wetland was the most efficient unit for nitrogen removal. The partially saturated VF wetland showed a greater performance in the reduction of nitrogen and highly biodegradable EOCs than the unsaturated VF bed. Finally, linear regression analyses performed between removal of water quality parameters, EOCs and fluorescence measurements suggested the possibility to use fluorescence indexes as useful indicators of water treatment efficacy and/or surrogate parameters for EOCs monitoring.