Removal of organic contaminants by constructed wetlands and solar-based oxidation processes

Abstract

Micropollutants (MPs), substances that exist in very small traces in water, have been attracting the attention of the scientific community because of their frequent occurrence in the aquatic environment even after passing through conventional water and wastewater treatment systems. A large number of sources thus contribute to the introduction of MPs into the environment. Waste water treatment plants (WWTP) are also considered the major source of MPs entrance in the aquatic environment. Thus, appropriate treatment processes capable of removing MPs and other relevant pollutants need to be adopted in order to preserve the environment. So that, a hybrid process constructed wetland (CW) and advanced oxidation process (AOP) has been investigated in this study. The performance of MPs removal from constructed wetlands was investigated using two different aquatic plants (Phragmites australis and Cyperus haspan) and two modes of operation (with or without recirculation). The results revealed that no significant differences were observed between plants. However, an enhancement of the MPs elimination was achieved in the CW with recirculation (about 80 % of some MPs) compared to the CW without recirculation (about 50 % of MPs elimination). Additionally, it was studied the potential of CWs as a pretreatment of photo-Fenton in order to improve the process’ efficiency on MPs degradation. The results disclosed that total removal of MPs were achieved in less than 30 min in the matrices pretreated with recirculated CW while less than 80% of MPs removal was obtained in 120 min without pretreatment.