Effects of Plants and Plant Fermentation Broth on the Removal and Characteristics of Dissolved Organic Matter in Self-Supplying Carbon Source Constructed Wetlands Treating Secondary Effluent

Abstract

Abstract In this study, four constructed wetlands (CWs) were developed. The effects of plants and plant fermentation broth on the removal and characteristics of dissolved organic matter (DOM) were evaluated. As the ratio of added COD to influent nitrate (CODAdd/NO3-N ratio) increased from 0 to 4, the DOC removal rate increased from 0.48 to 5.41 g m−3 d−1 in the unplanted microcosms, and from 0.75 to 5.73 g m−3 d−1 in the planted ones. The presence of plants could increase the DOC removal rate from 0.48–5.41 g m−3 d−1 to 0.75–5.73 g m−3 d−1. This indicated that both the addition of plant fermentation broth and planting could greatly improve the DOC removal during the CW treatment. Moreover, adding plant fermentation broth introduced highly aromatic compounds into the microcosms, and thus increased the UV254 and SUVA values of the effluent. The plants could lower the effluent UV254 value through improving the removal of aromatic compounds, but it increased the SUVA value by increasing the proportion of aromatic compounds in total DOMs.