Partition and Fate of Phthalate Acid Esters (PAEs) in a Full-Scale Horizontal Subsurface Flow Constructed Wetland Treating Polluted River Water

Abstract

When used as highly produced chemicals and widely used plasticizers, Phthalate acid esters (PAEs) have potential risks to human life and the environment. In this study, to assess the distribution and fate of PAEs, specifically inside a full-scale horizontal subsurface flow constructed wetland, four PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and bis (2-ethylhexyl) phthalate (DEHP) were investigated. In effluent, PAEs concentration decreased 19.32% (DMP), 19.18% (DEP), 19.40% (DBP), and 48.56% (DEHP), respectively. Within the wetland, PAEs partitioned in water (0.18–1.12 μg/L, 35.38–64.92%), soil (0.44–5.08 μg/g, 1.02–31.33%), plant (0.68–48.6 μg/g, 0.85–36.54%), air and biological transformation (2.72–33.21%). The results indicated that soil and plant adsorption contributed to the majority of PAE removal, digesting DMP (19.32%), DEP (19.18%), DBP (19.40%), and DEHP (48.56%) in constructed wetlands. Moreover, the adsorption was affected by both octanol/water partition coefficient (Kow) and transpiration stream concentration factors (TSCF). This work, for the first time, revealed the partition and fate of PAEs in constructed wetlands to the best of our knowledge.

Removal of Emerging Pollutants in Horizontal Subsurface Flow and Vertical Flow Pilot-Scale Constructed Wetlands

“…Table 4 shows no statistically significant differences (p > 0.05) in percent removal between the HSF-CW units. The removal of DEHP in the present study was found to be higher than the removals reported in previous studies, e.g., 48.6% DEHP removal in a full-scale HSF-CW [69]. Moreover, Xiaoyan et al [6] reported removal of 31-45% and 21-34% for DNOP and DEHP, respectively, in pilotscale HSF-CW units-values lower than in the present study.…”

“…Zheng et al [69] reported 19.4% DIBP removal in a full-scale HSF-CW, which is lower than that of the present study, and the main removal mechanism was the adsorption on the substrate. On the other hand, Reyes-Contreras et al [48] reported percent removals of about 30%, 20% and 50% in winter (February 2008) and 15%, 25% and 25% in summer (June-July 2009) for DEP, DIBP and DEHP, respectively, in an HSF-CW unit with 75 m 2 surface in plan-view and HRT of 2.3 days.…”

“…According to Verlicchi and Zambello [68], cattails have been found in some studies to be more effective in EP removal, while other studies found reeds to be more effective. Zheng et al [69] reported 19.2% DEP removal in a full-scale HSF-CW, which is lower than that of the present study.…”

“…This means that the contribution of plants to the removal of these compounds is negligible. On the other hand, many studies have reported that as LogK ow increases, there is a greater tendency for PEs to adsorb on substate or accumulate in plants [6,13,69,80]. DIBP, DNOP and DEHP have low water solubility and LogK ow > 4, and, therefore, high adsorption of them on substrate is expected.…”

Temporal and Spatial Evaluation of Mono(2-ethylhexyl) Phthalate (MEHP) Detection in Common Bottlenose Dolphins (Tursiops truncatus) from Sarasota Bay, Florida, USA

“…Phthalates are not chemically bound to the products they modify and can easily leach into the environment via wastewater, industrial releases, manufacturing disposal, and breakdown from products containing phthalates [1,7]. These inputs have been reported to contaminate freshwater [8,9], seawater [10], sediment [9,11], soil [12,13], the atmosphere [14,15], and the non-target biota in these matrices [16][17][18]. The pervasive use and migration of phthalates from consumer products have resulted in widespread marine contamination reported in areas that range from remote (e.g., Aleutian Islands [19] and the High Arctic [20]) to urbanized (e.g., coastal areas along the Persian Gulf [21] and the Qiantang River, China [22]) locations.…”