Phytoengineered Remediation of BTEX and MTBE Through Hybrid Constructed Wetlands Planted with Heliconia latispatha and Phragmites australis

Water pollution caused by petroleum-derived volatile organic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX), as well as methyl tert-butyl ether (MTBE), poses a growing threat to aquatic ecosystems and human health. These contaminants, together with the organic matter and nutrients present in municipal wastewater, highlight the need for sustainable treatment technologies adapted to tropical conditions. This study evaluated the removal efficiency of BTEX, MTBE, and conventional pollutants using hybrid constructed wetlands (HCWs) that combine vertical subsurface flow (VSSF-CW) and horizontal subsurface flow (HSSF-CW) systems. Two plant species—Heliconia latispatha and Phragmites australis—were tested, along with a polyculture and an unvegetated control. The hybrid systems treated synthetic influents formulated to simulate contaminated municipal wastewater. Parameters including COD, TSS, N–NH4+, N–NO3−, P–PO43−, BTEX, and MTBE were monitored and analyzed using ANOVA and Tukey’s test (p < 0.05). Vegetated systems achieved COD removal efficiencies exceeding 85%, compared with 72% in the control. Phragmites australis obtained the highest removal of suspended solids (92 ± 3%) and ammonium nitrogen (88 ± 2%), whereas Heliconia latispatha exhibited superior phosphorus removal (84 ± 4%). The polyculture displayed a synergistic effect, achieving removal rates of 93% for benzene, 91% for toluene, and 88% for MTBE, with statistically significant differences relative to the control (p < 0.05). In conclusion, hybrid constructed wetlands planted with Heliconia latispatha and Phragmites australis demonstrated high efficiency and stability in removing BTEX, MTBE, and conventional pollutants under tropical conditions, positioning themselves as a sustainable, low-cost, and esthetically valuable treatment alternative.