Effect of wastewater irrigation on mineral uptake of Typha latifolia and Phragmites australis in arid environment

Water scarcity and pollution are pressing challenges in arid regions where conventional wastewater treatment systems are often impractical. Constructed wetlands (CWs) offer a sustainable, low-cost alternative; however, the comparative mineral uptake capacities of key wetland species under arid conditions remain underexplored. This study reports a two-year field experiment in eastern Saudi Arabia comparing two species, Typha latifolia L. (T. latifolia) and Phragmites australis (P. australis) (Cav.) Trin. ex Steud. (P. australis), for their capacity to accumulate heavy metals and macronutrients when irrigated with wastewater. Plants were cultivated in controlled CW systems, and aboveground biomass was analyzed at multiple intervals. Results reveal that P. australis accumulated higher levels of trace metals, notably manganese, with concentrations of 161.47 mg·kg⁻¹ compared to 83.65 mg·kg⁻¹ in T. latifolia). This difference corresponds to a statistically significant 48.2% increase (p ≤ 0.05) relative to T. latifolia. Although aluminum (+ 14.5%) and vanadium (+ 25.5%) uptake was slightly higher in P. australis, these differences were not statistically significant. Uptake varied widely among elements, reflecting species-specific and temporal dynamics. In contrast, T. latifolia demonstrated a much stronger affinity for macronutrients, particularly for sodium (12,476 vs. 1065 mg·kg⁻¹) and potassium (13,475 vs. 4308 mg·kg⁻¹), exceeding P. australis by over 1000% and 200%, respectively (p ≤ 0.05), with highly significant differences (p ≤ 0.05). Magnesium uptake was also consistently higher in T. latifolia compared with P. australis (1823 vs. 1442 mg·kg⁻¹; p ≤ 0.05). These findings reveal complementary roles between the two macrophytes: P. australis is more effective at trace metals removal, while T. latifolia excels in macronutrient uptake and biomass production. Integrating both species in CWs can enhance multipollutant removal efficiency and long-term treatment performance. The study provides practical guidance for designing phytoremediation systems in arid regions and support the development of decentralized wastewater treatment solutions for small and rural communities where conventional infrastructure is limited.