Synergistic Pollution Removal in Paper Mill Wastewater Using Monoculture-Constructed Wetlands Optimized by RSM

The effectiveness of manmade wetlands with four different macrophyte species (Arundo donax, Typha latifolia, Pistia stratiotes, and Eichhornia crassipes) in treating wastewater from the paper recycling industry, located in the Hattar Industrial Estate in Haripur, is reported. The findings show that each plant species has distinct pollutant removal capacities, which contribute to the overall treatment effectiveness of the system. Notably, Arundo donax performed exceptionally well in lowering chemical oxygen demand (COD) from 1013 mg/L to 119.66 mg/L and nitrate levels from 79.66 mg/L to 10.66 mg/L. In contrast, T. latifolia was successful in reducing biochemical oxygen demand (BOD) from 436 mg/L to 55 mg/L and total solids from 837.66 mg/L to 242.66 mg/L. The P. stratiotes species have high phosphate removal capacity, lowering values from 134.66 mg/L to 25.66 mg/L. RSM revealed that time, Arundo donax, and wetlands significantly enhance pollutant removal, while specific plant–treatment combinations yield variable efficiencies, highlighting synergistic effects crucial for optimal performance. Furthermore, all plant species have shown competency in removing heavy metals from effluent. This study’s findings highlight the potential of artificial wetlands as a natural and eco-friendly alternative for treating complex industrial wastewater, promoting the development of sustainable wastewater treatment methods in industrial settings.