Sustainable Chemistry for the Environment (Mar 2024)
Optimization of landfill leachate through hybrid treatment of phytoremediation and photocatalysis using response surface methodology
Abstract
The pollution caused by landfill leachate (LFL) worldwide is increasing as more LFL is generated without appropriate treatment, especially in developing countries. This research combines photocatalytic degradation and phytoremediation processes to treat mature LFL effectively. Before biological treatment (phytoremediation), a pretreatment process (photocatalytic degradation) was applied to increase the biodegradability of LFL. The two processes were batch and water hyacinth (Eichhornia crassipes), which was the plant model used for phytoremediation. The treatment processes were investigated using the Association of Official Analytical Chemists (AOAC) standard method to evaluate the removal efficiency of some physicochemical properties total organic carbon [(TOC), chemical oxygen demand (COD), biological oxygen demand (BOD), ammonia nitrogen (NH3-N), total dissolved solids (TDS), total organic carbon (TOC) iron (Fe), zinc (Zn)]. The results showed that for phytoremediation, the best dilution was 4:1 leachate: water (v/v), and the significant removal of TDS, COD, NH3-N, TOC, BOD5, Fe, and Zn was 70.13%, 68.48%, 48.3%, 72.83%, 60.53%, 39.6%, and 42.75% respectively. Moreover, combining photocatalysis and phytoremediation treatments of LFL gave removal efficiency greater than 90% for all the parameters. The predicted COD removal efficiency via the RSM model is 68.89%, and the model was a quadratic regression with R2 of 98.55% and desirability of 1.0. The optimum conditions are pH (9.0), irradiation time (60 min), catalyst loading (0.95 g/L), and light intensity (400 W). The titanium dioxide-periwinkle shells ash (TiO2-PSA) nanoparticles have good recyclability, showing a strong possibility of the photocatalytic/biological combined treatment of LFL.
