Performance of coagulation-flocculation followed by ultra-violet/ultrasound activated persulfate/hydrogen peroxide for landfill leachate treatment
Hamza Bellouk, Imane El Mrabet, Karim Tanji, Mostafa Nawdali, Mourad Benzina, Mabrouk Eloussaief, Hicham Zaitan
Abstract
The advanced oxidation processes (AOPs) were assessed for enhancing the treatment of stabilized landfill leachate previously pretreated using coagulation-flocculation (C-F). The primary treatment by C-F using 20 g.L−1 of FeCl3 (optimal coagulant dosage) has removed 71% of chemical oxidation demand (COD) and 95% of turbidity. Thereafter, secondary treatment was applied using different system combinations of two inorganic oxidants (potassium persulfate, K2S2O8 (PS) (1500 mg. L−1) and hydrogen peroxide, H2O2 (1327 mg. L−1)) that were used simultaneously or separately with UV-A and/or ultrasonic (US) irradiations. The obtained results indicated that the oxidation systems with the presence of H2O2 were more efficient than other systems. Indeed, the H2O2-PS-US-UV-A system reached the highest COD removal of 89%, while PS-based combinations were the less efficient (PS alone 19%, PS-UV-A 22%, PS-US 32%, and PS-US-UV-A 35%). Hence, the sequential process including C-F as pretreatment followed by the application of the H2O2-PS-US-UV-A system has proven high efficiency for COD removal, absorbance at 254 nm, and color number of 97%, 97%, and 99%, respectively. The sequential application of AOPs after preliminary treatment using coagulation-flocculation is a promising alternative to reducing the high organic load of stabilized leachate and that could be largely applied to other types of effluents.