Treatment of Landfill Leachates with Combined Acidification/Coagulation and the Fe0/H2O2 Process

One of the major environmental concerns associated with waste disposal is the large amount of generated landfill leachates (LL), which are considered a type of wastewater with a complex composition. There is an urgent need to find an effective LL treatment method. LL were subjected to pretreatment followed by the Fe-0/H2O2 process. Pretreatment efficiency was coagulation at pH 6.0 >> coagulation at pH 9.0 > acidification at pH 3.0. Coagulation at pH 6.0 in an optimal Fe3+ dose of 1000 mg/L decreased total organic carbon (TOC) from the initial concentration of 1061 mg/L to 491 mg/L while acidification to pH 3.0 decreased TOC to 824 mg/L. After acidification, the Fe-0/H2O2 process with 8000/9200 mg/L Fe-0/H2O2 reagent doses decreased TOC to 499 mg/L after a processing time of 60 min. Performance of the Fe-0/H2O2 process after coagulation at pH 6.0 for optimal Fe-0/H2O2 8000/5540 mg/L reagent doses decreased TOC to 268 mg/L (75% TOC removal). Treatment of landfill leachates with combined process coagulation and Fe-0/H2O2 also increased their susceptibility to biodegradation, expressed as the biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio from 0.13 to 0.43, allowing LL to be considered as susceptible to biodegradation. Fe-0/H2O2 process kinetics was described. A statistical analysis confirmed the obtained results. The proposed method can be successfully applied for LL treatment.