Evaluation of final treatment with fenton oxidation of treated leachate by electrodialysis bipolar membrane process

In present study, according as solid waste storage time, young, middle-aged and old leachates were treated with the combination of ultrafiltration (UF), five stage ion exchanger and electrodialysis with bipolar membrane (EDBM) process. The final treatment with fenton oxidation was investigated for EDBM effluents.Operating parameters (H2O2:COD rate, H2O2:Fe+2 rates, pH and reaction time), which are important to Fenton oxidation, were determined and four factor-five level Central Composite Experimental Design was selected for obtaining experimental sets. Experimental studies for determination of the relationship between independent variables (H2O2:KOİ rate, H2O2:Fe+2 rate, pH ve reaction time) and dependent variables (response function; COD removal, TOC removal, color removal and NH3-N removal) have been optimized using Response Surface Methodology (RSM). Operating parameters of experimental sets, which were obtained from the highest COD removal efficiencies, were determined for middle-aged leachate (H2O2:COD=1, H2O2:Fe+2=15, pH=3, time=90 min), for young leachate (H2O2:COD=0,6, H2O2:Fe+2=5, pH=3, tine=90 min), and for old leachate (H2O2:COD=0,6, H2O2:Fe+2=5, pH=3, time=90 min).In middle-aged leachate treatment by Fenton oxidation, COD, TOC, color and NH3-N removal efficiency were achieved between 59-87%, 56-82%, 74-97%, and 19-37%, respectively. In young leachate treatment by Fenton oxidation, COD, TOC, color, and NH3-N removal efficiency were found between 29-54%, 8-38%, 74-97% and 40-55% respectively. In old leachate treatment by Fenton oxidation, COD, TOC, color and NH3-N removal efficiency were obtained between 2-79%, 1-74%, 14-98% and 35-59%, respectively. At the end of the optimization, the maximum removal efficiencies for COD, TOC, color, NH3-N were estimated by the model for all types of leachate. In consequence of the final treatment with Fenton oxidation, BOD5/COD rate increased to 0.554 from 0.275 for middle-aged leachate, increased to 0.679 from 0.470 for young leachate, and increased to 0.337 from 0.066 for old leachate.According to the results obtained from middle-aged and old leachate experiments, discharge limits have achieved the deep sea discharge criteria (COD<600 mg/L) based on İSKİ Sewer Discharge Regulation. On the other hand, for young leachate, the discharge limits (COD<4000 mg/L) have been provided for full-scale wastewater treatment systems from the end of sewer systems based on same regulation.