Oxidation Of Landfill Leachate Research Articles

Formation of disinfection byproducts during Fenton’s oxidation of chloride-rich landfill leachate

Because of the production of chlorine species in leachate during Fenton’s oxidation, harmful disinfection byproducts (DBP) can be formed but this has not been well studied before. Herein, we have investigated five classes of DBP: trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, and halonitromethanes during Fenton’s oxidation of landfill leachates. The results show that the DBP concentration increased with the increase of [H2O2]: [Cl−] ratio due to the increased concentration of chlorine species. The highest total DBP concentration was 4860 μg L-1 at [H2O2]: [Cl−] = 4.0 and the lowest was 84 μg L-1 at [H2O2]: [Cl−] = 0.25. Both the DBP concentration and DBP toxicity increased with the increase of the [H2O2]: [Fe2+] ratio, because of the increased concentration and lifetime of the chlorine species. Most of the DBP were formed during the first minute of the reaction and stayed stable up to 3 h, indicating that DBP may not be preferred targets of hydroxyl radicals in the presence of a large amount of organics. In most cases, trihalomethanes dominated the DBP concentration, while haloacetonitriles dominated the total additive toxicity. This study has provided important implications to understand DBP formation during Fenton’s oxidation.

Reduction of reagent requirements and sludge generation in Fenton's oxidation of landfill leachate by synergistically incorporating forward osmosis and humic acid recovery

Applications of Fenton's oxidation of landfill leachate is limited by both high reagent requirements and a large amount of sludge generation. To address those issues, forward osmosis (FO) and humic acid (HA) recovery were incorporated with Fenton's treatment. In the FO, leachate was concentrated by 3.2 times in 10 hours using a 5-M NaCl draw solution. The HA recovery increased from 1.86 to 2.45 g L−1 at pH 2 after FO concentration, mainly because of the replacement of O in the HA structure by other inorganics (i.e., Cl, Na, K) with higher molecular weights. Due to the movement of alkalinity causing species (i.e., HCO3−, CO32-) to the draw side driven by a concentration gradient, the H2SO4 requirement per g of recovered HA and per g of removed COD decreased by 46.4% and 17.1%, respectively. The HA recovery also decreased sludge generation by 30%. At a dimensionless oxidant dose of 0.5, the proposed system reduced the overall requirement of H2SO4 by 25.2%, NaOH by 34.6%, and both FeSO4.7H2O and H2O2 by 35%, compared to the standalone Fenton's treatment of raw leachate. Those results have demonstrated that the proposed system could greatly decrease the leachate volume, lower the reagent requirements, and reduce the sludge production towards sustainable leachate treatment.

DEVELOPMENT OF AN ELECTROCHEMICAL OXIDATION PROCESS FOR THE TREATMENT OF LANDFILL LEACHATES

ABSTRACTSome landfill site operators use wastewater treatment plants for the discharge of complex leachate waste. However, for the water company involved in managing the wastewater plant, leachates can pose a problem to the quality of the effluent, due to the high levels of Chemical Oxygen Demand (COD), ammonia and inorganic metal constituents. Electrochemical oxidation of landfill leachate has been successfully used by researchers(1,2,3,4) with current densities of 5 to 100 mA/cm2. A new laboratory system has been developed which utilises a low current density of 2.42 mA/cm2 and the performance has been evaluated with synthetic and ’real’ landfill leachates from 2 wastewater sites.This system reduces COD of synthetic mixtures by 58%, with complete removal of ammonia. For real leachates, 5 out of 8 samples resulted in ammonia reduction, with 2 samples experiencing approximately. 60% COD reduction. Power costs for treatment have been determined and the potential for a full‐scale installation considered.