Batch Sorption Experiments on Low-Cost Composite Adsorbent to Treat Total Iron in Landfill Leachate

摘要

Total iron is one of the problematic contaminants existing in the landfill leachate, which may lead to both ground and surface water pollution. This study was conducted to find out the potential of a low-cost composite adsorbent (COM) to treat total iron in landfill leachate using batch sorption experiments. The COM was composed mainly of brick-and-mortar waste and biochar with small amounts of granular activated carbon (GAC) and natural zeolite. Both kinetic and adsorption isotherm experiments were conducted for the COM as well as for its ingredients individually, to optimize the contact time and mass of the adsorbent, respectively. The removal efficiency of the COM was 95.0%, whereas that of high-cost zeolite and GAC were 89.7% and 93.0%, respectively. The initial total iron concentration, stirring speed, temperature, and initial pH were optimized for the COM. The total iron removal efficiency increased with the increment of the initial total iron concentration, stirring speed and temperature, and the reduction of the initial pH of the influent. Finally, a verification test was conducted with the COM at the optimum conditions. Four replicates were tested. All the replicates gave an average removal efficiency of 99.2 %. The average adsorption capacity was 1.3 mg/g, and the measurements were fitted the best with a Langmuir isotherm model with R~2 equal to 1. Hence, the COM has the potential to be applied as a reactive/packing medium in any treatment process of landfill leachate or wastewater of the similar characteristics as landfill leachate.