Electrochemical technology for the treatment of landfill leachate
Wastewater treatment, electrochemical technology, electro-Fenton, environmental remediation
Most solid waste ends up in landfills around the world, which hurts the environment in a number of ways. In particular, rain and waste decomposition in landfills result in the production of an aqueous leachate containing compounds with low biodegradability, high toxicity, and high organic load. To prevent the introduction of this toxic mixture into the environment, remedial measures are necessary. Electrochemical technologies are particularly suitable for wastewater purification and contaminant reuse. Therefore, in this study, the application of electro Fenton (EF) and photo electro Fenton (PEF) processes was investigated to treat local landfill effluent with high conductivity (k = 15.8 mS cm-1) and high organic content (total organic carbon (TOC) = 1220 mg L-1). Specifically, a flow cell containing a boron-doped diamond (BDD) anode and a carbon felt (CF) cathode was developed to evaluate the effects of applied current density (30, 60 or 90 mA cm-2), production of H2O2, and the source of UV radiation (UVC and UVA) on the chemical oxygen demand (COD) of the effluent. In addition, acetic and formic acids (final organic by-products of effluent degradation), as well as inorganic ion concentrations (Cl-, NO2-, NO3- and NH4+ and PO43-) were evaluated. Maximum degradation and mineralization of the effluent were obtained with increasing applied current density, at which more than 90% of the total organic carbon (TOC) was removed after 240 min of PEF UVC with the BDD anode at 90 mA cm-2. Therefore, EF and PEF are efficient and effective solutions for the remediation of organic pollutants in landfill effluents, especially when using the BDD anode. The integration of technologies for wastewater treatment can significantly increase the degradation efficiency of organic compounds, as well as make electrochemical technologies a sustainable alternative, through the use of renewable energy for the treatment of leachate from landfills in low-income countries.