Optimizing Treatment of Landfill Leachate

Managing leachate is an important part of operating and maintaining any landfill. The volume of leachate generated at a particular site can be reduced by taking measures to control stormwater. Evaporation-based methods are also effective at reducing the volume of landfill leachate. For some sites, off-site disposal of leachate may be the best option. The operator or manager of the landfill must consider the cost, efficacy, and environmental impact of the available options.

Many types of leachate treatment technologies can be classified as either biological or chemical/physical. Aerobic and anaerobic biological treatments are two methods. Another is physiochemical treatment—pH adjustment, chemical precipitation, oxidation, etc. Activated sludge is a common biological treatment that uses microorganisms to break down the organic contaminants present in leachate.

For treating the dissolved organic matter in landfill leachate, electrochemical oxidation (EO) is one option. A study was published this past week by the International Water Association’s journal, Water Research, that examines the energy efficiency of the EO method and the formation of oxidation byproducts (particularly ClO3− and ClO4−) that occurs.

The study is titled, “Changes of dissolved organic matter fractions and formation of oxidation byproducts during electrochemical treatment of landfill leachates: development of spectroscopic indicators for process optimization.” You might need an advanced degree in chemistry to fully understand the findings, but I've summarized some of the highlights below.

The researchers conducted EO treatment of landfill leachate “using representative active and nonactive anode materials, cell configurations and current densities,” according to the abstract. They noted that the sensitivity of dissolved organic matter (DOM) fractions to EO degradation depended on the anode material used.

“The nonactive boron-doped diamond (BDD) anode demonstrated the best performance for DOM oxidation,” the authors of the study write. Their findings indicate that it is possible to optimize the electrochemical oxidation of leachate by making adjustments to the current density based on feedback signals from monitoring the absorbance of leachate at 420 nm. This way, the EO method enables a balance between controlling the formation of oxidation byproducts and successfully degrading the dissolved organic matter.