Landfill leachate treatment: Comparison of standalone electrochemical degradation and combined with a novel biofilter

•Landfill leachate treatment involving electrolysis using DSA® electrodes and a new type of biological reactor.•With a current density of 83mA/cm2 for 240min can be obtained an effluent dischargeable into sewer.•Where ammonia is present, 82% of it is removed after 240min of electrolysis at 200mA/cm2.•At 133 and 200mA/cm2, the AOX concentration decrease if the electrolysis is extended over 60–70min.•Electrochemical treatment leads to a decrease in toxicity, regardless the applied current density. Raw leachate and a biological effluent coming from the same raw leachate that has been biologically treated in a new type of biological reactor, were electrochemically treated. A batch-type electrolytic cell using two patented DSA® electrodes was employed. Raw leachate, treated for 240min at a current density of 200mA/cm2, falls within the sewer discharge limits set by Italian legislation for the COD. Instead, effluent obtained through combined biological and electro-oxidation treatment (by using 83mA/cm2 and 133mA/cm2) has a COD such that could be discharged into the sewer and, after applying a current density equal to 200mA/cm2 after 240min, has a COD value such that can even discharged into receiving water bodies. The electrochemical oxidation carried out is only effective on nitrogen ammonia through indirect electro-oxidation; it is not effective on other nitrogen-containing species. In any case, where ammonia is present (i.e., in the raw leachate), 82% is removed by the end of the test (i.e., after 240min of electrolysis) at 200mA/cm2. Also, for the raw leachate, chloramine formation is most marked at low current densities. Nevertheless, the toxicity does not appear to be affected; in fact, decrease regardless of the applied current density.