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

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 240 min at a current density of 200 mA/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 83 mA/cm2 and 133 mA/cm2) has a COD such that could be discharged into the sewer and, after applying a current density equal to 200 mA/cm2 after 240 min, 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 240 min of electrolysis) at 200 mA/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.