Toxicity elimination of landfill leachate by hybrid processing of advanced oxidation process and adsorption

Landfill leachates are high polluting charge effluents, in particular those from stabilized landfill, so that they are difficult to treat by biological processes due to their high toxicity that inhibit the microbiological activity. This research investigates processes such as photoelectrooxidation (PEO) and the addition of activated carbon (PEO+AC) to treat a leachate from a stabilized landfill, as well as the influence of these processes in eliminating toxicity of the leachate through bioassays in Allium cepa (onion bulbs). PEO process improved the biodegradability of the effluent and, simultaneously, an ammonium nitrogen removal of 44% was achieved. However, PEO did not reduce the toxicity of the effluent, on the contrary, it caused an increase of species organic compounds. In Allium cepa assay the PEO treatment resulted only in the reduction of effluent toxicity. In contrast, the integration of PEO and activated carbon processes, have improved the efficiency of treatment, presenting a COD, ammonium nitrogen and total Kjeldahl nitrogen removal of 67.2%, 58.3% and 48.4%, respectively. After PEO+AC treatment all the concentrations tested reduced the effluent toxicity and did not differ in the mitotic index parameter from negative control indicating also the elimination of the cytotoxicity in Allium cepa.