A laboratory study on toxicity removal from landfill leachate in combined treatment with municipal wastewater

Combined treatment of landfill leachate and municipal wastewater were performed in order to investigate the changes of leachate toxicity during biological treatment. Three laboratory A2O models were operating under the same parameters (HRT- 1.5-1.6 d) except from the influent characteristic. The influent of modelA consisted of 15% (v/v) of landfill leachate and 85% (v/v) of tap water; influent of model B consisted of 15% (v/v) landfill leachate and 85% (v/v) of municipal wastewater; model C served as a control and its influent consisted of municipal wastewater only. Toxicity of raw and treated wastewater was determinate by three acute toxicity tests with Daphnia magna, Thamnocephalus platyurus and Vibrio fischeri. Landfill leachate increased initial toxicity of wastewater. It was concluded that synergetic toxic effect in mixture of leachate and wastewater was detected. During biological treatment significant decline of acute toxicity was observed but still mixture of leachate and wastewater was harmful to all tested organisms.