Decrease in ecotoxicity of leachate

Bio-essays indicated that leachate recirculated through the simulated aerobic bioreactor examined at the end of the experiment was not toxic for freshwater organisms. A toxicity test was performed on bioindicator Daphnia magna. In this test young Daphnia are exposed to various concentrations of the tested substance. The test involved the determination of the concentration of a substance in a water solution, where a half of the number of bioindicators dies. This value is called a lethal concentration (LC. It was stated that toxicity of the examined leachate dropped to zero after one year of the experiment (Table 4.2). That means that the chance to survival of the bioindicators in undiluted leachate was over 50% (Giannis et al. 2006). 

Metal Unit After 30 days After 240 days After 510 days 

Time of aeration [days] Lethal concentration LC u in 24 hours test [percent of leachate in diluted sample, %] 

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