Evaluation of Bio-toxicity Removal by Two-Stage Membrane Bioreactor for Landfill Leachate Treatment

Two-stage membrane bioreactor was applied to the treatment of municipal solid waste landfill leachate. This study aimed to evaluate the toxicity of treated leachate by this system. Bio-toxicity (acute and geno-toxicity) were conducted using O. niloticus and C. carpio. The lethal concentrations (LC50) of selected species exposed to raw leachate and treated leachate were investigated. Comet assay was utilized for evaluation of geno-toxicity potential of raw and treated leachate using carried out at the 10th percentile of lethal concentration (LC10) that obtained from the acute toxicity test. The relationship between pollutant concentrations i.e., NH3, COD and mortality were analyzed on Finney’s probit analysis. The results found that ammonia was the principal pollutants causing toxicity in landfill leachate. Nevertheless, toxicity effect between ammonia and organic concentrations was also observed. The corresponding ammonia concentration causing 50% mortality of C. carpio and O. niloticus after 96 hour exposure were 2.3-2.6 and 2.2-2.5 mg/l respectively. The sensitivity test of geno-toxicity effect at the level of DNA damage show that O. niloticus was considerably more sensitive to leachate. The membrane bioreactor system helps reducing toxic organic compounds and bio-toxicity on living organisms.