Résumé :
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Leachate samples were collected from the West New Territory Landfill (WENT), Hong Kong, and characterized in the laboratory. The analytical results confirmed that it has a typical nature of aged leachate with a low BOD COD ratio of 0.22 and a high strength of ammonia-nitrogen around 5 g L. A lab-scale study was conducted to investigate the inhibition of microbial activity of the activated sludge. In the first test, glucose-based synthetic wastewater was used in two parallel reactors. The experimental results demonstrated that COD removal declined from 95.1 to 79.1% and the dehydrogenase activity of the sludge decreased from 11.04 to 4.22 g TF mg mixed liquor suspended solids (MLSS), when the ammonia-nitrogen concentration increased from 50 mg L to 800 mg L progressively. The remaining NH-N residue in the treated wastewater increased from 0.58 mg L to 649 mg L extensively. In the second test, mixed wastewater samples containing glucose and raw leachate were fed into six parallel biological reactors and operated on batch mode. The experimental results showed COD removal decreased from 97.7 to 78.1% and the dehydrogenase activity decreased from 9.29 to 4.93 g triphenyl formazon (TF) mg MLSS, respectively, when the ammonia-nitrogen concentration increased within the same range.
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