Performance of biological treatment of high-level ammonia landfill leachate.
The biological treatment efficiency of landfill leachate (LFL) from a Tunisian site collection was investigated in this study. The raw effluent was highly charged with organic matter (more than 25 g l(-1) of chemical oxygen demand (COD)), ammonia (1.7 g l(-1) and salts (20 g l(-1)). With the presence of heavy metals, phenols and hydrocarbons, LFL exhibited high toxicity to organisms since it totally inhibited the bioluminescence of Vibrio fischeri and the germination of Lepidium sativum seeds. The biological oxygen demand (BOD5)/COD ratio of 0.5 indicates that the effluent can be biologically treated. Sludge from a wastewater treatment plant was acclimatized to the effluent in continuous batches. During the acclimatization phase, the consortia demonstrated a good ability to remove organic matter and toxicity in spite of an increase of introduced load reaching 3.2 g of COD 1.d. Consequently, the biodegradation experiments were carried out in a stirred tank reactor (STR) at organic loading rate (OLR) ranging from 0.5 to 5.4 g l(-1) per day. The hydraulic retention time was decreased from 50 days to 4.6 days. The process seemed to be efficient to eliminate organics and ammonia. The COD removal efficiency reached a maximum of 80% for a loading rate of 5.4 g l(-1) per day. The values of N-NH4+ became less than those recommended by standards requested for rejection in public canalizations. During the treatment process, the biomass was increased from 0.8 g l(-1) at the start-up of the process to 3 g l(-1). On the other hand, results of toxicity examinations showed that the treatment was efficient to provide detoxification of the effluent indicating a good adaptability of the consortia in spite of the presence of problematic compounds. The increase of the loading rate up to 6 g l(-1) was responsible for the perturbation of the system and caused an accumulation of residual COD and toxicity.
Ellouze
M
M
Laboratoire des Bioprocédés, Pôle d'Excellence Régional AUF, Centre de Biotechnologie de Sfax, BP: 1177, 3038, Sfax, Tunisia. ellouze_mariem@yahoo.fr
Aloui
F
F
Sayadi
S
S
D048908:Aliivibrio fischeri / Q000187:drug effects; D000641:Ammonia / Q000378:metabolism* / Q000633:toxicity; D001673:Biodegradation, Environmental; D019149:Bioreactors; D031220:Lepidium sativum / Q000187:drug effects; D009930:Organic Chemicals / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology; D014416:Tunisia; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
D009930:Organic Chemicals; D012722:Sewage; D014874:Water Pollutants, Chemical; D000641:Ammonia; D010100:Oxygen