Removal of chemical oxygen demand,nitrogen, and heavy metals using a sequenced anaerobic-aerobic treatment of landfill leachates at 10-30 degrees C |
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Authors: | Kalyuzhnyi Sergey Gladchenko Marina Epov Andrey Appanna Vasu |
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Institution: | (1) Department of Chemical Enzymology, Chemistry Faculty, Moscow State University, 119899 Moscow, Russia;(2) Department of Chemistry and Biochemistry, Laurentian University, Ramsey Lake Road, P3E 2C6 Sudbury, Ontario, Canada |
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Abstract: | As a first step of treatment of landfill leachates (total chemical oxygen demand COD]: 1.43–3.81 g/L; total nitrogen: 90–162
mg/L), performance of laboratory upflow anaerobic sludge bed reactors was investigated under mesophilic (30°C), submesophilic
(20°C), and psychrophilic (10°C) conditions. Under hydraulic retention times (HRTs) of about 0.3 d, when the average organic
loading rates (OLRs) were about 5 g of COD/(L·d), the total COD removal accounted for 81% (on average) with the effluent concentrations
close to the anaerobic biodegradability limit (0.25 g of COD/L) for mesophilic and submesophilic regimes. The psychrophilic
treatment conducted under an average HRT of 0.34 d and an average OLR of 4.22 g of ducted under an average HRT of 0.34 d and
an average OLR of 4.22 g of COD/(L·d) showed a total COD removal of 47%, giving effluents (0.75 g of COD/L) more suitable
for subsequent biologic nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for
elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulfides inside the
sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was
acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated
waste-water. |
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Keywords: | Landfill leachate upflow anaerobic sludge bed reactor heavy metals simultaneous anaerobic removal of ammonia and sulfate aerobic-anoxic biofilter nitrification denitrification |
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