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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 13, No. 1, 2016, pp. 21-30
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Bioline Code: st16002
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 13, No. 1, 2016, pp. 21-30
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Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration
Tomei, M.C.; Carozza, N.A. & Mosca Angelucci, D.
Abstract
Combined anaerobic–aerobic sludge digestion
has been demonstrated as a valid technological solution to
improve the sludge stabilization process, in terms of solid
reduction and sludge dewaterability properties. In this
study, we investigated the fate of all nitrogen species
(ammonia, nitrites, nitrates) in the sequential digestion
process when the post-aerobic step is operated with intermittent
aeration. Nitrogen course has been followed in the
two digesters operated in semi-continuous mode and in
batch nitrification–denitrification kinetic tests. Two-stage
digestion was applied to real waste activated sludge. High
volatile solid removal efficiencies (47 and 26 % in the
anaerobic and aerobic phases, respectively) confirmed the
potential of this technology. Moreover, the post-aerobic
stage allowed to successfully achieving nitrogen removal
through the simultaneous nitrification–denitrification process.
Nitrification and denitrification efficiencies were 95
and 70 %, respectively. Batch tests for nitrification and
denitrification were also carried out to investigate the
process kinetics. A process model has been formulated and
calibrated with a first set of experimental kinetic data.
Evaluated kinetic parameters were employed in the validation
phase successfully performed (correlation coefficients
R2 > 0.98) with different series of experimental
data.
Keywords
Alternate aeration; Nitrification– denitrification; Nitrogen removal; Process modelling; Sequential digestion
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