Wastewater COD characterization: biodegradability of physico-chemical fractions

Physico-chemical and biological characterization methods were applied to wastewater samples originating from 7 French WWTPs. The settleable fraction (S), unsettleable-coagulable fraction (US-C) and unsettleable-uncoagulable fraction (US-UC) were separated. Special emphasis was put on the determinati...

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Bibliographic Details
Published in:Water Science & Technology 2002-01, Vol.45 (6), p.89-97
Main Authors: GINESTET, P, MAISONNIER, A, SPERANDIO, M
Format: Article
Language:English
Subjects:
Activated sludge
Activated Sludge Process
Applied sciences
Biodegradability
Biodegradation
Biodegradation, Environmental
Biological and medical sciences
Biological treatment of waters
Biomass
Biotechnology
Colloids
Constants
Environment and pollution
Environmental Monitoring
Exact sciences and technology
France
Fundamental and applied biological sciences. Psychology
General purification processes
Hydrolysis
Industrial applications and implications. Economical aspects
Kinetics
Oxygen - analysis
Particle Size
Pollution
Reaction kinetics
Settleable solids
Sewage - chemistry
Sewage - microbiology
Sludge
Waste Disposal, Fluid
Wastewater
Wastewaters
Water treatment and pollution
Water treatment plants
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Summary:Physico-chemical and biological characterization methods were applied to wastewater samples originating from 7 French WWTPs. The settleable fraction (S), unsettleable-coagulable fraction (US-C) and unsettleable-uncoagulable fraction (US-UC) were separated. Special emphasis was put on the determination of hydrolysis kinetics associated with coagulable- and settleable-fractions in order to model their behaviour in activated sludge processes, as both these fractions are influenced by the SRT. The "soluble" fraction (i.e. US-UC) was composed of readily biodegradable COD (2 to 27%), readily hydrolysable COD (37 to 90%) and inerts (2 to 47%). The "colloidal" fraction (i.e. US-C) was composed of heterotrophic biomass (9 to 24%) and readily hydrolysable COD (6 to 82%), with the rest being inerts or very slowly biodegradable COD (0 to 70%). The "particulate" fraction (i.e. settleable) was composed of biomass (14 +/- 6%), readily hydrolysable COD (21 +/- 14%), slowly hydrolysable COD (about 45-50%) and 15 to 20% which can be considered as inert matter (X(I)). "Readily hydrolysable COD" was correctly modeled by a global first-order reaction. First-order constants (KH) were 9 +/- 2 d(-1) for raw-wastewater, 12 +/- 3 d(-1) for primary settled-wastewater and 16 +/- 5 d(-1) for coagulated-wastewater. "Slowly hydrolysable COD" was correctly modeled by a limited surface reaction. Concerning this fraction, the specific hydrolysis rate (kH) ranged from 0.25 to 1.05 d(-1), and the affinity constant (K(X)) ranged from 0.33 to 0.95 gCOD/gCOD based on settleable solids analysis.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2002.0096