A general Description of the IAWQ activated sludge model No.1
Introduction1983 IAWQ(IAWPRC) IAWQ model review , carbon oxidation, nitrification, denitrification single-sludge system task group
.IAWQ 1987 Activated sludge Model No. 1 .
, .
Model No.1 UCT Bisubstrate hypothesis death-regeneration hypothesis . Bisubstrate hypothesis , readily biodegradable slowly degradable(hydrolysis) Death-regeneration hypothesis
XS, XP hydrolysis SS.
growth hydrolysis. Activated sludge
Monod-equation (switch function ) . 8 process 13 component mass balance
.
Model component matrix . Matrix
, .Component carbonaceous compound nitrogenous compound readily biodegradable slowly biodegradable . component COD
, COD 2.86, 4.57 conversion factor .
switching function . Switching function electron acceptor . nitrification bacteria
. .
SO 1 , SO 0.
switching function .
denitrification anoxic .
Components in mathematical modelWastewater category . biodegradability .
Nonbiodegradable organic matter1. Inert soluble organic matter (SI)System influent .
. inert matter performance . Soluble inert COD
particulate VSS2. Inert suspended organic matter (XI)Activated sludge enmeshed waste sludge system . Wastage flow rate
system XI .3. Particulate organic matter (XP)
Biomass (XBH, XBA) decay , hydrolysis SS . XP, XS hydrolysis SS nutrient
.
Biodegradable organic matter4. Readily biodegradable (SS)SS , soluble material . SS heterotrophic bacteria aerobic, anoxic substrate
. Substrate XS . 5. Slowly biodegradable (XS)XS SS insoluble . XS
hydrolysis SS. Hydrolysis XS enmesh
SS . .
Hydrolysis SS utilization. Hydrolysis SS rate limiting step .
activated-sludge system real –time space –timefactor .
Biomass6. Heterotrophic bacteria (XBH)Heterotrophic bacteria aerobic, anoxic SS . anaerobic
generation . XBH decay , decay endogenous metabolism (predation, lysis, death, etc) mechanism . Decay XBH XS, XP . Decay
biomass biomass .7. Autotrophic bacteria (XBA)XBA aerobic condition ammonia nitrogen . Decay XBH
. anaerobic XBA .
Nitrogenous matter in a wastewater8. Soluble organic nitrogen (SND)
XBH ammonia nitrogen . Aerobic XBH SNDammonification SNH . * ammonification ......
9. Ammonia (free and saline) nitrogen (SNH)SND SNH . SNH XBH XBA autotrophic nitrifying bacteria . SNH autotrophic nitrifying bacteria nitrification nitrate, nitrite .
single-step .10. Nitrate, nitrite nitrogen (SNO)Nitrification/Denitrification intermediate . anoxic .
electron acceptor SNO anoxic. nitrate nitrogen XBH terminal electron acceptor .
* 2.86 4.57 , 11. Particulate organic nitrogen (XND)XBH, XBA decay particulate organic nitrogen release . XND
hydrolysis SND .
Dissolved oxygen DO . DO
simulation . utilization aerobic .
DO 4.57 autotrophs nitrate
<Characterization of Carbonaceous components >
<Characterization of Nitrogenous components >
<Mechanism of Activated sludge process >Dynamic process in the Model
4 ., , (ammonification), hydrolysis
.
1. Aerobic growth of Heterotrophic bacteria, XBH – Soluble substrate. kinetics substrate
oxygen . Monod switching function
0 , 1 .
2. Anoxic growth of Heterotrophic bacteria – XBH electron acceptor. Substrate nitrate nitrogen XBH nitrate nitrogen
. (denitrification) . Anoxic growth aerobic 3 . XBH anoxic growth
(<1) . Anoxic growth aerobic growth .
Nitrate nitrogen SS . Nitrate removed (SS removed – Cell formed)Anoxic growth nitrate nitrogen
. Anoxic, aerobic XBH ammonia nitrogen source
ammonia nitrogen .
3. Aerobic growth of Autotrophic bacteria, XBA – . (nitrification) autotrophic .
nitrate nitrogenautotrophic biomass .
4. Decay of Heterotrophic, autotrophic biomass – SRT biomass yield , SRT endogenous metabolism, Death, predation, lysis
(decay) . Decay particulate products, XP slowly biodegradable substrate, XS .
electron acceptor .
,
5. Ammonification of soluble organic nitrogen – , heterotrophic bacteria alkalinity .
Ammonification decay parallel SND XBH 1.
6. Hydrolysis – Carbonaceous, nitrogenous slowly biodegradablehydrolysis . enmeshed slowly biodegradable
. hydrolysis. SS hydrolysis
, SS time-delay .Hydrolysis activated – sludge model
.
Hydrolysis of particulate substrate
Hydrolysis of organic nitrogen
Characterization of wastewater and estimation of parameter value
Stoichiometric coefficientsActivated sludge Model No.1 5 .1. Heterotrophic yield, YHYield ,
.
2. Autotrophic yield, YA parameter autotrophic bacteria yield .
XBA nitrification activated sludge nitrifying population YA .
Nitrifying biomass YA YH .
3. Fraction of biomass yielding decay products, fpBiomass decay products XS XP . XP
fp . XP hydrolysis , inert .
4. Fraction of nitrogenous compound in biomass, iXBBiomass nitrogenous compound Model No.1 COD
nitrogen . iXB [mass Nitrogen / mass COD ] .
5. Fraction of nitrogenous compound in products, iXP stochiometric coefficient product COD
factor .
Kinetic coefficient kinetics .
Half–saturation coefficient switching function operation.
H, A specific growth rate Monod equation .Decay 1 b .
anoxic growth, hydrolysis correction factor, anoxic hydrolysis aerobic
.
<Half – Saturation >
Model Formulation
1. Heterotrophic biomass concentration, XBH
Anoxic growth g (<1) .
2. Autotrophic biomass concentration, XBA
Autotrophic biomass SS . Autotrophic SS. SNH
. Autotrophic .
3. Concentration of readily biodegradable substrate, SS
SS hydrolysis . yield YH H/YH biomass SS
.
4. Concentration of slowly biodegradable substrate, XS
Biomass decay XS, XP . XS hydrolysis. ƒp XP XS (1-ƒp) .
5. Concentration of inert particulate products, XP
6. Concentration of particulate organic nitrogen, XND
Decay XND . Biomass product iXB, iXP .
.
7. Concentration of soluble organic nitrogen, SND
XBH ammonia nitrogen convert . SND XND hydrolysis .
8. The ammonia concentration, SNH
SNH . XBHbiomass XBH . XBA
SNH .XBH ammonification .
9. Concentration of nitrate nitrogen, SNO
Nitrification – Denitrification process intermediate . Nitrification XBA aerobic growth , denitrification XBH anoxic growth .
2.86 COD .
10. Dissolved oxygen, SO
Model No.1 . , . .
XBH, XBA aerobic growth .