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 .