Symbol Explanation

Unit

(example)

Basic unit

Surface

Membrane area

Membrane constant

Membrane constant

Volume specific surface

Activity

Coefficient

Membrane constant Biot number Loading per volume Dimensionless concentration Integration constant Dimensionless dissolved concentration in equilibrium with gas concentration Dimensionless dissolved oxygen concentration

Concentration of special gas components in air Dissolved concentration Dissolved concentration in equilibrium with gas concentration Dilution rate Critical dilution rate Diameter

Diffusion coefficient Desorption capacity m m hg m-

L2 L2

Dispersion coefficient in x direction m2 h

Symbol Explanation

Unit

(example)

Basic unit

eA F

Fo2 fi

AG0 g h

H Hg

JD+C

Damkohler number II (= pmaxtv) Diameter

Hydraulic diameter Efficiency

Density of residence time Dimensionless efficiency Energy of activation Residence time distribution Power of resistence of oxygen molecules

Portion of inert biomass related to the total biomass Portion of particulate products related to biomass Difference of free reaction enthalpy

Earth acceleration

Distance of the stirrer from the bottom

Difference of enthalpy Henry coefficient Henry coefficient Henry coefficient "Height" of deep tanks Height

Strength of a electric current Strength of electric carrent Nitrogen in bacteria related to mass of bacteria and slowly biod. susbstrate

Nitrogen in bacteria related to particular inert organic matter Specific mass transfer rate (volume flux) Diffusion flux

Flux for diffusion and convection Standard volume flux Total mass transfer coefficient Bolzmann constant Saturation coefficient for oxygen Dissoziation constant m m kg (kWh)-1 O2 L-2 T2

Symbol Explanation

Unit

(example)

Basic unit

KiH> Ki

Kl KLa

kLa kG

kGa kd ks ke

LD50

Equilibrium constant -

Equilibrium constant L mg-1

Coefficients for excess substrate mg L-1 inhibition

Coefficient of non-competitive mg L-1 inhibition

Overall mass transfer coefficient m h-1 Specific overall mass transfer coefficient h-1

Michaelis-Menten coefficient mol L-1

Equilibrium constant -

Saturation coefficient for mg L-1 hydrolysis

Henry coefficient bar L g-1

Saturation coefficient for substrate mg L-1

Saturation coefficient -

Coefficient of reaction rate h-1

Theoretical maximal value of -reaction rate for T

Mass transfer coefficient for m h-1 liquid boundary

Specific mass transfer coefficient h-1 for liquid boundary

Mass transfer coefficient for m h-1 gaseous boundary

Specific mass transfer coefficient h-1 for gaseous boundary

Decay coefficient h-1

Coefficient of bacteria dying h-1

Coefficient of endogeneous h-1 respiration

Length m

Biofilm thickness m

Mass of a compound per mass of mg kg-1 living test organism, fatal to one-half of population if delivered rapidly

Molmass g mol-1

Mass g

Amount of moles mol

Symbol Explanation

Unit

(example)

Basic unit n ni nR

nPHB

SOTR S*

tRC tRX

tRXC

Speed of a stirrer s-1 T-

Number of droplets - -

Recycle ratio - -

Thickening degree - -

Fraction of PHB inside of bacteria

Number of stages of a cascade - -

Specific oxygenation capacity mol L-1 h-1

Oxygen transfer rate g O2 L-1 h-1

Oxygen transfer efficiency -

Power demand kW

Pressure bar

Flow rate m3 h-1

Radius m Gas constant [= 8.314 J (mol K)-1] J (mol K)-1

Resistance m-1

Retention coefficient %

True retention coeffcient %

Respiration rate g L-1 h-1 Growth rate of bacteria Concentration of substrates Standardized oxygen transfer rate mg L-1 h-Dimensionless dissolved oxygen concentration (= S'/K') - -

Selectivity - -

Temperature K, °C 0

Time h T

Mean retention time h T

Critical mean retention time h T

Mean retention time of bacteria h T

Critical sludge age h T

Voltage V M L2 T A-1

Volume m3 L3

Velocity m s-1 L T-1

g L-1d-1 MLSS M L-3 T-1 mg L-11), mol L-1 M L-3, NL-

Symbol Explanation

Unit

(example)

Y Yo

YX/S

YXC/SC

AX/S

Gaging void velocity Mean velocity Concentration of bacteria Dimensionless bacteria concentration (= X/K') Local coordinate Mole fraction Mole fraction

Mole fraction oxygen/carbon in bacteria

Yield coefficient True yield coefficient growth of bacteria/used substrate True yield coefficient growth of bacteria carbon/used substrate Apparent yield coefficient growth of bacteria/used substrate Dimensionless local coordinate Local coordinate m s g L-1

MLSS

Bi Biot number

Da Damkohler number

DaII Damkohler number II

Fr Froude number

Mo Monod number

Mo' Modified Monod number

Ne Newton number

Pe Peclet number

Pe' Modified Peclet number

Re Reynolds number

Sc Schmidt number

Sh Sherwood number

Sm Semenov number

Y Oxygen transfer number

Symbol Explanation

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