ASIM User Forum - [Kla unit in ASIM software]

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From: Anas (
Date: 07/04/2014

Hallo ASIM family,
i am working in a simulation by ASIM parallel to a labor 
model.By using the DO dissolved concentration instrument for

an intermittent reactor, the recorded data are processed in

order to estimate Kla value to use it in ASIM, but the 
problem is that Kla in labor about 0.5 (1/h) for a maximal 
DO about 2 mg/l, but wenn i write the input data in ASIM 
with the same unit for Kla , it would be too small value 
,and the DO curve is not similar to the real one.When i 
enter Kla about 110 it would be some thing similar to the 
real DO curve,
what is the problem here? what is the used unit for Kla in 

Reply #1
From: Rolf Fankhauser
Date: 07/09/2014
Dear Anas

In ASIM unit for kla-values is 1/day (according to the
tutorial that you can download from the download page).

Best regards

Reply #2
From: Anas (
Date: 07/15/2014
Dear Rolf,
thanks for the answer. Unfortunately, the resulted Kla by 
using this equation in a GUI matlab application is still 
something less than that ones in ASIM software:
∂C/∂t  = -R.X +Kla  (C*- C)	
where R.X could be estimated emmideatly after turnning  the

aeration off, and Kla is estimated then during turnning the

aeration system on untill having the maximal DO in an 
aeration cycle. With a small notice here that aeration 
system is not controlled by (if cause) system i.e. if DO >2

mg/l then turnning off.
the question is , what is the used equation to estimate Kla

in ASIM concepts?
Best regards
Anas Eissa

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