Chemical Forums
Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: Gerard on August 28, 2008, 10:03:00 AM
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Good day everyone,
i am the person who have wanted your help in the topic :"Assesment and Evaluation of Biogas Performance in anaerobic digesters"
the phase 1 of my research study is now over and phase 2 is now going....
my problem is quite simple, i am trying to determine the rate of reduction of pig manure in a large scale anaerobic digester and the corresponding methane production. my concern is is the reaction inside the anaerobic digester elementary? can i plot it in terms of r = -kCn
if the process is not elementary can i still plot it in terms of the monod kinetics or the michaelis-menten kinetics?
what is Methane Potential Rate (MP)? and what is the hydrolytic potential?
how do i measure these parameters? or do i need other methods to determine them?
and what is SAS? i know it is a statistical program to calculate data
please help me.. :P
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one more thing i am going to get the rate or reduction of the pig manure in terms of VS and the rate of production of methane....ill be fitting that with some established rate equations but i am also required to established my own modified rate equation,,,
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Hello artificial student,
The reaction rate is a very good question. There are soooo many variables that it is quite difficult to determine. Factors include the food of the pigs ate, the amount of time it remained in their lumen, the local flora, the temperature, type of reactor, mixing rate, etc....
When performing a test such as this, it is usually best to accumulate real data. Take measurements and start plotting, then determine if it is a first, second or third rate reaction.
Explaining what happened, rather than estimating what will happen is easier :).
I wish you the best.
Sincerely,
Eugene
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so i have to plot r=kCn?
but do i have to do monod, tiesser and chen and hanimoto kinetics plot too, right? so whats the difference between the r=kCn and the kinetic plot if the first rate equation will represent the whole reaction of the digester?
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Good day Eugene,
there has been a slight modification in the phase 2 of my research...
i am now requested to look for a good kinetic model for the degradation of substrates using ulva lactuca, not pig manure....
my plan is this, i will fabricate a batch digester feeding it with ulva lactuca...
from the mass balance of substrate (Ulva) i obtained an equation relating the HRT, substrate reduction and rate of substrate utilization via:
HRT = (Csin-Csout)/rs
where rs is the rate kinetics of utilization
Csin is the substrate in
CSout is the substrate out
HRT is the hydraulic retention time...
i would like to ask for guidance:
i will have one or more equation to represent rs (which can only be done by bacth experiments)
one is kCn, then the next is the monod, then the third is the chen and hashimoto, and the fourth is a model that i derived myself, i was thinking that i will represent only the model that will give the best curve fit, am i right?
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besides the above question, can i also ask if anyone has a technical paper, e-book or any helpful resources about the different kinds of biochemical kinetic equations? especially the chen-hashimoto model, teisser, monod and others....
i am using Octave Levenspiel's Chemical Reaction Engineering, J.M Smith's Chemical Engineering Kinetics and Bailey and Ollis's Biochemical Engineering but most of the books are used are so focused on Monod and Michaelis-Menten, i searched the net i only found a few but still not very informative.....i also heard about Hane's equation but i havent read about it....
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Hello artificial student,
I like your question of
"i was thinking that i will represent only the model that will give the best curve fit, am i right?"
There is a REALLY good chance that your reaction rate will be different than anyone else's. I don't want to tell you how to do the work, as there are many correct ways to perform work correctly.
Some loose thoughts are that you may want to develop your own model :).
Just my $0.02,
Sincerely,
Eugene
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thanks eugene..
im now conducting my ulva lactuca observation, my schoolmate is conducting a nutrient uptake of ulva lactuca, im sneaking into thier data so that i can understand their actvity before i digest them...
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can i borrow any e-file that explains the chen and hashimoto model and the contois model? i will be deriving a modified form of them thanx