Hi Haider,

I really want to give an scientific answer to you. Unfortunately, my research area is different from with you. I am afraid that my answer will confuse you further. Hence, I want to keep in view for this question. If you are interested it very much, may ask association to the researchers from the SMTC and R3C in NTU as well. Appreciated. Justin

Hi Justin,

Thank you a lot for passing by my question. Dude, I really need a scientific answer for that. A reviewer of one of my submitted research articles asked me that question, and the editor required me to answer carefully and scientifically, otherwise my paper will be rejected. The question also interesting for me and I also wish to know/understand the answer. Hence, I really appreciate if you can help me.

Thanks.

Dear Haider

attached a link of my paper, it may be help you to find your answer

www.scirp.org/journal/PaperInformation.aspx?PaperID=26261

best wishes

Dear Randa

Your paper contains a lot of valuable information but I cant find my answer there. Can you please summarise for me here?  

Hi Haider

from my experimental experience on anaerobic digestion using UASB reactor or CSTR, I found that in case of using UASB after good start-up operation which exceed 2-3 months not less. anaerobic bacteria tends to agglomerate and form granules that grow with time. So your substrate divided into part to form methane, part for maintaince and the last for growth.

as we increase COD in influent or increasing organic loading rate the growth rate increase and granulation process in progress. your blanket system operates as filter so the effluent stream is always contains lower COD values than the influent.

in case of CSTR, you must depend on soluble COD (filtrate) for influent and effluent streams 

Dr. Randa,

Thank you so much for your answer. But when you start-up the UASB, you need to use seed sludge right? This seed sludge will definitely have COD which is higher than the influent COD introduced to the reactor. So how to show the sludge COD won't affect the treatment process or even its not related?

Hi Jing Xiang,

Yes your analogy is correct but how to put in more scientific approach? I need to answer a reviewer of one of my submitted papers. Hence, I can't tell him analogy, he is already angry.

it's all about biomass retention, Haider, as Randa stated.

Your UASB works with internal sedimentation which is biomass retention which is COD retention. As long as your seed sludge (and any newly generated biomass) does not overflow but is kept in the UASB reactor (as designed), this COD will not (or barely) affect effluent COD, whatever its concentration will be. As in any system with biomass retention (e.g. activated sludge or biofilm systems) reactor COD is always one or more orders of magnitude higher than influent or effluent COD.

Dear Urs Baier

Thank you, you got it and really that what I meant in my  answer

Dear Haider

in your case, please monitor soluble COD for inlet and outlet streams to overcame this problem and avoid any suspended solids of anaerobic bacteria

Please see if this information link may help -

http://www.sswm.info/sites/default/files/reference_attachments/MES%202003%20Chapter%204.%20Methane%20production%20by%20anaerobic%20digestion%20of%20wastewater%20and%20solid%20wastes.pdf

It's not my paper. Title is -

"Methane production by anaerobic digestion of wastewater and solid wastes" by T.Z.D. de Mes, A.J.M. Stams, J.H. Reith and G. Zeeman1

Please click the internet link to open the pdf.

http://www.sswm.info/sites/default/files/reference_attachments/MES%202003%20Chapter%204.%20Methane%20production%20by%20anaerobic%20digestion%20of%20wastewater%20and%20solid%20wastes.pdf

Seeding means using a very tiny amount in comparison to the large volume being treated so that it ought not affect the overall COD at all. But seeding is always a good practice in wastewater treatment, aerobic or anaerobic alike.

 If you just go online and type in "Textbook on Wastewater Treatment Technology"

you'd get a whole bunch of titles including wastewater plant design, etc. Then on Amazon.com you might get someone to sell you used books at lower prices. 

Or you can just go to the library yourself.

Good luck!

Dear Friend

Seeding is just for  proper startup the digestion process. It does not long last later.

So at the time of seeding,  HLR  is less.

Dear Friend

Seeding is just for  proper startup the digestion process. It does not long last later.

So at the time of seeding,  HLR  is less.