Hi Jonas,

I am trying to understand what your case is. Probably it would be better if you explain what happened in details.

In anaerobic digestion, VFA content is highly related to pH, alkalinity, temperature, and system stability among others. When the VFA content, alkalinity, and temperature are known, the pH and system status could be explained. The VFA content may also describe the biogas composition and methane production. The VFA content and pH may also be used to monitor inhibition (e.g. from NH3).

I hope this answers your questions.

Regards

Alam

Hi alam Surya Wijaya

We know everything of the tank ( pH temperature total nitrogen and so on.) The only thing we don't know and we have to do it. Is the BRA content we know of the VFA that acetic acus is a major impact of the biogas production. So is there a way to conclude the test of what we know (pH CKD total nitrogen VOA and so one) and the VFA content in the tank.

Your precious answer helps me.

Jonas

Dear Jonas, I try to understand your questions, I don't see which is the thing that you don't know, maybe BRA but I don't know what means... If you wish to conclude how is your anaerobic digestion process in correlation to VFA content that you know and if the process goes well to methane or not, I would say that VFA profile could indicate clearly the stage of AD. You know that there are 4 stages of AD: hydrolysis, acidogenesis, acetogenesis and methanogenesis. If you know the VFA profile you can find out that AD is in the 2nd stage (mix of various VFA, also much propionic and butanic acids) or in the 3rd stage (if have mainly acetic acid). In the 3rd stage you must care to keep pH to neutral and have no temp fluctuations so that keep the methanogens alive, facilitate their growth and conduct the process to CH4. This is a delicate stage where AD could fail if acidogenic bacteria grow in much excess to the detriment of the methanogens that are very sensitive. pH and temperature are main parameters that must be controlled to help the process flow to methanogenesis. I'm not sure my answer is according to your questions, I honestly didn't catch what do you wish to analyze... Cheers.

...I was wondering why should you check total Nitrogen, also what CKD means and what for? I know that total C and total N are checked for the substrate before AD in order to see if there is a proper supply of C (energy source for bacteria) and N (as a component needed to develop new biomass (bacteria). Ammonium N can show process inhibition if exceeds some limits. But how to know such limits? Fermented slurry is tested for N, P, K and oligoelements to show its quality as a fertilizer. I cant indicate any link to VFA since I don't know why you did such testing during AD. I hope researchers with more experience will give you some answers, I'm also curious about the scope/need of such tests, what could they indicate during the process?