It is essential first to understand the terms competitive and non-competitive inbitions. The nano particles of silver inhibit the growth of micro organisms say for instance. In case, another particle similar to nano silver particles compete with each other due to their similar size and ionic charge, it is termed as competitive inhibition. Whereas, if the nano silver particle does not have any other particle to compete, it becomes non competitive and independent to act on microbial growth. There are instances, wherein the inhibitory effect of nano silver particles is reversed due to resistance of micro organisms through their self defensive mechanism, the process gets reversed. Whereas, if the nano silver particles are stronger in their effect on growth of micro organisms in suppressing their activity, it is called as irreversible inhibition.  If your objective is to suppress the microbial growth, you need to opt for irreversible inhibition by nano particles of silver, since reversible inhibition does not serve your objective.

Dear Srinivasa Reddy,

Thank you for kind explanation with examples!

Since I couldn't find irreversible inhibition term, I thought about use of reversible inhibition term with some modification (although I know the reversible inhibition expression does not serve my objective.). But based on your comment, I will try more on finding some papers dealing with irreversible inhibition! 

Regards,

SeHee,Pyo

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Dear Najafpour D.

Thank you for your recommendation for understanding enzyme as well as chemical reaction. I should study more about basic principle and the books will be helpful for me!

Regards,

SeHee, Pyo

Dear Sehee, Pyo

I found the next definition:

"Irreversible inhibition: Some compounds bind to enzymes irreversibly inactivating them. Thus, irreversible inhibitors decrease the enzyme concentration without affecting the reaction kinetics (Mathews et al. 2000)".

So, if you are trying to put into a model the inhibition effects of the nanoparticles, it may not work, because as the definition says, it does not affect the reaction kinetics.

An alternative is to evaluate the effect of such an inhibitor with the same kinetics of reaction or model, but by evaluating changes in the kinetic parameters used to calibrate the model, such changes would be caused by the presence of the inhibitor.

Best regards.

Dear Vital-Jacome,

At first, thank you for your clear definition about irreversible inhibition.

And I am sorry about my late reply for your elaborate answer to my question.

If possible, I want to follow your alternative to adjust misuse of irreversible inhibition term in my model. However, I am not sure that I got what you wanted to recommend me. I guess I need to follow these steps: 1) Do experiments with and without AgNP inhibition. 2) Calibrate model with the results of two cases. and 3) Compare the kinetic parameters obtained from calibration. And if I can find change in kinetic parameters, then I can conclude that irreversible inhibition of AgNP can affect on the kinetic parameters as well as reaction kinetics.

Did I follow your comment well??

Thank you for your reading.

Best regards. 

Hi Sehee, Pyo

Indeed, I think you caught my idea, but sorry if I did not explain properly.

As I understand your question, you want to quantify inhibition, in a bioprocess related to wastewater treatment, due to the presence of your nanoparticles.

And these nanoparticles have a heavy metal in its composition. Correct me if I'm wrong.

Heavy metals, by definition cause irreversible inhibition and this seems to be your case.

I've seen that in several works, that study the inhibition by heavy metals in activated sludge, the authors reported changes in kinetic parameters or changes in the degradation rates because of the presence of those metals, along with half inhibitory concentrations (IC50) among other factors. Although some other authors have dared to model these effects.

From my point of view, put an inhibition term in an ASM model from the start did not seem to be right. First you would have to evaluate the effect of the inhibitor on the kinetic parameters, it is necessary for any kind of inhibition. From there you will decide if it looks like some kind of inhibition, if it can be modeled in some way or if you just have to report the data (Similar to your 3 steps).

Here are some references that show somehow my idea:

Esquivel-Rios I, et al (2014) Microrespirometric characterization of activated sludge

inhibition by copper and zinc.

Pay TY, et al (2009) Novel modeling concept for evaluating the effects of cadmium and copper on heterotrophic growth and lysis rates in activated sludge process.

I hope this will be useful and did not confuse you more.

Best regards

Dear Vital-Jacome,

Really thank you for your recommendation about valuable papers for my understanding and reasonable idea about my question!

I will read the papers carefully and once again thank you for your replying.

Best regards,

SeHee, Pyo 

  In non-competitive inhibition, the inhibition reaction cannot be reversed by raising the substrate concentration.   I suggest you to read pp.138 - 158 of our book entitled "Modelling of Activated Sludge Systens" (by D. Orhon & N Artan) for what I would consider a satisfactory coverage of the subject. Good. Luck!..

Dear Derin Orhon,

Thank you for your reply!

I read your reply before and tried to find the book for free version.

Sadly, I could't find, later if possible I will try to read that book!

Thank you,

Best regards,

SeHee, Pyo