The most important parameters to characterize an activated sludge process are the organic loading rate and the sludge age. At low hydraulic retention time and high sludge age, your system will be in declining phase. You will obtain good COD removal efficiency and low sludge production due to high decay. In the case of a high loading rate and low sludge age, you will favor bacterial growth and get high sludge production.
Dear Dr. Nicolas Bernet,
Thanks for your attention
You are right. But How can I determine exact sludge retention time (SRT) or organic loading rate (OLR) in which activated sludge system has been operated in declining phase?
Dear Professor Atul Kumar Mittal,
Thanks a lot for your good answer.
Dear Atul Sir,
Can u please provide the reference paper so that we can quote?
I've never seen an activated sludge system operate in the log phase. Typical domestic wastewater has BODs of 300 mg/L. I'm not even sure if BODs of something like slaughter house effluent (20,000 to 40,000 mg/L) would get you log growth. We get log growth in culture conditions for E. coli at something about 1% substrate. That's about 10 g/L or 10,000 mg/L.
Conventional activated sludge systems basically operate with no remaining biodegradable substrate; the effuent being mainly residula soluble microbial products. Therefore, if low effuent substrate is targeted. It is not logical nor possible po operate an activated sludge system at near maximum specific grwoth rates.
Dear Mehdi
I think, you have to calculate F/M ratio or (Q×BOD5in)/(V×MLSS) and also SRT or sludge age.(V×x)/(Qw×MLSSr). Reciprocal of SRT is µ or Specific Growth Rate.
In this stage, you have to review the same treatment plants that works in the declining phase and also µ values given in the literature for this treatment plants for the comparison your results.
Also, you can determine the MLSS increasing in a define times and calculate the doubling time of the biomass and also review the literature for the comparison this item for the growth phase.
- Badges
- Science topic
- Similar topics
- Biological Science
- Microbiology
- Microorganisms
- Bacteria