• Blog
  • Wastewater Testing
  • Bioaugmentation Applications
  • Useful Information
  • About Us
BIOLOGICAL WASTE TREATMENT EXPERT
Contact Us

Leach Microbial Consulting just put a website with great resources for doing your own microscopic exam

4/30/2020

 
Picture
Probably the best quick test for evaluataing your biological treatment system's health, microscopic exam does not have to be a long, complex test. Just note the following:
  • floc appearance - size, density, filaments
  • Protozoa present & relative numbers
  • Any higher life forms 
The above exam takes 5 - 10 minutes while you are running SV30 tests.

Now there are times where you need more complex evaluation such as filament ID, EPS evaluation, and troubleshooting. Here is where I suggest sending samples out for evaluation while you also learn about the test and how the observations are interpreted. I have worked with Steve Leach of Leach Microbial Consulting for over 20 years and he combines microscopic exam experience with field operation of both municipal and industrial wastewater systems. He has finally set up a website with resources for performing micorscopic exam - this includes good documents and photos for doing everything from a cursory exam to filament ID.

His microscopic exam reports focus on your system's issues and helps you improve your operations. I find this much more useful than the standard outside microexam report.

Go check out his website and if you have a need for outside microscopic exam contact Steve.

www.leachmicrobial.com/ 

Dissolved Oxygen (D.O.) - why you can't always trust the D.O. meter

4/21/2020

 
Picture
I will start with something that puzzeled me for years. In the lab, ammonia oxidizing bacteria (AOB or nitrifiers) have excellent activity at a D.O. of 2.0. Moving up from 2.0 mg/L DO to say 4.0 mg/L gives a slight boost in growth rates, but is not worth the energy cost required to increase the oxygen residual. Meanwhile, I have seen working activated sludge systems where a D.O. residual below 3.0 mg/L results in a loss of nitrification. So what  is going on?

The answer came after we started running molecular tests that look directly at the microbial makeup of MLSS. Running these tests, we found obligate anaerobic bacteria growing inside high D.O. basins. We then did extensive work on AOB/NOB inhbition with various influents and MLSS from different systems. Here is what we found:
  • D.O. meter placement
    D.O. meters read oxygen residual in the water phase at the probe/water interface. D.O. residuals are subject to probe placement and mixing. Is your D.O. meter giving you a true average residual or D.O. you do manual checks at other locations to confirm readings?

  • Impact of MLSS concentrations
    The aeration basin is not a homogenous mixture. We have water phase and solids. For oxygen to get inside the floc, it must pass through EPS and move from the water column into the biofilm. Larger floc or higher biosolids mean lower oxygen residuals inside the floc compred to the water on the exterior.

  • Floc EPS levels
    Floc includes insolube organics, biopolymers, and inorganics. Increasing amounts of non-living materials result in lower oxygen transfer efficiency. Remember that high EPS levels can reduce how much oxygen moves into the floc. Check your EPS using India Ink for an easy on-site EPS test.
    ​
How do you get an idea on working D.O. (from a bacteria point of view)?
  • Check D.O. residual manually to confirm in basin meter numbers
  • Monitor D.O. meter numbers and see where you get needed activity from obligate aerobes (AOB/NOB). You can also look at denitrification or phosphate release/uptake that require anoxic and anaerobic zones.
  • Run Microbial Community Analysis (MCA) which is a molecular test that identifies all bacteria present. The MCA tells you what is growing and functioning in the system.

Ways to evaluate MLSS bacteria

4/2/2020

 
Picture
 How do you estimate bacterial activity in a wastewater system? This is a question, we often ask and a number of methods have been used. I figured a list of common monitoring methods could be useful.
  • Respiration Rate (Oxygen Uptake Rate)
    This can be complex using respirometer equipment or simple using a BOD bottle/DO probe on the benchtop. Here you use oxygen consumption as a measurement of microbial activity.
  • Plate Counts
    Using various plate count media, labs can evaluate numbers of microbes in wastewater plants. Most often used for coliforms, it can also be used for heterotrophic and specific organisms using selective media. Problems with plate counts include the number of organisms that don't grow on plates, plate development time, and expense/labor required to do pate counts.
  • ATP 
    Microbes store energy as ATP. Using a luminometer and various luciferase procedures, you can determine free ATP and cellular (bound) ATP. The more ATP present the more light produced in the reaction. A quick test, ATP can be used as a proxy for total plate count and a measure of non-specific microbial activity.
  • Flow Cytometry
    Requring specialized equipment, flow cytometry uses fluorescent dyes and various techniques to quantify individual cells in the sample. Flow cytometry allows for evaluation of cell viability. 
  • qPCR (molecular testing)
    qPCR or real-time PCR is a rapid test method for quantifying DNA present in samples. As dead cellular DNA is rapidly degraded in wastewater, PCR favors viable cells. While total bacteria qPCR tests are similar to rich media plates counts in looking at all bacteria present. qPCR can be used to evaluate key organisms. For example, qPCR can look at specific DNA sequences such as those for nitrifiers, filaments, nocardia, or any other group of interest. qPCR is a relatively quick test (hours versus days) and is highly accurate.

    Author

    Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater  facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.

    View my profile on LinkedIn

    RSS Feed

    Click to set custom HTML

    Archives

    December 2022
    November 2022
    October 2022
    September 2022
    August 2022
    June 2022
    May 2022
    March 2022
    February 2022
    January 2022
    November 2021
    October 2021
    September 2021
    August 2021
    June 2021
    April 2021
    March 2021
    February 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014

Proudly powered by Weebly
Photos used under Creative Commons from Picturepest, marcoverch, perzonseowebbyra, Picturepest, Picturepest, dsearls, dungodung, Massachusetts Office of Travel & Tourism, aqua.mech, vastateparksstaff, hile, Aaron Volkening, amishsteve, Neil DeMaster, mklwong88, KOMUnews, Picturepest, kaibara87