Are there methods of biomass testing that does not require me to disrupt the reactor column to collect the samples? I am currently working on an up-flow BAC reactor (granulated aerobic BAC) that is treating wastewater.
I would like to know if there is an alternative way to test for biomass concentration on the BAC column without disrupting the it.
Currently what i am doing is removing a portion of the BAC (approximately 5 g) then testing is via the conventional MLVSS method. (drying at 105 degree, then furnace at 550 degree Celsius) . however this method is not effective, as this will burn the carbon as well. are there alternative methods for biomass testing? hopefully one that has minimal disruption to the column.
to my knowledge, there is no reliable alternative, there are tests based on respirometry an indirect method see the links below
Article Respirometry a tool for rapid characterization of wastewater...
Article Estimating (combinations of) Activated Sludge Model No. 1 pa...
If you want to measure bioactivity in-situ, i.e. with disrupting the biomass, one can drop a DO probe into the bioreactor, turn off the air supply and measure the DO as it decreases over about 5 minutes. This Oxygen Uptake Rate (mg O2/L-hr) is a direct indication of bioactivity - but can be influenced by when feed is delivered. After feeding, OUR can increase if bioactivity is feed-limited.
Hi arnold,
Thanks for your suggestion. may i know how long do i have to wait after feeding to do the est? Also is there a reference paper i can refer to for the methodology?
Hi Brandon.
The important thing is to be consistent each time you do the test. The result is intended to be compared with previous results. Ideally, one would let your organisms starve for a few hours, do an OUR test, reaerate the bioreactor to get to a high DO, feed them and immediately do another OUR test. When you plot the DO vs. time on a graph, the slope of the line is the "oxygen uptake rate" is reported as mg O2/L-min, or mgO2/L-h. After feeding, the OUR will spike. If you then repeat the OUR test at 30 minute intervals (but without feeding), and plot the OUR vs. time, you can determine when the food has been consumed (i.e. when you are close to the before feeding OUR result). An on-line DO measurement will give you similar information (i.e. will drop after feeding, will gradually increase as feed is being consumed.) Repeat the before and after OUR tests a couple of times a week (following the same procedure) and you will see a trend that should reflect the biomass activity - and hence the amount of biomass in the system. Note: in an OUR test, if the DO drops below 1 mg/L, you can stop the test because at that level, the biomass may be oxygen limited. Metcalf & Eddy's Wastewater Engineering Treatment Disposal Reuse discuss OUR briefly. Most OUR's are done by collecting a biomass sample and adding it to a DO bottle (where probe seals opening of bottle) but dropping the probe into the bioreactor works very well.
I agree with Arnold Janson as a check, but to measure MLVSS we must take a mixed liquor sample and find the concentration by the regular test in (STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER). Regards
The challenge comes because Brandon states he is growing the biomass on activated carbon (BAC). How do you distinguish between biomass and carbon in an MLVSS test? Agreed, if it weren't as BAC, biomass measurement is simple, as per Standard Methods.
Hi arnold, thanks once again for clarifying. Yes currently i am facing the issue of distinguishing between biomass and carbon in an MLVSS test, as you mentioned. Reference to the paper below and your method suggested. I will look into this. Once again thank you for your feedback and suggestion. cheers!Article Precision determination for the specific oxygen uptake rate ...
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