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How to dispose of used culture media?

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Posted 16 April 2016 - 03:21 PM

Hi, i,m viviene, i want to know if there is any reference document stating how to dispose used cultuure media. Thanks


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Posted 17 April 2016 - 10:26 AM

Hi, i,m viviene, i want to know if there is any reference document stating how to dispose used cultuure media. Thanks


Hi, Viviene;


A citation and advice may depend entirely on many factors;

  • Type of microorganism
  • Type of media
  • Local regulations
  • Manufacturer's recommendation
  • Are enrichment vessels reused?


In short, generally the process is denaturing by way of chemical (bleach, acids) or thermal (incineration, autoclave, etc). Much of this may have to do with the media and microorganism.


e.g. I use a 20% bleach solution for denaturing listeria enrichment broth per manufacturers advice. This includes the test swab and tube. This methods satisfies both regulatory and GFSI scrutiny (I should note that in the U.S. there is not a single responsible authority for the disposal of bio-hazard).

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Posted 18 April 2016 - 10:31 AM

Hi Viviene,


The previous post spells out the kind of risk factors involved.


There is a  general discussion of available  disposal procedures in this classic text - Collins and Lyne's Microbiological Methods (8th ed 2004). 


I also noticed various  caveats that the information is intended for trained personnel.

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Posted 22 April 2016 - 01:49 PM

There is a difference between decontamination and disposal.  Usually, how you decontaminate your waste depends on what was growing, and how you dispose of it depends on what it is made of.


The CDC and the EPA set the guidelines for decontamination of infectious materials in the US.  You are supposed to use an "effective" method, which will depend on what you were growing (or might have grown.)  This is the method I used in a Biosafety Level 2 facility in the past.


1. For liquid medium. add enough chlorine bleach ("Clorox") give a final concentration of 20%.  Let it stand for a minimum of 20 minutes.  Then it can be treated as if it had not been used and disposed of in the usual fashion for unused medium.

2. For plated medium, it should be autoclaved, if you have one available.  After that, it can be disposed of in the way you would discard the plastic dishes and unused medium.


If you do not have an autoclave or cannot decontaminate the liquid with bleach, then how you dispose of your medium will depend on the laws in Nigeria for infectious waste/medical waste handling.  In the US, it is sent out to a medical waste disposal facility and either incinerated at very high temperatures or landfilled with safeguards.


Medium is a chemical, and plated medium is in plastic.  If you can't dump the chemicals in that medium down the drain when it is sterile, you can't dump them after bleach treatment.  If you can't throw out plastic in the trash normally, you can't after it is autoclaved.  Those are disposal considerations.


I would contact a hospital or clinical lab for some "how-to" information.  They grow infectious materials all the time and can tell you how your country requires them to be decontaminated and disposed of.


Martha (former Biosafety Officer for a research lab)

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