Biological Waste Disposal

The following biohazardous waste disposal guidelines are designed to protect not only the public and the environment, but also laboratory and custodial personnel, waste haulers, and landfill/incinerator operators at each stage of the waste-handling process. Workers who generate biohazardous waste in the laboratory must assure that the labeling, packaging, and intermediate disposal of waste conform to these guidelines. Decontamination, inactivation, and disposal procedures outlined in laboratory biosafety protocols must be followed. The appropriate packaging of all waste is fundamental for assuring protection of the handler and proper disposal.

What Types of Biohazardous Waste Require Decontamination

  • Microbiological laboratory waste: Cultures derived from clinical specimens and/or pathogenic microorganisms or any microbiological culture material.
    • Includes any item contaminated with biohazardous, potentially biohazardous, or recombinant specimens or substances.  Examples include but are not limited to: Gloves and other disposable PPE; Plasticware or glassware (e.g. pipettes, pipette tips, culture and sample containers); Disposable towels and other absorbent material
  • Medical waste: Tissues, liquid blood, cells and body fluids from humans.
  • Zoonotic waste: Tissues, liquid blood, cells, body fluids, and bedding from an animal that is carrying an infectious agent that can be transmitted to humans.
  • Animal waste: Tissues, liquid blood, cells, body fluids, and bedding from animals administered biological hazards.
  • Recombinant waste: Recombinant organisms, recombinant DNA/RNA
  • Exotic or virulent plant and animal pathogens.
  • Sharps waste: Contaminated medical and nonmedical sharps
  • Biological toxins
  • Plant Waste: All portions of exotic and non-endemic plants, transgenic plants and plants receiving plant pathogens or recombinant organisms. Please note that soil and pots may have special disposal consideration and disinfection/inactivation procedures are specified in the approved biosafety protocol.

How to decontaminate different wastes

Choosing the right method to eliminate or inactivate a biohazard is not always simple; it is difficult to prescribe methods that meet every contingency. Decisions are best left to the personnel directly involved, provided they are well informed and prepared to verify the effectiveness of the treatment. The choice depends largely on the treatment equipment available, the target organism, and the presence of  interfering substances (e.g., high organic content) that may protect the organism from decontamination. Other common factors that influence the efficacy of disinfection are contact time, temperature, water hardness, and relative humidity. The method of decontamination used must be outlined in the approved biological safety protocol.

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Autoclaving is the most common form of decontaminating biological waste.

When transporting bags to the autoclave, place the bags in a spill proof container (ie. plastic tub) on a cart for moving through the building. See Transport of Waste Poster.

Please see the Autoclave page for information and requirements for sterilizing via autoclave.  

Mixed Waste

For biological materials mixed with hazardous chemicals and/or radioisotopes, please contact Environment, Health and Safety with disposal questions.


Sharps can be divided into two main categories: Medical Sharps and Non-Medical Sharps.

See the Sharps Disposal page for information on the disposal of both types. 

Chemical Disinfection

Where autoclaving is not appropriate or feasible, an accepted alternative is to treat material with a chemical disinfectant, freshly prepared at a concentration known to be effective against the microorganisms in use.

See the UW-Madison Researchers’ Biosafety Manual for more detailed information on Chemical Disinfection. 


Many buildings on campus contract with Madison Environmental Resourcing, Inc. (MERI) for processing of potentially biohazardous waste and sharps containers. Check with your building manager to see if your building utilizes MERI for disposal services.

Waste must be bagged (bags can be orange, clear, or red with biohazard symbol), closed via a goose neck or overhand knot and placed in the MERI collection bins.

Here’s a link from MERI describing the proper way to tie bags for disposal.

Do not place “OK to Trash” stickers on waste that is going to MERI.

Do not tie your biohazard waste bag in a bunny ear fashion. Tying a bag in rabbit ears is not acceptable, because, if turned upside down, your bag will likely leak.

When transporting bags to the MERI, place the bags in a spill proof container (e.g. plastic tub) on a cart for moving through the building. Link to Transport of Biohazard Bags through Public Spaces Poster.


Animal Waste and Carcasses

Animal Waste: Disposal methods for biohazardous animal waste will vary based on the type of enclosure the animals are housed. Consult the approved biosafety protocol for specific details of how to handle the waste.

Animal Carcasses: Animal carcasses are picked up for incineration and disposal by Environment, Health and Safety.

See the Animal Disposal page for more information. 

Human Pathology

For proper disposal information, contact the source of the human pathology waste samples.

Other Biohazardous Waste Considerations

  • Biohazardous waste bag color matters. Red biohazardous waste bags are not allowed to go into the general trash after autoclaving. An “Ok to Trash” sticker does NOT make them acceptable for the trash. Only clear and orange biohazardous waste bags are allowed to the trash after they’ve been decontaminated via autoclave.
  • UV Sterilization is generally not sufficient for biohazardous waste.
  • Labs are responsible for purchasing their own biohazard bags and sharps containers.