Liquid Biological Waste

All liquid waste must be appropriately treated prior to disposal by either chemical disinfection or thermal sterilization to ensure complete sterilization of the material.


Appendix B of the Biosafety in Microbiological and Biomedical Laboratories manual provides guideance on selecting the most effective chemical agent to disinfect or sterilizae the material. Depending on which product or procedures is choosen, concentrations and exposure times vary depending on the formulation and the manufacturer’s instructions for use. The most common product used in microbiological laboratories is household bleach which can be uses as describe.

  • Collect liquid waste in a leak proof container with a biohazardous label
  • Using bleach, create a 10% v/v bleach solution with the liquid waste and allow it to sit for a minium of 30 min. Do not use bleach that that has been open for more than 30 days
  • Safely discharge into the laboratory sinks followed by copous amounts of water

If the solution contains other hazards such as chemicals or radioactive materials, ensure the sterilization agent is compatible with the underlying hazard first. Once sterilization is complete, the waste can be safely disposed into the appropriate hazardous waste stream. Liquid biohazadous waste mixed with any other chemical disinfeant should not be pour down the sink and must submited for hazardous waste pickup.

All disinfectant or sterilant used in this process must be registered with the Environmental Protection Agency (EPA) with a current registant.

Search EPA Database -

Selected list of EPA regitered Disinfectant -


  • Place the waste in a plastic autoclave bag
  • Apply a strip of autoclave tape on the bag of waste, or on the biohazard symbol if applicable, before beginning the sterilization cycle.
  • Use the following program parameters.
  1. minimum temperature of 121ºC
  2. pressure above 15 psi
  3. dwell time of at least 30 minutes. Porous materials and larger loads may need a pre-vacuum cycle and/or increase the dwell time, temperature, and pressure.
  • Fill in your information on the autoclave log book.

Longer exposure times may be necessary depending on the size and composition of waste.

When the cycle is completed, place the waste in an opaque or black trash bag. Tie the top and discard in the general laboratory trash. Make sure to deface any biohazard symbols before disposal.