Updated Liquid Biological Waste Disposal Protocol (BSL1)

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Liquids considered biological waste are those that contain living cells or DNA, including bacterial cultures (and supernatants from those cultures). These must be disposed of according to the biohazard waste stream detailed below and cannot just be poured down the sink. If you have questions, ask Jess!

For overnight bacterial cultures in flasks, remove what you need for experiments and leave the remaining culture in the flask covered with foil. Place in the plastic bin in the autoclave area that is labeled for biofilm flasks.

For small volumes (~1 ml, i.e. supernatant from spinning down cells in epi tubes), pour or pipette off into the small biohazard bins on the benchtop. These will later be transferred to the larger biohazard bag and will be autoclaved for safe disposal.

For medium volumes of bacterial culture or supernatant (>1 to 5 mL, i.e. samples in test tubes used at the spectrophotometer) should be transferred to the beaker by the sink labeled 'liquid biological waste'. Replace the foil over the top of the waste beaker when you are done. If this waste beaker is over half full, start a new biological waste beaker with labels, and alert the lab member who is responsible for disposing of liquid waste. Test tubes will still have residual bacterial culture remaining. In a beaker large enough to submerge the test tubes, create a 10% bleach solution. Submerge the test tubes in the bleach, ensuring that the liquid gets up into the tube all the way and there are no large air bubbles trapped in them. These should be submerged entirely for at least 20 minutes to properly disinfect. It is ok to leave them longer, HOWEVER if you are leaving the lab in between and are planning to leave them longer than 20 minutes, label your beaker with your initials and a time and date. This should be carefully tracked, because bleach loses its potency after 24 hrs and will not be effective. It is ok to use the same bleach solution as someone else as long as it is not over 24 hours old, and as long as all tubes will be submerged for over 20 minutes. After tubes have been properly disinfected, pour the bleach solution down the sink and rinse both the beaker and test tubes very thoroughly. Hang or put in a rack to air dry.