Disposal of Waste

1.2  Disposal of Waste
 

1. Waste substances can be divided into 2 types:

 

Can be thrown into the sink

  • The substance with a pH value between 5 to 9
  • Solution with low concentration
  • Examples
    • Neutral substances
    • Weak acids
    • Weak alkalis

 

Cannot be thrown into the sink

  • Solid waste
  • The substance with a pH value less than 5 or more than 9
  • Organic solvent
  • Toxic substance
  • Heavy metal
  • Organic waste
  • Examples; 
    • Acid
    • Grease
    • Oil
    • Oil paint
    • Hydrogen peroxide
    • Microbes
    • Carcasses
    • Radioactive waste
    • Volatile substances
    • Reactive substances

 

2. Way to dispose of toxic chemical substances

  • Treat the waste before dispose
  • Store in a closed container and labelled it

 

3. Standard operating procedure (SOP) for biological waste disposal

Examples SOP

A: Sharp waste

  • Syringe needles
  • Glass slides
  • Glass pipettes

Place the wastes in sharps waste bins before disposed

B: Non-sharp waste

  • Used tissue
  • Cotton wools
  • Gloves
  • Place the waste into biohazard plastic bags
  • Wastes collected must be autoclaved before being disposed

C: Carcasses, organs or tissues of organisms

  • Animal carcasses
  • Animal tissues
  • Plant tissues
  • Biological specimens
  • Wrap the wastes in tissue paper and put them into biohazard plastic bags
  • Waste collected must be autoclaved before being disposed

D: Bodily fluid waste

  • Blood
  • Saliva
  • Serum
  • Waste is decontaminated in autoclave machines
  • Dispose of wastes directly into the sewage system through the laboratory sinks or toilets
 
 

 

4. Steps to Handle Accidents in the Laboratory

 
Accidents of chemical substances spillage 
  1. Inform the teacher or laboratory assistance
  2. Make the spill area a restricted area
  3. Prevent the spillage from spreading using sand
  4. Scoop the spilled chemical substances
  5. Throw away safety
Accidents of a mercury spill
  1. Inform the teacher or laboratory assistance
  2. Make the spill area a restricted area
  3. Pour sulphur to cover the spill
  4. Inform the fire department 

* Mercury is toxic

It can attack the nervous system, digestive tract, reproductory system and kidneys.