Thank you for your suggestion. It is important to have accurate information on this topic.
Schools have a responsibility to identify, segregate and dispose of hazardous substances in a safe and environmentally conscious manner. Hazardous substances in schools can include: equipment that contains hazardous chemicals (i.e., batteries and radioactive sources), contaminated items such as sharps and broken glass, biological substances such as microorganisms, as well as chemicals used and produced in the school laboratories.
Science ASSIST has already developed information for the disposal of some waste substances. We are in the process of developing guidelines for microbiology that will include the disposal of biological waste. In addition, we are developing a Chemical Management Handbook (working title) that will cover the disposal of hazardous chemical waste. In the meantime, we provide some general guidance information here for the management of your laboratory waste.
Equipment Containing Chemicals
Battery disposal: check with local waste management companies.
Radioactive sources: See Science ASSIST SOP: Handling sealed radioactive sources.
Glassware contaminated with hazardous materials should be decontaminated before being reused or disposed. Glassware which cannot be decontaminated, should be disposed of as hazardous waste. See Science ASSIST AIS: Lab glass and porcelain disposal.
Biological Hazardous Wastes
Any microbiological equipment, for example agar plates, with microbial growth, or contaminated items such as gloves, test tubes etc., should be placed into an autoclave or oven bag and sterilised in a pressure cooker or autoclave at 121 °C, 15 psi for 15–20 minutes before being disposed of in the normal waste bin, or, in the case of equipment, being detergent washed and reused. See Science ASSIST AIS: Sterilising Agar.
Careful consideration is required for the disposal of any hazardous chemical. It is recommended that you check the safety data sheets (SDSs) of the chemicals in question for advice on disposal procedures. It is also recommended that the correct PPE be worn and that the disposal guidelines from your school jurisdiction and organisations such as your local council, water authority or the Environment Protection Authority (EPA) in your state be consulted for further advice on the disposal of specific chemicals.
A risk assessment should be conducted prior to any activity using chemicals to identify all hazards and wastes produced. Science ASSIST has produced a one page risk assessment template for use. See ASSIST Risk Assessment Template.
It is a good idea to allow students to assess their chemical waste as part of their laboratory activity.
Schools are recommended to try to minimise the chemical waste that they produce wherever possible.
- Purchase and use only small quantities of chemicals as required, so as to not stockpile potentially hazardous materials.
- Regularly dispose of old, or out of date, chemicals via licenced waste contractors. Do not allow them to accumulate.
- Unopened surplus chemicals might be able to be returned to the original supplier or manufacturer.
- Contemplate the use of micro-techniques in the classroom.
Chemicals can be disposed of in a number of ways depending on their hazardous nature. Detailed information for each chemical in our List of recommended chemicals for science in Australian schools will be provided in the (future) Chemical Management Handbook. Here are some very general guidelines.
- Non-hazardous solid chemicals: These can be disposed of in regular waste for disposal via landfill.
- Water soluble, non-hazardous, non-toxic chemicals: Some water authorities in Australia accept low concentrations of small quantities of dilute water soluble, non-hazardous, non-toxic chemicals being put down the sink. These chemicals should be non-hazardous to aquatic organisms. Unknown chemicals should never be put down any sink.
- Reuse or recycle chemicals: If considered safe and appropriate, some chemicals can be reused. For example, copper sulfate or alum can be recovered by recrystallisation or evaporation of the solution. Crystals of pure copper sulfate or alum from class crystal-growing activities can also be reused in the preparation of solutions.
- Neutralise or precipitate if appropriate: For example, acids and bases can be diluted and neutralised and washed to waste. Silver can be precipitated as silver chloride by the addition of solid sodium chloride and this can be stored for disposal by a licenced waste disposal contractor. Copper salts can be displaced with steel wool and disposed of in the regular bin. Solutions of iron salts, other than iron (III) chloride, can be evaporated and the resulting solid placed into the regular bin. Iron (III) chloride solutions can be neutralised, and the precipitate collected and disposed of in the regular bin.
- Collect by licensed waste disposal contractors: This applies to many organic liquids and heavy metal salts such as lead and mercury waste as well as large volumes of chemicals and any unknown chemicals.
- Label, segregate and store hazardous chemical waste: Any chemical waste generated for disposal by a licenced waste disposal contractor, should be collected into waste bottles that are correctly labelled, segregated by compatibility and Dangerous Goods class, and stored safely for removal by a licensed waste disposal contractor. Separate waste bottles should be provided for the collection of any generated chemical waste such as halogenated organic waste, non-halogenated organic waste, aqueous waste containing heavy metals and solid waste containing heavy metals. Where practicable, waste can be segregated further, for example, having a separate container for waste from each individual metal, such as silver, copper, chromium, zinc, lead and mercury residues.
Science ASSIST has previously answered a number of chemical disposal questions.
organic chemistry (this answer contains many links to national guidelines and state/territory authorities)
Queensland Department of Education Training and Employment. 2013, Guideline for Managing Risks with Chemicals in DETE Workplaces. Queensland DET website. http://education.qld.gov.au/health/pdfs/healthsafety/guideline-managing-chemicals.pdf (13 November 2013)
South Australia Department for Education and Child Development. 2013, Hazardous chemicals procedures. Department for Education and Child Development website. https://myintranet.learnlink.sa.edu.au/library/document-library/procedure/hr/health-and-safety/hazards/hazardous-chemicals.pdf (login required)
University of New South Wales. 2014, HS321 Laboratory Hazardous Waste Disposal Guideline, Version 3.2 University of New South Wales website. https://www.gs.unsw.edu.au/policy/documents/HS321.pdf (30 April 2014)
University of Wollongong, School of Chemistry. 2009, Laboratory Waste Disposal. Version 3 University of Wollongong website. https://www.uow.edu.au/context/groups/public/@web/@sci/@chem/documents/doc/uow016883.pdf (March 2009)