Laboratory chemical waste

This information provides advice on best practice laboratory waste management in relation to discharges to our wastewater system.

Laboratories vary greatly in the quantity and nature of chemical waste they produce depending on the type of laboratory: pathology, mineral testing, school, chemistry research, pharmaceutical etc. In all cases of chemical waste discharge to the wastewater system, an application to discharge must be completed.

This information applies to all laboratories discharging chemical waste to our wastewater system. It does not apply to radioactive or microbiological waste.

Chemicals of major concern

While small amounts of a wide range of chemical residues produced in laboratory operations may be safely disposed of to the wastewater system, the following chemicals are not permitted:

• persistent chemicals such as heavy metals and various organic compounds
• water-immiscible organic liquids such as petroleum hydrocarbons and chlorinated compounds
• compounds which produce toxic vapours, such as cyanide, ammonia, formaldehyde and glutaraldehyde
• strongly acidic or alkaline wastes
• highly reactive chemicals or flammable wastes.

We control the input of chemicals to our wastewater systems. This is necessary to protect the wastewater system itself, our workers within the system, the safety of the community, and to protect the environment.

Waste avoidance and waste minimisation

Much can be done to avoid or minimise the production of chemical wastes in the laboratory. The following hierarchy of strategies is recommended:

1. Replace hazardous compounds with less hazardous compounds, for example, selecting alternative protocols that avoid using certain toxic components.
2. Minimise the quantity of hazardous materials used, such as reducing testing procedures to semi micro or micro scale.
3. Recycle hazardous compounds (either within the laboratory or by external contractors).
4. Pre-treat wastes to remove hazardous materials prior to discharge of wastes to the sink, such as by chemical destruction, precipitation, solvent extraction or ion exchange.

Best management practices

To assist in implementing waste avoidance and waste minimisation measures, the following management practices should be adopted:

• avoid over-ordering chemicals, minimising costly waste disposal
• ensure that all chemicals, especially those to be disposed, are properly labelled (including experimental and analysis samples) - disposal companies tend to treat unlabelled containers as the highest risk (and highest cost)
• as staff leave, ensure they clear out all their old chemical stocks, either by returning them to store or properly labelling them and arranging for correct disposal
• take periodic inventories of all chemicals, and investigate all likely 'hiding places' for chemicals
• segregate incompatible waste solvents prior to cartage off-site, for example organochlorines, water miscibles and water immiscibles
• educate staff through regular training, target setting and feedback
• display signs to guide staff in correct procedures
• establish a laboratory waste disposal manual and ensure it is updated regularly
• provide appropriate handling and safety equipment to make correct waste management easy and convenient.

Specific requirements

1. All components of an industrial waste discharge must comply with our acceptance criteria for trade waste.  Where there is no criterion for a waste component, limits are set on a case-by-case basis.
2. All laboratory liquid waste approved for discharge to the wastewater system must pass through an appropriate pre-treatment fixture prior to discharge. In the case of acidic wastes (such as from mineral laboratories) a neutralisation fixture will be required. Other types of laboratories may require different pre-treatment.
3. Correctly monitor and maintain wastewater pre-treatment fixtures and equipment and keep a central register of these records.
4. Laboratory chemicals must not be stored in such a way that spillages will enter laboratory sinks. Significant volumes of liquids should be stored in areas with appropriate containment. Incompatible chemicals should not be stored together.
5. Spillages of organic solvents must be contained with absorbents such as sand, diatomaceous earth or appropriate absorbents, and not flushed down the sink.
6. Organic liquids that are immiscible with water must not be disposed to the sink.
7. Small amounts (less than 1 litre of concentrated solution) of wastes containing organic liquids miscible with water may generally be discharged to sink. Where these liquids have toxic or flammable vapours (such as formaldehyde) the wastes must be diluted with large amounts of water (see point 13). Larger quantities must be either destroyed chemically prior to discharge, or the wastes either recycled or disposed of off-site.
8. Large quantities of concentrated acids or alkalis (greater than Winchester size - 2.5 litre) must be neutralised prior to disposal to sink.
9. Wastes containing the heavy metals arsenic, cadmium, mercury and silver in amounts above 1 gram, or copper, chromium, lead, nickel and zinc above 10 grams must be pre-treated to remove these metals prior to discharge of the waste to sink.
10. Water miscible wastes apart from those already mentioned may generally be discharged to sink with appropriate dilution.
11. Small quantities of volatile solvents can be disposed of by evaporation in a fume hood. Larger amounts must be sent for recycle or disposal off-site.
12. For hospitals in Perth discharging to major wastewater treatment plants, glutaraldehyde solutions are to be diluted with water to below 0.1% before discharge to the sink. No more than 40 litres of 2% glutaraldehyde (or equivalent mass load of other concentrations) is to be discharged per day.
13. For hospitals in country areas, the acceptable amount of glutaraldehyde will be determined on a case-by-case basis.

References

• AS/NZS 2243 - Safety in Laboratories, Standards Australia.
• AS2508 - Safe Storage and Handling; Information Cards for Hazardous Materials', Standards Australia.
• Handbook on Laboratory Health and Safety Measures, 1985, edited by S.B. Pal (MTP Press).
• Handbook of Toxic and Hazardous Chemicals & Carcinogens, 2nd Edition, 1985, by M. Sittig (Noyes).
• Dangerous Properties of Industrial Materials, 7th Edition 1989, edited by N.I. Sax & R.J.Lewis (Van Nostrand Reinhold).

More information

For advice on recycling options or ultimate disposal of waste that cannot be discharged to sewer please contact Department of Water and Environmental Regulation.