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Chemical Waste

Preamble

Laboratories vary greatly in the quantity and nature of chemical wastes they produce depending on the type of laboratory e.g. pathology, mineral testing, school, chemistry research or pharmaceutical.

Several excellent references available on the disposal of chemicals are listed below.

 

Policy

Guidelines for disposal of chemical waste to sewer

Also refer to Industrial Waste to Sewer policy

Chemicals of major concern

Small amounts of a wide range of chemical residues produced in laboratory operations may be safely disposed of to the sewerage system. However, this method of disposal is not desirable for the following chemicals:

  • 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

The Water Corporation controls the input of chemicals to the wastewater conveyance and treatment system to ensure that:

  • workers are safe from the effects of noxious gases and fumes
  • the fabric and integrity of the sewer is maintained
  • the biological treatment processes at treatment plants are not poisoned
  • strict controls for the final disposal of effluents to the environment are complied with.
     

Procedures


Correct disposal of chemicals

 

Responsible person

Action

Departments
  • Laboratory liquid waste approved for discharge to the sewer should pass through a neutralisation/dilution pit prior to sewer discharge.
  • Laboratory chemicals should not be stored so that spillages can enter laboratory sinks. Significant volumes of liquids should be stored in areas with appropriate containment.
  • Segregate incompatible waste solvents prior to cartage off-site, e.g. organochlorines, water miscibles and water immiscibles
  • Spillages of organic solvents should be contained with absorbents such as sand, diatomaceous earth or appropriate absorbents, and not flushed down the sink.
  • Organic liquids that are immiscible with water should not be disposed to the sink.
  • Large quantities of concentrated acids or alkalis (greater than winchester size - 2.5 litre) should be neutralised prior to disposal to sink.
  • Small amounts (less than 1 litre of concentrated solution) of wastes containing organic liquids miscible with water may 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. Larger quantities should be either destroyed chemically prior to discharge, or the wastes either recycled or disposed off-site.
  • Hospitals in Perth which discharge to major Wastewater Treatment Plants, should dilute glutaraldehyde solutions 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.
  • Small quantities of volatile solvents may be disposed of by evaporation in a fume hood. Larger amounts should be sent for recycling or disposal off-site.
  • Wastes containing the heavy metals arsenic, cadmium, mercury and silver in amounts above one gram, or copper, chromium, lead, nickel and zinc above 10 grams should be pre-treated to remove these metals prior to discharge of the waste to sink.
  • Water miscible wastes apart from those already mentioned may be discharged to sink with appropriate dilution.

Waste Avoidance and Waste Minimising

Strategies for avoiding and minimising production of chemical waste in laboratories:

  • replace hazardous compounds with less hazardous compounds
  • minimise the quantity of hazardous materials used e.g. reduce testing procedures to semi micro or micro scale
  • recycle hazardous compounds (either within the laboratory or by external contractors)
  • pretreat wastes to remove hazardous materials prior to discharge of waste to the sink by chemical destruction, precipitation, solvent extraction or ion exchange. 
     

Procedures

Waste avoidance and minimisation

Responsible person

Action

Departments
  • Avoid over-ordering chemicals, thereby minimising costly waste disposal ensure chemicals, especially those to be disposed, are properly labelled (including experimental and analysis samples) - disposal companies treat unlabelled containers as the highest risk and therefore highest cost
  • Require staff leaving the University to clear out old chemical stocks, by returning them to store or labelling them and arranging for correct disposal
  • Take periodic inventories of chemicals and investigate likely hiding places for chemicals
  • Educate staff through regular training, target setting and feedback
  • Post clearly visible 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
  • Correctly monitor and maintain sewer pre-treatment fixtures and equipment
  • Keep a central register of these records

 

References

  • Safety and Health Office's Waste Management Policies.
  • AS2243 - 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 & 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).
  • Hazards in the Chemical Laboratory, 4th Edition, 1986, edited by L. Bretherick.

 

Contacts

  • UWA Environmental Manager : x 3534
  • Industry Services Officer, Industrial Waste Section (9420 2371) regarding requirements for discharge of specific chemicals
  • Office of Waste Management, Department of Environmental Protection (9222 0422) for advice on recycling options or ultimate disposal of wastes which cannot be discharged to sewer
  • Safety and Health Office : x 2307

 

Date created:
July 2000

Approved by:

Director, FM

Previous edits:

 October 2003

Responsible:

Environmental Manager

Date for review:

2006

File reference:

F

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