School of Physics Safety Manual

9. DISPOSAL PROCEDURES

General

Flammable substances and water immiscible substances must not be discharges down sinks. In addition, the following substances must not be poured down the sink (the Red List of proscribed substances):

Mercury and its compounds Cadmium and its compounds gamma-Hexachlorocyclohexane

DDT Pentachlorophenol Hexachlorobenzene

Hexachlorobutadiene Aldrin Dieldrin

Endrin Carbon Tetrachloride Polychlorinated Biphenyls

Dichlorvas 1,2-Dichloroethane Trichlorobenzene

Atrazine Simazine Tributyltin compounds

Triphenyltin Trifluralin Fenitrothion

Azinphos-methyl Malathion Endosurfan

Chemicals

All postgraduate workers and staff are responsible for arranging the safe disposal of samples and chemicals that they have ordered but no longer require. This must be in consultation with Supervisors. At the termination of work, when keys are returned, affirmation will be required that all outstanding disposals have been dealt with. Charges may be made to Supervisors who persistently leave unwanted materials.

The following guidelines must be adhered to regarding disposal of chemicals:

• Purchase only enough chemical to complete your experiment.
• When designing and COSHH assessing experiments, remember to give due consideration to the safe disposal of waste.
• Toxic waste for disposal should be clearly labelled with details and concentration of contents, date and laboratory and user’s name.
• Waste mercury from broken thermometers is best collected, stored under water and saved for recycling. Traces of mercury remaining should be treated with zinc or sulphur dust, brushed up and put into a screw-capped jar before sending for disposal.
• Advice should be sought from the School COSHH Adviser over material that requires specialized licensed disposal.
• Small quantities of material contaminated with chemicals that require incineration, for example, tips contaminated with ethidium bromide or acrylamide, should be placed in a YELLOW bag marked Biohazard and sent for incineration (see below). Keep this waste to a minimum.
• Large volumes of acid or strong alkali should be neutralised before washing to waste with copious quantities of water.
• Silica Gel Waste and other chromatographic media must be placed in labelled plastic containers. When full, the waste containers must be sent to the stores (do not place in the laboratory waste bins). Stores will continue to hold a stock of suitable plastic containers available on request.
• Under no circumstances should any chemical waste be placed in the normal laboratory waste bins; consult with technical staff if in doubt.

Solvents

• Waste solvents must be poured into properly labelled waste solvent containers (please remove original labels if re-using bottles). DO NOT throw solvents down the drains.
• Halogenated hydrocarbon waste should be segregated from non-halogenated hydrocarbon waste.
• As there is a real possibility of explosion of waste acetone and chloroform in the presence of alkali, ACETONE should only be added to the blue labelled waste bottles; if for some reason it is contaminated, then it should be sent for disposal in a separate container clearly labelled ‘Do not mix with other waste solvent’.
• In general, waste solvent that contains a high concentration of acid or base should not be indiscriminately added to general waste solvent containers but disposed of separately.
• Decompose reactive materials before placing in waste solvent bottles.

Glass

There is a dedicated broken glass disposal bin in each laboratory. All chemicals must be rinsed off and any glassware used for microbiological work must be autoclaved before disposal as this glass is ground and recycled for road surfacing. Never put broken glass in ordinary waste bins in case of accidental injury to staff collecting the waste. Bottles and containers supplied by Fisher are recycled; these may be returned to the Stores for collection (wash out first please).

Sharps

Blades, hypodermic needles, capillary spotters and other ‘sharps’ should be placed in a yellow ‘sharps’ disposal container available from the Stores. Containers of biologically contaminated sharps should be autoclaved before disposal. Containers should then be placed in the yellow wheelie bin for incineration.

Green Waste

Low risk waste should be placed in the bins provided.

Disposal of Ionising Radiation Waste

See Section 10

Disposal of Biological Waste Material

See Section 12