SOM030
School of Materials Guidance Notes on:
Disposal of Waste
Including chemical, biological, general waste
It is illegal and unethical to dispose of anything in an inappropriate or unsafe manner. This
includes the cleaner emptying the waste bin, the bin men emptying the skip, the environment
from many sources of waste.
This document outlines general and specific guidelines on preferred methods to dispose of
materials. If it is unclear how to dispose of your material or it is not covered by this document
contact your Supervisor and the Safety Advisor.
Disposal Guidelines
Description of
Waste
1
Paper
2
Cardboard
3
Plastic
4
Glass (clean)
5
Batteries
6
Organic
solvents
7
Chemicals
8
Asbestos
9
Toxic
Substances
Other
Includes
Office paper
Does not include
Card board
Card board
Fizzy drink bottles, milk
bottles
General glass
General domestic
batteries
Various
various
Campus Waste Paper bins
Campus Waste Card board
bins
Campus Waste Plastic bins
Pyrex or silica glass or
contaminated glass
Car or large batteries
Campus Waste Glass bins
various
See Organic solvent disposal
various
See Chemical disposal
All asbestos
Campus Waste battery buckets
Safety advisor must be
informed. Double bagged in
specific bags and disposed via
disposal company
Bottled and disposed via waste
disposal company
Mercury
Metal, general rubbish,
wood, rubble
Disposal Route
Any of above
Use skip, some sites have
separate metal disposal
General Hazardous Waste guidelines:
All laboratory waste containers must be:
 In good condition with no leaks or cracks, and suitable for contained waste, e.g.
strong acids may not be stored in plastic bottles and hydrofluoric acid may not be
stored in glass bottles. Empty containers of which the product was originally
received are best reused as waste containers.
 Kept closed except when adding waste,
 Separated from other incompatible wastes,
 If necessary, stored in clean and compatible secondary containment,
 Affixed with a fully completed hazardous waste label, with records indicating
contents, approx concentrations, date and name,
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 Funnels left in bottle mouth is not acceptable,
 Do not over fill liquid containers; leave enough air space for expansion.
Spill kits are available in all chemical areas also use appropriate personal protective
equipment. Report all major spills, i.e. if hazardous or large amount on the
Universities Accident (if an injury) or Incident forms.
Organic Solvent Disposal:
1. Non - Chlorinated Organic Solvents
Acetone
Methanol
Butanol
Isopropanol
Meths (IMS)
Tetrahydrofuran (THF)
Dimethyl Acetamide (DMAc)
Toluene
Ether
Ethanol
Petroleum Ether
Hexane
Heptane
Xylene
Butanone (MEK)
Cyclohexane
DimethylFormamide (DMF)
1,4 Dioxan
Amassed in lab in properly labelled container,
transferred to outside chemical store for disposal by
waste disposal company, recording what the waste is,
who is disposing it and when.
A vented cap should be used if there is any possibility of
the waste generating / liberating gas or vapours. When
a ventilated cap is used, the waste should be kept in a
well ventilated area.
2. Halogenated Organic Solvents
Trichloroethylene
Chlorobenzene
Dichloromethane
Chloroform
Carbon TetraChloride
Amassed in lab in properly labelled container,
transferred to outside chemical store for disposal by
waste disposal company.
3. Nitrogenised Organic Solvents
Pyridine
Amassed in lab in properly labelled container,
transferred to outside chemical store for disposal by
waste disposal company.
Chemical Disposal:
1. Acids
a. Hydrofluoric Acid – see SOM017 – Hydrofluoric Acid Solutions
2. Bases
3. Heavy Metal Salts - e.g. nickel chloride, lead chloride, platinum chloride etc.
4. Amines
5. Oxidisers
6. Extremely Toxic compounds
a. Mercury – mercury spills can be avoided by using supplies and equipment that do
not contain mercury. However, most mercury spills do not pose a high risk.
The initial response to a spill of elemental mercury should be to isolate the spill
area and begin the clean up procedure. Those doing the clean up should wear
protective gloves. The cleanup should begin with collecting the droplets. The large
droplets can be consolidated by using a scraper or a piece of cardboard, and the
pool of mercury removed with a pump or other appropriate equipment. For
cleaning up small mercury droplets, use wet towelling, which consolidates the
small droplets to larger pieces, or picked up with a piece of adhesive tape.
Commercial mercury spill sponges and spill control kits are available. The
common practice of using sulphur should be discontinued because the practice is
ineffective and the resulting waste creates a disposal problem. The mercury
should be placed in a thick-wall high density polyethylene bottle and transferred to
a central depository for reclamation. After a mercury spill the exposed work
surface and floors should be decontaminated by using an appropriate
decontamination kit.
SOM030
b. Ethidium Bromide (Gels and solutions) – Ethidium Bromide is commonly used
in molecular biology laboratories. While it is not recognised as hazardous waste,
the mutagenic properties of this substance may present a hazard if it poured down
the drain untreated or placed in the solid waste bins. Gloves, test tubes, paper
towels, etc., that are grossly contaminated with ethidium bromide should be
placed in the medical waste for incineration.
i. Gels – Trace amounts of ethidium bromide in gels should not pose a
hazard. Higher concentrations, e.g., when the colour of the gel is dark pink
or red, should not be placed in laboratory waste bins. It is recommended
that:- Less than 0.1% ethidium bromide: place in laboratory waste, more
than or equal to 0.1%: place in biohazard waste for incineration.
ii. Solutions – Aqueous solutions containing <10µg/ml ethidium bromide can
be released to the drain. Aqueous solutions containing >10µg/ml ethidium
bromide should be filtered or deactivated using one of the methods
described below. Charcoal filtration is strongly recommended over chemical
deactivation. Solutions containing heavy metals, organics, cyanides or
sulfides should be disposed as hazardous waste.
1. Charcoal Filtration – Filtering the aqueous ethidium bromide waste
solutions, free of other contaminants, through a bed of activated
charcoal is a relatively simple and effective method for removal of
ethidium bromide. The filtrate may be poured down the drain with
copious amounts of water. The charcoal filter can be placed in a
sealed bag and placed in bio-hazardous waste for incineration.
There is also a ‘Green bag’ method which also uses a charcoal
absorbent.
2. Chemical method – There are several chemical methods for
neutralisation of ethidium bromide – see supervisor and local rules
for guidance.
Disposal of Reaction Solutions
Read these instructions before proceeding
All described procedures should be carried out in a fume hood. Use additional
shielding as required. Suitable and proper Personal Protective Equipment, PPE (lab
coat, safety glasses and appropriate gloves) must be worn.
Please consult primary literature and your supervisor for details on protocols for the
proper handling of waste not listed here.
DO NOT pour ‘reaction’ solutions down the drain.
These solutions should be disposed of carefully.
Prior to disposal all solutions need to be checked for oxidisers and pH.
SOM030
If the presence of oxidisers is suspected then take a small sample and dilute, say 4 times
with water and make acidic, then check with starch iodide [white if neutral and blue to violet
if present].
Acids or bases should be checked for with pH paper before disposal [pH7].
To do this take a sample of the solution and dilute it [e.g. 250 ml to 5 litre of water]. If the
acid or base is highly concentrated, it is prudent to first dilute it with cold water (adding the
acid or base to the water) to a concentration below 10%. Then neutralise with either sodium
or magnesium hydroxide or sulphuric or hydrochloric acid, respectively can be used.
If oxidisers are present, then the solution needs to be neutralised [reduced], this is carried
out by adding ferrous sulphate, whilst the solution is in the acidic state, until the presence of
oxidisers can no longer be detected.
If your solution is not acidic then it needs to be acidified with a mineral acid e.g. HCl, H 2SO4.
If you are removing or neutralising a solution containing ‘heavy metals’, e.g. chromium, then
the solution needs to be acidic and to contain iron, e.g. iron shot, iron filings etc.
The solution is then neutralised using sodium carbonate to pH7. [it is necessary to use
calcium chloride when fluorides are present in the solution, e.g. 250 gm for 1 litre of 5% HF
solution].
When neutral from an oxidising point of view and neutral from a pH point of view [pH7] the
supernatant solution is ‘safe’ to discard down the sink with copious amounts of water, and
any non-hazardous waste solids are to be bagged and discarded.