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HealthcareWaste

The Treatment And Disposal Of Healthcare Waste

Healthcare waste refers to any waste produced by, and as a consequence of, healthcare activities within the NHS, in the community and
from non-NHS healthcare sources and includes both hazardous and non-hazardous wastes (see Table 1).

Legislation

Legislation of particular relevance to the management of healthcare waste includes:

  • Waste Management Licensing Regulations
  • Landfill Regulations
  • Hazardous Waste Regulations (as applicable to England, Wales and Northern Ireland) and Special Waste Amendment (Scotland)
    Regulations
  • Controlled Waste Regulations
  • Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations (the Carriage Regulations)
  • Control of Substances Hazardous to Health Regulations (COSHH)
  • Pollution Prevention and Control Regulations.

Definition Of Clinical Waste

The definition of clinical waste is used to describe waste, produced from healthcare and similar activities, that poses a risk of infection or that may prove hazardous. It can broadly be divided into two categories:

1 waste that poses a risk of infection: including human1 or animal tissue, sharps, blood and other bodily fluids

2 medicinal waste: including waste arising from veterinary or dental practice, investigation, research and treatment.

Clinical waste should be segregated from other types of waste and be treated or disposed of appropriately in suitably permitted,
licensed or exempt facilities according to the hazard involved.

Proper segregation is key to the safe management of healthcare waste and helps control management costs. The use of colour-coded receptacles (see Table 2), whilst not mandatory, is considered best practice:

Reference is made to the minimum required standard of waste treatment/disposal. However, waste may be sent to alternative treatment/
disposal methods that operate to an equivalent or higher standard.

   
   
   
   
   
   
   
   
   
   
   
   
   

Treatment And Disposal

All treatment and disposal facilities are required to "render safe" the waste. How this is achieved depends on the type of waste
treated and on the nature of the contaminants present, but it must:

  • demonstrably reduce the number of infectious organisms present in the waste to a level that no additional precautions
    are needed to protect workers or the public against infection
  • destroy anatomical waste such that it is no longer generally recognisable
  • render sharps unusable and no longer in their original shape and form
  • destroy the component chemicals of medicinal waste.
  • Treatment and disposal systems fall broadly into two categories:
  1. High temperature processes (incineration/combustion)
  2. Non-burn/low temperature alternative technologies.

High Temperature Processes

Incineration

Healthcare waste incinerators generally have a primary combustion chamber operating at 800-1?000°C and a secondary chamber operating at 850-1?100°C with gas retention times of two seconds. The incinerator plant includes gas-cleaning equipment to reduce emissions to air and comply with the Waste Incineration Directive.

Pyrolysis

Pyrolysis involves the high temperature (545-1000°C) combustion of waste in the absence of oxygen. This treats the waste, destroys pathogens and reduces the volume of clinical waste.

Plasma Technology

In a plasma system, an electric current is passed through an inert gas (eg argon) to ionise it and this causes an electric arc to create temperatures as high as 6?000°C.

The clinical waste within the system is brought to temperatures of 1?300-1?700°C, destroying pathogenic microbes and converting the waste into a glassy rock or slag, ferrous metal and inert gases.

Gasification

the waste materials are thermally decomposed in an oxygen-starved atmosphere.

No additional fuel is required except for that required to initiate combustion. The decomposition results in the generation of
volatile gases and, depending on the waste content, various vaporised taroil substances. The waste gas is passed through a series of scrubbers, filters and cyclonic separators to provide a clean "producer gas".

Non-Burn/Low-Temperature Treatments

Thermal Disinfection Systems:

Autoclave: saturated steam is introduced into a vessel above atmospheric pressure. Some autoclaves shred the waste during
treatment whilst others require the waste to be macerated before treatment.

Steam Auger: waste is shredded prior to introduction into a steam auger at atmospheric pressure.

Dry Heat: pathogens are destroyed by electrically generated hot oil.

Microwaves: electromagnetic waves with a frequency between radio waves and infrared waves, thermally destroy pathogens. It
is important for the waste to be wet, either as a result of moisture naturally occurring in the waste stream or by the addition of
moisture in the form of steam. The combination of the two - microwaves and moisture - creates the thermal process.

"Dry" microwave systems are also available, which use direct microwave energy in a nitrogen atmosphere to treat the waste
and produce higher treatment temperatures.

Macrowaves: lowfrequency radio waves inactivate microbes by heating the waste from the inside of the materials to the outer
surface.

Chemical Disinfection Systems

Chemicals commonly used are sodium hypochlorite, chlorine dioxide, peracetic acid, glutaraldehyde and quaternary
ammonium compounds. The waste is shredded to bring all surfaces into direct contact with the chemicals. Some systems
combine heat with the chemicals to reduce the treatment cycle. It is important that the disinfectant has the ability to act on all
the key pathogen groups and is maintained in the waste at sufficient concentration and for sufficient time to achieve the
required level of treatment. Care must be taken to ensure that the treated waste is not rendered chemically hazardous by the
disinfectant.

Landfill

Infectious waste is banned from landfill without pretreatment. Guidance on the pretreatment requirements in England and Wales,
Northern Ireland, and Scotland is available from the respective regulatory authorities (EA, EHS and SEPA).

The following require specialist treatment:

waste known, or suspected, to be contaminated with transmissible spongiform encephalopathy (TSE) agents, including CJD2

waste contaminated with cytotoxic and/or cytostatic substances

waste contaminated with genetically modified microorganisms (GMMs)

waste contaminated with Mercury

dental amalgam(3).

References & Useful Links

1 Human Tissue Authority Code of Practice, www.hta.gov.uk/regulation/codes

2 Guidance from the ACDP TSE Working Group; www.advisorybodies.doh.gov.uk/acdp/tseguidance

3 Hazardous/Special Waste Regulations - Guidance and Background Material; www.defra.gov.uk/environment/waste/special/index.htm

Health Technical Memorandum 07-01: Safe Management of Healthcare Waste