Advisory Council on the Environment

Proposed Clinical Waste Control Scheme

(ACE Paper 12/2002)
For discussion


This paper seeks Members' views on a revised proposal for the control of the collection and disposal of clinical waste.


2. Clinical waste is waste arising from practice or research for dental, medical, nursing, veterinary, pathological/laboratory testing or pharmaceutical purposes. It includes mainly used or contaminated sharps like syringes/needles, laboratory wastes, human and animal tissues/organs, infectious materials from patients, and surgical dressings. We estimate that about eight tonnes of clinical waste are currently produced every day, largely in hospitals, clinics, and medical laboratories.

3. Clinical waste is potentially dangerous since some may carry infectious disease, and sharps like needles and scalpels may cause injury. Many private clinics and medical laboratories are located in residential and commercial establishments. Hence, waste collectors and the public may inadvertently come into contact with clinical waste. At present, the Government has no special requirement for the collection and disposal of clinical waste. Most clinical waste is disposed of in landfills without treatment.

4. To safeguard public health and safety, we introduced in 1997 a proposed Clinical Waste Control Scheme (the Control Scheme) to control the handling, collection and disposal of clinical waste for consultation with stakeholders, this Council and the LegCo Environmental Affairs / Health Services Panels. Under this Control Scheme, it was proposed that:

  1. legislative control on major clinical waste producers (i.e. hospitals, maternity homes and Government clinics) should be the first step to tackle the issue;
  2. legislative control on small clinical waste producers (such as private medical, dental and veterinary clinics and laboratories) could be held in abeyance if these producers can demonstrate a satisfactory level of control through self-regulation; and
  3. the collected clinical waste should be disposed of at the Chemical Waste Treatment Center (CWTC) at Tsing Yi.

5. An Environmental Impact Assessment (EIA) was completed and concluded that the CWTC is suitable for treating clinical waste in an environmentally acceptable manner. This Council endorsed the EIA report in May 1999 (para 18 below). The Legislative Council, in examining the disposal issue, requested us to provide more information on alternative technologies for clinical waste treatment.

6. Consequently, the Environmental Protection Department (EPD) engaged Mr. William K. Townend1, an international expert on clinical waste management, to study available treatment technologies worldwide, review international practices, and advise on the application of such technologies in Hong Kong. At the same time, in view of increasing public concern over the potential risks associated with improper handling of clinical waste, we also reviewed the proposed two-phase approach regarding the control of clinical waste collection.

Revised Proposal for Handling and Collection of Clinical Waste

7. We completed the review on clinical waste collection in 2001. To better safeguard public health and safety, we propose to adopt a more robust collection system which would extend legal control to all major and small clinical waste producers simultaneously, requiring them to segregate properly clinical waste from other wastes, and arrange for proper disposal of the waste.

The Revised Control Scheme

8. The revised Control Scheme comprises the following key elements:

  1. establishing a statutory licensing framework to regulate the handling of clinical waste by collectors and disposal facility operator(s);
  2. requiring clinical waste producers to consign their waste to licensed clinical waste collectors. Alternatively, healthcare professionals should deliver not more than 5 kilograms of clinical waste to the disposal facility or authorized collection points set up by waste collectors or individual waste producers;
  3. issuing two codes of practice - one for waste collectors and major clinical waste producers, and one for small waste producers - to provide guidance on segregation, packaging, labelling, collection, handling, storage, transportation and disposal of clinical waste;
  4. putting in place a trip ticket system to track the movement of clinical waste from its source to the disposal facility; and
  5. requiring clinical waste producers to pay a charge to cover part of the waste disposal cost.

Consultation with Relevant Sectors

9. In November 2001, we issued a Consultation Document on the revised Control Scheme together with a draft "Code of Practice for the Management of Clinical Waste for Small Clinical Waste Producers" (Annex A) for consultation with stakeholders, including the medical, Chinese medical, dental, nursing and veterinary sectors, elderly homes, green groups, academic institutions, waste collectors and other related organizations. We also attended eight meetings or discussion forums2 to explain the revised Control Scheme to the parties concerned and to collect their views.

10. We received 27 written submissions at the end of the consultation period. The submissions show general support for the revised Control Scheme. A summary of the comments received and our response to the comments is at Annex B MS Word Version. Major issues raised in the written submissions and in meetings with the relevant trades include:

  1. Level of collection charges
    Some small waste producers are concerned about the level of collection charges to be levied by waste collectors and suggested that Government should subsidize the cost, or regulate future fee increases. At present, there are already nine collectors providing collection service3. We believe this number should allow sufficient competition in a free market and help ensure that the collection cost is kept at a reasonable level. In addition, we have included in the revised Control Scheme some flexibility that allows small waste producers to deliver their clinical waste to authorised collection points or to the disposal facility if they do not wish to hire collectors (para. 8(b) above).

  2. Disposal cost at the waste disposal facility
    There are concerns over the proposal to charge waste producers the waste disposal cost, and how future increases would be controlled. Some respondents suggested that such a fee should be waived. We do not agree with this view. We consider that the User Pays Principle should apply and there is no reason for taxpayers to bear the disposal cost for waste producers. We estimate that a small clinic producing 0.4 kg of clinical waste a day would pay less than $35 for disposal each month. Moreover, we believe the disposal cost would help create an economic incentive for waste reduction and proper segregation by clinical waste producers.

  3. Establishing collection points
    Some respondents suggested Government set up collection points at Government clinics or public hospitals to serve the small waste producers. As there are already a number of clinical waste collectors in the market, we do not think Government should provide this service. Furthermore, the public should not bear the collection cost nor should Government compete with private waste collectors.

11. There is no change to the control on major waste producers. A copy of the draft Code of Practice applicable to them is at Annex C MS Word Version.

Treatment of Clinical Waste

12. Mr. Townend has already completed the review of treatment technologies. The study report, together with reviews carried out by the Hospital Authority and relevant information gathered by EPD, is at Annex D.

Findings of the Review

13. The review has examined the following technologies for the treatment of clinical waste:

  1. chemical disinfection;
  2. thermal disinfection - wet thermal treatment (autoclave), dry thermal treatment (hot screw-feed technology) and electromagnetic wave treatment (microwave & radio wave);
  3. thermal treatment - incineration, pyrolysis and gasification which operate on a similar principle but use different levels of oxygen in the process; and
  4. novel treatment technologies - plasma based systems and irradiation.

14. In comparing the various treatment technologies, the review has taken into account their health, safety and environmental impacts, efficacies in killing infectious microorganisms, reliability and ease of maintenance, weight and volume reduction of waste, handling of residues and further treatment requirements, space requirements, public perception of risk, as well as their costs and financial implications. In brief, the findings are as follows:

  1. Chemical Disinfection
    • Chemical disinfection involves the addition of chemicals to the clinical waste to kill or inactivate the pathogens. Pre-treatment shredding of the waste is required to ensure maximum contact of the chemical with the waste.
    • This is a relatively economical means to treat clinical waste.
    • However, it introduces an additional chemical burden on the environment. The use of chemicals and the operation of the pre-treatment shredder may pose occupational safety hazards to workers who operate the system. It cannot destroy the residual hazardous chemicals in the clinical waste. It is also not suitable for treating cytotoxic drugs, human tissue and body parts, pharmaceuticals and chemicals.

  2. Autoclaving
    • Autoclaving is a wet thermal treatment process that involves the use of steam to sterilize the waste at 121°C-131°C. Pre-treatment shredding of the waste is normally required, or else there could be cold spots where the steam could not reach. The steamed waste is then incinerated or landfilled.
    • It is a relatively cheap treatment method and may be operated in hospitals.
    • However, vapour will be formed during the process, and residual chemicals in the waste that cannot be destroyed under low temperature would be vaporized and escape into the environment. The emissions, the presence of cold spots and the need for shredding all pose occupational safety hazards to workers who operate the system. It is not suitable for treating cytotoxic drugs, human tissue and body parts, pharmaceuticals and chemicals.

  3. Screw-feeding
    • This is a dry thermal treatment process where the waste is heated by a rotating auger to 100°C-131°C. Pre-treatment shredding is required. The residues are then incinerated or landfilled.
    • It has the same drawback and inadequacies as autoclaves. Similar to autoclaving, the need for shredding poses occupational safety hazards to workers who operate the system. It is not suitable for treating cytotoxic drugs, human tissue and body parts, pharmaceuticals and chemicals.

  4. Microwaving & Radiowaving
    • This is an electromagnetic wave thermal disinfection process that involves the use of high-intensity radiation to heat the moisture inside the waste. The treated waste is then incinerated or landfilled. Pre-treatment shredding is required.
    • Both maintenance of the shredder and the exposure to high intensity electromagnetic wave radiation may pose occupational safety hazards to workers who operate the system. Moreover, similar to autoclaving, vapour will be formed during the process, and residual chemicals in the clinical waste that cannot be destroyed under low temperature would be vaporized and escape into the environment. Again, it is not suitable for treating cytotoxic drugs, human tissue and body parts, pharmaceuticals and chemicals.

  5. Incineration
    • This involves burning of waste at over 1200°C.
    • The process can destroy all types of infectious microorganisms, sharps, cytotoxic drugs, chemicals and toxic volatile compounds. Residual hazardous chemicals in the waste can be destroyed and waste can also be made unrecognizable. The volume and weight of waste can be reduced by over 80% without shredding, and the residual ashes can be disposed of in landfills.
    • Pollutants like dioxins will be generated and pollution control devices are required. Both fly ash and bottom ash will be generated. They need to be stabilized and disposed of at landfills.

  6. Pyrolysis
    • Pyrolysis is the process of chemical decomposition of organic materials by heat (up to 2500°C) in the absence of oxygen.
    • The process can significantly reduce the volume and weight of clinical waste and can destroy all infectious micro-organisms and residual amount of cytotoxic drugs, pharmaceuticals and toxic chemicals effectively.
    • Similar to incineration, there may be dioxin emission and pollution control devices are required. There is currently only one clinical waste pyrolysis plant in Europe, and it also has an "after-burn" unit i.e. a post-pyrolytic treatment incinerator.

  7. Gasification
    • Gasification is a process where the materials (that have a high carbon content) are heated to about 1300°C with a limited amount of oxygen.
    • Similar to incineration and pyrolysis, this technology can destroy all micro-organisms, cytotoxic drugs, pharmaceuticals and toxic chemicals effectively. Waste volume and weight can also be significantly reduced.
    • Similar to incineration and pyrolysis, there may be dioxin emission and pollution control devices are required. Again, most gasification plants consist of after-burn units to incinerate the residual waste.

  8. Plasma-based Systems & Irradiation
    • Plasma-based systems use high temperature (as high as 10,000°C) ionised gas to convert waste to a vitrified substance with separation of molten metal. Irradiation is the use of electron beam or other high energy particles emitted from radioisotopes to disinfect waste.
    • Both technologies may kill all microorganisms and make clinical waste unrecognizable. Plasma systems can also significantly reduce the volume and weight of clinical waste.
    • However, these are relatively new technologies and there is insufficient information for us to assess the cost and the long-term environmental impacts. They also have a limited proven track record to demonstrate their operational reliability. In cases where the use of radioisotopes is involved, radioactive waste may be generated.

Recommendation on Treatment Technology

15. The review has concluded that technologies described in para 14(a)-(d) are not satisfactory as they cannot properly handle all kinds of clinical waste. These technologies require post-treatment landfilling or incineration and are thus not a total solution in handling clinical waste. Most of them also emit pollutants because they cannot treat the residual chemicals in the waste. Occupational hazards remain a primary concern as there are already cases elsewhere where workers who operate these treatment facilities contract infectious disease. Plasma-based systems and irradiation (para 14(h)) do not pose such problems but they are relatively new and their operational reliability and environmental impacts have yet to be fully established.

16. As for gasification and pyrolysis (para 14(f) & (g)), Mr Townend is of the view that they do not have specific advantages over incineration, as they do have the same emission problems as incineration. These are new technologies, and there are only a few gasification/pyrolysis plants in operation overseas. Furthermore, incineration is still needed as part of the treatment process. Given that the CWTC is already an existing facility, using incineration to treat clinical waste would obviate the need to build a new facility. Incineration has been developed for many decades and its impacts have been widely studied. With advancement in incineration and pollution control technologies, its environmental impacts including emission of dioxins can be tackled effectively. It remains the most commonly adopted method in treating clinical waste in most advanced economies including the Mainland, the US, Europe, Canada, Australia and Japan.

17. The review recommends that as a medium-term solution, the CWTC, which still has spare capacity, be modified for treating clinical waste. The review suggests that, in the longer term, the Government should keep abreast of international developments and should not preclude the option of installing an alternative treatment facility at a later stage.

Proposed Way Forward

18. Having taken into account the review findings, we consider that we should proceed with the planned modification of the CWTC to treat clinical waste. As mentioned in para 5 above, an EIA on the proposed use of the CWTC for this purpose had been completed in 1999. The findings confirmed that the CWTC, which is a purpose-built waste treatment facility with suitable pollution control devices, is suitable to treat clinical waste in an environmentally acceptable manner. A very tight emission monitoring programme has also been put in place since the CWTC's commissioning. This Council endorsed the EIA report in May 1999 with the following conditions:

  1. stringent requirements on mercury monitoring must be included as part of the environmental monitoring and audit programme of the CWTC;
  2. performance test must be undertaken before the full operation of the clinical waste handling facilities at CWTC; and
  3. the ACE would be informed of any serious problems arising from the performance test or operation.

All findings and recommendations of the EIA report will be adopted, and the conditions set down by this Council will be met.

Legislative and Implementation Timetable

19. We plan to submit the Waste Disposal (Amendment) Bill and the draft Waste Disposal (Clinical Waste) (General) Regulation to the Legislative Council later this year. Subject to the enactment of the Bill and the Regulation, we will implement the revised Control Scheme in 2004.

Resource Implications

20. We plan to seek funding approval from the Legislative Council later this year for the modification of CWTC to treat clinical waste. The capital cost of the modification work is estimated to be $51 million at September 2001 prices. The work is expected to be completed in 2004. The annual recurrent cost for treating clinical waste is estimated to be around $22 million.

21. We intend to recover part of the recurrent cost from clinical waste producers through disposal charges. We propose that the charging mechanism follow that of land-based chemical waste treatment at the CWTC i.e. we will recover 31% of the variable operating cost as a start, gradually raising it to full recovery of the variable operating cost. The capital and fixed operating cost will not be charged. At present, the variable operating cost for the CWTC to treat clinical waste is estimated to be $7.7 per kg. This means a charge of less than $3 per kg, or less than $35 each month for an average clinic that produces 0.4 kg of clinical waste each day (para 10(b)).

Advice Sought

22. Members are invited to comment on the revised Clinical Waste Control Scheme as set out in this paper.

Environment and Food Bureau
Environmental Protection Department
March 2002

1Mr Townend was the former President of the Institute of Waste Management in the United Kingdom and the current Chairman of the Working Group on Health Care Waste of the International Solid Waste Association. He has been a consultant and adviser to the World Health Organisation (WHO), and is also the co-author of the WHO publication "Teacher's Guide - Management of Wastes from Health-care Activities".

2These include seminars/meetings with the Hong Kong Medical Association, the Hong Kong Dental Association, the Hong Kong Veterinary Association, the Hong Kong Waste Management Association, representatives from 13 Chinese medical practitioners associations, and the existing clinical waste collectors.

3According to information provided by existing clinical waste collectors and private medical practitioners that are using their service, the service charge ranges from $30 to $300 per month.





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