GB2572265A - A waste remediation apparatus and method - Google Patents

Abstract

A waste remediation method for the treatment of pharmaceutical and/or contaminated medical waste, the method comprising the steps of sterilising the medical waste in a sterilising chamber, collecting liquid run-off during the sterilising step, capturing vapour evolved during the sterilising step and condensing the vapour, and combining the condensed vapour and liquid run-off together as liquid effluent for disposal in an incinerator. A waste remediation apparatus for the treatment of pharmaceutical and/or contaminated medical waste comprising a sterilising chamber, a run-off liquid collection mechanism, a vapour collection mechanism, a vapour capturing mechanism, a cooling device for condensing the vapour and an arrangement for combining the run-off liquid and the vapour as a liquid effluent.

Description

A WASTE REMEDIATION APPARATUS AND METHOD

FIELD

The present teachings relate to a waste remediation apparatus and method. In particular, but not exclusively, the present teachings relate to a remediation apparatus and method for medical waste that may be contaminated with pharmaceuticals and potentially infectious bodily fluids.

BACKGROUND

It is known to treat medical waste that is potentially infectious using treatment processes such as autoclaves, direct steam injection or microwave treatments in order to kill pathogens by elevating the temperature within a vessel to a level where they are killed. The steam and effluent generated by such processes is considered to be pathogen free and therefore is allowed to escape into the atmosphere and drain respectively.

If it is determined that the pathogens are of such a virulent nature that this approach is not sufficient (e.g. Ebola, Anthrax or CJD) then the effluent from an autoclave is subjected to further heat treatment before being allowed to go to drain.

Where clinical waste further comprises pharmaceutical substances such as may be found on or inside used syringes or the like, environmental regulations, at least in the UK, stipulate that steam and effluent from autoclaves is not permitted to go to drain or atmosphere since it may allow pharmaceutical substances to accumulate in the environment with a risk of harmful effects on human and animal life. As a result, such clinical waste is required to be sent for specialist high temperature incineration at considerable cost.

In addition, the capacity of such incinerators is constrained, therefore resulting in undesirable delays before incineration takes place or the need to ship waste considerable distances, with attendant cost increases and environmental damage.

The present invention seeks to overcome, or at least mitigate, the problems of the prior art.

SUMMARY

A first aspect of the teachings provides a waste remediation method for the treatment of pharmaceutical and/or contaminated medical waste, the method comprising the steps of:

a) sterilising the medical waste in a sterilising chamber;

b) collecting liquid run-off during the sterilising step;

c) capturing vapour evolved during the sterilising step.

d) condensing the vapour; and optionally

e) combining the condensed vapour and liquid run-off together as liquid effluent for disposal in an incinerator.

Advantageously this process allows for the safe disposal of pharmaceutically contaminated medical waste in an environmentally friendly manner, and may have lower capital and/or operating costs than has previously been achieved

The method may comprise the further step f) after step e) of heating the effluent in an incinerator operating at a temperature of greater than 850°C.

Incineration in excess of this temperature has been found to effectively de-nature pharmaceuticals or chemicals found in the effluent.

The effluent may be heated in the incinerator up to a temperature of l,200°C.

The effluent may be heated in the incinerator up to a temperature of 950°C.

Incineration at up to this temperature is a characteristic of standard refuse incinerators such as energy from waste incinerators, and allows for the safe disposal at lower cost than high temperature hazardous material incinerators. The effluent may be used as quench water in the incinerators.

The method may comprise the further step g) of collecting solid waste remaining after step a) and incinerating the solid waste in an incinerator operating at a at a temperature of greater than 850°C.

The incineration may occur in an incinerator operating at up to a temperature of l,200°C.

The incineration may occur in an incinerator operating at up to a temperature of 950°C.

Incineration at up to this temperature is a characteristic of standard refuse incinerators such as energy from waste incinerators and allows for the safe disposal at lower cost than high temperature hazardous material incinerators. The solid waste may be burned as Refuse Derived Fuel (RDF) or Solid Recovered Fuel (SRF).

In step d) the vapour may be condensed in a heat exchanger.

In step a) the sterilisation or disinfection may occur in an autoclave.

An autoclave is an effective way of killing normal pathogens in medical waste.

The autoclave may be operable by introducing steam into the chamber at a temperature in excess of 100°C, preferably in excess of 120°C.

The autoclave may be operable at a pressure in the chamber in excess of 1 bar, optionally in excess of 3 bar.

In step e) the effluent may be stored in a mobile container for transportation to an incinerator.

It is likely that the apparatus cannot usually be co-located with an incinerator and therefore transportable storage is desirable.

In step e) the effluent may be cooled to a temperature of 80°C or less prior to storage in the mobile container.

Step d) may occur directly after step c) with no intervening process.

Step e) may occur directly after step d) with no intervening process.

The method may comprise a further step h) prior to step a) of shredding the medical waste.

This ensures the effective sterilisation of the waste.

The method may comprise a step i) after step c) of compacting solid waste remaining after step a).

This minimises the volume the waste requires for storage or transportation.

In step i) further run-off may be collected in the compacting step is combined with the condensed vapour and liquid run-off.

This ensures that there is no escape of pharmaceutically contaminated liquid via this route.

In step e) the vapour and liquid run-off may combined prior to step d).

This ensures the rapid cooling of all of the effluent.

A second aspect of the teachings provides a waste remediation apparatus for the treatment of pharmaceutical contaminated medical waste comprising:

a sterilising chamber configured to sterilise the medical waste;

a liquid collection mechanism for collecting liquid run-off from the sterilising chamber;

a steam capturing mechanism for capturing vapour in the sterilising chamber;

a cooling device for condensing the vapour; and optionally an arrangement for combining the run-off and the vapour as a liquid effluent.

Advantageously this apparatus allows for the safe disposal of pharmaceutically contaminated waste in an environmentally friendly manner, and may have lower capital and/or operating costs than has previously been achieved.

The cooling device may be a heat exchanger.

The sterilising chamber may be an autoclave.

An autoclave is an effective way of killing pathogens in medical waste.

The autoclave may comprise a control system configured to introduce steam at a temperature of in excess of 100°C, preferably in excess of 120°C.

The apparatus may further comprise a compactor arranged to compact solid waste remaining after sterilisation in the sterilisation chamber.

This minimises the volume the waste requires for storage or transportation.

The compactor may comprise a drain arranged to collect further liquid run-off from the solid waste for combining with the condensed vapour and liquid run-off.

This ensures that there is no escape of pharmaceutically contaminated liquid via this route.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the present teachings are now described by way of example only with reference to the accompanying Figure 1 which is a schematic diagram illustrating a treatment process of the present teachings.

DETAILED DESCRIPTION

With reference to Figure 1, an embodiment of the apparatus of the present teachings is illustrated schematically as indicated by the reference numeral 10.

A remediation method of the teachings that utilises the apparatus starts with the collection of medical waste at a healthcare facility that may include infectious bodily fluids as well as pharmaceutical waste. Such waste is of the type defined by European Waste Codes (EWC codes) 180103 and 180109. The waste may include syringes and other medicine delivery systems with or without sharps (needles) attached. The waste may contain pharmaceuticals or pharmaceutical residue. Further, the waste may include other medicinal items that could have been in contact with blood and other bodily fluids that have contained or may be contaminated with pharmaceutical and/or chemical products or residues. This may include tubes of creams, intravenous (IV) delivery tubes or materials used to clean up such as wipes, disposable towels and laundry. These materials become classed as hazardous medicinal waste within these codes once a part of the item pierces the skin or comes into contact with a mucous membrane.

Once this occurs the waste is collected in a clinical waste container or bag compliant with UN code UN3291. Sharps are deposited in a suitable sharps container. Certain such containers are reusable whereas other containers are single use, e.g. single use sharps bins. Once collected at a healthcare facility such as a hospital, doctors' practice, dental practice or veterinary practice, the waste is typically delivered to a central facility which comprises the apparatus 10 for remediation, either at a separate site or potentially on site in the case of a hospital. Transport of individual waste packages may commonly occur in a larger container such as a UN3291 compliant 770 litre clinical waste bin or an over pack. The delivery of such waste to a remediation facility in accordance with the teachings of the invention is illustrated by arrows 12a and 12b.

Arrow 12a denotes the delivery of waste in reusable containers. In this instance the waste is delivered to a decanter and washer 14 where the waste to be treated is emptied from the reusable containers before the containers are cleaned and returned to the healthcare facility for reuse.

The waste is then delivered to a shredder 16 to be broken apart to render them unrecognisable as medical waste and to reduce the size of the individual items. Waste in single use containers may be delivered directly to the shredder 16 as denoted by the arrow 12b. For example, large reusable clinical waste bins filled with single use containers and other contaminated items may be lifted and inverted over such a shredder 16 to deposit waste therein.

The shredder 16 is typically a multi-shaft shredder that breaks apart syringes and the like in order that the shredded waste is in a condition where it can be effectively sterilised by the downstream process. Typically such a shredder will break the waste into particles that are between around 10 and 50 mms in size. In an example industrial scale process of the teachings a suitable shredder 16 may have a capacity to shred between 1,000 and 3,000 kg of waste per hour (depending upon the composition and density of the waste). Such a shredder 16 has suitable isolation from the outside environment including filtration systems to avoid the escape of contaminated air and fluids and interlocks that ensure the shredder is not operable unless fully closed.

Shredded waste is collected in suitably sized autoclave bins 18 that catch the waste as it falls from the shredder 16 under gravity. To minimise the need for cleaning of the autoclave bins 18 they are typically lined with a disposable liner and in the example industrial process of the teachings, each has a capacity of approximately 1.7 m³.

In this embodiment, an autoclave 20 is provided that has a capacity to receive multiple autoclave bins 18 within its autoclave chamber. In this embodiment, the autoclave chamber has a capacity of 24 m³ and is able to house seven autoclave bins 18 of the type described above for treatment in a single batch. It will be appreciated that in other embodiments the size of the autoclave 20 and bins 18 may however be adjusted as required. In other embodiments alternative sterilising chambers may be employed such as rotating drum autoclaves or continual feed steam injection systems, chemical, microwave or heat disinfection units. In some cases - e.g. rotating drum autoclaves - the use of a shredder upstream may not be required.

Autoclaves 20 use high pressure steam to sterilise material placed therein. The apparatus 10 comprises a steam generating system including a water pre-treatment device 22 to remove water hardness and other impurities, a boiler hot well 24 and a boiler 26 to generate saturated steam to be delivered into the autoclave. The use of a boiler hot well is preferred as it reduces the risk of thermal shock damaging the boiler. A range of suitable steam temperatures and pressures to be achieved in the autoclave 20 are 120 to 160 °C and 1 to 10 bar respectively. For an autoclave of the type of the present example, the boiler 26 is required to deliver steam at a flow rate of around 2,600 kg per hour, but up to as high as 3,100 kg per hour. The steam delivered may be fully saturated steam. A suitable autoclave control system, e.g. a programmable logic controller (PLC) is provided to ensure that the autoclave 20 operates at the correct temperature and pressure.

Operation of the autoclave 20 is as follows: following completion of a previous treatment cycle, the autoclave 20 is loaded with autoclave bins 18 and a door thereof secured. The control system comprises an interlock to ensure that the sterilisation cycle cannot start until this has occurred. An operator selects the required cycle parameters in order to start the treatment process. A vacuum is first drawn within the autoclave 20 chamber to remove air and aid subsequent penetration ofthe steam into the waste material. The boiler 26 will then provide the required steam to the interior of the autoclave to heat the autoclave to the desired temperature, for example 136 °C and a suitable pressure, for example 8 bar. Once the required temperature and pressure is achieved, a timer starts for the required sterilisation time at this temperature. Typically, the autoclave will operate on 2-3 cycles of steam injection followed by drawing a vacuum. For example there may be two cycles in which steam is held within the chamber for 3-5 mins and a third cycle where steam is held for 18-22 mins, each cycle being separated by a period where the chamber is under vacuum. The cycle times are determined at a commissioning stage of the autoclave 20 to achieve the required level of disinfection. Once the cycles are completed, the steam is removed from the autoclave 20 and the load of waste in the autoclave bins 18 is allowed to cool.

Whilst the sterilisation process is ongoing, steam condenses within the autoclave 20 and liquid run-off is discharged under gravity from steam traps. This run-off is collected rather than being allowed to go to drain as in known processes. Further, vapour (steam) that is emitted from the process via a steam outlet, which would normally be discharged into the atmosphere or drain, is also captured such that no effluent is allowed to escape via either route. Both the vapour and the run-off may contain pharmaceutical residues that may be harmful if allowed to escape into the environment.

The run-off collected from the bottom of the autoclave 20 and the vapour collected from the steam outlet at the top of the autoclave are collectively referred to as effluent and are fed to a heat exchanger 28 to cool the effluent. The heat exchanger 28 is fed with ambient temperature cooling water, e.g. from a mains supply that is indirectly used to condense and cool the effluent (i.e. it never comes into contact with the effluent). The heat exchanger may be of any suitable type, e.g. shell and tube, plate type, plate and shell type or plate fin type. In other embodiments the heat exchanger may be an air-to-air condenser (blast cooler), not requiring a supply of cooling water. The heat exchanger is sized to have sufficient cooling contact with the effluent to provide the level of cooling required at the required flow rate of effluent. In this embodiment the flow rate of effluent to be cooled is approx. l,000ltrs/hr and the heat exchanger is sized appropriately.

The cooled effluent then passes into a buffer vessel 30, before in this embodiment being fed into a tank for onward transportation at a filling station 32. For example, in this embodiment the buffer vessel 30 has a capacity of approximately 400 litres and the liquid may be decanted into Intermediate Bulk Containers (IBCs) that have a capacity of approximately 1,000 litres at the filling station 32. In the case of filling IBCs, which have plastic tanks, the temperature of the effluent should be at or below 80°C before decanting, so as not to damage the IBCs. If being decanted into other tanks such as bulk stainless steel tanks mounted on a truck, or other metal tanker configurations higher temperatures (but less than boiling point) may be possible.

It should be noted that in a preferred embodiment, the cooling water from the heat exchanger 28 may be utilised as feed water for the boiler 26 or water for the washing of the apparatus 10, having passed through the heat exchanger. This has the advantage of minimising the energy requirements of the method.

The filling station 32, is configured to supply the effluent to one of two IBCs located in suitable filling points. As such, once one IBC is filled it may be removed for storage or onward transportation whilst a second one is filled. A control system is provided to monitor the fill level, e.g. by using a load cell, to automate the switching of filling from one IBC to another. If, due to a fault in the process, both IBCs are filled, along with the buffer tank 30, the control system may initiate an alarm to alert an operator to shut down the steam generation process or interface directly with the autoclave control system to automatically shut the autoclave 20 down. An emergency effluent overflow system may also be provided to capture any excess effluent.

Referring back to the autoclave 20, once the sterilisation cycle has been completed, and the temperature has cooled to a level at which it is safe to open the door, the control system releases the door interlock, enabling an operator to remove the autoclave bins 18, with the remaining solid waste therein no longer being infectious.

In this embodiment, the bins are then transferred to a waste compactor 34 for the sterilised waste to be compressed in volume to permit it to be efficiently transported to another location for onward recovery. In this embodiment, the compactor has a volume of approximately 22 m³ such that it will hold approximately 10 tonnes of sterilised waste when compacted. The waste compactor 34 may be provided with a suitable integral lifting mechanism to lift and tip the autoclave bins into it.

The compacting process may liberate further effluent from the waste, and to ensure that this is also retained, a drain at the bottom of the compactor 34 allows the liquid effluent to be collected and subsequently transferred into the IBCs 32, e.g. via a feed into the buffer tank 30 or directly into the IBCs.

In this embodiment the waste compactor may itself be loaded onto a suitable truck, e.g. by using a hook lift arrangement.

At this point, the liquid effluent and the compacted waste are both sterilised, but may contain pharmaceutical and/or other chemical residues. However, the pharmaceutical/chemical residue has been found to be safely disposed of via incineration at a standard domestic/municipal or non-hazardous industrial waste incinerator - e.g. an energy from waste incinerator. Energy from waste incinerators are typically municipally run facilities that burn domestic waste to generate electricity and/or heat for buildings in their locality. At such an incinerator the solid waste is permitted to be processed as Refuse Derived Fuel (RDF) or Solid Recovered Fuel (SRF). These fuels have the EWC codes 190210 and 19026. In addition, the liquid effluent can also be processed in such an incinerator as quench liquid under EWC code 161002.

In particular, the apparatus and process of the teaching can achieve a State and Territorial Association on Alternate Treatment Technologies (STAATT) level III and potentially STAATT level IV as set out in the table below. Whilst STAATT is a US standard its principles have also been adopted in the UK, and therefore meeting this standard allows the process to be granted a permit for operation in the UK by the Environment Agency.

STAATT	Description
Level III	Inactivation of vegetative bacteria, fungi, lipophilic/hydrophilic viruses, parasites and mycobacteria at a 6 loglO reduction or greater; and inactivation of B. stearothermophilus or B. atrophaeus spores at a 4 log 10 reduction or greater.
Level IV	Inactivation of vegetative bacteria, fungi, lipophilic/hydrophilic viruses, parasites and mycobacteria and B. stearothermophilus spores at a 6 log 10 reduction or greater.

It is important to note that energy from waste incinerators typically operate at a lower temperature than hazardous waste incinerators that have previously been used for disposing of hazardous clinical waste. The temperatures are shown to fully denature pharmaceutical materials and energy from waste incinerators have been found to be suitable for the proposed wastes. The temperatures of energy from waste incinerators are typically around 850°C and utilise a single combustion chamber. By contrast hazardous waste incinerators utilise two chambers. In the primary chamber waste is burned at around 900 to 1,000 °C. Gases from this chamber then travel to a second chamber where they are held at 1,000-1,200°C for two seconds. In addition, energy from waste incinerators generally have a higher capacity than hazardous waste incinerators - e.g. 1.2m tonnes/year as opposed to 100,000 tonnes for hazardous waste incinerators, but often less than 10,000 tonnes for incinerators that handle clinical waste.

As a result of the lower capacity of high temperature incinerators for hazardous waste and their stricter operational requirements, it is significantly more expensive to dispose of waste using high temperature incineration as compared to energy from waste type incineration making the process of the present teachings significantly more attractive than the known process, whilst maintaining environmental and public safety. Of course, it would remain possible for the liquid and solid waste from the process of the teachings to be sent to a hazardous waste incinerator, but this may negate or reduce the cost benefits thereof.

Once the IBCs and compactor have been emptied at the incinerator, they may be returned to the location of the apparatus 10 for refilling. In the interim, other IBCs and compactors will be filled in their place at the apparatus 10. As such it is possible for the apparatus to operate as a continuous batch process.

It will be understood that numerous changes may be made within the scope of the present invention. For example, alternative treatment processes may be used in place of the autoclave such as microwave treatment, heat disinfection units (HDUs), hot oil augers, chemical disinfection or the like. In addition, alternative means of transport may be used between the apparatus 10 and the incinerator, such as bulk tankers in the case of liquid, or direct pipework if close enough, etc. Further, although not preferred, the solid waste may be transported to the incinerator in a non-compacted state. The solid waste may be baled for transport to an energy from waste plant locally or further afield. In addition, if the incinerator is on the same site as the apparatus 10, conveyor belts or the like may transport the solid waste from the autoclave bins to the incinerator.

It will be appreciated that whilst the process is fundamentally that of an industrial scale, it may be scaled up or down as required for particular requirements. For example, if designed for use on site at a hospital it may be reduced in size from that described above. In addition, it is envisaged that the apparatus may be adapted for transportation on a truck for on-site treatment and/or may be scaled to fit within a standard shipping container for rapid deployment to a particular site.

Claims (25)

1. A waste remediation method for the treatment of pharmaceutical and/or contaminated medical waste, the method comprising the steps of:

a) sterilising the medical waste in a sterilising chamber;

b) collecting liquid run-off during the sterilising step;

c) capturing vapour evolved during the sterilising step.

d) condensing the vapour; and

e) combining the condensed vapour and liquid run-off together as liquid effluent for disposal in an incinerator.

2. The method of claim 1 further comprising the further step f) after step e) of heating the effluent in an incinerator operating at a temperature of greater than 850°C.

3. The method of claim 2 wherein the effluent is heated in the incinerator up to a temperature of l,200°C.

4. The method of claim 2 wherein the effluent is heated in the incinerator up to a temperature of 950°C.

5. The method of any preceding claim comprising the further step g) after step a) of incinerating the solid waste in an incinerator operating at a temperature of greater than 850°C.

6. The method of claim 5 wherein the incineration occurs in an incinerator operating at up to a temperature of l,200°C.

7. The method of claim 5 wherein the incineration occurs in an incinerator operating at up to a temperature of 950°C.

8. The method of any preceding claim wherein in step d) the vapour is condensed in a heat exchanger.

9. The method of any preceding claim wherein in step a) the sterilisation or disinfection occurs in an autoclave.

10. The method of claim 9 wherein the autoclave is operable by introducing steam into the chamber at a temperature in excess of 100°C, optionally in excess of 120°C.

11. The method of claim 9 or claim 10 wherein the autoclave is operable at a pressure in the chamber in excess of 1 bar, optionally in excess of 3 bar.

12. The method of any preceding claim wherein in step e) the effluent is stored in a mobile container for transportation to an incinerator.

13. The method of claim 12 wherein in step e) the effluent is cooled to a temperature of 80°C or less prior to storage in the mobile container.

14. The method of any preceding claim wherein step d) occurs directly after step c) with no intervening process.

15. The method of any preceding claim wherein step e) occurs directly after step d) with no intervening process.

16. The method of any preceding claim comprising a further step h) prior to step a) of shredding the medical waste.

17. The method of any preceding claim comprising a step i) after step c) of compacting solid waste remaining after step a).

18. The method of claim 17 wherein in step i) further run-off collected in the compacting step is combined with the condensed vapour and liquid run-off.

19. The method of any preceding claim wherein in step e) the vapour and liquid run-off are combined prior to step d).

20. A waste remediation apparatus for the treatment of pharmaceutical contaminated medical waste comprising:

a sterilising chamber configured to sterilise the medical waste;

a liquid collection mechanism for collecting liquid run-off from the sterilising chamber;

a steam capturing mechanism for capturing vapour in the sterilising chamber;

a cooling device for condensing the vapour; and an arrangement for combining the run-off and the vapour as a liquid effluent.

21. The apparatus of claim 20 wherein the cooling device is a heat exchanger.

22. The apparatus of claim 20 or claim 21 wherein the sterilising chamber is an autoclave.

23. The apparatus of claim 22 wherein the autoclave comprises a control system configured to introduce steam at a temperature of in excess of 100°C, preferably in

5 excess of 120°C.

24. The apparatus of any one of claims 20 to 23 further comprising a compactor arranged to compact solid waste remaining after sterilisation in the sterilisation chamber.

10

25.The apparatus of claim 24 wherein the compactor comprises a drain arranged to collect further liquid run-off from the solid waste for combining with the condensed vapour and liquid run-off.