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Biomedical Waste Management

Waste generated is termed as "Biomedical Waste" which means a waste that may contain human pathogens of sufficient virulence and in sufficient concentrations that exposure to it by a susceptible host could result in disease.Now that we have defined what biomedical waste is, let us have a look on what all waste is produced in a dental operatory, how is it segregated and packaged and finally treated and disposed off.All wastes must be correctly categorized and disposed of appropriately.

Management of waste generated in Dental Operatory

Management of waste amalgam and wastes containing mercury: As all of us know that amalgam is used for restorations very widely.An operator of a dental operation that produces waste water containing dental amalgam must:
  •  install and maintain an amalgam separator according to the manufacturer's or supplier's recommendations.
  •  ensure that all wastewater containing dental amalgam is treated using the amalgam separator. install an accessible monitoring point at the outlet of the amalgam separator at a location upstream of the discharge of any other waste.
  •  locate the amalgam separator in such a manner that an accidental spill, leak or container failure will not result in waste containing amalgam entering any sewer.
  •  ensure that dental amalgam collected in an amalgam separator.
  •  a collecting container or any other device is not discharged into a sewer.
Some recmmendations for management of waste mercury:
  •  Mercury storage and work areas should be designed to provide secondary containment in the event of a spill or leak.
  •  A mercury spill kit should be maintained in the office near the mercury storage and work areas.
  •  Spilled mercury should be transferred to a labelled, sealed, leak-proof glass container and stored for pick up by a waste disposal vendor.
  •  Written mercury spill clean-up procedures should be pasted in a visible location and all personnel handling mercury should be trained in spill clean-up procedures
Best management practices that can help prevent these wastes containing mercury from entering the sewer or septic system from any source includes:

  • use precapsulated amalgam
  •  mix only the amount of amalgam required for each restoration
  •  collect large waste amalgam scraps (scrap amalgam) from preparation, placement and removal of fillings, place in labelled leak-proof containers and recycle using a waste disposal vendor. Do not dispose of scrap amalgam into the garbage (municipal solid waste) or into sinks or drains that are not connected to an amalgam separator.
  •  use disposable chair-side (primary) traps. Reusable traps are more difficult to clean and may result in loss of amalgam particles into the sewer or garbage.
  •  change chair-side (primary) traps at least once a week or as recommended by the supplier or manufacturer.

All recovered liquid waste containing amalgam should be stored in labeled, leak proof containers in a secure location, in such a manner that an accidental spill,leak or container failure will not result in amalgam waste entering any sanitary sewer or storm drain. If such a location is not available, adequately sized secondary containment should be provided or all floor drains in the area should be capped.Do not dispose of amalgam wastes into the garbage, the sewer system or mix them with biomedical wastes.

Waste produced during surgical process:

Some of the waste products produced during a surgical process are dressings,sponges, gloves or other soft material dripping with blood or purulent discharge.These should be placed in a strong plastic bag or double-bagged, then disposed of into garbage containers, picked up by municipal garbage collectors and taken to the landfill. Blood and/or body fluids contained in absorbent materials are not known to pose a risk for disease transmission and, therefore, do not require incineration

Regular garbage:

Regular garbage generated from clerical office procedures or kitchen waste should be disposed of within the usual garbage system

Human blood and fluids

These can be discharged directly to sanitary sewer with permission from regional municipality; or use approved carrier to approved receiver

Highly infectious waste: should be sterilised by autoclaving.Infusion sets, bottles and gloves should be cut with curved scissors and then discarded in red bags and transported

Disinfection of sharps, soiled linen, plastic and rubber goods: is to be achieved at point of generation by usage of sodium hypochlorite with minimum contact of 1 hour. Fresh solution should be made in each shift.

Colour coding-biomedical waste (management and handling) rules, 1998 (schedule II)

Bags shall be sealed by forming a secure closure which results in a leak-resistant seal. Biomedical waste to be transported off-site shall be labeled immediately after packaging Once we have identified and separated the waste we should proceed to our penultimate goal: its treatment and disposal

Treatment and disposal technologies for health-care waste

1. Incineration

2. Chemical disinfection

3. Wet and dry thermal treatment

4. Microwave irradiation

5. Land disposal

6. Inertization

Incineration

It used to be the method of choice for most hazardous health-care wastes and is still widely used. It is a high temperature dry oxidation process that reduces organic and   waste to inorganic, incombustible matter and result in a very significant reduction of waste volume and weight.The process is usually selected to treat wastes that cannot be recycled, reused or disposed off.

Chemical disinfection

Chemicals are added to waste to kill or inactivate the pathogens it contains, this treatment usually results in disinfection rather than sterilization. Chemical disinfection is most suitable for treating liquid waste such as blood, urine, stools or hospital sewage.

Wet and dry thermal treatment

Wet thermal treatment: it is based on exposure of shredded infectious waste to high temperature, high pressure steam. It is inappropriate for the treatment of anatomicalwaste and animal carcasses and will not efficiently treat chemical and pharmaceutical waste.Screw feed technology: it is the basis of a non-burn, dry thermal disinfection process in which waste is shredded and heated in a rotating auger.

Microwave irradiation

Most micro-organisms are destroyed by the action of microwave of a frequency of about 2450 MHz and a wavelength of 12.24 cm. The water contained within the waste is rapidly heated by the microwaves and the infectious components are destroyed by heat conduction.

Land disposal

There are two types of disposal land:

1. Open dumps

2. Sanitary landfills

Health care waste should not be deposited on or around open dumps. The risk of either people or animals coming into contact with infectious pathogens is obvious.

Inertization

The process of "inertization" involves mixing waste with cement and other substances before disposal in order to minimize the risk of toxic substance contained in the waste migrating into surface water or ground water. A typical proportion of the mixture is: 65% pharmaceutical waste, 15% lime, 15% cement and 5% water. A homogenous mass is formed and cubes or pellets are produced on site and then transported to suitable storage site

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