CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND INFORMATION
Incineration uses combustion to make infectious medical waste harmless and reduce the waste mass and volume by more than 90 per cent. Proper incineration can convert certain wastes into gases and incombustible solid residues (e.g., ash) that are relatively harmless. A dual-chamber incinerator operated within the optimal temperature range of 650° to 1,000°C results in a lower level of emissions. The gases from incineration are released into the atmosphere (with or without gas cleaning). Residue ash from proper incineration can be encapsulated in designated ash pits or controlled landfills without any major risk. However, when the conditions are not adequate—for example, when the waste is not properly segregated or the incinerator is not properly constructed or operated—toxic compounds can be found in the unburned waste, and harmful gases can be released into the atmosphere. Good planning, technical oversight, and sustained supportive supervision of incinerator systems are critical to ensuring safe incineration.
Large-capacity, cleaner-burning incinerators usually rely on electricity and fossil fuels to maintain their emission standards. These technologies are often installed in large cities where electric power is available. The units can also be used as part of a collection and transport system. However, such systems are limited in many settings, especially when the roads are impassable or in poor condition as they often are during the rainy months. In addition, such centralized systems put a budgetary strain on governments, and they may fail for lack of fuel, power, and spare parts.
Small-scale incinerators that meet minimum performance parameters can significantly improve current waste treatment practices, particularly in the short and medium term. Although WHO has not issued performance, quality, and safety (PQS) standards for small-scale incinerators, small-scale brick incinerators, such as the De Montfort and Waste Disposal Unit (WDUs), have been purchased and constructed for immunization campaigns and in some curative health settings. Experiences with small-scale incinerators in developing countries over the past ten years point to several performance criteria that reduce emissions and improve incinerator quality and safety. Although the WHO policy paper on safe does not identify clear performance criteria for small-scale incinerators, evaluations have determined that several factors improve performance. Ideally; small scale incinerators should operate within a temperature range of 650° to 1,000°C, have at least two incinerator chambers, and have a minimum of one second of smoke-residence time.
Incineration converts discarded materials, including paper, plastics, metals and food scraps into bottom ash, fly ash, combustion gases, air pollutants, wastewater, wastewater treatment sludge and heat. There are 113 waste incinerators in the U.S. and 86 of these are used to generate electricity. No new incinerators have been built in the U.S. after 1997, due to public opposition, identified health risks, high costs, and the increase of practices such as recycling and composting. In recent years, the incinerator industry has tried to expand their sector by marketing their facilities as “Waste to Energy” (WTE), using misleading claims. This is in line with the environmental waste policy, aimed to minimize the adverse impacts of waste handling and disposal on public health and the environment. The best strategy adopted in waste management in hospitals is undoubtedly to control waste generation which has been recognized by environmental waste management policy (Bontoux, 1999). This therefore called upon to control the waste produced.
It is estimated that half the world’s population is at occupational, environmental or public health risk from poorly treated medical wastes. This problem is particularly serious in developing world, (e.g Nigeria) where improvements in healthcare services are not matched by strengthening of the waste management infrastructure (Harhay et al. 2009). The wastes that are treated in these incinerators include plastic materials, especially polyvinyl chloride (PVC), whose incineration is strongly associated with emissions of dioxins and furans. Incineration of medical waste can also lead to release of heavy metals (e.g. mercury, from broken thermometers, or lead or cadmium from plastics) and acid gases, such as sulphur oxides, hydrogen chloride, nitrogenous gases and particulates.
Many African countries have relied on incinerators as their only means of medical waste disposal, although alternative technologies have been used for decades in many industrialized countries in place of medical waste incinerators. During the 2006 World Health Organization (WHO) regional workshop on health‐care waste management in Nairobi, Kenya, African delegates reported many problems with small‐scale incinerators but little familiarity with alternative technologies. The problems reported include the poor physical state of small‐scale incinerators constructed on‐site in several countries, low capacity of incinerators, complaints from local communities about the smoke; and low efficiency in reaching the desired burning temperature.
Biomedical waste refers to any waste that includes anatomical waste, pathological waste generated in health care facilities and medical laboratories that requires special handling. Previously, the terms ‘pathological’ and ‘institutional’ wastes were used to refer to what is now consider ‘biomedical’ waste.
Therefore, this project is aimed at improvement on the designed, construction and testing of medical waste incinerator, describing the process, type and their components, and to discuss the combustion process as it relates to medical waste (specifically polythene, plastic and PVC waste). Also, intended to describe current practices associated with medical waste generation, segregation, handling, and transportation and to further analyse the amount of gases discharged into the atmosphere from combustion of medical waste which may comprises; oxygen (O2) carbon (iv) oxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2) etc.
The performance of the incinerator will vary depending on the moisture content of the particular medical waste but a throughput of up to 15kg/hour can be achieved.
1.2 WORLDWIDE STRATEGY FOR AIR POLLUTION
Potential health hazards due to particulate air pollution are a significant concern in both urban areas and rural areas in the United States. Several air sheds are currently classified by United States Environmental Protection Agency (US EPA) as non-attainment areas for airborne particulate matter with an aerodynamic diameter of less than 10 μm (PM10). Non-attainment areas are identified based on National Ambient Air Quality Standards (NAAQS) set by the Clean Air Act Amendments (CAAA) of 1990 (Pulugurtha Srinivas S. et al., 2006).
In the 1990s, WHO updated its Air quality guidelines (AQG) for Europe, to provide detailed information on the adverse effects of exposure to different air pollutants on human health. The prime aim of these guidelines was to provide a basis for protecting human health from effects of air pollution. The guidelines were in particular intended to provide information and guidance for authorities to make risk management decisions. The European Union (EU) used the WHO guidelines as a basis to set binding air quality limit values and target values for all EU member states for several pollutants (World Health Organization, 2003)
1.3 STATEMENT OF THE PROBLEM
It is not farfetched that hospitals and other medical laboratories are pruned to generate varieties of wastes on a regular basic which are; pathological waste, anatomical waste, hazardous waste, infectious waste etc. It is of immense value to have Incinerator available to minimize the adverse impacts of waste handling and disposal on public health and environment particularly university of agriculture’s clinic.
1.4 OBJECTIVES
This project is aimed at:
- To improve on the designed incinerator.
- To improve on the incinerator from local materials.
- To analyse the amount of gases discharge.
- To analyse the influence of excess air on combustion of the medical waste from UAM.
1.5 SIGNIFICANCE OF THE WORK
The cost of constructing this incinerator is relatively cheap so that it could be affordable even by a smaller/private health centre and also to ensure that it solved:
- Environmental problems arising from hospital waste disposal.
- Risk of land filling of hospital waste will be considered.
- Care will be taken in exposing oneself to the gases discharged
1.6 SCOPE OF THE WORK
There are many hospital wastes that are not properly disposed most especially those located in rural areas due to astronomical cost of purchasing a standard incinerator. However, the advent of this project on improvement on the designs and the construction of medical waste incinerator to analyse the amount of gases discharged to the atmosphere is limited to a particular hospital waste such as; plastics, polythenes, PVC and rubbers.
