3 Best practices for incineration - WHO

1 12 3 Best practices for incineration This section discusses best practices for incineration , which can lead to substantial reductions in the formation, emission and exposure to toxic substances from waste incineration . Waste reduction Waste reduction reduces the volume and toxicity of materials for incineration (or other treatment option), thus decreasing incinerator use, emissions and the resulting health and environmental risks.

2 For example, incineration might be reserved for only the most dangerous types of waste, , contaminated sharps. Waste reduction can substantially lower demands for incineration and provide other important benefits, , greater environmental protection, enhanced occupational safety and health, cost reductions, reduced liability, regulatory compliance, and improved community relations (HCWH 2001). As mentioned, extensive reviews of waste reduction have been provided elsewhere (HCWH 2001; 2002; WHO 1999).

3 General approaches include source reduction, material elimination, recycling, product substitution; technology or process change, use of good operating practices , and preferential purchasing. Hospitals and other facilities have many opportunities to minimize waste, including: Segregating wastes. This requires clearly marked and appropriate containers, staff training to separate various wastes (health-care waste, hazardous waste such as mercury, low-level radioactive waste, and regular trash), minor maintenance infrastructure (containers, suitable space) and management support.

4 Studies in Nigeria and Benin show that health-care waste is either not segregated or insufficiently segregated (Adama 2003). The same study shows that policies and action plans are not sufficient or not comprehensive enough to address this problem. Reducing unnecessary injections (as much as 70% of all injections may be unnecessary) (Gumodoka et al., 1996). Recovering silver from photographic chemicals. Eliminating mercury products and mercury-containing instruments. Buying PVC-free plastic products. Treatments to remove and concentrate waste, , filters and traps to remove mercury from wastewater.

5 Effective waste reduction programs require commitment of top management and effective communication among hospital staff. Physicians, other medical staff and managers must be made aware of waste generation and associated hazards. Source reduction requires involvement of purchasing staff and periodic reassessment. These programs require staff and moderate infrastructure support, planning and organization, assessment, feasibility analysis, implementation, training, and periodic evaluation.

6 A waste audit will generally be helpful. Design Proper design and operation of incinerators should achieve desired temperatures, residence times, and other conditions necessary to destroy pathogens, minimize emissions, avoid clinker formation and slagging of the ash (in the primary chamber), avoid refractory damage destruction, and minimize fuel consumption. Good combustion practice (GCP) elements also should be followed to control dioxin and furan emissions (Brna and Kilgroe 1989).

7 Table 2 provides recommendations for small-scale intermittent incinerators. 13It appears that the temperature, residence time and other recommendations in Table 2 are rarely achieved by small-scale incinerators. Additionally, as mentioned earlier, few small-scale units utilize air pollution control equipment. Siting The location of an incinerator can significantly affect dispersion of the plume from the chimney, which in turn affects ambient concentrations, deposition and exposures to workers and the community.

8 In addition to addressing the physical factors affecting dispersion, siting must also address issues of permissions/ownership, access, convenience, etc. Best practices siting has the goal of finding a location for the incinerator that minimizes potential risks to public health and the environment (EPA 1997). This can be achieved by: Minimizing ambient air concentrations and deposition of pollutants to soils, foods, and other surfaces, , o Open fields or hilltops without trees or tall vegetation are preferable.

9 Siting within forested areas is not advisable as dispersion will be significantly impaired. o Valleys, areas near ridges, wooded areas should be avoided as these tend to channel winds and/or plumes tend to impinge on elevated surfaces or downwash under some conditions. Minimizing the number of people potentially exposed, , o Areas near the incinerator should not be populated, , containing housing, athletic fields, markets or other areas where people congregate. o Areas near the incinerators should not be used for agriculture purposes, , leafy crops, grasses or grains for animals.

10 Appropriate sizes for buffer surrounding incinerators are based on dispersion modeling (Section ). For typical small-scale units, especially if nighttime operation may occur, a 500 to 750 m buffer surrounding the facility is advisable to achieve dilution ratios above 1000. During the day, a 250 m buffer should obtain the same dilution ratio. These distances are based on ideal conditions, , relatively flat and unobstructed terrain. 14 Table 2 Recommendations of key design/operating parameters for small-scale intermittent incinerators.