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Alternatives for treatment and disposal cost reduction of regulated

medical wastes

Byeong-Kyu Lee

a,

*

, Michael J. Ellenbecker

b

, Rafael Moure-Ersaso

b aDepartment of Civil and Environmental Engineering, University of Ulsan, Ulsan, South Korea

bDepartment of Work Environment, University of Massachusetts, Lowell, MA, USA Accepted 1 October 2003

Abstract

Many hospitals or health care facilities have faced financial difficulties and thus they have attempted to find cost-effective treat-ment and disposal methods of their regulated medical wastes (RMWs). This study investigated generation volume and sources, composition, and treatment and disposal methods for RMWs obtained from three out of the five typical city hospitals in Massa-chusetts for which we could obtain relevant data on medical waste. Also, this study compared the generation patterns and amounts of RMWs between the hospital and the medical school. The yearly operational treatment and disposal costs of RMWs based on different treatment and disposal methods were analyzed for one hospital. The most cost-effective option of four different treatment and disposal options studied was to combine on-site incineration and microwave technologies. Finally, this study identified mea-sures for the effective waste characterization methods for the reduction of treatment and disposal costs of RMWs. By careful exclusion of non-RMW from RMW waste streams, hospitals can reduce the RMW volume that requires special treatment and reduce disposal costs.

#2003 Elsevier Ltd. All rights reserved.

1. Introduction

Each year more than 3.5 million tons of medical wastes are produced in the United States (MWC, 1994; Hyland, 1993). According to the literature relevant to the generation rate of medical waste for different coun-tries (Alvim Ferraz et al., 2000; Kerdsuwan, 2000; Maderira, 1995; Giroletti and Lodola, 1994; MWC, 1994), each country has different ranges of medical waste production depending upon its medical situations (see Table 1). Medical waste can be classified into two types: general waste and special waste. Since general waste is not regulated or defined as hazardous or potentially dangerous wastes, it does not require special handling, treatment, and disposal (CEC, 1993; Hassel-riis and Constantine, 1992). Therefore, it is sometimes called non-regulated medical waste (NRMW) ( Waste-Tech and Konheim and Ketchham, 1991; Marrack, 1988). Special waste includes materials considered to be

potential health hazards, requiring special handling, treatment, and disposal, usually according to specific regulations and guidelines such as Medical Waste Tracking Act (MWTA). Special waste can include che-mical waste, infectious waste, and radioactive waste

(Kerdsuwan, 2000; Hasselriis and Constantine, 1992).

Therefore, most of special waste is treated as regulated medical waste (RMW) (Davis, 2000; Hall, 1989).

There are many technologies for the treatment of medical wastes (Park and Jeong, 2001; Yoon, 2001;

MWC, 1994; CEC, 1993). According to the treatment

studies of medical wastes, about 59–60% of RMWs are treated through incineration, 37–20% by steam ster-ilization, and 4–5% by other treatment methods (Park

and Jeong, 2001; Hyland et al., 1994). Currently, the

proportion of off-site treatment and disposal has been increasing up to 84% due to severe regulations con-cerning on-site incineration (Park and Jeong, 2001; Senatore, 1994). Historically, incineration has been used as an important treatment method for RMW. That is because incineration has many advantages including putrefaction prevention and sterilization of pathological or anatomic wastes, volume reduction, and waste heat 0956-053X/$ - see front matter#2003 Elsevier Ltd. All rights reserved.

doi:10.1016/j.wasman.2003.10.008

www.elsevier.com/locate/wasman

* Corresponding author. Tel.: 2864; fax: +82-52-259-2629.

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recovery (Hyland, 1993). Many hospitals are employing on-site incineration for treatment of their RMWs

(MPCA, 1991). However, RMW includes significant

quantities of chlorine containing wastes, such as poly-vinyl chloride (PVC) or disinfectants, and it might be incinerated with status lacking proper controls and emission reduction devices. Therefore, incineration of RMWs might produce dioxins and furans known as hazardous pollutants (Alvim Ferraz et al., 2000; Walker and Cooper, 1992; Glasser et al., 1991; Lee et al., 1991;

Powell, 1987). Considerable amounts of heavy metals

waste can also be emitted as forms of fumes or vapors, particles and ashes produced from incineration of RMW (Fritsky et al., 2001; Yuhas et al., 1994). Hence the public is fearful of potential exposure to these pol-lutants produced from the incineration of medical waste or RMW (Hu and Shy, 2001). Consequently, many new techniques without incineration are now being devel-oped. New technologies being considered by RMW disposal engineers include microwaving, autoclaving, radiowaving, and electrotechnologies, which incorpo-rate electron-beam irradiation, pyrolysis and oxidation, steam sterilization, and steam detoxification (Waste Prevention Association, 2003; Park and Jeong, 2001; Salkin and Krisiunas, 1998; O’Connor, 1994; Jordan,

1994; Borowsky and Fleischauer, 1993). Currently,

microwaving and autoclaving have been considered as positive alternative treatment methods to incineration. Microwaving might be economically competitive with incineration and applicable to continuous—or batch operation (CEC, 1993). Wastes are microwaved for 30 min in a preheated treatment chamber and then held at a minimum temperature of 93–95 C to ensure proper

disinfection. However, microwaving is not sufficient for sterilization temperature above 120C. By microwaving

spores are activated and some spores may survive (Cha

and Carlisle, 2001; CEC, 1993). In autoclaving

(some-times referred as to steam sterilization), steam, dry heat or radiation is introduced into a tightly sealed chamber and wastes in the chamber are maintained with tem-perature between 121 and 163C for sterilization which

destroys spores. This treatment method by autoclaving is widely used for recyclable items such as paper, plastics and labtrash. However, microwaving and autoclaving are generally not applicable for pathologi-cal, radioactive, laboratory and chemotherapy wastes.

Recently, many hospitals have faced financial diffi-culties and some of them have tried to merge with other hospitals in order to overcome their financial problems. Therefore, they are trying to find some cost-effective treatment or disposal means of their wastes. For exam-ples, a few hospitals and companies have investigated alternative disposal methods through recycling of their medical plastic wastes (Lee et al., 2002; Anderson et al., 1999; Marrack and Meyers, 1994; Batholomew et al., 1994). The main reasons that recycling programs of medical plastic waste should be developed are because the plastic content of medical waste is significantly higher than that of municipal solid waste (MSW) and plastic wastes require significant costs for transportation to disposal facilities (US EPA, 2002; Lee et al., 1995). In addition, the total costs for treatment and disposal of RMW were much more expensive than those of NRMW or MSW (Park and Jeong, 2001; Lee et al., 1995). To shed light on the magnitude of this problem and opportunities for mitigation, we identified genera-tion volume and patterns, sources, treatment and dis-posal methods, and disdis-posal costs of RMW in hospitals, Massachusetts. Also, we investigated cost-effective treatment and disposal methods through a comparison analysis of treatment and disposal costs of RMW and finally proposed some alternatives to save the total costs for treatment and disposal of RMW.

2. Methods

Lee et al.’s previous study focused on analysis of the recycling potential of medical plastic wastes generated from five typical city hospitals and three typical animal hospitals in Massachusetts (Lee et al., 2002). In this study we focused on cost-effective waste stream analysis methods, treatment and disposal methods, and waste characterization methods of RMW.

We investigated generation volume and sources, treatment and disposal methods, and cost-effective waste stream analysis methods of medical wastes obtained from five typical city hospitals and three med-ical schools in Massachusetts. As the first step for this research, we made phone calls to identify relevant per-sonnel and collect information of hospitals and medical schools. More than 200 survey letters were sent to managers or responsible personnel of waste generation departments such as cafeterias, laboratories, emergency rooms and operating rooms, waste collection depart-ments such as environmental services and/or house-keeping departments, facilities and purchasing departments, and administration departments. In the survey letters information on the following items was solicited: number of beds, bed occupancy rate by patients, waste generation volume and sources, waste treatment and disposal methods and costs, waste Table 1

A generation rate of medical waste in different countries Country Generation rate,

kg/(bed day)

Reference

Thailand 1 Kerdsuwan (2000)

Portugal 3.8 Alvim Ferraz et al. (2000)

2.5–4.5 Giroletti and Lodola (1994)

Italy 3–5 Maderira (1995)

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collection methods, and information of site-visit and personnel to contact. In a few days after sending the survey letters we had made more than four hundred phone calls to discuss or collect the survey items or set up site-visit schedules. About 30% of the sent survey letters were returned to us and about 50% of those returned contained significant information.

We then visited more than forty departments in fifteen hospitals or health care facilities to collect survey letters and discuss this study through interviews with managers and personnel of waste generating, collecting and managing departments that we had sent the survey let-ters. Some managers or responsible personnel concern-ing waste management of hospitals gave us significant information from hospital reports or analysis data on waste composition, waste generation volume and sources, treatment and disposal methods and costs per-formed by their hospitals or expert analysis companies. We could investigate only a limited fraction of RMW produced from a few hospitals under a control of rele-vant personnel of hospitals. Thus, most of data con-cerning RMW were obtained from the reports on waste analysis performed in the hospitals that we investigated or other relevant hospital reports (Anderson et al., 1999;

UMASS, 1995; Waste-Tech and Konheim and

Ketchham, 1991; Marrack, 1988). This paper focuses on

generation volume and sources, composition, and treatment and disposal methods for RMWs obtained from three out of the five city hospitals investigated. In this paper, thus we excluded two hospitals that we could not get the relevant data to RMW through this study. Since each hospital categorizes its RMW with different ways or classification methods, a statistical analysis on the obtained data was not performed. However, we analyzed significant characteristics of waste streams and disposal and treatment methods of RMW. We also compared RMW generation patterns between the hos-pital and the medical school where we obtained the relevant data. We analyzed the yearly operational treatment and disposal costs of RMW to identify the most cost-effective treatment and disposal method among on-site incineration, on-site incineration including expanding a current incineration capacity, on-site microwaving without on-site incineration, and on-site incineration combining microwaving depending on segregated waste types. Finally, we attempt to sug-gest cost-effective waste segregation methods.

3. Results and discussion

3.1. Regulated medical waste stream analysis

The medical waste stream can be classified into four major categories, i.e., three special wastes containing infectious, pathological, and radioactive waste, and

general waste.Table 2shows a summary of waste gen-eration volume and types, on-site incingen-eration, and off-site disposal costs of RMW produced by hospital D. Significant amount of general waste, 80.4 ton per year, was considered as infectious waste and it was treated by on-site incineration. The off-site disposal cost, based on unit weight, of radioactive waste and liquid chemical waste was 24 and 28 times as expensive as compared to that of general solid waste. The waste stream analysis method shown inTable 2can provide a framework that might identify a relationship between waste types and treatment and disposal methods (on-site incineration and off-site disposal), and analyze types or sources of wastes generated. However, the detailed identification of the waste composition of medical waste from this simple waste classification is relatively difficult.

Table 3 shows a comparison of RMW generated by

the hospital and the medical school associated with hospital D. The hospital produces a large proportion of general medical wastes (not requiring a special treat-ment such as incineration) and sharps [loosely defined as anything that can cause a penetrating injury to humans or puncture containers (Davis, 2000)]. This is because the hospital focuses on patient care and many people frequently visit the hospital as visitors or patients. However, the medical school produces a large proportion of RMW such as pathological and labora-tory wastes. This is because the medical school focuses on activities related to medical research. That is, this difference indicates that the generation patterns of RMW in a typical city hospital and a medical school associated with the hospital were different because of different activities. In addition, this result implies that the waste generation patterns produced from hospitals with a special purpose, such as an eye and ear hos-pital, children’s hospital and animal hoshos-pital, will be different from those of a general city hospital.

3.2. Analysis of treatment or disposal methods and costs of medical wastes

Table 4 shows the waste stream and main treatment

and disposal methods for medical waste generated by hospital C. The major disposal method for general solid waste generated from hospitals was landfilling and most of paper and cardboard were mainly recycling like the MSW. However, most of the RMW is first treated by incineration, and then it is disposed of. Because of the potential for the production of dioxins, furans and heavy metals from incineration of RMW, new treatment techniques such as microwaving and autoclaving have been considered as alternative treatment methods to incineration. According to one report 90% of intra-venous (IV) bag cases studied were not contaminated by infectious materials during use by patient (Batholomew et al., 1994). This means that hospitals can develop a

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Table 2

Waste stream analysis of regulated medical wastes in hospital D

Generator Type of waste Amounts generated

(t/year) Relative percentage (%) Off-site disposal cost ($/kg) On-site incineration

Hospital Infectious waste

Sharps 22.7 0.9

Laboratory 35.9 1.4

General medical 80.4 3.2

Subtotal 139.0 5.5

Research labs Pathological

Animal carcasses 6.5 0.3

Research labs Radioactive waste

Vials 16.3 0.6

Labwaste 16.3 0.6

Animals 9.1 0.4

Subtotal 41.7 1.1

Subtotal (on-site incineration) 187.2 7.4

Off-site disposal (shipped out)

Hospital and labs Infectious waste 84.7a 3.4 0.79

Research labs Radioactive waste 1.2 0.05 2.87

Research labs Liquid chemical waste 6.4a 0.3 3.44

Hospital General solid waste 2242.1 88.9 0.12

Subtotal (shipped out) 2334.6 92.6

Total waste produced 2521.6 100

a If the incineration capacity increases, it could be incinerated by on-site incineration.

Table 3

Comparison of regulated medical wastes in hospital D and its associated medical school

Type of waste Hospital Medical school

kg/20 days % kg/20 days %

Regulated medical waste

Pathological 0 0 1607 52.3

Sharps 1713 17.8 87 2.8

Laboratory 1605 16.7 1259 40.9

General medical waste 6288 65.5 124 4.0

Total 9606 100 3077 100

Relative content of each source to total waste produced 75.7% 24.3%

Table 4

Waste stream and treatment and disposal method of medical wastes produced in hospital C

Type of waste Volume

(t/year)

Relative percentage (%)

Main treatment/ disposal method

Solid wastes (plastics) 1115.6 20.0 Landfilling

Solid wastes (others) 2515.1 45.2 Landfilling

White paper recycling 191.4 3.4 Recycling

Cardboard recycling 186.8 3.4 Recycling

Construction wastes 439.0 7.9 Landfilling/recycling

Regulated medical waste 1119.2 20.1 Incineration

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recycling program even for RMW through effective waste classification or separation.

Table 5shows the source identification, typical treat-ment and disposal cost and method of medical wastes generated from hospital B. This table also shows the relative percentage by volume, weight and treatment or disposal cost of medical wastes generated from each department. The sum of volume of wastes generated from facilities, laboratories, and cafeterias occupied about three-fourths of the total medical wastes. The relative percentage by weight of cafeteria wastes is almost the same as amounts of those of laboratories. However, in a comparison of treatment or disposal costs of wastes from two departments, the relative costs for treatment or disposal of cafeteria wastes are much lower than those for treatment or disposal of wastes produced in laboratories. This is due to different treat-ment or disposal methods of wastes generated from different sources. That is, wastes produced from laboratories mainly are treated by incineration, while cafeteria waste was mainly disposed of by landfilling or recycling. Also, incineration cost per unit of weight is much greater than landfilling or recycling cost.

Cafeterias produce a much higher volume of waste than operating and emergency rooms. In a comparison of treatment or disposal cost and waste generation volume, treatment or disposal cost per unit volume of wastes produced from cafeterias is much lower than that from operating rooms or emergency rooms. Since wastes from operating rooms or emergency rooms have high potential to be infected, these wastes are con-sidered infectious wastes. Infectious wastes are mainly treated by incineration, which requires high disposal costs. However, non-infectious wastes like cafeteria wastes are mainly disposed of by landfilling, which requires relatively lower disposal costs. Currently, treatment or disposal cost of infectious wastes can be about 10–20 times more than that of non-infectious wastes (Park and Jeong, 2000). In addition, while some cafeteria wastes are recyclable, waste from operating rooms or emergency rooms have a lower chance for recycling. Since the recycling of wastes can reduce the

amount of wastes incinerated and return money from selling recyclable materials, recycling is very important to reduction of treatment or disposal costs of medical waste.

The medical wastes, which waste generating depart-ments or waste characteristics were unidentified, are mainly treated by incineration. That is, since waste col-lecting or housekeeping staffs do not know whether those wastes are infected or non-infected, those medical wastes might be considered as infected wastes. For an example of this,Table 2represents that more than 60% of the infectious waste treated by on-site incineration consisted of unidentified general medical waste. The medical wastes unidentified in their waste generation characteristics or types or infection status are mostly treated by incineration incurring high treatment costs. This implies that clear labeling or description of char-acteristics of each waste at the waste generating point can contribute to the reduction of treatment and disposal costs of medical wastes.

3.3. Operational cost reduction for treatment and disposal of RMW by a combination of treatment and disposal methods

Table 6contains an analysis of the yearly operational treatment and disposal costs associated with various treatment and disposal methods for the RMW gener-ated from hospital D. Treatment and disposal costs given in this table were based on the RMW incineration study performed in hospital D and the recent informa-tion relevant to treatment technologies (Waste Preven-tion AssociaPreven-tion, 2003; Salkin and Krisiunas, 1998;

UMASS, 1995). The incineration study compared the

treatment and disposal costs for different treatment technologies to equal amounts of RMW currently being treated by on-site incineration facilities. In this compar-ison study it is assumed that there is an existing incin-erator that meets new regulations on medical waste incineration. In every option, hospital D is assumed to treat as much medical wastes as possible by using its own treatment facilities. The remaining RMW is Table 5

Treatment and disposal characteristics of medical waste produced from different waste generation department in hospital B Department Waste volume

(m3/month)

Treatment and disposal cost ($/year)

Relative percentage by compared unit (%) Typical treatment or disposal method

Volume Weight Cost

Cafeteria 88.4 10,000 23.5 20 6.7 Recycling/landfilling/composting

Operating room 7.5 15,000 2.0 10 10.0 Incineration/recycling

Emergency room 14.6 15,000 3.9 5 10.0 Incineration

Laboratories 58.8 20,000 15.7 20 13.3 Incineration

Facilities 132.5 40,000 35.3 30 26.7 Incineration/recycling

Administration 29.6 20,000 7.8 10 13.3 Recycling/landfilling

Other 44.2 31,000 11.8 5 20.0 Recycling/landfilling

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disposed of by off-site disposal facilities. Even though the proportion of the residuals remaining after inciner-ation and/or microwave treatment is highly dependant upon waste types and treatment parameters, it is assumed that 20% of the RMW volume remains after treatment by incineration and/or microwave (Waste Prevention Association, 2003; Wark et al., 1998). Although the unit and total disposal cost of the residuals is dependent upon the types and the relative proportions of the resi-duals, the total disposal costs of the residuals are rela-tively very minor compared to the total costs for treatment and disposal of RMW. Thus this study assumes that the residuals are disposed of as general solid waste in hospitals, having a unit disposal cost of 0.12 $/kg.

Option B, having larger capacity of on-site incinera-tion as compared to opincinera-tion A, was a cheaper disposal method than option A. In the option A, because of the limited capacity of the on-site incinerator, considerable amounts of infectious waste should be sent to off-site disposal facilities. Therefore, the total costs for treat-ment and disposal of medical wastes greatly increased. In option B, since the incinerator capacity was scaled-up, the hospital could reduce the waste volume to be disposed of off-site. That is, the hospital could increase the waste proportion to be incinerated on-site. Thus the treatment and disposal cost per unit weight of waste in the option B became cheaper than that of in the option A. In addition, the hospital could also save significant contracted disposal costs through increasing on-site incineration capacity.

Option C using the microwave treatment method instead of incineration on-site was the most expensive option in terms of the total costs for treatment and dis-posal, even though its treatment cost per unit of weight is much lower than other methods. This is due to the presence of a considerable amount of RMW that is not suitable for treatment by microwave, but suitable for treatment by incineration. By operating only the micro-wave treatment method on-site, those medical wastes might not be properly treated on-site. Thus a large pro-portion of RMW under this option must be shipped to off-site disposal facilities. Therefore, the hospital would pay the additional costs for shipping to the off-site as well as the expensive off-site disposal costs.

The most economical treatment and disposal method of the four different options considered in this study was option D that employed a combination of incineration and microwaving. That is, the RMWs to which waving was applicable were treated by on-site micro-wave, while other RMWs to which microwaving was not applicable were treated by on-site incinerator. The other RMWs, to which microwaving or incineration was not applicable, were sent to off-site disposal facil-ities. In a comparison of the total costs for treatment and disposal of RMWs, between two cheaper options D

Ta ble 6 Ana lysis of the yea rly operat ional treatmen t and dispo sal co sts of regu lated medic al w astes in hospita l D Treatment/disposal method option Option A Option B Option C Option D Treatment/disposal method applied On-site incineration Off-site disposal On-site incineration Off-site disposal Microwave Off-site disposal On-site incineration Microwave Off-site disposal Treatment/disposal cost per unit waste 1.56 $/kg 1.21 $/kg 0.16 $/kg 1.56 $/kg 0.16 $/kg Type of waste Waste stream (kg/year) Disposal cost ($/year) Infectious 83,278 78,173 67,664 123,687 – 13,324 – – 13,324 – Pathological 2963 4608 – 3600 – – 5184 4608 – – Radioactive (low) 18,928 29,437 – 22,998 – – 606,720 29,437 – – Radioactive (high) 551 – 3479 – 3 479 – 3479 – – 3479 Chemical (hazardous) 244 – 22,155 – 22,155 – 22,155 – – 22,155 Residual after incineration o r m icrowave treatment – 2524 – 2 524 – 1999 – – 2524 Subtotal 105,964 112,218 95,822 150,285 28,158 13,324 639,537 34,045 13,324 28,158 Relative cost based on treatment and d isposal method within each option 53.9% 46.1% 84.2% 15.8% 2.0% 98.0% 39.1% 19.6% 4 1.4% Total cost of treatment/disposal option 208,040 178,443 652,861 68,080 Assumptions: 1. The size of the on-site incinerator for option B is greater than that for option A. 2. The sizes of the on-site incinerators for options D and A are the same. 3. Off-site disposal cost per unit w eight depends highly upon the type of waste and the same value is assumed for each option. 4. The a mount of residual is set at 20% of the RMW volume before treatme nt, and its unit disposal cost is the same a s general solid waste in hospitals (0.12 $/kg).

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and B, produced from hospitals or health care facilities having a medical waste production rate of about 100 ton per year, option D was much cheaper up to $110,000 per year than option B. This cost saving is large enough to warrant implementation of the neces-sary segregation of medical waste. Thus, an application of the treatment and disposal method suitable for each waste type or characteristic of RMW can minimize the total costs for treatment and disposal. In addition, treatment on-site, such as on-site incineration and microwaving, should be considered for the cost-effective treatment of RMW.

3.4. Waste characterization for treatment and disposal cost reduction

Hospitals employ different classifications of wastes. This is due to the absence of a single definition of med-ical waste. Tables 2 and 4 present different ways of characterizing medical waste streams. Table 2 focuses on the components and amounts of waste incinerated and shipped-out from a hospital. This table includes information on waste type, source and volume of wastes, on-site incineration, and off-site disposal costs of RMW. This characterization method is useful for comparing various treatment and disposal methods, such as on-site incineration, off-site incineration, and other off-site disposals, of RMW generated in the hos-pital and the research laboratories of the medical school. From a characterization concerning disposal of wastes shipped-out, disposal cost per unit of weight of infectious waste (0.79 $/kg) is much greater than that of general solid waste (0.12 $/kg) (seeTable 2). This indicates that reduced disposal costs through an effective characterization or sorting of RMW can be achieved. However, this table does not present detailed information on waste components and treatment meth-ods. Therefore, this characterization method is not helpful for identifying methods to reduce treatment costs of medical waste through the application of dif-ferent treatment methods according to type of waste.

Table 4 presents information on the proportion of

RMW, solid wastes, paper and cardboard that are recycled, and treatment or disposal methods of wastes generated in a hospital. It helps identify RMW requir-ing special treatment and disposal, and plastics, both are about 20% of the total medical wastes. This table also summarizes the relative proportion of current treatment or disposal methods such as incineration, landfilling, and recycling for each waste. This classifica-tion method can be useful for the identificaclassifica-tion of recyclable products in that hospital. However, it lacks information about metal and glass recycling programs and detailed information on solid wastes and RMW. In addition, this table does not contain information on disposal sites and treatment or disposal costs.

The continuously increasing treatment and disposal costs of medical waste are related to the misclassifica-tion of wastes and the improper disposal of wastes. Every hospital needs to employ a proper classification system, and utilize different treatment and disposal methods according to the classification or waste type. For example, the waste segregation and handling pro-cesses should specify which wastes generated at specific sources should be collected by which type of collection containers, such as red, blue, green or white bags. Reg-ularly training for all workers in hospitals is necessary to improve management of their medical wastes.

Finally, the most cost-effective treatment and disposal methods suitable for each properly-classified waste type can be applied. This will save additional costs due to avoiding improper treatment or disposal and improper classification. In addition, by employing effective treat-ment and disposal methods based on the characteristics of medical wastes, exposure risks to hazardous air pollu-tants, such as dioxins and furans, produced from impro-per treatment of medical wastes could be much reduced.

4. Conclusions

This study of the treatment and disposal of RMW generated by three city hospitals in Massachusetts has found that most of the RMW was incinerated, leading to high treatment costs.

Currently, hospitals are employing many different waste stream analysis or treatment and disposal meth-ods for their medical wastes. Even though their cafeter-ias produce much higher volume of waste than operating rooms (OR) or emergency rooms (ER), treat-ment or disposal costs per unit of volume for cafeteria wastes were much lower than those of OR and ER. This was due to the employment of different waste treatment or disposal methods according to the activity char-acteristics of each waste generation department.

In the analysis of the yearly operational treatment and disposal costs of RMW, treatment by microwaving was the least expensive in terms of the treatment cost per unit weight of RMW. However, RMW treatment by microwaving was found to have limited applicability and inadequate sterilization capability. Thus, much RMW had to be sent to off-site disposal facilities which require high costs for the waste transportation. There-fore, employing only a microwave technology on-site without incineration was one of the most expensive treatment and disposal methods. In contrast, the treat-ment and disposal method that combined incineration and microwave technologies at on-site was the most cost-effective method.

Finally, this study indicates that hospitals could highly reduce the total costs for treatment and disposal of medical wastes by improving their classification

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method for medical wastes and then employing effective treatment or disposal methods based on the character-istics of their particular medical wastes. By careful exclusion of non-RMW from RMW waste streams, hospitals can reduce the RMW volume that requires special treatment and reduce disposal costs.

Acknowledgements

This study was funded by the Commonwealth of Massachusetts through the Center for Environmentally Appropriate Materials (CEAM), University of Massa-chusetts, U.S.A. The authors wish to acknowledge the excellent assistance provided by C.A. Pace, Dr. M.D. Paerlmutter, M.E. Armington, Dr. S.S. Yoon, Dr. M.S. Kim, Dr. L. Richard, C. Riley, P. DeFilippi, L. Pontae, P. Mackinnon, W. Brook, D. Baker, Dr. J.P. Remensy-der, P. Barthlomew, G. Banchieries, Dr. C. Murphy, Dr. M. Laposata, hospital operators and secretaries, and numerous people who generously helped us find their hospitals data concerning waste stream, compo-nents, and disposal methods and costs of medical waste.

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