SELECTION OF HEALTH CARE RISK WASTE TREATMENT
TECHNOLOGIES FOR GAUTENG
Dave Baldwin
Director, Environmental & Chemical Consultants, PO Box 2856, Cresta, 2118
Co-Author:
Torben Kristiansen, Chief Technical Advisor, Gauteng Department of Agriculture,
Conservation, Environment and Land Affairs, Rambøll, Hannemann & Hojland
ABOUT THE SPEAKER
Dave Baldwin graduated with a BSc Honours and PhD in chemistry from the University of Manchester
Institute of Science and Technology in 1967. After three years of postdoctoral research in inorganic
chemistry at the University of Washington, Seattle and University College London, he joined the
Chemistry Department, University of the Witwatersrand in 1970 as a lecturer in Inorganic Chemistry
and was involved in teaching and research, largely in inorganic chemistry for the next 16 years. This
period included one-year sabbatical leaves at the California Institute of Technology, Pasadena in
1977and the Albert Einstein College of Medicine, New York in 1984. In 1982, Dave developed a
strong interest in general and hazardous waste management and became a consultant to industry
initially on all aspects of hazardous waste treatment and disposal. In 1986, he joined the CSIR as a
programme manager, where he developed his interest in providing consulting services to industry in
analytical chemistry, the development of chemical processes and solid and liquid waste management.
He left the CSIR in 1990 to start Environmental and Chemical Consultants cc and has since provided
consulting services in this area and been a director of Waste-tech (Pty) Ltd and Fraser Alexander
Holdings. He was involved in the introduction of commercial “medical waste” treatment services into
South Africa and developed a system for chemical waste management for small producers. He was a
member of the working group that developed the Minimum Requirements for the Handling,
Classification and Disposal of Hazardous Waste, which was published in 1994 and was the South
African Hazardous Waste Consultant during the development of the National Waste Management
Strategy in 1997 and 1999. Clients include waste management companies, the chemical and allied
industries, mining industry and national, provincial and local government.
ABSTRACT
During the development of a Sustainable Health Care Waste Management Programme for Gauteng, a
comparison was made of the environmental, health and safety impact and the advantages and
disadvantages of the various treatment technologies for health care risk waste, i.e. burn technologies
such as incineration, and non-burn technologies, such as microwaving and autoclaving. The costestimates are based the price level of 2002 and on South African manufactured incinerators, whereas
the key technology component of non-burn treatment plants was assumed to be imported typically
from the US or Europe. Furthermore, the costs are based on the environmental minimum
requirements set out in the Health Care Waste Management Policy (November 2001) by the Gauteng
Legislature and the current draft Health Care Waste Management Regulations that are expected to be
promulgated in Gauteng in 2003. These requirements result in the need to install flue gas cleaning
systems for all incinerators for the removal of acid gases, dioxins and heavy metals as well as the
removal of dust, whereas the non-burn treatment plants will need to carry out detailed verification of
the level of disinfection achieved. The study also included a cost comparison of the various
technologies, which showed that microwaving was generally more expensive up to a capacity of
2000kg/hr. At low throughput capacities, i.e. <200kg/hr, incineration was more expensive than
autoclaving but the costs became more comparable once the throughput increased above 500kg/hr.
The costs of monitoring the emissions from incinerators and the sterilisation efficacy of non-burn
technologies were also evaluated and will be presented.
SELECTION OF HEALTH CARE RISK WASTE TREATMENT TECHNOLOGIES
FOR GAUTENG
INTRODUCTION
South Africa has mainly used incineration as the technology of choice for the treatment of health care
risk waste. However, an investigation into the status quo of health care risk waste management in
Gauteng completed in 2000 (GDACEL, 2000) confirmed the general impression held by many
practitioners that the management of this hazardous waste was in a parlous state. Most incinerators,
particularly those in the public and private hospitals, were not operated to the required standards and,
therefore, represent a significant environmental and health risk. During the subsequent development
of a Sustainable Health Care Waste Management Programme for Gauteng, a comparison was made
of the environmental, health and safety impact and the advantages and disadvantages of the various
treatment technologies for health care risk waste, i.e. burn technologies such as incineration, and nonburn technologies, such as microwaving and autoclaving. Since, health care risk waste consists of four
major waste types, i.e. infectious waste including sharps, chemical waste including pharmaceutical
waste, pathological waste and radioactive waste, a waste management programme must cater for all
four types of waste. A treatment technology, which is normally developed for sterilisation of the
infectious component of the waste, must either be able to treat all waste streams or the different types
must be separated at source. The main treatment options for health care risk waste include:


Combustion Technologies, i.e. thermal treatment/combustion technologies:
 Incineration which includes: excess air, controlled air, rotary kiln and fluidised bed
 Plasma Arc and
 Pyrolysis
Sterilisation/Disinfection Technologies,
 Steam sterilisation, e.g. Autoclaving
 Chemical sterilisation, e.g. with chlorine, glutaraldehyde
 Gas sterilisation, e.g. with ethylene oxide, formaldehyde
 Dry heat sterilisation, e.g. oil heated screw feed technology
 Electro-thermal deactivation (ETD),
 Microwave sterilisation,
 Irradiation sterilisation
Cobalt-60 gamma rays
Ultra violet
Electron beam sterilisation
The technologies indicated in italics are experimental or have limited commercial application
internationally: UV treatment is largely effective only as surface treatment. Recent developments have
resulted in the introduction of commercial non-burn facilities using Electrothermal Deactivation in
Gauteng and the Western Cape, and Autoclaving in KwaZulu-Natal and a number companies are
proposing the introduction of microwave facilities and a chemical sterilisation technology. Also,
modern incinerators with scrubbers are being introduced or existing facilities are being modified to
meet the expected more stringent gas emission standards. All of the above treatment technologies
result in a residue, i.e. ash in the case of burn technologies or a sterilised/disinfected waste that has to
be disposed to landfill. Note that in terms of the South African Minimum Requirements for the
Handling, Classification and Disposal of Hazardous Waste, health care risk waste cannot be landfilled
unless it is incinerated or otherwise sterilised.
There are significant differences between burn and non-burn technologies and the most important of
these are the types of health care risk waste that can be treated and the residues that are generated,
as well as the type of emissions and where they occur; these are illustrated in figure 1. In the diagram
it is assumed that the combustion treatment facility meets all the National and Provincial Standards
and, therefore, can accept three of the major types of health care risk waste, i.e. infectious waste
including sharps, chemical waste including pharmaceuticals and pathological waste, and that a gas
cleaning system is used. Pathological (Anatomical) waste, which includes recognisable human parts,
and chemical waste should not be handled by non-burn technologies and alternative technologies
must be used for their treatment and disposal. Radioactive waste is not included in Figure 1, although
selected low radioactive waste that comes from health care facilities could be treated, subject to
permits. However, no radioactive waste can be treated by non-burn technologies and all must be
disposed to special permitted waste landfills/depositories.
Burn treatment technologies
Infect
waste &
sharps
Pathological
waste
Chemical
waste
Incineration
Ash
Landfill
Flue gas
cleaning
residuals
Emissions to air
Leachate
generation
Non-burn treatment technologies
Infectious
waste &
sharps
Pathological
waste
Chemical
waste
Non-burn
treatment
Incineration,
Cremation or
Burial
Treatment
as a
hazardous
waste
Noninfectious
waste
Landfill
Ash or
body
parts
Cemetery
Waste or
treatment
residues to
landfill
Leachate generation +
gas emissions to air
Figure 1: Generic Differences Between Non-burn and Burn Technologies for the Treatment of Health
Care Risk Waste
INCINERATION/COMBUSTION TECHNOLOGY
The main elements of modern incineration technology are illustrated schematically in Figure 2.
Historically single chambered incinerators have been used for the treatment of health care risk waste
and there are many still in use in Gauteng and the rest of the country. Further, developments included
the introduction of multi-chambered incinerators, both excess air and starved air/controlled air types
specifically designed and permitted for the treatment of the infectious waste stream. These
incinerators are potentially capable of handling small quantities of chemical hazardous waste. An
automatic feeding system is used for feeding the waste into the incinerator. The waste is
combusted/pyrolysed in the primary combustion chamber with a stoichiometric deficit of air at
temperatures ranging from 650oC to 1100oC. A support burner, usually fired by fuel oil or gas, is used
both during start up and intermittently during operation to achieve and maintain the required
temperature. The result is a bottom ash or slag and a gas stream containing combustible volatile
organic compounds, particulates and potential pollutants. In the secondary combustion chamber, an
excess of air is added and a secondary support burner fired by fuel oil or gas is used, if required, to
maintain the temperature above 1100 oC to give complete burning of the combustible gases and solids
from the primary chamber. A minimum retention time of 2 seconds is usually required. Energy can be
recovered via a water/steam boiler but in South Africa this has been found to be uneconomic largely
due to the small size of the incinerator and the relatively low cost of energy. The flue gas is cleaned
using either wet, dry or semi-dry flue gas cleaning including a dust filter. Normally wet flue gas
cleaning is not economic for health care risk waste incinerators because of their small size; hence,
most plants make use of semi-dry or dry flue gas cleaning. Using flue gas cleaning systems, the strict
emission limits for acid gases, particulates, heavy metals and dioxins set by many countries can be
achieved. Common filters used are bag house filters or the more temperature tolerant ceramic filters.
Typical neutralising agents for acid gases used are lime or bicarbonate products, possibly with
activated carbon added for dioxin or heavy metal removal.
Inputs:
Waste
Electricity, support
fuel (oil/gas) & air
Support fuel
(oil/gas) & air
Coling water
(circulated)
Dry process: Chemicals
or Wet Process:
chemicals + water
Process:
Feeding system
Primary
combustion
chamber (solids
and gases)
Secondary
combustion
chamber (flue
gases)
Boiler/heat
exchanger/cooling
system
Flue gas cleaning
system
Stack
Heat and/or hot
water (to be utilised)
Dry process: Fly ash +
used chemicals
(landfilled) or Wet
process: Fly ash +
sludge (landfilled) and
waste water (sewer
system)
Cleaned flue gas
(to the air)
Outputs:
Bottom ash
(landfilled)
Figure 2: Flow Diagram of a Modern Incineration Plant.
The typical inputs and outputs of materials and energy for the modern incineration process are also
indicated in figure 2. The ash and any other solids and liquid wastes, e.g. from gas cleaning, must be
classified, as required by the Department of Water Affairs and Forestry’s Minimum Requirements for
the Handling, Classification and Disposal of Hazardous Waste, and disposed to an appropriate
hazardous or general waste landfill.
ADVANTAGES AND DISADVANTAGES OF INCINERATION
The main advantages and disadvantages of incineration as a technology for the treatment of health
care risk waste are listed in table 1.
Table 1: Advantages and Disadvantages of Incineration
Advantages of incineration
 Safe elimination of all infectious organisms in the
waste at temperatures above ~700oC
 Flexible, as it can accept pathological waste and
depending on the technology chemical waste.
 Residues are not recognisable
 Reduction of the waste by up to 95% by volume or
83 to 95% by mass: typically 5-17% ash is
obtained.
 Very well proven technology
 No pre-shredding required
 No special requirements for packaging of waste
 Full disinfection is assumed to have occurred
provided the high temperatures are maintained and
the ash quantity is adequate. No monitoring of
sterilisation efficiency is required.
Disadvantages of incineration
 Normally higher investment costs required for
incinerator and flue gas cleaning compared to nonburn technologies
 Point source immediate emissions to the air (as
opposed to attenuated emission of CH4 and CO2
from landfill body over a period of decades)
 High cost of monitoring gas emissions and
demonstrating compliance to emission standards.
 Solid and liquid by-products must be handled as
potentially hazardous waste (may not apply to
bottom ash if waste is well sorted and FGC
residues handled separately)
 Incineration is perceived negatively by many
sections of the community.
 PVC and heavy metals in the waste provide a
significant pollutant load on the gas cleaning
system (and for heavy metals on the quality of
bottom ash also).
 Existing health care risk waste incinerators in
South Africa cannot accept significant amounts of
chemical waste because of refractory damage (but
above you argue that modern plants can to some
extent.)
Separation at source is a key requirement for the correct management of health care risk waste, but
incineration with flue gas cleaning is more forgiving than many other technologies, as it can accept
pathological waste and, depending on the amount, the type of incinerator and its construction,
chemical waste. For many of the pyrolytic dual chamber incinerators currently in use in South Africa,
the amounts of chemical, including pharmaceutical waste that can be accepted is low. Thus, like
normal household waste, which contains small amounts of hazardous chemical waste, the infectious
waste stream must be expected to include small amounts of pharmaceuticals, chemicals used in
wards, such as disinfectants, solvents, etc., even when a programme for separation at source has
been instituted. An incinerator can readily accept this waste stream. However, most of the current
incinerators available in South Africa should not deliberately accept chemical including pharmaceutical
waste due to damage to the incinerator and significantly increased requirements for gas cleaning.
ENVIRONMENTAL, HEALTH AND SAFETY IMPACT OF INCINERATION
Incineration has proven to be a very effective way of sterilising health care risk and no special tests to
determine the efficacy of the sterilisation process is normally required. However, in the past, most of
the health care risk waste incinerators in South Africa have been poorly operated and almost all have
not been fitted with emission control equipment. Tests on the emissions have shown that the
incinerators are unable to meet the current DEAT Emission Guidelines for a Schedule 39 Process for
some heavy metals and for HCl. Gauteng Province has decided to insist that, in future, incinerators
meet the DEAT Emission Guidelines as a minimum requirement and this means that gas-cleaning
equipment will be needed. With modern wet or dry gas cleaning techniques, incinerators have been
able to meet the strict standards imposed in the USA and the European Union.
Apart from gas emissions, incinerators produce an ash, which normally classifies as hazardous,
although it can be delisted to general sites, if chemically stabilised with lime or treated by cementation;
the volumes of ash generated are small. Source separation can result in reduced amounts of heavy
metals being present in incinerator ash and potentially facilitate delisting of the ash, although two of
the major problem metals, lead and zinc, are introduced with PVC because of the use of lead and zinc
soaps during the production process. Gas cleaning can be accomplished by both wet and dry
scrubbing. Dry scrubbing is generally preferred, as it is more economic for the typical HCRW
incineration plant capacity, and, the resulting solid, which may be classified as hazardous, can be
disposed to hazardous waste landfill, whereas the liquid wastes generated by wet scrubbing is
charged a premium when disposed to landfill.
Incineration is still a very common technology for health care risk waste treatment internationally, as it
can meet the required strict environmental requirements, provided they are well operated and have
good emission control equipment. However, in world regions with no or limited mass incineration of
domestic or commercial waste steam sterilisation, microwave treatment and other non-burn
technologies are fast becoming the most effective HCRW treatment technology with increasing costs
of flue gas cleaning.
MICROBIAL INACTIVATION USING NON-BURN TECHNOLOGIES
Increasing emission requirements resulting in increasing cost of flue gas cleaning for incineration
plants as well as an unfavourable perception of incineration has lead to the development of a range of
sterilisation/disinfection technologies for the treatment of health care risk waste (see the introduction).
Autoclaving, microwaving and ETD sterilise result in heating of the waste to moderate temperatures,
90oC to 160 oC, which results in its sterilisation, provided all the waste is subjected to the required
temperatures for sufficient time. The sterilisation standards are discussed in the following paper (L
Godfrey et al., 2003). Chemical treatment on the other hand uses a chemical sterilising agent to
achieve equivalent treatment standards. In this paper, microwave technology will be briefly discussed
as a typical non-burn technology. In the microwaving process, infectious waste is normally wetted or
exposed to high-temperature steam, shredded and the moisture in the waste heated by a series of
microwave generators for a specified period. The temperatures reach ~95 oC and the microorganisms
are killed in the process, resulting in a residue that is confetti-like and slightly moist. Microwaving has
been used to treat such items as sharps, microbiological materials, blood, and biological fluids. It is not
suitable for the treatment of pathological chemically hazardous, or radioactive wastes and large
quantities of metals can reduce the effectiveness of the microwaves’ penetration of the waste. Air
emissions from the shredder and treatment plant are usually treated to remove moisture and volatile
organic carbon compounds. The volume of the final waste product is reduced significantly by
shredding and compaction of the final product, but almost no mass reduction occurs.
Inputs:
Waste
Water (if waste is
dry)
Power to feed
microwave
generator
Process:
Feeding system
Size reduction
Heat and
microwave
treatment
Compaction
Water vapour
Waste water
Unloading to
container/truck
Transport to
landfill
Gas
Cleaning
Outputs:
Gas Emissions
Landfilling of
treated waste
Figure 2: Flow Diagram of a Typical Microwave Plant
ADVANTAGES AND DISADVANTAGES OF NON-BURN STERILISATION TECHNOLOGIES
The main advantages and disadvantages of autoclaving, microwaving and ETD technologies are in
many ways similar and these are listed in the first row of table 2: there are some differences, however,
and these are highlighted in rows 2 to 4.
Table 2: Advantages and Disadvantages of Autoclave, Microwave and ETD Sterilisation Technologies
Advantages
Autoclaving, Microwaving ETD and DHS
(Cross cutting)
 High sterilisation efficiency under appropriate
conditions;
 Volume reduction depending on type of
shredding/compaction equipment that has
been installed
 Low risk of air pollution
 Moderate operation costs
 Easier to locate as generally more
acceptable to communities and neighbours
than incineration
 Recovery technologies can be used on
sterilised waste
Disadvantages











Autoclaving
 Proven system that is familiar to health-care
providers
 Relatively High Sterilisation Temperature




Microwaving
 Low capacity units are available for small
waste producers e.g. clinics and GPs
 Moderate investment costs
 Low Sterilisation Temperature may lower
energy costs
Electro-thermal Deactivation
 Low Sterilisation Temperature may lower
energy costs




Not suitable for pathological waste and chemical
waste, including pharmaceuticals and cytotoxic
compounds
Good waste segregation required
No or limited mass reduction
Shredders are subject to breakdowns and blocking
and repairs are difficult when the waste is infectious.
It is not possible to visually determine that waste has
been sterilised
Waste is not rendered unrecognisable or unusable, if
not shredded either before or after sterilisation.
High monitoring costs to demonstrate compliance with
sterilisation standards
Treated waste must be disposed to landfill
Air filtration is needed
Operation requires highly qualified technicians.
HEPA filters must be maintained and replaced
regularly.
Significant amounts of volatile organic carbon
compounds produced
Contaminated water must be discharged to sewer
Waste and containers must have good steam
permeability, especially if there is no prior shredding
No waste reduction
Unsuitable for very high quantities of infected metal
(e.g. needles from inoculation campaigns)
Low sterilisation temperature increases time required
for treatment.
Relatively high investment and operating costs
Low sterilisation temperature increases time required
for treatment.
Autoclave, Microwave, ETD and DHS technologies cannot accept all the health care risk waste
streams. Pathological (anatomical) waste, chemical waste and radioactive waste should be separated
as well as possible at source. However, it is estimated that these components only represent 5% of
the total health care risk waste stream and therefore non-burn technologies can treat the bulk of the
waste stream.
ENVIRONMENTAL, HEALTH AND SAFETY IMPACT OF STERILISATION TECHNOLOGIES
The environmental and health impacts of the Autoclaving, Microwaving, and ETD technologies are
potentially low compared to incineration, which generates large quantities of gas that is immediately
emitted to the air. However, landfilling of sterilised waste results in anaerobic biodegradation of the
waste, which will give methane a gas, which is a greenhouse gas with greater impact than carbon
dioxide. One of the main problems is that good separation at source is required particularly to ensure
that chemical including pharmaceutical wastes are not treated as the resulting sterilised waste will
probably be classified as hazardous.
Small amounts of gaseous emissions must be expected to be released during the sterilisation process
and shredding, particularly if the waste has been poorly segregated at source, and appropriate
precautions must be taken to remove these. Also, most sterilisation technologies require the waste to
be shredded and, if accomplished before the sterilisation process, there are potentially significant
health and safety risks for the staff, when a shredder breaks down or becomes blocked, e.g. by a large
metal object. The cleaning procedure must be well defined, include the use of appropriate PPE and
preferably include disinfection or sterilisation of the waste before manual cleaning and repair is
undertaken. For the microwaving and ETD processes, special precautions must be taken to protect
personnel against the electromagnetic radiation that is used.
A COST COMPARISON OF SELECTED HCRW TREATMENT TECHNOLOGIES
Financial estimates of the costs of the various health care risk waste treatment technologies were
made and were based on data obtained from suppliers, and companies that are actually in the
process of setting up or are operating such facilities. The data has, however, been adjusted for civil
works, environmental protection measures, and should be viewed as indicative costs only: the price
level used in all calculations was that pertaining in February 2002. The assumptions used were:











The estimated salary costs would include all statutory contributions, holidays, shifts, sick leave,
medical etc.
The cost for the establishment of a new building or renovation of an existing building to house the
plant is included in the estimated costs.
A standard fixed amount for consultancy fees and other expenditure required to obtain an EIA
authorisation from the Province plus any other legal requirements such as a Schedule 39 permit
for an incinerator was included.
Salaries were based on normal South African levels.
The cost of equipment was based on International/South African price levels for delivery in
Gauteng and was obtained from suppliers, plant operators and international publications.
Incinerators include gas-cleaning equipment, i.e. lime treatment plus a ceramic filter. Note that,
often, building some or all of a plant in South Africa can considerably reduce costs and the capital
estimates for incinerators include this assumption.
The cost of civil works and installation were based on Gauteng prices
Economic life of civil works and treatment technologies: 12 years
Economic life of internal storage and transportation equipment: 10 years
The following costs are not included:
i)
Infrastructure at the generators site,
ii)
Establishment of public utilities used, e.g. landfills
iii)
Cost of administration, invoicing, marketing etc.
iv)
Cost of training of operators
v)
Cost of PPE/OSH programmes.
vi)
Value Added Tax.
Depreciation costs are estimated as 10 years for equipment and 15 years for other capital and a
real interest rate of 12% p.a.
The operational hours for the plants were based on operation for 26 days per month and 12
months per year. However, the maximum operational hours were varied as follows:
i)
Incinerators < 200kg/hr: 12 hrs per day with manual de-ashing
ii)
Incinerators  200kg/hr: 20 hours per day with automatic de-ashing
iii)
Non-burn Technologies: 24 hours per day


The costs for disposal of residues, such as the ash and gas cleaning waste from incinerators, and
sterilised the waste from non-burn technologies, were estimated using current disposal costs. It
was assumed that the ash from incinerators requires treatment with 2.5% lime in order to minimise
its impact on the landfill. Residues from non-burn are assumed deposited at normal landfill sites,
whereas residues from incinerators are assumed deposited at a Hazardous Waste Landfill site.
For non-burn technologies an estimate of the costs of disposal of pathological waste and chemical
waste that could not be treated by the technology was included.
Table 4 gives the comparative costs estimated for microwaving, autoclaving and incineration. The data
for microwaving and autoclaving technology can be taken as being illustrative of the costs expected
for the other non-burn thermal technologies such as the ETD and Dry Heat Sterilisation, as the
investment costs and operational costs are expected to be similar for these technologies.
Table 3: Comparative Costs for Various HCRW Treatment Technologies
Investment Cost, R
Running Costs*, R
R/kg
millions
millions/yr
Microwaving
100
5.83
2.33
3.27
250
7.40
3.10
1.95
1000
10.61
5.09
1.08
Autoclaving
100
4.84
1.82
3.03
250
6.34
2.55
1.34
1000
9.90
5.14
1.71
Incineration
100
3.96
1.66
5.55
250
5.16
2.49
2.00
1000
7.42
4.53
0.97
* Running Costs = Interest + Depreciation on Capital + Operating Costs but cost of monitoring excluded
Capacity, kg/hr
The results indicated the following:
a) As expected, the cost for treating a kg of waste decreases dramatically as the capacity of the plant
increases.
b) For incineration, there is a discontinuity that occurs below 200kg/hr due to the assumptions made,
i.e. the capital cost for the larger plants is increased because automatic de-ashing is included but
this is accompanied by an increase in the maximum operating hours for the larger automated
plants from 12hrs per day to 20hrs per day. This increase in operating hours decreases the
expected cost per kilogram significantly.
c) The costs in table 3 are based on operating the facility at its maximum capacity. For example,
operating the 1000kg/hr autoclaving plant for 8 hrs/day or one shift gives a treatment cost of
R1.71/kg; for 16 hours or two shifts, R0.85/kg, and for 24 hours or three shifts, R0.71/kg. Clearly,
the treatment facility should be operated as far as possible at full capacity, as this decreases the
overall costs of treatment: a central facility handling waste from many sources will clearly be more
cost effective than many small plants, particularly in urban areas, where the transport distances
are relatively small.
d) According to the available data, microwaving is relatively expensive compared to the other two
technologies but the costs per kilogram treated become comparable with those of other
technologies at higher loads.
e) The investment costs for incineration appear to be relatively low compared to the other two
technologies. This can, at least in part, be attributed to the fact that the cost of the incinerators are
based on them being manufactured in South Africa, whereas capital costs for the other two
technologies are based on imported equipment.
MONITORING OF INCINERATOR EMISSIONS
One of the major concerns expressed by participants in the Gauteng project was the potentially high
cost of monitoring of the performance of health care risk waste treatment technologies. A study was
undertaken for Department of Agriculture, Conservation, Environment and Land Affairs (Baldwin,
2003) on the costs of testing incinerator emissions and a separate study considered the cost of
evaluating the sterilisation efficiency non-burn technologies (L Godfrey et al., 2003), which is
considered in detail in the next paper.
Until the new Air Quality Management Bill is enacted and new emission standards have been set, the
current requirements in terms of schedule 2 of the Air Pollution Prevention Act (Act 45 of 1965) have
been used, see table 4. An incinerator will have to undergo performance testing, where the operator
demonstrates that the facility can meet the requirements set out the ROD and undergo a standard or
minimum monitoring programme for at least one year. Once the facility has demonstrated that it
routinely meets the requirements, it can apply for a reduction in frequency of analysis, i.e. to the
minimum required programme. Note that from table 4, continuous monitoring of PM/dust, CO, O 2,
water vapour, HCl and SO2 is proposed. The instrument and operating costs were obtained from a
number of reputable South African suppliers of equipment and an average value taken for instruments
from various sources. Note the cost of a dioxin analysis of R80000.00 includes the collection of
duplicate samples by a South African company and analysis by a laboratory overseas, e.g. in
Germany.
Table 4: Approximate Costs for the Performance Testing and the Standard and Minimum Monitoring
Programmes
Minimum Requirements
Performance
Testing
Monitoring Frequency
(Permit conditions can vary)
Standard
Performance
Standard
(minimum) per
Analysis,
Analysis,
year
R
R per year
Minimum
Analysis,
R per year
Units
mg/Nm3
PM/dust
180
Continuous
Continuous
a)
CO
O2
Water vapour
TOC
Dioxin/furan
(nanogram) TEQ
-
Continuous
Continuous
Continuous
-
Continuous
Continuous
Continuous
-
a)
a)
a)
-
68 000
9 000
b)
-
68 000
9 000
0.2
1
2(1)
80000
160 000
80 000
HCl
30
Continuous
Continuous
a)
100 000
100 000
HF
SO2
25
Continuous
Continuous
a)
11 500
11 500
NOx
-
-
-
-
-
-
NH3
-
-
-
-
-
-
0.5
1
2 (1)
10000
20 000
10 000
60
720
720
90,000
868,000
1,041,000
370,000
283,000
Pb, (same for Cr,
Be, Ar, As, Sb, Ba,
Ag, Co, Cu, Mn,
Sn, V, Ni)
Cd (same for Tl)
Hg
LOI for ash
0.05
0.05
<5%
1
1
1
2 (1)
2 (1)
12
-
Total Estimated Costs (to nearest R1000)
a)
b)
c)
Capital Cost
Equipment Depreciation Cost
Annual Running Costs
Costs already included as continuous monitors fitted.
No additional cost, as normally measured by CO analyser.
Value to be confirmed with DACEL – may change.
Thus, the monitoring cost for the standard programme is estimated at ~R370,000 per annum and the
minimum analysis as R280,000 per annum, a reduction of ~24%. Clearly, the actual cost per kilogram
of waste treated will vary significantly depending on the amount of waste that is treated in the
incinerator. In order to get a better comparison of the impact of monitoring costs on the overall cost of
treating health care risk waste, the values derived in table 6, were used to calculate the treatment cost
per kilogram for incinerators ranging from 100kg/hr to 1000kg/hr: the results are presented in table 5.
Note that the scenario is based on that used in the project feasibility study and assumes the
incinerators are all working at full capacity, i.e. for a 100 kg/hr incinerator for 12 hours per day and for
the larger incinerators for 20 hours per day and 26 days per month.
Table 5: Cost per kilogram of waste treated
Waste
First Year
Monitoring,
Throughput, kg/hr
Standard
% of cost/kg*
Programme, R
100
7.09
22
250
2.37
16
500
1.43
8.2
1000
1.00
7.0
* Compared to zero monitoring costs
Second & Subsequent
Years Minimum
Programme, R
6.49
2.22
1.36
0.96
Monitoring,
% of
cost/kg *
14
9.0
6.2
4.0
CONCLUSIONS AND RECOMMENDATIONS
Incineration and non-burn technologies have been compared both from a financial and environmental
point of view and, provided all are operated within the proposed standards, there appears to be little to
choose between them. Incineration is, however, more versatile since if fitted with gas cleaning
equipment it can readily handle most types of health care risk waste, whereas separation of chemical
and pathological waste at source must be undertaken with non-burn technologies. As might be
expected, the greater the capacity of the treatment facility and the higher the operating hours, the
lower the cost of treatment, which supports the provision of a few large facilities in an urban
environment such as Gauteng.
A study was also undertaken into the monitoring of incinerator stack emissions and continuous
monitoring is proposed for the parameters, PM/dust, CO, O2, water vapour, HCl and SO2. A monitoring
programme clearly increases the overall cost of treatment significantly for a small incinerator, whereas
the percentage increase in cost for a large facility is relatively small.
REFERENCES
Baldwin D, Report “Evaluation of the Emission Monitoring Requirements for HCRW Incinerators” for
Gauteng Department of Agriculture, Conservation, Environment and Land Affairs, September
2002
Gauteng Department of Agriculture, Conservation, Environment and Land Affairs, Final Report on
Feasibility Study into the Possible Regionalisation of Medical Waste Treatment/Disposal
Facilities in Gauteng, September 2000
Godfrey L et al, Validation and Monitoring of Non-Burn Health Care Risk Waste Treatment Facilities in
Gauteng, Conference “Healthcare Waste Management in Africa Today”, Sandton Convention
Centre, Sandton, South Africa, August 2003