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Selection of HCRW Treatment Selection of HCRW Treatment Technologies for GautengTechnologies for Gauteng

David A Baldwin, PhD, Pr.Sci.Nat.Environmental and Chemical Consultants ccand

Torben KristiansenChief Technical Advisor. Gauteng Department of Agriculture, Conservation, Environment and Land AffairsRambøll, Hanneman and Hojland

August 2003

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IntroductionIntroductionStatus Quo Study into HCRW in Gauteng – 2000: Confirmed parlous state of HCRW management in

Gauteng Treatment facilities included 70 incinerators at 58

different locations Only 58 were “operational” but only 25 had a permit Many incinerators were poorly operated and maintained Only one fitted with emission control equipment, which

was not operational Capital and operating costs were estimated at only R1.00

per kilogram of waste treated

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Introduction to Technologies -1Introduction to Technologies -1

Thermal treatment/combustion technologies:

– Incineration which includes: excess air, controlled air, rotary kiln and fluidised bed

– Plasma Arc and

– Pyrolysis

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Introduction to Technologies -2Introduction to Technologies -2

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

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Waste Pathway for IncinerationWaste Pathway for Incineration

Infectious waste & Sharps

Pathological Waste

Chemical Waste

Incineration

Ash

Flue gas cleaning residues

Landfill

Emissions to Air

Leachate

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Waste Pathway for Non-Burn Waste Pathway for Non-Burn TechnologiesTechnologies

Infectious waste & Sharps

Pathological Waste

Chemical Waste

IncinerationCremation or Burial

Non-Burn Treatment

Ash or Body Parts

Waste Treatment Residues to Landfill

Treatment as Hazardous Waste

Non-infectious waste

Landfill

Cemetery

Leachate + Gas Emissions

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Inpu ts : W asteE lec tric ity , support fue l (o il/gas) & a ir

S upport fue l (o il/gas) & a ir

C o ling w a te r (c ircu la ted )

Process: F eed ing sys tem

P rim ary com bustion

cham ber (so lids and gases)

S econdary com bustion

cham ber (flue gases)

B o ile r/hea t exchanger/coo ling

sys tem

F lue gas c lean ing sys tem

S tack

Outpu ts : B ottom ash (land filled )

H ea t and /o r ho t w a te r (to be u tilised )

C leaned flue gas (to the a ir)

D ry p rocess : C hem ica ls or W et P rocess :

chem ica ls + w a te r

D ry p rocess : F ly ash + used chem ica ls

(land filled ) or W et p rocess : F ly ash +

s ludge (land filled ) and w aste w a te r (sew er

sys tem )

Flow Diagram of Modern Incineration PlantFlow Diagram of Modern Incineration Plant

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Advantages of IncinerationAdvantages 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.

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Disadvantages of IncinerationDisadvantages of Incineration Normally higher investment costs required for incinerator and flue gas

cleaning compared to non-burn 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 Existing health care risk waste incinerators in South Africa cannot accept

significant amounts of chemical waste because of refractory damage.

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Flow Diagram a Typical Microwave PlantFlow Diagram a Typical Microwave Plant

Inputs: WasteWater (if waste is

dry)

Power to feed microwave generator

Process: Feeding system Size reductionHeat and

microwave treatment

CompactionUnloading to

container/truckTransport to

landfill

Outputs: Water vapour Waste waterLandfilling of treated waste

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Advantages Non-Burn Technologies -1Advantages Non-Burn Technologies -1

Autoclaving, Microwaving ETD and DHS (Cross cutting)

– High sterilisation efficiency under appropriate conditions

– Low temperature of operation 90oC to 160oC

– 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

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Advantages Non-Burn Technologies -2Advantages Non-Burn Technologies -2

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

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Disadvantages Non-Burn Technologies -1Disadvantages Non-Burn Technologies -1Autoclaving, Microwaving ETD and DHS (Cross cutting) Not suitable for pathological waste and chemical waste 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 “High” monitoring costs to demonstrate compliance with sterilisation

standards Treated waste must be disposed to landfill Air filtration is needed – some odour problems Operation requires highly qualified technicians. HEPA filters must be maintained and replaced regularly

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Disadvantages Non-Burn Technologies -2Disadvantages Non-Burn Technologies -2 Autoclaving

– 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 Microwaving

– Unsuitable for very high quantities of infected metal (e.g. needles from inoculation campaigns)

– Low sterilisation temperature increases time required for treatment. Electro-thermal Deactivation

– Relatively high investment and operating costs– Low sterilisation temperature increases time required for treatment.

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Cost Comparison of Selected HCRW Cost Comparison of Selected HCRW Treatment Technologies - 1Treatment Technologies - 1

Assumptions: Salary costs include all normal contributions The cost for the establishment of a building in the estimated costs. A standard fixed amount for consultancy fees and other expenditure

required to obtain an EIA authorisation, etc The cost of equipment was based on International/South African

price levels for delivery in Gauteng. Incinerators include gas-cleaning equipment, i.e. lime treatment plus

a ceramic filter. The cost of civil works and installation were based on Gauteng

prices

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Cost Comparison of Selected HCRW Cost Comparison of Selected HCRW Treatment Technologies - 2Treatment Technologies - 2

Economic life of civil works and treatment technologies: 12 years Economic life of storage and transportation equipment: 10 years The following costs not included:

– Infrastructure at the generators site,

– Establishment of public utilities used, e.g. landfills

– Cost of administration, invoicing, marketing etc.

– Cost of training of operators

– Cost of PPE/OSH programmes.

– 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.

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Cost Comparison of Selected HCRW Cost Comparison of Selected HCRW Treatment Technologies - 3Treatment Technologies - 3

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: – Incinerators < 200kg/hr: 12 hrs per day - manual de-ashing – Incinerators 200kg/hr: 20 hours per day - automatic de-ashing– 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. 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

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Costs for HCRW Treatment TechnologiesCosts for HCRW Treatment Technologies

Technology Capacity, kg/hr

Investment Cost, R m

Running Cost, R m* R/kg

Microwaving 100 5.83 2.33 3.27

  5.83 7.40 3.10 1.95

  2.33 10.61 5.09 1.08

Autoclaving 3.27 4.84 1.82 3.03

  250 6.34 2.55 1.34

  7.40 9.90 5.14 1.71

Incineration 3.10 3.96 1.66 5.55

  1.95 5.16 2.49 2.00

  1000 7.42 4.53 0.97* Running Costs = Interest + Depreciation on Capital + Operating (monitoring excluded)

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Cost of HCRW TechnologiesCost of HCRW Technologies Treatment cost decreases dramatically as plant capacity

increases For incineration, there is a discontinuity that occurs below

200kg/hr due to the assumptions made The costs are based on operating the facility at its maximum

capacity. According to the available data, microwaving is relatively

expensive but the costs become comparable at higher loads. The investment costs for incineration appear to be relatively

low compared to the other two technologies.

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Testing and Monitoring Incineration Plants - 1Testing and Monitoring Incineration Plants - 1

Requirements: Performance Testing – to conform to ROD Standard Testing – at least over first year of operation Minimum Programme – once prove conformance Analysis Required:

– Continuous Monitoring of PM, carbon monoxide, oxygen, water vapour, hydrochloric acid and sulphur dioxide

– Dioxins: Performance x 1; Standard – 2/yr; Minimum – 1/yr

– Metals: Performance x 1; Standard – 2/yr; Minimum – 1/yr– Loss on Ignition for Ash: Performance x 1; Standard and

Minimum – 12/yr

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Testing and Monitoring Incineration Plants - 2Testing and Monitoring Incineration Plants - 2

Performance Analysis

Standard Analysis

Minimum Analysis

Capital Cost R868,000

Depreciation R1,041,000

Running Cost R90,000 R370,000 R283,00

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Testing and Monitoring Incineration Plants - 3Testing and Monitoring Incineration Plants - 3

Waste Throughput,

kg/hr

Standard Programme Minimum Programme

Treatment Cost R/kg

Monitoring Cost as %

Treatment Cost R/kg

Monitoring Cost as %

100 7.09 22 6.49 14

250 2.37 16 2.22 9.0

500 1.43 8.2 1.36 6.2

1000 1.00 7.0 0.96 4.0