What duct material does SBKJ recommend for a waste-to-energy boiler economiser outlet and downstream flue gas treatment?

Layered by service temperature and chemistry. The boiler economiser outlet duct at 180 to 220 degrees Celsius carrying dry flue gas with sulphur dioxide and hydrogen chloride is carbon steel with welded seams, refractory lined where appropriate. The economiser-to-bag-filter run carrying activated carbon and lime sorbent injection is 304L stainless because trace acid attack on galvanised begins above 130 degrees Celsius and the carbon loading is abrasive. The bag-filter clean-side outlet to the induced draft fan and the wet scrubber where present is 316L stainless because chloride and fluoride concentration after the dry sorbent reaction remain corrosive, condensing at around 60 degrees Celsius. The wet scrubber outlet to the stack carries saturated gas with residual chloride and is 316L stainless minimum, with super-austenitic grades 904L or duplex 2205 specified where the chloride bleed concentration exceeds 1,000 parts per million. The stack itself is 316L stainless for the inner liner above the wet scrubber. SBKJ runs 304L and 316L through the SBAL-V auto duct line up to 1.5 millimetres and through the SBSF-1525 stitchwelder for the welded seams mandatory on hot acidic service.

What capture velocity and biofilter sizing does a composting facility need for ammonia and odour control?

Australian compost facilities — Soilco at Kingaroy, Centro at Sydney, Australian Native Landscapes, Veolia and Cleanaway composting operations — extract from the receival floor, the windrow turning hall or in-vessel reactor and the maturation hall at 4 to 6 metres per second capture velocity into a biofilter for ammonia and odour treatment. Total extract volume on a 100,000 tonne per annum facility is typically 50,000 to 150,000 cubic metres per hour. The biofilter media is open-bed wood-chip or bark over a perforated plenum at 50 to 65 percent moisture content, with 30 to 45 second empty-bed residence time. Ammonia loading is the operative design driver — the Safe Work Australia workplace exposure standard for ammonia is 25 parts per million 8-hour time-weighted average and 35 parts per million short-term, and the residential boundary nuisance threshold is around 1 to 2 parts per million depending on state EPA framework. The duct between the process and the biofilter is 316L stainless because compost off-gas at 30 to 50 degrees Celsius is humid, ammonium-acetate-laden and condensing, and galvanised corrodes within months. SBKJ runs 316L through the SBAL-V auto duct line and produces the biofilter return riser through the SBFB-1500 spiral tubeformer.

What hazardous area zoning applies to lithium-ion battery recycling shredder hoods?

Lithium-ion battery recycling shredder enclosures — operated by Envirostream Australia at Campbellfield, Strategic Power Corporation, Sims Lifecycle Services, Australian Refined Alloys and B-cycle drop-off processors — are Zone 1 hazardous areas inside the enclosure during normal operation and Zone 2 in adjacent rooms during fault conditions. The thermal runaway gas mixture released by a single cell entering thermal runaway contains hydrogen, methane, carbon monoxide, hydrogen fluoride, hydrogen bromide and phosphoryl fluoride at temperatures up to 700 degrees Celsius. The HVAC duct response is fourfold under NFPA 855 and AS/NZS 5139 alignment. First, the shredder enclosure runs under continuous nitrogen or argon blanket with oxygen concentration held below 4 percent. Second, NFPA 68 explosion vent panels on the enclosure and downstream baghouse with welded heavy-gauge 304L stainless duct construction. Third, a three-stage scrubber train — caustic primary, acid secondary, activated carbon polish. Fourth, continuous gas detection on hydrogen, hydrogen fluoride, hydrogen bromide, hydrogen chloride, carbon monoxide and oxygen interlocked to fast-acting isolation dampers, inert gas knock-down and process trip. The duct material from enclosure to baghouse is welded heavy-gauge 304L stainless, the scrubber interstage is 316L because chloride carryover demands the molybdenum content, and the stack is 304L stainless with continuous emissions monitoring for hydrogen fluoride, hydrogen bromide, hydrogen chloride and total volatile organic compounds.

What machinery line covers a typical Australian waste-to-energy or hazardous waste facility duct package?

One SBAL-V auto duct line at 16 metres per minute with 87 kilowatt total connected load handles the rectangular galvanised supply and return majority and switches to 304L and 316L stainless with the stainless tooling package for the flue gas treatment train, the boiler economiser run, the wet scrubber interstage and the stack inner liner. One SBTF-1500C spiral tubeformer covers the round biofilter return riser and the gas-to-energy engine compound. One SBSF-1525 stitchwelder produces the welded longitudinal seams mandatory under NFPA 660 deflagration rating for fly ash silo extract, scrap metal shredder pre-vent and post-combustion chamber wall sections. One SBFB-1500 folder at 7.5 kilowatts and 1.20 metres per minute covers the heavy-gauge folded sections around access doors and reinforcement frames. One SBPC1500 plasma cutter handles 304L and 316L stainless plate work for boiler casing penetrations, scrubber inlet cut-outs and stack saddle plates. One SBLR-600A roll bender at 7.6 metres per minute delivers the radius transitions on stack tie-ins, scrubber inlet bends and gas-to-energy engine flue connections. Total connected load is around 115 kilowatts, footprint 600 to 800 square metres, throughput 1,200 to 1,800 square metres of finished duct per shift. Payback is typically 2 to 3 Australian WtE, landfill biogas-to-energy or hazardous waste facility projects.

What Safe Work Australia workplace exposure standards bind waste-to-energy and waste treatment HVAC design?

The operative values for waste-to-energy, landfill biogas, composting, e-waste and hazardous waste service are methane at 1000 parts per million asphyxiant threshold and 5 percent lower flammable limit, carbon monoxide at 30 parts per million 8-hour time-weighted average, nitrogen dioxide at 5 parts per million short-term exposure limit, sulphur dioxide at 2 parts per million 8-hour, hydrogen chloride at 5 parts per million short-term exposure limit, hydrogen fluoride at 1.8 milligrams per cubic metre time-weighted average and 3 parts per million short-term, dioxins and furans at trace levels regulated through the EU Industrial Emissions Directive 0.1 nanograms toxic equivalent per normal cubic metre stack standard, heavy metals — mercury 0.025 mercury vapour, lead 0.05, cadmium 0.01, arsenic 0.05, chromium six 0.05 milligrams per cubic metre — respirable dust at 10 milligrams per cubic metre and respirable crystalline silica at 0.05, ammonia at 25 parts per million time-weighted average and 35 short-term, hydrogen sulphide at 10 parts per million time-weighted average and 15 short-term, bioaerosol with no formal limit but documented capture and treatment expected, and polycyclic aromatic hydrocarbons indexed by benzo[a]pyrene. The HVAC duct system must hold every breathing-zone receptor below the workplace exposure standard with margin and discharge the stack below the state EPA licence condition. Hydrogen sulphide and methane are dual hazards on landfill and anaerobic digestion biogas service — extreme toxicity in addition to flammability.

Insights · Waste-to-Energy & Waste Treatment

Waste-to-Energy, Landfill Biogas, Composting, E-Waste, Scrap Metal, Used Oil and Hazardous Waste HVAC Duct Guide — Australian Engineering Reference

An Australian engineer's working reference for HVAC ductwork in waste-to-energy incineration plants, landfill biogas extraction and gas-to-energy plants, composting facilities, e-waste recycling, lithium-ion battery recycling, scrap metal shredding yards, used oil re-refining plants, hazardous waste high-temperature incineration, contaminated soil thermal desorption and asbestos and cytotoxic waste handling. Covers MSW bunker negative pressure extract, post-combustion chamber 1100 degrees Celsius dioxin destruction, flue gas treatment train with selective non-catalytic reduction, dry sorbent injection, activated carbon and bag filter, fly ash silo NFPA 660 dust extract, landfill biogas Zone 1 hazardous area, anaerobic digestion biogas conditioning, composting biofilter return, scrap metal aluminium dust NFPA 660, used oil AS 1940 flammable liquid storage, contaminated soil thermal desorption rotary kiln, hazardous waste 0.1 ng TEQ per Nm3 EU IED dioxin standard, materials selection by zone, capture velocities, Safe Work Australia Workplace Exposure Standards, AS 1668.2 process exhaust, AS 4254 construction class, AS 1318 industrial chimney, AS/NZS 60079 hazardous area zoning, with SBKJ machinery suitability called out across the duct package. Written from Box Hill North, Victoria, against the regulatory and operational environment Veolia, Cleanaway, Sims, Hydrodec, EnviroPacific, Envirostream and the major Australian state operators are building into in 2026.

By SBKJ Engineering Team · Published May 15, 2026 · 45 min read · Reviewed by SBKJ QA & Engineering

Why waste treatment and waste-to-energy HVAC is not general industrial HVAC

Australian waste treatment HVAC is the most regulated industrial HVAC environment outside a nuclear or pharmaceutical facility. The duct system has to satisfy a fire engineer's deflagration risk assessment, a hazardous area engineer's AS/NZS 60079 zone classification, a state EPA's licence emission limits at the stack, a Safe Work Australia workplace exposure standard at every breathing-zone receptor, the NEPM Hazardous Waste tracking framework, the federal Recycling and Waste Reduction Act 2020 producer responsibility scheme, and the operator's ISO 14001 environmental management system reporting cycle. Where the recycling and materials recovery sector handles dust and odour, the waste treatment sector handles dust plus odour plus methane plus hydrogen sulphide plus dioxin plus heavy metal plus deflagration plus thermal runaway plus high-temperature acid gas plus radiant heat from combustion plus, in the hazardous waste segment, the gas mixture from whatever was in the drum.

The 2024 commissioning of the Kwinana East Rockingham Resource Recovery Facility in Western Australia — Australia's first major municipal solid waste energy-from-waste plant — marked the start of a new phase for the Australian waste treatment industry. The Maryvale Energy from Waste in the Latrobe Valley Victoria and the Sydney Veolia plant in New South Wales are following. Parallel investment is happening across landfill biogas extraction and gas-to-energy, anaerobic digestion biogas plants at Yarra Valley Water Aurora, Sydney Water biosolids digestion at St Marys, Liverpool and Quakers Hill, and Murray Goulburn Saputo dairy effluent at Cobram. Composting facilities are expanding under state government source separation programs. Lithium-ion battery recycling is the fastest-growing recycling segment in the country, with Envirostream Australia at Campbellfield Victoria leading the segment alongside Strategic Power Corporation, Sims Lifecycle Services and Australian Refined Alloys. Scrap metal shredding remains dominated by Sims Limited, OneSteel Recycling and InfraBuild Recycling. Used oil re-refining at Hydrodec Bomen Wagga Wagga and Wakefield Oil Co Brisbane is the established Australian capability. Contaminated soil remediation across Veolia In Situ, EnviroPacific, Hibbins, Total Earth Solutions and Sustainable Group services every major redevelopment project. Hazardous waste high-temperature incineration is concentrated in Cleanaway and Veolia, with high-temperature incineration capability for chlorinated organics, polychlorinated biphenyl and asbestos packaging.

This guide is the working reference our Box Hill North engineers use when scoping ductwork machinery for these projects. It is written for the mechanical consulting engineer specifying the system, the head contractor pricing the package, the fabricator deciding which SBKJ machine line covers the project mix, and the operator trying to read both the drawings and the tender returns. It is distinct from our companion MRF, CDS, e-waste and battery recycling HVAC duct guide, which covers the materials recovery sortation segment. This guide covers the downstream treatment, energy recovery, biogas and re-refining sectors that the recycling sector eventually delivers material to. Where SBKJ machinery is the right tool, we say so. Where the project needs something outside our scope — high-temperature alloy reactor pressure vessels, FRP wet scrubber bodies, refractory-lined combustion chamber walls — we say so as well.

The Australian waste treatment and waste-to-energy operator landscape in 2026

The 2026 Australian waste treatment operator landscape is concentrated at the top and fragmented at the smaller-volume specialist end. Understanding who operates each plant type matters because the operator's procurement habits and technical standards drive the duct specification more than any code reference.

Waste-to-energy operators

Kwinana East Rockingham Resource Recovery Facility (KERRRF), commissioned 2024, is the Australian benchmark — a 400,000 tonne per annum municipal solid waste energy-from-waste plant in Western Australia, developed by ARC, Acciona, Macquarie, Differential Group and SUEZ with Veolia operating the facility under contract with Rockingham City Council and the Western Australian regional municipalities. The plant produces 36 megawatts of electrical generation, equivalent to approximately 50,000 average Western Australian homes, and processes the residual MSW that previously went to landfill at Henderson and other Perth metropolitan sites.
Maryvale Energy from Waste in the Latrobe Valley Victoria is the second major Australian WtE under construction, developed by Veolia in partnership with Australian Paper to provide steam and electrical generation for the integrated paper mill operation. The plant is sized for around 350,000 tonnes per annum of residual MSW from Gippsland and Greater Melbourne, with commissioning anticipated 2027.
Sydney Veolia Recycling Centre in Western Sydney is the third major Australian WtE under construction, sized for around 500,000 tonnes per annum of residual MSW, with commissioning anticipated 2027 to 2028.
East Rockingham Australia Resource Recovery (ARC), the concession holder for KERRRF, is part of a consortium with Acciona, Macquarie, DIF and SUEZ. The plant operations contract sits with Veolia, but the underlying ownership is split across the concession partners under a long-term power purchase and waste supply arrangement.
Several smaller alternative-fuel and gasification plants are under development across Australia, including pyrolysis projects for tyre processing and refuse-derived fuel gasification trials. These are an order of magnitude smaller than the major MSW WtE projects and operate closer to a chemical plant than a power station in HVAC design terms.

Landfill, biogas and gas-to-energy operators

Veolia Australia operates major landfills with active biogas extraction at Woodlawn south of Goulburn (NSW), Hampton Park (VIC) and others, with gas-to-energy plant tied to the landfill envelope. Veolia inherits European group HVAC standards alongside Australian standards.
Cleanaway Waste Management (ASX:CWY) operates a national network of landfills with active gas extraction, including Eastern Creek (NSW), Inkerman Hill (VIC), Lucas Heights and Belrose. The Cleanaway landfill gas-to-energy portfolio is one of the larger generators of renewable electricity from landfill biogas in the country.
LMS Energy specialises in landfill biogas extraction and gas-to-energy generation across multiple sites, often as the energy partner to a council-owned landfill envelope. The LMS gas-to-energy plants typically run reciprocating gas engines for electrical generation.
SUEZ Recycling and Recovery Australia (departed Australia 2022, legacy operations transferred to Veolia and Cleanaway) operated major landfills with biogas extraction in its former portfolio.
Visy Industries (Pratt Industries) operates kerbside MRF and recycling envelopes, with some biogas tie-in at integrated facilities.
Yarra Valley Water at the Aurora plant (VIC) operates an anaerobic digestion facility processing source-separated food waste and trade waste, generating biogas for on-site cogeneration. The Aurora plant is a reference benchmark for Australian food waste anaerobic digestion.
Sydney Water operates anaerobic digestion of biosolids at St Marys, Liverpool, Quakers Hill and other wastewater treatment plants, with biogas fed to cogeneration on each site.
Hunter Water in New South Wales and the equivalent state water authorities (SA Water, Melbourne Water, Power and Water Northern Territory) operate anaerobic digestion at major treatment plants.
Murray Goulburn Saputo at Cobram (VIC) operates anaerobic digestion of dairy effluent, generating biogas for on-site cogeneration. Cargill Wagga Wagga (NSW) and other agricultural processors run similar effluent digestion plants.
Olympic Dam Wastewater (BHP) operates wastewater treatment with biogas tie-in at the Olympic Dam mine site in South Australia.
City Council waste departments across the major capitals operate the landfill and gas extraction assets either in-house or under operator contract, with the technical standards typically mirroring the operator's specification.

Composting operators

Soilco at Kingaroy (QLD) operates one of the larger commercial composting operations in Australia, processing green waste, food waste and biosolids into compost, mulch and soil products.
Australian Native Landscapes (ANL) in Sydney operates large-scale composting and mulch production.
Centro in NSW operates compost and organics recovery.
Cleanaway Compost and Veolia Compost operate composting under the parent waste management groups.
Living Earth in Tasmania operates state-level composting.
Australian Compost operates a national network of facilities, with both windrow and in-vessel operations.
Council-run compost facilities are operated across all Australian states under source-separation programs, with technical standards typically mirroring the state EPA approval template.
Vermicomposting operators (worm farm) are niche specialists in commercial composting, with HVAC requirements at the lower end of the segment.

E-waste and battery recycling operators

Sims Lifecycle Services (Sims Limited ASX:SGM) is the largest Australian e-waste processor, with operations integrated into the broader Sims metal recycling network at Newcastle, Sydney, Brisbane, Adelaide and Perth.
TES Australia (Element Solutions) operates major e-waste recycling in Sydney and Melbourne.
Reverse Logistics Group, EcoCycle (Australian-owned) and Total Recycling Industries operate smaller specialist e-waste lines.
Envirostream Australia at Campbellfield (VIC), a Lithium Australia subsidiary, is the first commercial lithium-ion battery recycler in Australia. The Campbellfield plant processes spent EV batteries, consumer cells, e-bike batteries and grid storage cells through a mechanical shred and hydrometallurgical recovery train.
Strategic Power Corporation (SPC) operates lithium-ion battery processing.
Australian Refined Alloys operates national lead-acid battery recycling with associated lithium-ion processing.
B-cycle (Mobile Muster Telstra, Optus, TPG industry-funded scheme) operates consumer battery collection nationally, with downstream processing through the established recyclers.
Tronox Holdings at Bunbury (WA) operates lead-acid battery recycling adjacent to its Cooljarloo synthetic rutile operation.
VIP Recycling at Yarraville (VIC), a Visy subsidiary, operates lead-acid battery recycling.
Hydromet (NSW) operates metal recovery including lead-acid battery components.
Asia Recycling operates lead-acid and related metal recovery across multiple sites.

Scrap metal recycling operators

Sims Limited (ASX:SGM) is the dominant Australian and global scrap metal recycler, with yards in Newcastle, Sydney, Brisbane, Adelaide and Perth. The Sims yards run heavy-duty automotive shredders, eddy current separation and dense media separation, exporting recovered ferrous and non-ferrous metal to global steel mills.
OneSteel Recycling (Liberty Primary Steel) operates yards integrated with the Whyalla steel mill operation in South Australia and the Australian east coast.
InfraBuild Recycling (Liberty) operates national yards feeding the InfraBuild downstream rolling operations.
LMS Metal Recycling operates yards alongside the LMS Energy landfill biogas portfolio.
Australian Steel Recycling, Coppin Metal Recyclers (NSW) and a long tail of smaller operators round out the segment.

Used oil re-refining operators

Hydrodec Australia at Bomen Wagga Wagga is the Australian benchmark for transformer oil re-refining, producing recovered base oil to specification for re-use in electrical equipment.
Wakefield Oil Co in Brisbane operates re-refining of waste lubricating oil and engine oil.
Cleanaway Used Oil operates national used oil collection and processing.
Wallace and Co in NSW operates used oil services.

Contaminated soil remediation operators

Veolia In Situ operates in-situ and ex-situ contaminated soil remediation across all Australian states, with thermal desorption capability at major sites.
EnviroPacific operates a national contaminated soil remediation network including thermal desorption, soil washing and biological remediation.
Hibbins operates contaminated soil services across the east coast.
Total Earth Solutions in Brisbane and Sustainable Group across multiple states operate remediation services including bioremediation, chemical oxidation and thermal desorption.
Newman Manning in NSW operates regional contaminated soil services.

Hazardous waste treatment operators

Cleanaway Waste Management (ASX:CWY) operates the largest Australian hazardous waste portfolio, with high-temperature incineration capability for chlorinated organics, polychlorinated biphenyl, asbestos packaging and certain pharmaceutical waste streams.
Veolia Australia operates hazardous waste treatment with the European group's high-temperature incineration heritage.
ResourceCo Group operates alternative fuel recovery from hazardous waste residuals across multiple Australian states.
LMS Energy operates hazardous waste tie-ins to its landfill and gas-to-energy portfolio.

Industry bodies and regulatory framework

Waste Management and Resource Recovery Association of Australia (WMRR), Australian Council of Recycling (ACOR), Waste Authority WA, Bioenergy Australia, Australian Energy from Waste Industry and the Australian Council for Sustainable Energy and Environment (ACOSEE) are the major industry bodies. The Renewable Energy Industry Association represents the renewable generation tie-in including landfill gas-to-energy and anaerobic digestion biogas.
The federal regulatory framework is the Recycling and Waste Reduction Act 2020, the National Environment Protection Measure (Hazardous Waste 1999 and Solid Waste 2010), the Container Deposit Scheme at state level, the Waste Reduction and Recycling Act 2011 (QLD) and the equivalent state legislation, and the Hazardous Substances classification under the Work Health and Safety Regulations.
The state regulators are the NSW EPA (Hazardous Waste licence), VIC EPA (Environment Protection Act 2017 development licence), QLD Department of Environment and Science (DES, Environmental Protection Act 1994 environmental authority), WA Department of Water and Environmental Regulation (DWER, works approval), SA EPA, Northern Territory EPA, ACT Environment Protection Directorate (EPD) and Tasmania EPA.

The eight-zone HVAC duct map of a waste treatment facility

Every waste-to-energy, landfill biogas plant, composting facility, e-waste recycler, scrap metal yard, used oil re-refinery, hazardous waste treatment plant and contaminated soil remediation envelope decomposes into eight HVAC zones. The zone map drives the pressure cascade, the duct routing, the material selection at the boundary and the smoke and fire damper schedule.

Receival and front-end handling. MSW bunker, tipping floor, scrap metal yard intake pad, used oil truck unloading bay, contaminated soil receival pad, e-waste drop-off area. Dust load is moderate to heavy and highly variable. Odour, hydrogen sulphide and methane evolution dominate on putrescible streams. Negative pressure relative to the boundary is the operative requirement.
Process preparation and front-end shredding. Refuse-derived fuel shredder line, magnetic and density separator, e-waste shredder hood, lithium-ion battery enclosure, scrap metal automotive shredder, contaminated soil rotary blender, used oil dewatering tank. Dust load is heavy and deflagration risk dominates the design.
Primary thermal or biological treatment. WtE primary combustion chamber, hazardous waste rotary kiln, contaminated soil thermal desorption rotary kiln, composting windrow or in-vessel reactor, anaerobic digester, landfill biogas extraction well, used oil distillation column. The high-temperature combustion zones and the high-humidity biological zones diverge sharply on HVAC duct demand.
Secondary treatment and post-combustion. Post-combustion chamber at 1100 degrees Celsius for dioxin destruction, secondary digestion stage, compost maturation hall, hazardous waste post-combustion at 1200 degrees Celsius for chlorinated organics. The acid gas and high-temperature alloy requirements dominate.
Flue gas treatment, scrubber, biofilter and emissions control. Selective non-catalytic reduction and selective catalytic reduction, dry sorbent injection, activated carbon injection, fabric filter baghouse, wet scrubber, biofilter, thermal oxidiser. The chloride-bearing 316L stainless duct dominates the cost.
Stack and discharge. AS 1318 industrial chimney, continuous emissions monitoring, dispersion modelling demonstration at the residential receptor. Stack material is 304L or 316L stainless inner liner, with high-temperature alloy on the WtE and hazardous waste stack base.
Storage, output and material handling. Fly ash silo, bottom ash storage, biogas storage gasholder, anaerobic digester sludge storage, used oil base oil storage tank, contaminated soil clean stockpile, hazardous waste residuals drum storage. Combustible dust extract dominates on the fly ash silo; AS 1940 flammable liquid extract dominates on the used oil and solvent storage.
Plant utilities, control rooms, amenities and worker change rooms. Positive-pressure clean supply, isolated from the process exhaust, with HEPA recovery and overpressure protection where it abuts hazardous waste, lithium-ion battery, e-waste or contaminated soil processing. Chemical and biological contamination controlled change rooms are mandatory on hazardous waste and asbestos handling envelopes.

The pressure cascade rule is clean-to-dirty flow, never the reverse, with positive pressure on the clean side and progressively deeper negative pressure as the feedstock becomes more contaminated. The cascade is enforced by variable air volume box modulation on supply and return with offset air determined by the differential pressure controllers on each room, verified during commissioning under both static and worst-case door-open conditions.

Municipal solid waste energy-from-waste — the post-combustion 1100 degrees Celsius dioxin destruction line

Municipal solid waste incineration in Australia from 2024 onwards is designed to the European Industrial Emissions Directive Annex VI emission limit framework — the global benchmark for waste-to-energy emissions performance. The operative emission limits are 0.1 nanograms toxic equivalent per normal cubic metre for dioxins and furans (PCDD and PCDF), 0.05 milligrams per normal cubic metre for mercury, 200 milligrams per normal cubic metre for NOx, 50 milligrams per normal cubic metre for sulphur dioxide, 10 milligrams per normal cubic metre for hydrogen chloride, 1 milligram per normal cubic metre for hydrogen fluoride, 10 milligrams per normal cubic metre for total particulate, and 50 milligrams per normal cubic metre for carbon monoxide, all at a reference condition of 11 percent oxygen, dry gas, 273 kelvin and 101.3 kilopascals.

The HVAC duct response is a six-stage flue gas treatment train modelled on European practice and aligned to NFPA 86 industrial furnace and NFPA 850 fire protection electric generating standards. The MSW combustion chamber operates at 850 to 1100 degrees Celsius with grate-fired combustion of mixed MSW or rotary kiln combustion of bulkier residual streams. The post-combustion chamber holds the flue gas above 1100 degrees Celsius for a minimum two-second residence time, which is the operative thermal condition for chlorinated organic destruction and prevention of de novo dioxin synthesis. The post-combustion chamber wall ductwork is refractory-lined carbon steel with welded seams, with the duct backing plate in heavy-gauge AISI 309 or 310 high-temperature stainless rated to 1000 degrees Celsius continuous service. This is at the upper edge of SBKJ's normal scope — the high-temperature alloy reactor pressure vessel work goes to specialist boilermaker fabricators, but SBKJ supplies the backing plate fabrication through the SBPC1500 plasma cutter and the SBSF-1525 stitchwelder for the welded heavy-gauge construction.

The boiler steam generation is downstream of the post-combustion chamber. A typical Australian WtE boiler runs 100 to 300 tonnes per hour of steam at 40 to 65 bar and 380 to 450 degrees Celsius, driving a steam turbine for electrical generation. The boiler is operated under AS 4036 and AS 4037 boiler and pressure vessel rules, with the boiler casing and the high-pressure steam piping under the relevant pressure equipment regime. The HVAC duct demand around the boiler is general ventilation at 4 to 8 air changes per hour to manage the radiant heat — typical boiler house upper-level air temperatures reach 50 to 55 degrees Celsius in summer — and localised exhaust at the burner front and the soot-blower lance access platforms. Duct material is carbon steel with welded seams at the upper elevations because the long-term temperature exceeds zinc's service envelope. Below the air heater on the cold side, galvanised G90 is acceptable on the secondary ventilation.

The air heater sits between the boiler exit and the flue gas treatment train, recovering heat from the outgoing flue gas to preheat the combustion air. The flue gas enters the air heater at 280 to 380 degrees Celsius and leaves at 130 to 180 degrees Celsius. The 130 to 180 degree exit temperature is the critical engineering line in any WtE — it is the acid dew point of sulphuric and hydrochloric acid formed from sulphur dioxide and hydrogen chloride combining with water vapour. Drop below it and the duct walls condense acid; stay above it and the duct walls stay dry. Everywhere upstream of the air heater is dry hot flue gas — manage with carbon steel, often refractory-lined. Everywhere downstream of the air heater the duct walls may run wet with dilute acid in service, and 316L stainless steel is mandatory.

The flue gas treatment train sequence from the air heater outlet is selective non-catalytic reduction or selective catalytic reduction for NOx, dry sorbent injection of hydrated calcium hydroxide lime (Ca(OH)2) for sulphur dioxide, hydrogen chloride and hydrogen fluoride neutralisation, activated carbon injection for residual mercury vapour and dioxin polish, fabric filter baghouse for the consolidated fly ash plus reacted lime plus loaded carbon stream, and an induced draft fan to the stack. Where the residual chloride bleed remains high, a wet scrubber polish stage is added between the baghouse and the induced draft fan, with the scrubber outlet duct in 316L stainless and the saturated stack inner liner in 316L stainless.

The duct material specification across the flue gas treatment train is:

Boiler economiser outlet to air heater inlet (280 to 380 degrees Celsius, dry): carbon steel with welded seams or 309 stainless. Refractory-lined.
Air heater outlet to selective catalytic reduction (130 to 180 degrees Celsius, transitional): 304L stainless. The acid dew point line is operative — galvanised will fail within months.
Selective catalytic reduction outlet to dry sorbent injection: 304L stainless. Trace ammonia slip and trace SO3 from the catalyst demand the corrosion resistance.
Dry sorbent injection to activated carbon injection: 304L stainless. Lime sorbent carryover is mildly abrasive but the chemistry remains dry.
Activated carbon injection to bag filter: 304L stainless. Loaded carbon is mildly abrasive and the dry chemistry continues.
Bag filter clean-side outlet to induced draft fan (around 140 degrees Celsius): 316L stainless. The residual chloride and fluoride concentration after the lime neutralisation remains corrosive, particularly during start-up and shutdown transient conditions.
Wet scrubber inlet and outlet (saturated gas at 50 to 60 degrees Celsius): 316L stainless minimum. Super-austenitic 904L or duplex 2205 where chloride bleed exceeds 1,000 parts per million.
Stack inner liner above wet scrubber: 316L stainless.
Stack outer carbon steel structural shell: weatherproofing only.

SBKJ supplies the duct fabrication machinery for the flue gas treatment train from the air heater outlet through to the stack. The SBAL-V auto duct line in 304L and 316L stainless configuration covers the rectangular runs. The SBSF-1525 stitchwelder produces the welded longitudinal seams mandatory on hot acidic service. The SBTF-1500C or SBTF-2020 spiral tubeformer in stainless configuration handles the round wet stack liner sections. The SBPC1500 plasma cutter handles the heavy plate work for the high-temperature alloy backing plates and the stack saddle plates. The SBLR-600A roll bender produces the radius transitions on the stack tie-ins and the scrubber inlet bends. The primary scrubber body itself is normally FRP and outside SBKJ scope, with SBKJ providing the duct interfaces in 316L on the inlet and outlet.

WtE MSW bunker — large negative pressure odour extract and biofilter

The MSW bunker is the receival void where incoming trucks tip residual municipal solid waste. The bunker is sized for around 5 to 7 days of fresh waste storage, with a typical Australian WtE bunker capacity of 6,000 to 12,000 cubic metres of waste. The waste is putrescible and the odour, hydrogen sulphide and ammonia evolution is intense. The bunker is operated as a strong-negative-pressure environment with the combustion air for the boiler drawn from inside the bunker — the combustion air intake is positioned at the upper elevation of the bunker, drawing roughly 80 to 120 cubic metres per second of bunker air into the primary combustion chamber, which is the dominant odour disposal path for the facility.

The HVAC duct design around the MSW bunker addresses the air intake, the fugitive emission from the truck unloading door and the bunker overflow ventilation during boiler outage. The bunker is held at a differential pressure of 25 to 50 pascals below the surrounding tipping hall and truck access road, maintained by the combustion air intake during normal operation. During boiler outage the differential is maintained by a dedicated ventilation fan that draws the bunker air to a biofilter at 30,000 to 80,000 cubic metres per hour, with the biofilter sized for 30 to 45 second empty-bed residence time on open-bed wood-chip or bark media. The truck unloading door is a fast-acting roll-up door with an air-curtain blower to limit the open-door volumetric loss during truck arrival. The tipping hall above the bunker runs at 8 to 12 air changes per hour with strong differential pressure to the boundary, exhausted through the bunker air intake during normal operation and through a dedicated extract to the biofilter during boiler outage.

Duct material in the MSW bunker envelope is 316L stainless steel on the bunker air intake to combustion chamber path because the gas stream is humid, hydrogen-sulphide-bearing and ammonium-condensing. The tipping hall extract above the bunker is 316L stainless on the section between the building exit and the biofilter for the same reasons, transitioning to 316L stainless on the biofilter return riser. Galvanised G90 corrodes within 12 months in this service. The fan motor on the dedicated biofilter extract is rated to AS/NZS 60079 Zone 2 because the methane evolution from the bunker approaches the lower flammable limit in fault conditions. Continuous methane and hydrogen sulphide gas detection is mandatory at the bunker upper elevation interlocked to the boiler air intake damper and the biofilter extract.

Refuse-derived fuel preparation — MSW shredding to fuel pellet or fluff

Refuse-derived fuel (RDF) preparation is the front-end of any Australian WtE that takes processed feedstock rather than raw mixed MSW. The bulky residual is screened, then primary shredded to 100 to 300 millimetres, magnetic-separated for ferrous metal recovery, eddy-current-separated for non-ferrous metal recovery, density-separated for inert removal and secondary shredded to 30 to 80 millimetres. The output is a refuse-derived fuel that feeds the combustion chamber or a cement kiln, depending on the project.

The HVAC duct demand on the RDF preparation hall is dominated by combustible dust extract from the shredder discharge, the conveyor transfers and the bulk storage. Dust load is heavy and the deflagration risk is the operative design driver. The dust is classified St-1 with Kst values commonly in the 100 to 200 bar metres per second range, depending on the composition. The shredder hood extract is at 1.5 to 2.5 metres per second face velocity, routed through heavy-gauge galvanised G90 or 304L stainless construction with stitchwelded longitudinal seams to AS 4254.2 medium-pressure class. The extract terminates in an explosion-vented fabric filter baghouse with NFPA 68 vent panels sized for the worst-case Kst and NFPA 69 isolation on the inlet by rotary airlock or chemical suppression. The fan is spark-resistant AMCA Type A or B with aluminium-bronze impeller, and the fan motor is rated to AS/NZS 60079 Zone 22 dust hazardous area.

Continuous carbon monoxide and methane gas detection is mandatory in the RDF preparation hall and the RDF bulk storage bunker. Carbon monoxide above 25 parts per million at the bunker exhaust indicates active microbial decomposition and triggers an inspection. Methane evolution is credible where the moisture content is high, with AS/NZS 60079 Zone 2 classification in the bunker headspace at typical operating conditions and Zone 1 during upset. SBKJ supplies the duct fabrication for the entire RDF preparation envelope through the SBAL-V auto duct line in switchable galvanised and 304L configuration, the SBSF-1525 stitchwelder for the welded heavy-gauge construction and the SBFB-1500 folder for the heavy-gauge folded transitions around the shredder hood.

WtE fly ash silo and truck loading — Class II hazardous heavy metal and dioxin trace

The WtE fly ash silo is the storage vessel for the consolidated stream from the bag filter — fly ash plus reacted lime sorbent plus loaded activated carbon. The combined stream is classified Class II hazardous waste under the NEPM Hazardous Waste framework because of the lead, cadmium, mercury, chromium and trace dioxin content captured from the flue gas. The fly ash silo is mechanically dosed at the top by the bag filter pulse-jet system and discharged at the base into a sealed bulk truck for transport to a licensed hazardous waste landfill or, in some jurisdictions, to a stabilisation and solidification plant for treatment before disposal.

The HVAC duct demand around the fly ash silo is combustible dust extract at the silo top, the discharge cone, the truck loading station and the access manholes. The dust load is fine and the heavy metal concentration is the operative hazard — lead at 0.05 milligrams per cubic metre Safe Work Australia workplace exposure standard, cadmium at 0.01, mercury vapour at 0.025, chromium six at 0.05 — all of which the duct system must hold the breathing zone below at every operator position. The dust capture is via a dedicated dust collector with HEPA H13 or H14 polish stage on the clean side, with the polish stage HEPA bagged-out as Class II hazardous waste at quarterly intervals.

Duct material is 304L stainless on the silo top extract, the discharge cone extract and the truck loading hood extract. The 304L specification is for ease of decontamination at end-of-life rather than corrosion resistance — galvanised would survive the chemistry, but stainless allows wipe-down and licensed heavy metal waste recovery when the silo is decommissioned. Duct velocity is 18 to 22 metres per second to keep the fine dust entrained. The fan is spark-resistant AMCA Type A or B with aluminium impeller, and the fan motor is rated to AS/NZS 60079 Zone 22 dust hazardous area. The truck loading station is enclosed with a closed-loop dust capture, with the truck bag connection sealed before loading to prevent ambient release. SBKJ supplies the duct fabrication through the SBAL-V auto duct line in 304L configuration with the SBSF-1525 stitchwelder for the deflagration-rated extract.

WtE bottom ash handling — minor extract

The WtE bottom ash is the residual at the bottom of the grate combustion chamber — clinker, metal fragments and inert mineral matter. The bottom ash typically falls out of the grate into a water-quenched conveyor or a dry mechanical conveyor and is transferred to a magnetic and eddy current separation line for ferrous and non-ferrous metal recovery. The processed bottom ash is then either landfilled or, in some markets, used as a road sub-base aggregate after stabilisation and screening.

The HVAC duct demand on the bottom ash handling envelope is light — dust extract at the conveyor transfers, the magnetic and eddy current discharge and the road truck loading. Typical extract volume is 5,000 to 15,000 cubic metres per hour on a 200,000 tonne per annum WtE bottom ash stream. Duct material is galvanised G90 throughout to AS 4254.1, with stitchwelded longitudinal seams on the heavy-gauge transport sections. The bottom ash is generally classified Class IIB hazardous if the metal content includes lead, cadmium or mercury fragments at concentrations exceeding the threshold — in practice the heavy metal content of the bottom ash is much lower than the fly ash because of the partitioning during combustion, but the operator typically segregates the bottom ash from the fly ash and routes to a separate landfill cell.

Landfill biogas extraction — Zone 1 hazardous area and 50 to 2000 ppm hydrogen sulphide

Landfill biogas extraction is the gas-side process of recovering methane and carbon dioxide from the anaerobic decomposition of buried waste in an Australian landfill envelope. The extraction system comprises vertical extraction wells drilled into the waste mass with horizontal collector pipes connecting the wells to a manifold, a gas conditioning skid that knocks out water and condensate, a blower or compressor that draws the gas under negative pressure from the well head, and either a flare stack or a gas-to-energy plant at the discharge end. Major Australian operators of landfill biogas-to-energy include Veolia at Hampton Park, Cleanaway at Eastern Creek and Lucas Heights, LMS Energy across multiple sites, and a long tail of council-owned landfills with operator-managed gas-to-energy plants.

The biogas composition at the extraction well is typically 50 to 55 percent methane, 35 to 45 percent carbon dioxide, 50 to 2000 parts per million hydrogen sulphide and trace siloxanes, halogenated organics and ammonia. The methane concentration is well above the lower flammable limit of 5 percent in air, so the gas-side ductwork is Zone 0 inside the duct and Zone 1 immediately surrounding any flanged joint or pressure relief point. The hydrogen sulphide concentration is the operative material driver — at 2000 parts per million the gas is corrosive to galvanised within months, and even at 50 parts per million the long-term exposure damages galvanised joint seals. Duct material is 304L stainless or epoxy-painted carbon steel because hydrogen sulphide attacks galvanised within months. Flange joints are 316L for the wetted face, with Viton gasket selected for hydrogen sulphide service.

The fan or compressor on the biogas extraction skid is rated to AS/NZS 60079 Zone 1 with Ex-d or Ex-e motor and the appropriate temperature class. Gas detection is intrinsically safe Ex-ia to Zone 0 inside the duct for methane and hydrogen sulphide at multiple positions. Earth bonding across every flanged joint dissipates static. The flare stack at the end of the extraction path is sized for the worst-case extraction flow at 3 to 5 times the steady-state flow to handle methane release during gas-to-energy engine trip. The flare is positioned at least 15 metres clear of any building opening and any access route. The flare stack inner liner is 316L stainless with carbon steel structural shell, and the radiant heat envelope is included in the AS 1318 industrial chimney structural calculation.

Where the biogas is routed to a gas-to-energy plant rather than a flare, the gas conditioning train upgrades to remove hydrogen sulphide and siloxanes. The hydrogen sulphide removal is typically via iron sponge or activated carbon with iron oxide impregnation, with the loaded media replaced quarterly. The siloxane removal is typically via temperature swing adsorption with activated carbon. The conditioned biogas at the engine inlet is below 100 parts per million hydrogen sulphide and below 10 milligrams per cubic metre siloxanes, with methane content at 50 to 55 percent and the calorific value at 18 to 22 megajoules per normal cubic metre.

The gas-to-energy plant itself is normally a reciprocating gas engine running on the conditioned biogas, producing electrical generation at 35 to 42 percent efficiency. The engine compound is AS/NZS 60079 Zone 2 for the off-skid envelope. The engine flue exits at 350 to 450 degrees Celsius and passes through a heat recovery boiler or directly to the stack at AS 1318 industrial chimney. The engine flue inner liner is 304L stainless and the stack is sized against dispersion modelling at the residential receptor. SBKJ supplies the duct fabrication for the biogas conditioning train, the engine compound general ventilation and the engine flue stack inner liner through the SBAL-V auto duct line in 304L and 316L configuration with the SBSF-1525 stitchwelder for the welded seams.

Anaerobic digestion — Sydney Water biosolids, Yarra Valley Water food waste, dairy effluent

Anaerobic digestion of biosolids, food waste, agricultural effluent and trade waste is the parallel biogas generation technology to landfill biogas. Major Australian operators include Sydney Water at St Marys, Liverpool and Quakers Hill (biosolids digestion), Yarra Valley Water at Aurora (food waste digestion), Hunter Water in NSW, Murray Goulburn Saputo at Cobram (dairy effluent), Cargill at Wagga Wagga (oilseed) and the Olympic Dam BHP wastewater treatment plant.

The anaerobic digester is a sealed tank operated at mesophilic (35 to 40 degrees Celsius) or thermophilic (50 to 55 degrees Celsius) temperature, with the feedstock retained for 15 to 30 days. The biogas composition is similar to landfill biogas — 55 to 65 percent methane, 30 to 40 percent carbon dioxide, 50 to 500 parts per million hydrogen sulphide and trace ammonia. The lower hydrogen sulphide concentration on a controlled digester relative to a landfill is the main advantage for the gas conditioning train.

The HVAC duct demand around the anaerobic digester is similar to the landfill biogas envelope. The digester headspace is Zone 0 inside, Zone 1 immediately surrounding. The biogas pipework to the gas conditioning train and the engine is Zone 0 inside, Zone 1 surrounding. The duct material is 304L stainless on the gas-side; the digester structural tank itself is normally concrete with an internal coating or stainless steel pressure vessel construction (out of SBKJ scope). The agitator and mixing pumps are Ex-d or Ex-e rated to the zone classification. Continuous methane, hydrogen sulphide and ammonia gas detection is mandatory.

The engine compound general ventilation and the engine flue stack inner liner are the SBKJ duct fabrication scope — the SBAL-V auto duct line in 304L and 316L configuration covers the work. Where the anaerobic digester feedstock includes high-sulphur content (animal manure, certain trade waste streams), the hydrogen sulphide loading on the gas conditioning train climbs and the duct material upgrade to 316L extends further upstream from the engine.

Composting facility — biofilter return, ammonia, hydrogen sulphide, bioaerosol

Composting facilities process garden organics, food organics, biosolids and other organic feedstock into compost product through a combination of windrow turning, aerated static pile and in-vessel reactor technology. Australian compost operators include Soilco at Kingaroy, Centro NSW, Australian Native Landscapes ANL in Sydney, Cleanaway Compost, Veolia Compost, Living Earth in Tasmania, Australian Compost nationally and a network of council-run facilities.

The HVAC duct demand on a compost facility is dominated by odour, ammonia, hydrogen sulphide and bioaerosol management. The receival floor, the active windrow turning hall (or in-vessel reactor where applicable), the trommel screen and the maturation hall all generate dimethyl sulphide, ammonia, hydrogen sulphide and a long tail of organic volatile compound at concentrations that breach the AS 3580 residential receptor target without treatment. The Safe Work Australia workplace exposure standard for ammonia is 25 parts per million 8-hour time-weighted average and 35 parts per million short-term. For hydrogen sulphide the standard is 10 parts per million time-weighted average and 15 parts per million short-term. Bioaerosol has no formal exposure standard but state work health and safety regulators expect a documented capture and treatment regime, with respiratory infection risk on operators handling FOGO and biosolids.

The HVAC response is a biofilter scrubber train — primary chemical or biofilter, polishing activated carbon where required, stack discharge or open-bed atmospheric discharge. The composting biofilter is typically open-bed wood-chip or bark over a perforated plenum, with 30 to 45 second empty-bed residence time, irrigated to 50 to 65 percent moisture content. Total extract volume on a 100,000 tonne per annum facility is typically 50,000 to 150,000 cubic metres per hour, scaling with the active surface area of the windrow operation and the in-vessel reactor capacity.

The extract duct between the process and the biofilter is 316L stainless steel because compost off-gas at 30 to 50 degrees Celsius is humid, ammonium-acetate-laden and organic-acid-condensing — galvanised corrodes within months in this service. The biofilter media is normally on a concrete plenum slab with the perforated air distribution plate in 316L stainless or fibreglass reinforced plastic. The biofilter return riser (where the biofilter discharges through a stack rather than open-bed to atmosphere) is 316L stainless. Open-bed biofilters discharge directly to atmosphere with no stack — the air-to-media interface is the discharge point. Enclosed biofilters with a stack require AS 1318 industrial chimney design with the stack inner liner in 316L stainless and the stack height set against AS 3580 receptor positions.

The in-vessel reactor (where used) operates at elevated temperature — typically 50 to 60 degrees Celsius during the thermophilic phase — and the humidity is at saturation. The reactor extract duct is 316L stainless throughout from the reactor outlet through to the biofilter. The reactor enclosure is AS/NZS 60079 Zone 2 because methane evolution from the early thermophilic stage approaches the lower flammable limit in fault conditions. Continuous methane and ammonia gas detection is mandatory inside the reactor headspace. SBKJ supplies the duct fabrication through the SBAL-V auto duct line in 316L configuration, with the SBFB-1500 spiral tubeformer for the round biofilter return riser sections and the SBLR-600A roll bender for the radius transitions on the riser tie-ins.

E-waste recycling — heavy metal HEPA H13/H14 capture and lithium-ion thermal runaway

E-waste recycling in Australia processes computer monitors and televisions (cathode ray tube and flat panel), laptops, mobile phones, printed circuit boards, consumer batteries (lithium-ion, nickel-metal hydride, alkaline, lithium primary), capacitors and bulk plastic and metal casing. Major operators include Sims Lifecycle Services (the largest), TES Australia, Reverse Logistics Group, EcoCycle, Total Recycling Industries and the smaller specialist processors.

The HVAC duct demand is the highest-specification capture in the recycling sector outside dedicated lithium-ion battery shredding. The shredder hood is enclosed and capture is taken at 2.0 to 2.5 metres per second face velocity. The duct routes through 304L stainless steel construction with welded longitudinal seams, stitchwelded transverse joints, AS 4254.2 medium-pressure class with NFPA 660 deflagration reinforcement. The baghouse is fitted with HEPA H13 polish stage on the clean side because the dust contains lead, cadmium, beryllium and mercury at concentrations that exceed Safe Work Australia workplace exposure standards many times over at the source. The baghouse-to-stack run is 304L stainless throughout. The fan is spark-resistant with aluminium impeller and the fan motor is rated to AS/NZS 60079 Zone 2 because the lithium-ion ignition risk is credible despite the inerting attempts upstream.

The heavy metal dust caught in the baghouse and the HEPA stage is regulated waste under the NEPM Hazardous Waste framework and is sealed and transferred to a licensed recovery facility. The duct cleaning regime under operational AS 1851 inspection is monthly internal inspection with quarterly HEPA bag-out replacement, and personal monitoring of operators against Safe Work Australia workplace exposure standards for lead (0.05 milligrams per cubic metre), cadmium (0.01), mercury (0.025 vapour) and beryllium (0.0002) is the operative compliance regime.

Lithium-ion battery recycling — Envirostream, SPC, Sims Lifecycle Services

Lithium-ion battery recycling is the fastest-growing recycling segment in Australia. Envirostream Australia at Campbellfield Victoria is the first commercial lithium-ion battery recycler in the country, operating as a Lithium Australia subsidiary. Strategic Power Corporation operates a comparable line, Sims Lifecycle Services has integrated lithium-ion capability into its broader e-waste portfolio, and Australian Refined Alloys operates national lead-acid battery recycling with associated lithium-ion processing. The B-cycle scheme (Mobile Muster — Telstra, Optus, TPG) operates consumer battery collection nationally with downstream processing through the established recyclers.

The thermal runaway risk is the operative HVAC design driver. A single 18650 cell entering thermal runaway releases hydrogen, methane, carbon monoxide, hydrogen fluoride, hydrogen bromide and phosphoryl fluoride into the extract duct at temperatures up to 700 degrees Celsius. Hydrogen fluoride is the lead acute hazard at workplace exposure standard 3 parts per million short-term exposure limit (1.8 milligrams per cubic metre time-weighted average) — exposure above this can cause acute pulmonary injury. The electrolyte salt LiPF6 hydrolyses on contact with moisture to release hydrogen fluoride, so the gas mixture is severely hydrogen fluoride dominated.

The HVAC duct response layers four controls aligned to NFPA 855 and AS/NZS 5139:

Inerted enclosure. The shredder operates under continuous nitrogen or argon blanket with oxygen concentration held below 4 percent. The extract duct from the enclosure carries the inert gas plus the entrained dust load, and the makeup gas is metered against extract flow.
Explosion vent and isolation. NFPA 68 vent panels on the shredder enclosure and the downstream baghouse, sized for the worst-case deflagration pressure pulse. NFPA 69 isolation by chemical suppression or fast-acting valve on the inlet duct breaks propagation back to the process. The duct construction between the enclosure and the baghouse is welded heavy-gauge 304L stainless to AS 4254.2 with reinforcement against the design pressure pulse.
Three-stage scrubber train. Caustic primary for hydrogen fluoride, hydrogen chloride and hydrogen bromide knock-down (typically 5 to 8 percent sodium hydroxide solution), acid secondary for ammonia and amine capture (typically 5 percent sulphuric acid solution), and activated carbon polish for organic carbonate solvents. The primary scrubber body is normally fibreglass reinforced plastic (outside SBKJ scope). The interstage ducts are 316L stainless because chloride concentration from caustic carryover demands the higher molybdenum content. The carbon polish-to-stack run is 304L stainless. The stack discharge is 304L stainless with continuous emissions monitor for hydrogen fluoride, hydrogen bromide, hydrogen chloride and total volatile organic compounds.
Continuous gas detection and process interlock. Hydrogen, hydrogen fluoride, hydrogen bromide, hydrogen chloride, carbon monoxide and oxygen sensors at the enclosure interlocked to fast-acting isolation dampers, inert gas knock-down and a process trip on the shredder drive. The detection logic is fail-safe — any sensor fault closes the dampers and trips the drive.

SBKJ supplies the duct fabrication machinery for the extract path from the shredder through to the stack. The SBAL-V auto duct line in 304L stainless configuration covers the rectangular main runs. The SBSF-1525 stitchwelder produces the welded longitudinal seams mandatory under NFPA 660 and NFPA 855 for the deflagration-rated extract sections. The SBTF-1602 spiral tubeformer produces the round transition sections between rectangular main and the scrubber inlet. The SBLR-600A roll bender covers the radius transitions on stack tie-ins. The total duct fabrication for a typical 5,000 tonne per annum lithium-ion battery shred line is 2,500 to 4,000 square metres of duct, fabricated in 3 to 5 shifts on an SBAL-V running double shift.

Lead-acid battery recycling — Tronox, VIP Recycling, Hydromet

Lead-acid battery recycling processes spent vehicle and stationary lead-acid batteries through case breaking, lead separation, sulphuric acid neutralisation and lead smelting and refining. Australian operators include Tronox Holdings at Bunbury (WA) adjacent to its Cooljarloo synthetic rutile operation, VIP Recycling at Yarraville Victoria (Visy subsidiary), Hydromet in NSW and Asia Recycling across multiple sites.

The HVAC duct demand around lead-acid battery recycling combines lead aerosol capture, sulphuric acid mist capture and ammonia capture from electrolyte handling. Lead at 0.05 milligrams per cubic metre Safe Work Australia workplace exposure standard is the operative driver — the duct system must hold every breathing zone below this with margin. Sulphuric acid mist is captured at the case breaking and acid neutralisation positions at 0.5 to 1.0 metres per second face velocity, routed through 316L stainless duct because the acid is corrosive to galvanised within weeks. The lead smelting and refining furnace flue is the dominant duct on the project — typical extract volume on a 50,000 tonne per annum lead recovery line is 30,000 to 80,000 cubic metres per hour, routed through a baghouse with HEPA H13 polish stage, an acid gas scrubber and a stack with continuous lead and sulphur dioxide monitoring against the state EPA licence.

Duct material is 304L stainless on the dust-side from the case breaking through to the baghouse, 316L stainless on the acid-side from the neutralisation through to the scrubber stack. The fan is spark-resistant AMCA Type A or B with aluminium-bronze impeller and the fan motor is rated to AS/NZS 60079 Zone 22. SBKJ supplies the duct fabrication through the SBAL-V auto duct line in 304L and 316L configuration with the SBSF-1525 stitchwelder for the welded heavy-gauge sections.

Scrap metal recycling — Sims, OneSteel, InfraBuild, aluminium NFPA 660

Scrap metal recycling in Australia is dominated by Sims Limited (ASX:SGM, the largest globally), OneSteel Recycling (Liberty Primary Steel), InfraBuild Recycling (Liberty), LMS Metal Recycling, Australian Steel Recycling and Coppin Metal Recyclers. The major Sims yards in Newcastle, Sydney, Brisbane, Adelaide and Perth run heavy-duty automotive shredders that process end-of-life vehicles and white goods into shredded ferrous metal, non-ferrous metal and automotive shredder residue (ASR).

The HVAC duct demand on a scrap metal yard is dominated by the shredder hood extract. The shredder generates a heterogeneous dust load with multiple combustible dust risks — aluminium and magnesium from non-ferrous shred (NFPA 660 St-2 to St-3 with Kst commonly above 400 bar metres per second), mixed paper and plastic from the auto-shredder residue (NFPA 660 St-1), oil mist and grease from residual lubricant on the feed, and spark from the shredder hammers contacting steel components. The combination is the most challenging combustible dust environment in Australian recycling.

The HVAC response is heavy-gauge galvanised G90 or 304L stainless construction with stitchwelded longitudinal seams from the shredder hood at 1.5 to 2.5 metres per second capture velocity through to an explosion-vented baghouse with NFPA 68 vent panels sized for the worst-case Kst and NFPA 69 isolation on the inlet by rotary airlock or chemical suppression. The fan is spark-resistant AMCA Type A or B with aluminium-bronze or aluminium impeller, and the fan motor is rated to AS/NZS 60079 Zone 22 dust hazardous area classification. The duct main between the shredder hood and the baghouse is the most critical run on the yard — a deflagration-rated weld failure under pressure pulse propagates the explosion into the building.

Total extract volume on a Sims-scale automotive shredder is 80,000 to 200,000 cubic metres per hour, with the baghouse footprint comparable to the shredder building itself. The baghouse is normally located at the back of the yard with the longest duct main routed at low elevation to allow the dust to drop out at the inlet. SBKJ supplies the duct fabrication through the SBAL-V auto duct line in galvanised G90 and 304L configuration with the SBSF-1525 stitchwelder running parallel to produce the welded longitudinal seams. The SBLR-600A roll bender produces the radius transitions on the long duct main, and the SBPC1500 plasma cutter handles the heavy plate cutting for the shredder hood plenum.

Aluminium-only shred lines (where the yard processes pure aluminium feedstock separately from mixed scrap) require a dedicated wet dust collector rather than a fabric filter baghouse — aluminium dust at NFPA 660 St-2 or St-3 ignites readily in dry collection and a wet collector with a downflow water-curtain captures the dust without ignition risk. The duct construction upstream of the wet collector is 304L stainless throughout because the water spray carryover is corrosive to galvanised, and the fan is spark-resistant with aluminium impeller. The wet collector itself is normally an FRP or 316L stainless tank, with SBKJ providing the duct interfaces on the inlet and outlet.

Used oil re-refining — distillation, vapour control, AS 1940 flammable liquid

Used oil re-refining processes waste lubricating oil, transformer oil and engine oil through dewatering, distillation, hydrotreatment or acid wash to recover base oil for re-sale to lubricant blenders. Australian operators include Hydrodec at Bomen Wagga Wagga (transformer oil re-refining is the Hydrodec specialty), Wakefield Oil Co in Brisbane, Cleanaway Used Oil nationally and Wallace and Co in NSW.

The HVAC duct demand on a used oil re-refinery is dominated by vapour control on the distillation column overhead, the dewatering vapour from the feedstock pretreatment, the storage tank vents under AS 1940 flammable liquid rules, and the thermal oxidiser inlet for the residual non-condensible vent gas. The vapour streams contain volatile organic compounds, sulphur compounds, polychlorinated biphenyl traces in legacy transformer oil and polycyclic aromatic hydrocarbons. The distillation column overhead vapour and the dewatering vapour are flammable and the entire processing compound is AS/NZS 60079 Zone 1 inside the column and Zone 2 in the surrounding pump compound.

Duct material from the distillation column overhead to the condenser is 316L stainless because the acid sulphur compounds attack galvanised within weeks. The condenser-to-vent run is 304L stainless. The vent gas thermal oxidiser inlet and outlet are 316L stainless throughout because trace hydrogen chloride from polychlorinated biphenyl decomposition is corrosive. Storage tank vents are routed through a vapour recovery unit or carbon scrubber under AS 1940 rules. The fan motor on every gas-side run is Ex-d or Ex-e rated to the zone classification with appropriate temperature class.

The used oil tank farm is governed by AS 1940 flammable liquid storage rules. Mechanical ventilation at 12 to 20 air changes per hour with bottom-draw extract captures heavier-than-air vapour. The tank vents are routed through a vapour recovery unit or carbon scrubber. The bund is AS/NZS 60079 Zone 1 inside and Zone 2 in the surrounding access area. Electrical and ventilation accessories are rated to the zone classification.

SBKJ supplies the duct fabrication for the distillation overhead, the condenser tie-in, the thermal oxidiser inlet and outlet, and the tank farm general ventilation through the SBAL-V auto duct line in 304L and 316L configuration with the SBSF-1525 stitchwelder for the welded heavy-gauge sections. The total duct fabrication for a typical 30,000 tonne per annum used oil re-refinery is 1,800 to 3,200 square metres of duct.

Contaminated soil remediation — thermal desorption, soil washing, biological remediation

Contaminated soil remediation processes impacted soil from former industrial sites, fuel station decommissioning, asbestos-impacted sites, fire-fighting foam (PFAS) impacted defence training grounds and other environmental incidents. Australian operators include Veolia In Situ, EnviroPacific, Hibbins, Total Earth Solutions, Sustainable Group and Newman Manning. The treatment technologies are soil washing (water-based separation of contaminants from soil particles), thermal desorption (rotary kiln heating at 100 to 500 degrees Celsius to volatilise organic contaminants), biological remediation (bioaugmentation with hydrocarbon-degrading bacteria), chemical oxidation (in-situ or ex-situ application of hydrogen peroxide, ozone or potassium permanganate), and solidification-stabilisation (binding contaminants with cement or pozzolanic agents).

The HVAC duct demand on a thermal desorption rotary kiln is the most demanding of the contaminated soil treatment options. The kiln rotates the soil through a heated drum at 100 to 500 degrees Celsius, volatilising the organic contaminants — volatile organic compounds, polycyclic aromatic hydrocarbons, certain pesticides and heavy metal vapours — into the kiln off-gas. The off-gas is then routed to a thermal oxidiser at 850 degrees Celsius for organic destruction, quenched to 130 degrees Celsius, passed through a bag filter for dust capture, lime sorbent injection for acid gas neutralisation (where chlorinated solvent contamination is credible), activated carbon polish for residual mercury and dioxin, and stack discharge.

Duct material is heavy-gauge 304L stainless steel from the rotary kiln outlet through to the thermal oxidiser inlet. The thermal oxidiser combustion chamber is refractory-lined carbon steel with the backing plate in AISI 309 or 310 high-temperature stainless. The thermal oxidiser outlet to the quench is 309 stainless, transitioning to 304L stainless at the bag filter inlet and 316L stainless at the activated carbon polish and the stack. The duct material upgrade to 316L applies wherever chloride concentration exceeds 200 parts per million from chlorinated solvent contamination.

The stack is monitored continuously for volatile organic compounds, carbon monoxide, NOx, sulphur dioxide and total particulate against the state EPA approval condition. Heavy metal vapour — particularly mercury and lead — is sampled by 6-hour integrated test at the start of each campaign to validate the activated carbon polish performance. PFAS impacted soil treatment requires additional capture and monitoring because the thermal destruction of perfluorinated chains demands 1100 degrees Celsius residence time exceeding 2 seconds, comparable to the WtE post-combustion specification.

SBKJ supplies the duct fabrication for the kiln outlet, the quench, the bag filter and the stack inner liner through the SBAL-V auto duct line in 304L and 316L configuration with the SBSF-1525 stitchwelder for the welded heavy-gauge sections. The thermal oxidiser combustion chamber refractory and high-temperature alloy work is outside SBKJ scope.

Hazardous waste high-temperature incineration — Cleanaway, Veolia

Hazardous waste high-temperature incineration in Australia is operated by Cleanaway Waste Management (the largest portfolio) and Veolia Australia, with high-temperature incineration capability for chlorinated organics, polychlorinated biphenyl (PCB), asbestos packaging waste, certain pharmaceutical waste streams and other Schedule 1 hazardous wastes under the NEPM Hazardous Waste framework.

The hazardous waste rotary kiln incinerator operates at 1100 to 1200 degrees Celsius with a post-combustion chamber at 1200 degrees Celsius for a minimum 2-second residence time. The post-combustion chamber design is the operative thermal condition for chlorinated organic destruction and prevention of dioxin formation. The waste is fed as drums, bulk liquids or shredded solids depending on the stream, with the feed temperature and the air-to-fuel ratio modulated against the calorific value of the feed.

The flue gas treatment train downstream of the post-combustion chamber is comparable to the WtE flue gas treatment train but with additional capture intensity because the hazardous waste feedstock has higher chloride and metal loading than MSW. The sequence is selective non-catalytic reduction for NOx, dry sorbent injection of hydrated lime for sulphur dioxide and hydrogen chloride, activated carbon injection for mercury and dioxin polish, fabric filter baghouse for the consolidated stream, wet scrubber polish (mandatory on hazardous waste rather than optional on MSW WtE), induced draft fan and stack. The wet scrubber polish stage demands 316L stainless throughout from the bag filter outlet through to the stack inner liner. Super-austenitic 904L or duplex 2205 stainless extends further downstream than on MSW WtE because the chloride bleed exceeds 1,000 parts per million on most hazardous waste streams.

Asbestos waste handling is a parallel hazardous waste segment that does not pass through the high-temperature incinerator. Asbestos is classified Class IIA hazardous and is transferred under negative-pressure HEPA-bagged transport from the decommissioning site through to the licensed asbestos landfill cell. The HVAC duct demand on the asbestos transfer station is HEPA H13 final filtration with 304L stainless duct on the bagged-out transfer envelope, with the HEPA polish stage bagged out as Class IIA waste at quarterly intervals.

Quarantine waste from the federal DAFF border quarantine framework (international airline catering waste, agricultural plant material, imported food residuals) is processed either by landfill burial under specific licence or by high-temperature incineration to ensure biosecurity. The incineration option uses the same post-combustion chamber design as standard MSW WtE, with the addition of dedicated container handling and bag-out at the receival end.

SBKJ supplies the duct fabrication for the entire flue gas treatment train downstream of the post-combustion chamber, the bag filter inlet and outlet, the wet scrubber interstage and the stack inner liner through the SBAL-V auto duct line in 304L and 316L configuration with the SBSF-1525 stitchwelder for the welded heavy-gauge sections. The high-temperature alloy reactor pressure vessel work and the FRP scrubber body work are outside SBKJ scope.

Materials selection by zone

Material selection across the WtE, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste and contaminated soil duct package is more nuanced than in general HVAC. Getting it wrong is expensive — both as a direct cost and through accelerated failure of mis-specified runs. The following table summarises the SBKJ specification by zone.

WtE post-combustion chamber backing plate (1100 degrees Celsius, dry): AISI 309 or 310 high-temperature stainless. Refractory-lined.
WtE boiler economiser outlet to air heater inlet (280 to 380 degrees Celsius, dry): Carbon steel with welded seams or 309 stainless. Refractory-lined where appropriate.
WtE air heater outlet to flue gas treatment train (130 to 180 degrees Celsius, transitional): 304L stainless. Galvanised will fail within months.
WtE flue gas treatment train (selective non-catalytic reduction, dry sorbent, activated carbon, bag filter inlet — dry chemistry): 304L stainless throughout.
WtE bag filter clean-side outlet to induced draft fan, wet scrubber and stack (acid-condensing): 316L stainless. Super-austenitic 904L or duplex 2205 where chloride bleed exceeds 1,000 parts per million.
WtE stack inner liner above wet scrubber: 316L stainless. AS 1318 industrial chimney structural design.
WtE MSW bunker air intake and tipping hall extract: 316L stainless because of humidity, hydrogen sulphide and ammonium condensation.
WtE refuse derived fuel preparation shredder extract: Heavy-gauge galvanised G90 or 304L stainless with stitchwelded longitudinal seams. NFPA 660 deflagration reinforcement.
WtE fly ash silo, discharge cone and truck loading extract: 304L stainless for ease of heavy metal decontamination at end-of-life.
WtE bottom ash handling general extract: Galvanised G90 to AS 4254.1.
Landfill biogas extraction header, gas conditioning skid, blower inlet: 304L stainless or epoxy-painted carbon steel. Galvanised fails under hydrogen sulphide attack within months.
Landfill biogas flange wetted face: 316L stainless. Viton gasket for hydrogen sulphide service.
Landfill biogas flare stack inner liner: 316L stainless. AS 1318 industrial chimney structural design.
Landfill gas-to-energy engine compound general ventilation: Galvanised G90. Engine flue inner liner 304L stainless.
Anaerobic digestion biogas pipework, digester headspace, conditioning train: 304L stainless. Same materials specification as landfill biogas.
Composting receival floor, windrow turning hall, in-vessel reactor extract: 316L stainless from process to biofilter because of humidity, ammonium acetate, organic acid condensation.
Composting biofilter return riser (enclosed biofilter with stack): 316L stainless or fibreglass reinforced plastic depending on residual chloride. AS 1318 industrial chimney structural design.
E-waste shredder extract from hood to baghouse: 304L stainless with welded longitudinal seams. NFPA 660 deflagration reinforcement. HEPA H13 polish stage downstream.
Lithium-ion battery shredder extract from inerted enclosure to baghouse: Welded heavy-gauge 304L stainless. NFPA 855 deflagration reinforcement.
Lithium-ion battery scrubber interstage (caustic primary, acid secondary, carbon polish): 316L stainless because of chloride carryover. Primary caustic scrubber body in fibreglass reinforced plastic (outside SBKJ scope).
Lithium-ion battery carbon polish to stack: 304L stainless. AS 1318 industrial chimney structural design.
Lead-acid battery case breaking and acid neutralisation: 316L stainless on acid-side. 304L stainless on dust-side.
Lead-acid battery smelting furnace flue, baghouse, scrubber and stack: 316L stainless from baghouse outlet through to stack.
Scrap metal shredder pre-vent extract from hood to baghouse: Heavy-gauge galvanised G90 or 304L stainless with stitchwelded longitudinal seams. NFPA 660 deflagration reinforcement.
Scrap metal aluminium-only shred line to wet collector: 304L stainless because of water spray carryover. Spark-resistant fan blade. AS/NZS 60079 Zone 22 fan motor.
Used oil distillation column overhead to condenser: 316L stainless because of acid sulphur compounds.
Used oil condenser to vent and thermal oxidiser inlet: 304L stainless transitioning to 316L stainless at the thermal oxidiser because of trace hydrogen chloride.
Used oil tank farm general ventilation and AS 1940 vent recovery: Galvanised G90 to AS 4254.1.
Contaminated soil thermal desorption rotary kiln outlet to thermal oxidiser: Heavy-gauge 304L stainless. NFPA 660 deflagration reinforcement.
Contaminated soil thermal oxidiser outlet to quench, bag filter, activated carbon, stack: 309 stainless at oxidiser outlet, transitioning to 304L stainless at bag filter and 316L stainless at activated carbon polish and stack.
Hazardous waste post-combustion chamber backing plate: 309 or 310 stainless. Refractory-lined.
Hazardous waste flue gas treatment train, wet scrubber and stack: 316L stainless throughout from bag filter outlet. Super-austenitic 904L or duplex 2205 where chloride exceeds 1,000 parts per million.
Asbestos transfer station HEPA bag-out envelope: 304L stainless with HEPA H13 polish.
Worker amenity, change room and control room positive-pressure clean supply: Galvanised G90 to AS 4254.1 with HEPA recovery at the boundary to high-risk zones.

For a deeper comparison of the material trade-offs and where each grade is appropriate, see our reference on galvanised vs stainless steel duct selection.

AS 4254 construction class and AS 1318 industrial chimney

AS 4254 is the Australian ductwork construction standard, split between AS 4254.1 (flexible duct and acoustic duct) and AS 4254.2 (rigid duct). The relevant pressure class for most waste treatment ductwork is medium-pressure AS 4254.2, with structural reinforcement on long collector inlet ducts under negative pressure and stitchwelded heavy-gauge construction on shredder pre-vent, fly ash silo extract, lithium-ion battery extract and post-combustion chamber backing plate. AS 1318 is the Australian industrial chimney standard, governing stack design for height, structural load, inner liner material and external corrosion resistance.

AS 4254.1 (low pressure, up to 500 Pa): General supply to control rooms, amenities and clean-supply zones. Slip-flange or TDF flange construction with EPDM gasket. Galvanised G90 in most cases.
AS 4254.2 medium pressure (500 to 1500 Pa): General extract from MSW bunker, refuse derived fuel preparation hall, composting receival, scrap metal yard, used oil tank farm, contaminated soil receival pad. Slip-flange or TDF flange. Galvanised G90 default; 304L or 316L on the wet and acidic-condensing runs.
AS 4254.2 high-pressure / negative-pressure (above 1500 Pa): Shredder pre-vent, fly ash silo extract, scrubber interstage, lithium-ion battery enclosure extract, post-combustion chamber backing plate, thermal desorption kiln outlet, biofilter return riser. Stitchwelded longitudinal seams. TDF flange with PTFE gasket on chemical service. NFPA 660 deflagration reinforcement on combustible dust service.
AS 1318 industrial chimney: WtE stack, hazardous waste high-temperature incineration stack, landfill biogas flare, gas-to-energy engine flue stack, thermal desorption stack, lead-acid smelter stack. Stack height set against dispersion modelling at residential receptor. Inner liner material selected per gas chemistry (typically 316L stainless above wet scrubber). External structural shell carbon steel with weather protection coating.

The construction class drives the gauge schedule, the flange specification, the reinforcement spacing and the joint sealing. A consulting engineer specifying ductwork for a waste treatment facility should mark every duct run on the drawing with the AS 4254 class, the gauge schedule and the AS 1318 reference where applicable, leaving no ambiguity for the fabricator at the take-off.

Fire-rated penetrations, AS 1530.4 and AS 1851 damper maintenance

Every wall, floor and ceiling penetration where the duct crosses a fire-rated barrier requires AS 1530.4 tested and certified seal. The seal system is normally specified by the fire engineer on the project drawings — typical solutions include intumescent collar, mortar fill, proprietary firestop system, or fire-rated duct wrap on the duct itself. The seal is detailed at every penetration, with the certification number recorded on the project compliance schedule.

Fire dampers are required at every penetration of a fire-rated barrier on a duct that does not have an equivalent fire-rated duct construction. The damper specification is to AS 1682, with the operational regime under AS 1851 — drop test on a 12-month cycle, with the test record kept in the operations file. The damper actuator is either a fusible link (typically 74 degrees Celsius for general HVAC, 100 degrees Celsius or higher for process exhaust where the operating temperature is elevated), an electric actuator wired into the BMS, or a pneumatic actuator with a fail-closed configuration.

On waste treatment facilities, the fire damper schedule is augmented with fast-acting isolation dampers on the high-risk extract paths — biogas, lithium-ion battery, used oil distillation, fly ash silo, scrap metal shredder pre-vent and the WtE flue gas treatment train. These are typically pneumatic-actuated with sub-second response time, interlocked to gas detection and process trip. They are not AS 1682 fire dampers; they are process safety dampers under AS/NZS 60079 zone classification, and the maintenance regime is monthly functional test with annual full overhaul.

Safe Work Australia Workplace Exposure Standards in the duct design

The duct design is bounded by Safe Work Australia Workplace Exposure Standards at the breathing zone. The operative values for waste-to-energy, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste and contaminated soil:

Methane (CH4): 1000 parts per million asphyxiant threshold and 5 percent lower flammable limit. Critical on landfill biogas, anaerobic digestion biogas, MSW bunker headspace, paper bale storage tunnel, FOGO compost tunnel. AS/NZS 60079 hazardous area implications.
Carbon monoxide (CO): 30 parts per million 8-hour time-weighted average. Driven by boiler combustion, hazardous waste high-temperature incineration, RDF storage bunker microbial decomposition, and any incomplete combustion service.
Nitrogen dioxide (NO2): 5 parts per million short-term exposure limit. Driven by combustion services, particularly the boiler and the high-temperature incinerator.
Sulphur dioxide (SO2): 2 parts per million 8-hour time-weighted average. Driven by WtE combustion of sulphur-bearing MSW and hazardous waste incineration.
Hydrogen chloride (HCl): 5 parts per million short-term exposure limit. Driven by PVC combustion, polychlorinated biphenyl decomposition, contaminated soil chlorinated solvent volatilisation, lithium-ion battery thermal runaway.
Hydrogen fluoride (HF): 1.8 milligrams per cubic metre time-weighted average and 3 parts per million short-term exposure limit. Driven by lithium-ion battery thermal runaway (LiPF6 hydrolysis), fluoropolymer thermal decomposition, fluorinated waste incineration. Highest acute hazard in the sector.
Dioxins and furans (PCDD/PCDF): Extremely toxic at trace levels. No formal Safe Work Australia workplace exposure standard, but the stack discharge standard is 0.1 nanograms toxic equivalent per normal cubic metre aligned to the EU Industrial Emissions Directive. The bag filter plus activated carbon plus lime sorbent plus wet scrubber polish train is the operative control.
Heavy metals — mercury (Hg) vapour 0.025 mg/m3, lead (Pb) 0.05 mg/m3, cadmium (Cd) 0.01 mg/m3, arsenic (As) 0.05 mg/m3, hexavalent chromium (Cr VI) 0.05 mg/m3: Driven by WtE fly ash, e-waste shred, lead-acid battery smelting, contaminated soil thermal desorption.
Respirable dust: 10 milligrams per cubic metre 8-hour time-weighted average. Driven by every dust source — refuse derived fuel preparation, scrap metal shredder, fly ash silo, e-waste shredder.
Respirable crystalline silica: 0.05 milligrams per cubic metre 8-hour time-weighted average. Driven by inert fraction of MSW, glass cullet, construction and demolition waste in residual stream.
Ammonia (NH3): 25 parts per million time-weighted average and 35 parts per million short-term exposure limit. Driven by composting, anaerobic digestion, MSW bunker putrescible fraction, lead-acid battery electrolyte.
Hydrogen sulphide (H2S): 10 parts per million time-weighted average and 15 parts per million short-term exposure limit. Driven by landfill biogas, anaerobic digestion, MSW bunker, septic biosolids. Extreme toxicity at high concentration plus odour nuisance.
Volatile organic compounds (VOC general): No single Safe Work Australia workplace exposure standard — individual species (toluene, xylene, benzene, formaldehyde) have specific limits, and the duct system must hold each below the relevant standard. Driven by used oil distillation, contaminated soil VOC volatilisation, plastic recycling extruder vent.
Polycyclic aromatic hydrocarbons (PAH): Indexed by benzo[a]pyrene. Driven by combustion services, used oil residual fraction, contaminated soil thermal desorption.
Bioaerosol and endotoxin: No formal Safe Work Australia workplace exposure standard, but state work health and safety regulators expect a documented capture and treatment regime. Driven by composting, anaerobic digestion biosolids, MSW bunker putrescible fraction. Respiratory infection risk on operators handling fresh feed.

The duct design must hold airborne concentrations below the workplace exposure standard at every breathing-zone receptor. The calculation runs forward from the contaminant generation rate at the source, through the dilution by general ventilation and the capture by local extract, to the residual concentration at the operator position. A duct system that meets AS 1668.2 mechanical ventilation rate but fails the workplace exposure standard at the breathing zone is non-compliant — process exhaust is the operative driver, not general ventilation.

Stack discharge, NEPM Air Toxics and state EPA licence conditions

The duct discharge from any Australian waste treatment facility is bounded by the receptor air quality at the residential boundary and the stack discharge concentration at the chimney top. The operative standards are AS 3580 (boundary air monitoring methods), the National Environment Protection Measure for Air Toxics (ambient air quality goals at the receptor for benzene, formaldehyde, polycyclic aromatic hydrocarbons, toluene, xylenes and benzo[a]pyrene), and the state EPA licence conditions (stack discharge limits derived through dispersion modelling from the NEPM goal).

For WtE and hazardous waste high-temperature incineration the stack discharge limits are aligned to the EU Industrial Emissions Directive Annex VI at 0.1 nanograms toxic equivalent per normal cubic metre for dioxins and furans, 0.05 milligrams per normal cubic metre for mercury, 200 milligrams per normal cubic metre for NOx, 50 milligrams per normal cubic metre for sulphur dioxide, 10 milligrams per normal cubic metre for hydrogen chloride, 1 milligram per normal cubic metre for hydrogen fluoride, 10 milligrams per normal cubic metre for total particulate, and 50 milligrams per normal cubic metre for carbon monoxide, all at 11 percent oxygen reference.

The duct design implications are stack height, stack velocity, stack location and continuous emissions monitoring instrumentation. Stack height is set against dispersion modelling — typically 1.5 to 2.5 times the height of the tallest building within 100 metres, with corrections for terrain and wind rose. Stack velocity is typically 15 to 25 metres per second to ensure plume rise and to clear the building cavity. Stack location is set against the residential boundary and the public access positions. The stack itself is normally 304L stainless or 316L stainless because solar and discharge thermal cycling rapidly degrades galvanised in this service. Continuous emissions monitoring of particulate, carbon monoxide, NOx, sulphur dioxide, hydrogen chloride, hydrogen fluoride, mercury and total volatile organic compounds at the stack outlet feeds the state EPA reporting cycle. Dioxins and furans are sampled at the EU IED frequency — typically twice per year by 6-hour integrated sample.

Operator boundary monitoring is a state EPA licence condition. AS 3580 sets the methods — high-volume sampler for particulate, sorbent tube for VOC, real-time CO and SO2 instruments where required, advisory PFAS monitoring on selected legacy contamination sites. Complaint risk from the residential boundary is a leading reason that waste treatment facilities require expensive duct upgrades through the operational life — a complaint pattern triggers a state EPA review which typically prescribes additional capture or treatment at the source. Designing the duct to clear the receptor target with margin at commissioning is significantly cheaper than retrofitting later.

SBKJ machinery suitability across the waste treatment duct package

The Australian fabricator pricing a WtE, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste or contaminated soil duct package needs a machinery line that covers the rectangular galvanised majority, the round biofilter and engine flue component, the heavy-gauge stitchwelded shredder pre-vent and fly ash silo extract, the 304L and 316L stainless flue gas treatment train and stack inner liner, and the special bracketry and access panels. The SBKJ machinery offer maps to the duct package as follows.

SBAL-V auto duct line. 16 metres per minute production speed, 87 kilowatts total connected load, 0.5 to 1.5 millimetres gauge range, 1500 millimetres maximum coil width. Covers the rectangular galvanised majority — MSW bunker general supply, refuse derived fuel preparation hall general supply, boiler house secondary ventilation, control room and amenity supply, scrap metal yard general supply, used oil tank farm general supply, contaminated soil receival pad general supply. Configurable for 304L and 316L stainless with the stainless tooling package, covering the entire WtE flue gas treatment train from air heater outlet through bag filter and wet scrubber to stack inner liner, the lithium-ion battery extract and scrubber interstage, the e-waste shredder extract, the composting biofilter return, the used oil distillation overhead and thermal oxidiser inlet, the contaminated soil thermal desorption kiln outlet and the hazardous waste flue gas treatment train. The mandatory machinery for any Australian fabricator pricing waste treatment work as a primary segment. See SBAL-V product page for full specifications.
SBAL-III auto duct line. 14 metres per minute, 15.7 kilowatts. Lower-throughput alternative to SBAL-V for fabricators with smaller project mix. Covers the same materials range.
SBAL-II auto duct line. 18 metres per minute, 5.5 kilowatts. Entry-level auto duct line for small-volume specialty work and Container Deposit Scheme depot adjacent projects.
SBTF-1500C / SBTF-1602 / SBTF-2020 spiral tubeformers. Round duct production for biofilter return riser, gas-to-energy engine flue, stack tie-ins, ducted transitions between rectangular main and scrubber inlet. Different models cover different diameter ranges and gauge schedules. Stainless configuration available for 304L and 316L work.
SBFB-1500 spiral tubeformer alternative configuration. Round biofilter return riser sections for the composting biofilter stack and the anaerobic digestion engine flue.
SBEM-1250 elbow making line. Round-duct elbow production for the biofilter return riser, the gas-to-energy engine flue and the stack tie-in sections.
SBSF-1525 stitchwelder. 2.5 kilowatts. Continuous welded longitudinal seams on heavy-gauge galvanised, 304L stainless and 316L stainless. Mandatory for the WtE post-combustion chamber backing plate, the fly ash silo extract, the lithium-ion battery scrubber interstage, the scrap metal shredder pre-vent, the refuse derived fuel preparation shredder extract, the e-waste shredder extract, the contaminated soil thermal desorption kiln outlet, the hazardous waste flue gas treatment train heavy-gauge sections, the stack inner liner welded sections, and any service above AS 4254.2 medium-pressure class or NFPA 660 deflagration-rated. See SBSF-1525 product page.
SB-ZF1500 stitchwelder. Critical for the stainless flue plenum and the acid scrubber housing on the WtE flue gas treatment train and the hazardous waste flue gas treatment train. The 1500 millimetre throat depth accommodates the larger flue gas treatment train plenum dimensions.
SBFB-1500 folder. 7.5 kilowatts, 1.20 metres per minute. Heavy-gauge folded sections around access doors, transitions, bracketry and reinforcement frames. Covers the special fabrication that does not fit through the auto duct line — fly ash silo discharge cone folded plates, scrap metal shredder hood plenum folded transitions, post-combustion chamber backing plate folded sections.
SBHF hydraulic folding machine. Heavy-gauge plate folding for stack saddles, scrubber inlet plates, post-combustion chamber backing plates and reinforcement plates above the standard SBFB-1500 capacity.
SBPC1500 plasma cutter. 1500 millimetres cutting width for 304L and 316L stainless plate work, post-combustion chamber backing plate cut-outs, scrubber inlet cut-outs, access door cut-outs, branch take-offs and the heavy plate work on the WtE flue gas treatment train and the hazardous waste flue gas treatment train.
SBLR-600 / SBLR-600A roll bender. 7.6 metres per minute. Radius transitions on stack tie-ins, scrubber inlet bends, large-radius duct bends, gas-to-energy engine flue connections, biofilter return riser tie-ins.
SBLR-600 welder. Companion welder for the radius transitions and the post-combustion chamber backing plate.
Spark-resistant fan blade and IECEx Ex-d ATEX motor packages. Specified separately by the consulting engineer, but the duct construction supports the spark-resistant fan and Ex motor as a single integrated assembly on every extract path that classifies under AS/NZS 60079 — biogas Zone 1, lithium-ion battery Zone 2, aluminium dust NFPA 660, scrap metal dust, used oil distillation, fly ash silo, refuse derived fuel preparation shredder. The fan motor is rated IECEx Ex-d to the zone classification with appropriate temperature class.

A representative machinery line for an Australian fabricator pricing WtE, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste and contaminated soil work as a primary segment is one SBAL-V auto duct line with the stainless tooling package, one SBTF-1500C spiral tubeformer in stainless configuration, one SBSF-1525 stitchwelder, one SB-ZF1500 stitchwelder for the larger flue plenum work, one SBFB-1500 folder, one SBPC1500 plasma cutter and one SBLR-600A roll bender with the SBLR-600 welder. The total connected load is around 115 kilowatts, the footprint is around 700 to 900 square metres, and the fabrication throughput is around 1,200 to 1,800 square metres of finished duct per shift. The machinery investment typically pays back within 2 to 3 Australian WtE, landfill biogas-to-energy or hazardous waste facility projects, after which it covers maintenance retrofits and adjacent industrial work across the operator's local region.

For fabricators with primary work in hazardous waste or contaminated soil thermal desorption, the machinery line is augmented with stainless tooling on the SBAL-V (extra cost in the 12 to 18 percent range), additional stitchwelder capacity (a second SBSF-1525 or SB-ZF1500 running parallel), and increased plasma cutter capacity (SBPC1500 with second torch for productivity on the high-temperature alloy work). For fabricators with primary work in landfill biogas-to-energy plants and composting facilities, the line can be reduced to a single SBAL-V with one SBTF-1500C and one SBSF-1525, covering the duct package at lower capital cost.

Adjacent industry references

The Australian waste-to-energy and waste treatment sector shares technical territory with several adjacent industries the SBKJ catalogue addresses in dedicated guides. Specifiers cross-referencing experience benefit from the comparisons.

MRF and recycling sortation — the front-end materials recovery feeds the waste treatment downstream. See our companion MRF, CDS, e-waste and battery recycling HVAC duct guide for the sortation perspective on the same waste streams.
Plastic and polymer recycling manufacturing — the plastic recycling extruder vent and the polymer melt off-gassing overlap the waste treatment exhaust regime. See our plastic polymer injection blow moulding extrusion recycling manufacturing HVAC duct guide.
Critical minerals, lithium and battery refining — the lithium-ion battery recycling shred line is the reverse problem of the lithium and rare earth refining stream. See our critical minerals lithium rare earth battery refining HVAC duct guide for the upstream perspective on the same chemistry.
Coal and gas power plant — the WtE boiler and the air heater dew point line share the design framework of a coal-fired or gas-fired power station. See our coal and gas power plant HVAC duct guide for the power generation perspective.
Specialty chemicals and petrochemical manufacturing — the used oil distillation and the hazardous waste high-temperature incineration share the chemical plant exhaust framework. See our specialty chemicals and petrochemical manufacturing HVAC duct guide.
Battery gigafactory HVAC — the lithium-ion thermal runaway controls applied in battery recycling are the reverse problem of those applied at the cell manufacturing end. See our battery gigafactory HVAC duct guide.
Australian HVAC duct fabrication setup — for the fabricator setting up an Australian shop to service waste treatment projects, see our Australian HVAC duct fabrication setup 2026 guide.
Galvanised vs stainless steel duct selection — for the material trade-off across galvanised, 304L and 316L stainless, see our galvanised vs stainless steel duct selection guide.

Cost benchmarks and budget guidance

HVAC ductwork including supply, return, exhaust, flue gas treatment train, scrubber interstage and stack on an Australian waste-to-energy, landfill biogas-to-energy, hazardous waste high-temperature incineration or thermal desorption facility typically represents 6 to 12 percent of total facility capital cost. For a major MSW WtE in the AUD 500 million to AUD 1.5 billion range, this implies AUD 30 to 180 million in ductwork material, fabrication and installation. For a typical 50,000 to 200,000 tonne per annum hazardous waste high-temperature incineration plant with capital cost in the AUD 80 to 250 million range, the ductwork share is AUD 6 to 30 million. For a 5,000 to 25,000 tonne per annum lithium-ion battery shred and hydrometallurgical recovery plant with capital cost in the AUD 30 to 80 million range, the ductwork share is AUD 3 to 10 million.

Within the package:

General supply and return (galvanised G90): 25 to 35 percent of total ductwork spend.
Process extract and capture (galvanised G90 with stitchwelded heavy-gauge sections): 20 to 30 percent.
Flue gas treatment train, scrubber interstage, biofilter return (304L and 316L stainless): 25 to 40 percent. Concentrated on the WtE flue gas treatment train, the hazardous waste flue gas treatment train, the lithium-ion battery scrubber interstage and the composting biofilter return.
Stack inner liner and structural shell (AS 1318): 5 to 10 percent.
High-temperature alloy backing plate and refractory-lined transitions (309/310 stainless, carbon steel refractory-lined): 3 to 8 percent. Concentrated on the WtE post-combustion chamber, the hazardous waste rotary kiln and the contaminated soil thermal desorption kiln.
Insulation, protection and fire-rated penetration sealing: 8 to 12 percent.

For a landfill biogas-to-energy plant or anaerobic digestion plant the ductwork share is at the lower end — 4 to 7 percent of facility capital — because the duct package is smaller relative to the gas engine and the digester tank. For a composting facility the ductwork share is mid-range at 5 to 8 percent, with the biofilter return riser being the dominant single duct cost. For a contaminated soil thermal desorption plant the ductwork share is at the higher end — 10 to 15 percent — because of the high-temperature alloy content and the stainless flue gas treatment train.

The fabrication labour share is what local on-site fabrication with appropriate duct-forming machinery directly attacks. Moving from imported pre-fabricated duct to local fabrication on an Australian shop with an SBKJ machinery line typically reduces installed cost by 15 to 25 percent on the stainless work and by 10 to 15 percent on the galvanised work, accounting for machinery capital amortisation, operator training and shop overhead. The lead-time benefit is significant on the stainless work — local fabrication delivers in 4 to 6 weeks against 16 to 24 weeks for imported pre-fabricated. On a project with a tight construction window — the typical Australian WtE has a 30 to 36 month construction programme from financial close to commercial operations — the lead-time advantage of local fabrication can be the deciding factor on the project schedule.

Validation, commissioning and ongoing compliance

HVAC commissioning on a waste treatment facility is more rigorous than general industrial HVAC because the duct system is a primary process safety system and a primary environmental compliance system. The validation suite typically includes:

Pressure decay testing on completed duct sections before insulation and concealment. Tightness verification at 1.5 times design static pressure for 15 minutes minimum. Sections that fail are repaired and re-tested before sign-off.
Capture velocity verification at every local extract hood with calibrated anemometer. ACGIH Industrial Ventilation Manual target plus or minus 10 percent at the design face position.
Air change rate verification by tracer gas decay or anemometric supply measurement on every zone. Verified to plus or minus 10 percent of AS 1668.2 design.
Pressure cascade verification at every airlock with all doors closed and worst-case door-open scenarios. Calibrated micromanometer to 0.5 pascal resolution.
Smoke test capture verification at every hood with smoke generator. Visual confirmation of capture to within the design face position.
Baghouse pressure drop characterisation across the filter loading cycle, with the operational alarm threshold set at 1.5 times clean-filter pressure drop.
Explosion vent inspection on every NFPA 68 vent panel before commissioning, with the rupture pressure verified against the design Kst.
Gas detection calibration with reference gas at multiple concentrations on every methane, hydrogen sulphide, ammonia, carbon monoxide, hydrogen fluoride, hydrogen bromide, hydrogen chloride and oxygen sensor.
Hazardous area boundary verification with calibrated gas detector and witness against the AS/NZS 60079 classification document.
Fire damper drop test on every AS 1682 damper with command from BMS, verifying actuator response time and the fail-closed position.
Process safety damper functional test on every fast-acting isolation damper on biogas, lithium-ion battery, used oil distillation, fly ash silo and shredder pre-vent extract paths.
Personal monitoring against Safe Work Australia workplace exposure standards for the active contaminants — methane, carbon monoxide, hydrogen sulphide, ammonia, hydrogen fluoride, hydrogen chloride, mercury, lead, cadmium, respirable crystalline silica.
Boundary monitoring against AS 3580 at the residential receptor for at least 30 days of continuous operation.
Stack continuous emissions monitoring commissioning against the state EPA licence condition for the discharge — particulate, carbon monoxide, NOx, sulphur dioxide, hydrogen chloride, hydrogen fluoride, mercury and total volatile organic compounds.
Stack dioxin and furan sampling against the EU Industrial Emissions Directive 0.1 nanograms toxic equivalent per normal cubic metre standard, by 6-hour integrated sample to a certified laboratory.

The full commissioning report is a deliverable to the operator and is required documentation for the operations and maintenance handover. The ongoing compliance regime typically runs daily collector pressure drop logging, weekly explosion vent visual inspection, monthly gas detector calibration, monthly process safety damper functional test, 12-monthly AS 1851 fire damper drop test, 5-yearly AS 3957 dust hazard re-validation, continuous stack emissions monitoring, biannual stack dioxin sampling, and continuous boundary monitoring against AS 3580 and NEPM Air Toxics. The duct system operational records feed the operator's ISO 14001 environmental management system, where applicable, and the state EPA licence reporting cycle.

How SBKJ engages an Australian waste treatment duct project

From Box Hill North, Victoria, SBKJ engages an Australian WtE, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste or contaminated soil duct project across three phases.

Phase 1 — concept design support. An SBKJ mechanical engineer reviews the consulting engineer's concept duct schedule and identifies the zones, materials and construction class. The engineer recommends a machinery line that covers the duct package at the fabricator's target throughput, with a configuration that handles the stainless flue gas treatment train, the biogas Zone 1 hazardous area runs, the lithium-ion battery scrubber interstage and the post-combustion chamber backing plate without forcing the fabricator to sub-contract. The output is a single-page machinery recommendation and a budgetary capital estimate for the fabricator's project tender.

Phase 2 — detail design fabrication and machinery commissioning. Once the project is awarded, the SBKJ engineer works with the fabricator on the duct-by-duct take-off, the gauge schedule, the welding procedure for the stitchwelded sections, the high-temperature alloy backing plate work and the tooling configuration on the auto duct line. The machinery is shipped, installed and commissioned by SBKJ engineers on the fabricator's site, with operator training delivered in English. Lead time from machinery order to commissioning is 16 to 22 weeks, comparable to European-built alternatives. See the full machine catalogue.

Phase 3 — operational support and spare parts. SBKJ provides a 10-year minimum parts support commitment in writing, in line with the typical 20 to 30 year operational horizon of an Australian WtE plant, hazardous waste high-temperature incineration plant or major landfill biogas-to-energy facility. Spare parts are held in Box Hill North for next-day dispatch across the Australian east coast and in the SBKJ Australian distribution network for the broader Pacific region. Operator training records are maintained as part of the fabricator's ISO 14001 EMS.

Discuss your Australian waste-to-energy, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste or contaminated soil duct project with SBKJ →

FAQ

What flue gas treatment train does an Australian municipal solid waste incinerator need to meet the EU IED dioxin emission standard?

Six stages. Post-combustion at 1100 degrees Celsius for two seconds residence time to destroy chlorinated organics. Selective non-catalytic or catalytic reduction for NOx using urea or ammonia. Dry sorbent injection of hydrated lime for SO2, HCl and HF neutralisation. Activated carbon injection for mercury and dioxin polish. Fabric filter baghouse for the consolidated fly ash stream. Wet scrubber polish where chloride bleed remains high. The stack discharge is monitored continuously for particulate, CO, NOx, SO2, HCl, HF, Hg and VOC, with dioxins and furans sampled biannually by 6-hour integrated test against the EU IED standard of 0.1 ng TEQ per Nm3 at 11 percent O2 reference.

What is the AS/NZS 60079 zone classification for landfill biogas extraction?

Zone 0 inside the duct in continuous service, Zone 1 immediately surrounding flanged joints and pressure relief points. Methane is well above the lower flammable limit of 5 percent. The duct material is 304L stainless because hydrogen sulphide at 50 to 2000 ppm attacks galvanised within months. Fan motor is Ex-d or Ex-e rated to Zone 1. Gas detection is intrinsically safe Ex-ia to Zone 0 for methane and hydrogen sulphide.

What duct material does an Australian WtE air heater outlet require?

304L stainless minimum at the air heater outlet because the gas temperature is on the acid dew point line at 130 to 180 degrees Celsius and galvanised will fail within months. The bag filter clean-side outlet to the induced draft fan and the wet scrubber is 316L stainless because residual chloride and fluoride after dry sorbent neutralisation remain corrosive at around 60 degrees Celsius condensing. Super-austenitic 904L or duplex 2205 is specified where chloride bleed exceeds 1,000 ppm. The stack inner liner above the wet scrubber is 316L stainless.

How is a composting facility biofilter sized for ammonia and odour control?

Open-bed wood-chip or bark over a perforated plenum, 30 to 45 second empty-bed residence time, irrigated to 50 to 65 percent moisture. Total extract volume 50,000 to 150,000 cubic metres per hour on a 100,000 tonne per annum facility. Capture velocity at the source 4 to 6 metres per second. Duct between process and biofilter is 316L stainless because compost off-gas at 30 to 50 degrees Celsius is humid, ammonium-acetate-laden and organic-acid-condensing. Biofilter return riser (where enclosed) is 316L stainless. Open-bed biofilters discharge directly to atmosphere.

What is the four-layer control for lithium-ion battery recycling shredder hoods?

Inerted enclosure under nitrogen or argon blanket with oxygen below 4 percent. NFPA 68 explosion vent panels on the enclosure and downstream baghouse with welded heavy-gauge 304L stainless duct. Three-stage scrubber train (caustic primary, acid secondary, activated carbon polish) with 316L stainless interstage because of chloride carryover. Continuous gas detection on hydrogen, hydrogen fluoride, hydrogen bromide, hydrogen chloride, carbon monoxide and oxygen interlocked to isolation dampers, inert gas knock-down and process trip. Aligned to NFPA 855 and AS/NZS 5139.

What duct construction does an Australian scrap metal shredder require?

Heavy-gauge galvanised G90 or 304L stainless with stitchwelded longitudinal seams from the hood at 1.5 to 2.5 metres per second capture velocity through to an explosion-vented baghouse with NFPA 68 vent panels sized for the worst-case Kst (commonly above 400 bar metres per second for aluminium and magnesium dust). NFPA 69 isolation by rotary airlock or chemical suppression on the inlet. Spark-resistant AMCA Type A or B fan with aluminium-bronze impeller. Fan motor rated to AS/NZS 60079 Zone 22 dust hazardous area.

What duct material does used oil distillation require?

316L stainless from the distillation column overhead to the condenser because the acid sulphur compounds attack galvanised within weeks. 304L stainless on the condenser-to-vent run. 316L stainless on the thermal oxidiser inlet and outlet because of trace HCl from PCB decomposition in legacy transformer oil. Storage tank vents routed through vapour recovery or carbon scrubber under AS 1940 flammable liquid storage rules. AS/NZS 60079 Zone 1 inside the column and Zone 2 in the surrounding pump compound.

How is contaminated soil thermal desorption handled in the duct design?

Heavy-gauge 304L stainless from the rotary kiln outlet at 100 to 500 degrees Celsius through to a thermal oxidiser at 850 degrees Celsius for organic destruction, quench to 130 degrees Celsius, bag filter for dust capture, lime sorbent for acid gas, activated carbon polish for residual Hg and dioxin, and stack discharge. The duct upgrade to 316L stainless applies wherever chloride exceeds 200 ppm from chlorinated solvent contamination. Stack monitored continuously for VOC, CO, NOx, SO2 and total particulate. PFAS impacted soil requires 1100 degrees Celsius residence above 2 seconds at the thermal oxidiser.

What machinery line covers a typical Australian WtE or hazardous waste facility duct package?

One SBAL-V auto duct line (16 m/min, 87 kW, 0.5 to 1.5 mm, 1500 mm) with stainless tooling for the rectangular and flue gas treatment train. One SBTF-1500C spiral tubeformer in stainless for the round biofilter return and engine flue. One SBSF-1525 stitchwelder (2.5 kW) for the welded heavy-gauge construction. One SB-ZF1500 stitchwelder for the larger flue plenum. One SBFB-1500 folder (7.5 kW). One SBPC1500 plasma cutter for the stainless plate work. One SBLR-600A roll bender with SBLR-600 welder. Spark-resistant fan and IECEx Ex-d ATEX motor packages on every classified extract path. Total connected load around 115 kW, footprint 700 to 900 square metres, throughput 1,200 to 1,800 m2 per shift. Payback typically 2 to 3 Australian WtE, hazardous waste or landfill biogas-to-energy projects.

What Safe Work Australia workplace exposure standards bind waste treatment HVAC design?

Methane 1000 ppm asphyxiant and 5 percent LFL (landfill biogas, anaerobic digestion, MSW bunker), CO 30 ppm 8-hour TWA (combustion), NO2 5 ppm STEL (combustion), SO2 2 ppm TWA (incineration), HCl 5 ppm STEL (PVC and chlorinated waste combustion), HF 1.8 mg/m3 TWA and 3 ppm STEL (lithium-ion battery, fluorinated waste), dioxins regulated at the stack to EU IED 0.1 ng TEQ per Nm3, Hg vapour 0.025 mg/m3 (WtE fly ash, e-waste), Pb 0.05 mg/m3 (lead-acid battery, e-waste, WtE), Cd 0.01 (e-waste, WtE), respirable dust 10 mg/m3, respirable crystalline silica 0.05 mg/m3, NH3 25/35 ppm TWA/STEL (composting, anaerobic digestion), H2S 10/15 ppm TWA/STEL (landfill, anaerobic digestion, MSW bunker), VOC species-specific, PAH benzo[a]pyrene indexed, bioaerosol no formal limit but documented capture expected.

How much does HVAC ductwork cost as a percentage of an Australian WtE or hazardous waste facility build?

6 to 12 percent of total facility capital cost for a typical Australian WtE or hazardous waste high-temperature incineration plant. For a major MSW WtE in the AUD 500 million to AUD 1.5 billion range this implies AUD 30 to 180 million in ductwork. Within the package, general supply and return is 25 to 35 percent, process extract and capture 20 to 30 percent, flue gas treatment train and stainless 25 to 40 percent, stack and AS 1318 5 to 10 percent, high-temperature alloy backing plate 3 to 8 percent, insulation and fire-rated sealing 8 to 12 percent. Composting and landfill biogas facilities run lower at 4 to 8 percent; contaminated soil thermal desorption runs higher at 10 to 15 percent.

12-hour reply

Got a waste-to-energy, landfill biogas, composting, e-waste, scrap metal, used oil, hazardous waste or contaminated soil ductwork specification question? An SBKJ mechanical engineer based in Box Hill North, Victoria replies within 12 hours — not a salesperson. We can review your concept duct schedule against AS 1668.2, AS 4254, AS 1318, AS/NZS 60079, NFPA 660, NFPA 86, NFPA 850, NFPA 855 and the EU IED dioxin emission standard 0.1 ng TEQ per Nm3, and recommend the machinery line that covers the package without sub-contracting.

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