In line with our decade’s resolutions released in January this year, we believe it’s about time to have a closer look at our “Don’t Waste” objectives. Our goal as environmental scientists and engineers has always been to move towards the top of the Waste Hierarchy (Figure 1): avoidance and waste minimisation. For us, it is becoming ever more urgent to rethink our waste.
According to the National Waste Report 2018, waste generation has increased over the past 10 years by 3.9Mt (6%) (Department of Agriculture, Water and the Environment 2020). With more limited opportunities to export plastics, for example, China’s 2018 ‘National Sword Policy’ has banned international imports, Australia must look internally for waste solutions.
Many states have been looking at waste management strategies recently. From an air quality perspective, one of the biggest challenges is balancing the benefits of the circular economy whilst maintaining good air quality. How can governments ensure that the strategies that they develop today will be good for us in the long run?
In this article, we’ll provide an overview of waste management strategies benefits and disadvantages. We’ll also discuss important strategies that help minimise the emissions of pollutants to the air and mitigate the risk to the environment.
Common Air Pollutants
The air quality concerns that are common to most waste management facilities are the emissions of dust (TSP, PM10 and PM2.5) and odour. Where combustion is involved (e.g. landfill gas), oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) are also important. Combustion of waste is also likely to generate a number of additional air pollutants that require appropriate management and advanced emission control systems.
However, it is safe to say that strategies that avoid the disposal of waste in landfills are preferable where they have an otherwise positive impact on the environment.
A promising trend
Whilst the highest priority is avoiding waste production, there are some interesting trends now emerging in areas of reuse, recycle and energy recovery to deal with the waste once it has been generated.
Recent advances in resource recovery technologies have prompted Waste Management companies to invest in sorting solutions that aim to recover potentially valuable resources whilst reducing the amount of waste that goes into landfill.
Materials Recovery Facilities (MRF) for instance, employ mechanical sorting systems to separate waste into its useful constituents. The products of sorting are mainly for reuse or sale to processors, sometimes overseas. Clean MRF technology is already well-established and quite developed in Australia and internationally especially in conjunction with kerbside collection programs. Such facilities are potential sources of dust and odour, which are generally manageable in most circumstances.
A Process Engineered Fuel (PEF) facility processes source-separated waste to produce a fuel that can be substituted for fossil fuels. PEF can be a sustainable alternative that harnesses the energy already contained in some combustible materials such as plastics, textiles, cardboard, paper and wood that would otherwise be disposed of in a landfill. A PEF facility can generate dust and odour emissions, which like a MRF, are generally manageable.
The Air Quality Challenges
There is a range of activities that are associated with reuse, recycling and recovery of energy from waste that generate air emissions. For example, shredding and screening of material can be a source of dust emissions. Similarly, air sorting systems generate dust that is generally captured by bag filtration or similar systems. Facilities that receive and process organic wastes are potentially a source of odours as the wastes biodegrade. So these facilities need to be designed to manage and control odorous emissions. Respirable crystalline silica can also be emitted from activities involving crushing, grinding or other mechanical breakdown of silica-containing materials such as concrete.
Combustion of some types of wastes has the potential to produce air toxics (e.g. heavy metals, VOCs and dioxins). Modern energy recovery facilities effectively capture or prevent these air pollutants from being generated and emitted ensuring that these facilities can operate safely.
The net environmental benefits of reuse, recycling and recovery of energy are expected to outweigh the emissions of pollutants to air when appropriate management and controls are in place. A study from the NSW EPA, for example, based on a Life Cycle Assessment methodology (NSW EPA, 2010) confirmed that “recycling generates environmental benefits”. However, this alone is not sufficient to gain development approval. The proponent of any new facility needs to demonstrate its environmental suitability.
In Katestone’s experience, the following aspects are critical to minimise the potential for air quality impacts from waste recycling activities: site selection, dust management, odour management and management of potentially toxic emissions.
Site selection is important for any facility and is particularly important for waste facilities with residual emissions to air. Site selection should account for the proximity of sensitive receptors, meteorological and terrain features that may influence dispersion, existing air quality, compatibility with nearby land-uses and risk of future encroachment. Whilst certain emission controls can improve the suitability of a site, it is important to have contingencies in place in the event that controls fail.
Dust management usually takes the form of filtration systems on process building vents, enclosure and water controls on crushing, grinding and sizing activities, watering of unpaved haul roads, cleaning of paved roads and management of stockpiles and cleared areas. Proactive management through monitoring and dust risk forecasting, whilst new to the waste industry, has proven to be very effective in mining and quarrying allowing better outcomes whilst optimising resources.
Odour management and control can be achieved in some instances through siting or the selection and management of incoming waste streams, which can limit the need for active odour controls. Whilst remote sites can have an advantage, encroachment by sensitive uses is commonplace in many areas. Retrofitting odour controls is usually difficult and costly.
Where potentially odorous wastes are a key feedstock, careful design, planning and management are necessary. Targeted odour collection and extraction to biofilters, scrubbers and activated carbon filtration are effective odour controls. Regulatory agencies will require data (e.g. dispersion modelling, performance guarantees) to demonstrate that the controls will meet appropriate benchmarks.
Where toxic emissions may be generated, proven best practice controls will need to be implemented. Regulatory agencies will require data to demonstrate that the controls will meet appropriate emissions and health benchmarks.
This July, the Australian Government has announced that it will commit $190 million to a new Recycling Modernisation Fund (RMF) expected to generate $600 million of recycling investment and drive a billion-dollar transformation of Australia’s waste and recycling capacity.
“The RMF will support innovative investment in new infrastructure to sort, process and remanufacture materials such as mixed plastic, paper, tyres and glass, with Commonwealth funding contingent on co-funding from industry, states and territories.” (Australian Government 2020)
The strategy is being praised for its job-creating capacity, among other things. We see this as a great opportunity for companies to develop and modernise their activities. Air quality is a key component in the viability of waste facilities. Benchmarking studies can be conducted to inform best practices and improve emission controls, which will assist the industry to future-proof their investments.
Energy from Waste Facilities
Combustion of waste is not new. Its use as a waste disposal option in Australia diminished significantly during the 1980s and 1990s. This was, in part, because of its potential to generate toxic emissions and its focus on volume reduction rather than energy recovery.
Globally, Waste-to-Energy (WtE) or energy-from-waste (EfW) has been a hot topic for many years; however, it was relatively recently that large, mixed residual WtE facilities started gaining traction in Australia.
New technologies can control toxic emissions allowing combustion of waste for energy generation to be viable. To obtain approval, Governments expect proponents of WtE facilities to demonstrate that:
- Emission control technologies are proven, effective and robust for the waste input streams
- Best practice management and controls will be implemented
- Regulatory limits will be achieved
- Health risks will be minimised.
There are also a wide range of alternatives to direct combustion that can utilise the energy content of wastes, including:
- Anaerobic digestion: where controlled decomposition of organic materials produce methane and other gases that are captured and combusted to generate heat and electricity.
- Gasification or pyrolysis: where organic materials are combusted in low oxygen environment to generate a syngas that can be used for a range of purposes.
Besides the reduction of waste going to landfill, electricity generated by WtE facilities can displace fossil fuel usage and may be eligible for the Emissions Reduction Funds.
How can Katestone help?
Katestone is experienced in conducting thorough air quality assessments of all types of waste facilities. Katestone’s work is highly regarded by industry, governments and other stakeholders. We assist our clients to address regulatory compliance obligations and to design and operate their facilities in a manner that contributes to the wellbeing of the neighbouring population.
In our 30 years of operations, we have conducted many air quality assessments, peer reviews, greenhouse gas assessments, plume rise and odour assessments for planned and operational waste management facilities.
Katestone is also experienced in NPI and NGERs reporting for waste facilities.
Notes about this article
Some of the references used in this article can be found below:
- Department of Agriculture, Water and the Environment. 2020. National Waste Report 2018 | Department of Agriculture, Water and the Environment. [ONLINE] Available at: https://www.environment.gov.au/protection/waste-resource-recovery/national-waste-reports/national-waste-report-2018. [Accessed 29 July 2020].
- Epa.nsw.gov.au. 2010. Environmental Benefits Of Recycling. [online] Available at: <https://www.epa.nsw.gov.au/-/media/epa/corporate-site/resources/warrlocal/100058-benefits-of-recycling.pdf> [Accessed 13 July 2020].
- Australian Government. 2020. Joint Media Release: $1 Billion Waste And Recycling Plan To Transform Waste Industry | Ministers. [online] Available at: <https://minister.awe.gov.au/ley/media-releases/1-billion-waste-and-recycling-plan-transform-waste-industry> [Accessed 13 July 2020].
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This article featured in the Katestone’s Clear Skies 2020 Winter edition. Click here to view other featured articles.