Reducing the landfilling of biodegradable and other wastes: call for evidence

6. Questions

6.1 Sorting residues and other mixed waste

The majority (around 86% in 2022) of waste landfilled in Scotland is under three waste codes: the mixed waste codes EWC 20 03 01 (mixed municipal waste) and EWC 19 12 12 (other wastes (including mixtures of materials) from mechanical treatment of wastes other than those mentioned in 19 12 11); and soils EWC 17 05 01 (Soils).

Sorting residues is an umbrella term that encompasses residue from several waste codes^[9]. The amount of sorting residues arising has increased as more waste from all sources is treated to recover useful material rather than being landfilled directly. For example, almost no mixed construction and demolition waste is now directly landfilled, a significant change over the past decade.

Following implementation of the ban on landfilling BMW, it is unlikely that any EWC 20 03 01 wastes will be able to be accepted at landfills in Scotland.

Given the broad definition and use of the EWC 19 12 12 code to classify waste from a range of sources, it is difficult to estimate the amount of these wastes arising from the treatment of non-municipal wastes. We are seeking to better understand the amount and nature of sorting residues from non-municipal sources that may be landfilled after implementation of the landfill ban.

Sorting residues are one of the least well understood waste streams. While we know that around 53% of the sorting residues landfilled in Scotland were landfilled under the lower rate of Scottish Landfill Tax, and 47% under the higher rate, this does not provide information on the characteristics of environmental risks of these wastes. Recent sampling carried out on these wastes by England’s Environment Agency highlighted significant variability and potential environmental risk. We are, therefore, keen to gain a better understanding of the characteristics of these wastes to inform policy development. In particular we would welcome evidence on the composition and biodegradability of sorting residues from non-municipal sources.

Sorting residues are also difficult to manage and a source of non-compliant activity in the waste industry – misclassification and misdescription, landfill tax avoidance and illegal disposal are often associated with these wastes. There is very limited use of this fraction as it stands and, depending on the source and composition it may be only suitable for further sorting, incineration or landfill. Moreover, some of these sorting residues will also be unsuitable for incineration and landfill may be the only disposal option. We would welcome information on options to divert sorting residues from landfill, and what characteristics could make sorting residues only suitable for landfill.

In its recent Call for Evidence, Defra noted an intention to explore further separation of waste fines from mixed waste coded as 19 12 12; with waste fines being considered the smaller fractions of waste produced by any waste treatment process. Given the variability in sorting residues, the definition of some waste codes, for example fluff (19 10 04) and soils (17 05 01), may be particularly broad and capture a range of wastes. We are interested to gather initial opinions on whether there are benefits or drawbacks to aligning our approach in Scotland with those in England, if they do ultimately decide to create separate waste codes.

6.2 Other potentially biodegradable non-municipal wastes to landfill

While data on municipal waste streams is generally good, information on non-municipal wastes is poor. We are undertaking work to improve this data, potentially including composition analyses and the development of a mandatory digital waste tracking service, which will both improve information. However, there will still be uncertainties around the characteristics and potential treatment options for wastes. We are therefore seeking information on waste that is likely to be highly biodegradable, particularly on their biodegradability and barriers to diverting them from landfill.

Table 6.2.1 sets out the waste streams that are likely to be biodegradable and where over 1000 t of these wastes were landfilled in 2022. Table 6.2.2 sets out the waste streams where over 1000t was landfilled in 2020 that might be biodegradable.

Impacts and alternative treatment methods for biodegradable non-municipal waste

For some wastes, particularly mixed wastes, that are unavoidable and unrecyclable, incineration is the most common alternative to landfill. One barrier to diverting waste from landfill may be the lack of suitable treatment options either due to the suitability of technology to treat the waste, or the lack of capacity locally of treatment options. We also recognise, however, that for some wastes, landfill may continue to represent the best environmental outcome, particularly where wastes have no alternative treatment route.

We are, therefore, interested in what alternative treatments, including pre-treatment processes, are available and emerging for the treatment of biodegradable wastes, particularly those set out in tables 6.2.1 and 6.2.2.

The forthcoming ban on landfilling biodegradable municipal waste has led to investment in alternative treatment infrastructure, primarily energy from waste. However, the Independent Review of the role of Incineration in the Waste Hierarchy noted that site locations were often driven by a series of commercial considerations, and therefore not necessarily strategically located in terms of a national spread.

In addition, we are keen to understand what the Scottish Government could do to support the development of the right infrastructure in the right place to manage wastes being diverted from landfill.

6.3 Soils to landfill

Soils and mineral wastes make up over a third of waste landfilled in Scotland. Some of this is used as backfill and for engineering purposes on sites.

The landfilling of soils (topsoil and subsoils) is generally assumed to lead to lower greenhouse gas emissions than the landfilling of some other wastes. However, the organic matter in topsoil is a valuable carbon sink and a rich biodiversity habitat. Activities such as the construction of buildings and infrastructure, as well as the drainage of soils to create public open space, can reduce levels of organic matter in soils and release carbon. In the our Circular Economy and Waste Route Map we set a proposed action to 2030 to investigate and promote ways to reduce soil and stones disturbance, movement and volumes going to landfill. This proposed intervention will focus on improving our understanding of the opportunities to reduce soil disturbance, and soil movement within and off site.

Given this intervention in the Route map, and that the purpose of expanding the ban to non-municipal biodegradable wastes is to reduce generation and emission of methane from landfill, we propose to exclude soils from an extension of the ban. However, we want to ensure that we continue to encourage the reuse and recycling of soils where possible.

6.4 Testing of non-municipal biodegradable wastes

The tests and thresholds to determine if municipal waste is biodegradable and whether or not it can be accepted at landfill once the ban comes into force (31 December 2025) are set out in legislation^[10]. SEPA’s guidance notes that the biodegradability of some wastes can be determined based on their composition, for example it is likely to be fair to assume that wastes such as glass or metal are not biodegradable.

The legislation for the biodegradable municipal waste (BMW) ban sets out two approaches to test the biodegradability of BMW, depending on the treatment method. For incineration residues, the legislation allows for total organic carbon (TOC) and waste with a TOC of equal to or less than 5% is able to be accepted at landfill. For other forms of waste treatment such as bio-stabilisation the landfill regulations also specify biodegradability thresholds:

• Respiration activity after a static respiration test (AT4) is less than 10 milligrams of oxygen for each gram of dry material (10 mg O2/g dry matter); or
• Dynamic respiration over one hour is less than 1000 milligrams of oxygen for each kilogram of volatile solids.

While we expect these methods to be suitable for testing BMW waste, it is unclear if these testing approaches will be suitable for the potential range of non-municipal wastes that could require testing to determine their biodegradability ahead of landfilling, if the BMW ban was extended to include other wastes.

6.5 Other (likely non-biodegradable) waste

Mattresses

Scotland discards approximately 12,500 tonnes of mattresses each year. There is currently limited reuse and recycling of EoL (end of life) mattresses in Scotland with the majority collected with furniture and other miscellaneous bulky household wastes and processed, with some difficulty, for incineration with energy recovery, or landfilled. However, international schemes have resulted in increases in mattress reuse and recycling of up to 80%.^[11]

Mattresses are a problematic waste-stream for several reasons. They are greater in volume than weight, are notable within fly tipping incidents, and pose safety issues for landfill operators. There was a 7% increase in mattress and furniture fly-tipping incidents in 2020/21, 16% of all incidents. This results in an unwanted financial burden on local authorities, and therefore the taxpayer, as well as on local landowners. In addition:

• their low density and large bulk make transportation costly,
• being difficult to compact means they form voids in landfill where explosive methane gas can accumulate,
• they cause damage to Refuse Collection Vehicles (RCV) at landfill sites,
• the spring-sets are difficult to shred, prior to incineration,
• and their shape blocks the hoppers in the energy from waste plants.

There are a number of mattress reuse initiatives in Scotland, along with several operators in Scotland recycling materials from mattresses and reducing the amount of waste sent for disposal at end-of-life. However, we understand that reprocessing capacity is underutilised, while reprocessed material can be of relatively low value.

Collection is considered to be one of the most crucial barriers to increased mattress reuse and recycling by stakeholders across the supply chain. Unlike waste streams such as packaging, there is no direct mandate for Local Authorities to reuse or recycle mattresses and hence it is undertaken on an ad hoc basis. Some end of life (EoL) mattresses are collected through retailer take-back schemes, where an old mattress is collected with the delivery of a new one. The data and destination from this are unknown.

We are interested in your opinions on the barriers and opportunities to divert more mattress away from disposal and further up the waste hierarchy. It is important to note that this is focused on landfill, however we welcome any further comments on barriers felt regarding recycling mattresses.

6.6 Policy interactions and timings of an extended ban on biodegradable waste

The amount and composition of residual waste produced is largely dependent on decisions around the use and treatment of materials higher up supply chains and actions to manage materials further up the waste hierarchy.

Our Circular Economy and Waste Route Map^[12] sets out a range of measures that will support the management of materials further up the waste hierarchy, including a product stewardship approach to prioritise how we tackle the environmental impact of priority products; actions to reduce food waste at household and business-levels; supporting the development of regional Scottish hubs and networks for the reuse of construction materials and assets; and the co-design of a new Household Recycling Code of Practice to modernise recycling services.

In addition to these actions, the Decarbonising Disposal section sets out a range of actions to reduce the environmental impacts of disposing of unavoidable and unrecyclable waste. These include:

• Supporting the expansion of the UK Emissions Trading Scheme to include incineration and energy from waste, which will put a price on fossil emissions from these sectors;
• A Residual Waste Plan to ensure the best environmental outcome for unavoidable and unrecyclable waste and set strategic direction for management of residual waste to 2045 (see Section 6.9)
• As part of the Residual Waste Plan, develop a Sector-Led Plan to Reduce Carbon Impacts of the Energy from waste Sector, to ensure we minimise environmental impacts of disposing of waste.

The actions set out in the Route Map will support the reduction of both biodegradable and non-biodegradable wastes sent for disposal. In addition to government-led policies such as the Scottish Landfill Tax and the ban on landfilling biodegradable municipal waste, organisations are increasingly implementing their own policies to divert as much waste from landfill as possible, as part of their Environmental Social and Governance considerations. We are interested in views on whether there are additional policies, either government or organisational led that could encourage the diversion of wastes, particularly biodegradable wastes, away from landfill.

Scottish Landfill Tax continues to be an important driver for the diversion of waste away from landfill. There are currently two tax rates, a higher rate for active waste and a lower rate for inert waste, which are charged at £103.70 and £3.30 per tonne, respectively, (from 1 April 2025, new rates of £126.15 and £4.05 apply). Following the ban on landfilling biodegradable municipal waste to landfill, a large proportion of waste falling under the standard rate of Scottish Landfill Tax will not be able to be landfilled in Scotland. We would welcome views on whether there are potential changes to Scottish Landfill Tax, or other fiscal levers, that could incentivise the diversion of waste that will not fall under the ban on landfilling biodegradable municipal waste from landfill.

Implementation of the ban on landfilling BMW, and evidence from experience across Europe, has highlighted the need for both early announcement of any bans as well as early action by the private and public sector to ensure preparations are in place ahead of a ban coming into force. However, this must be balanced with a need to act quickly to tackle the climate crisis; we know that earlier actions result in greater climate benefits.

6.7 Impacts and unintended consequences of reducing waste to landfill

Extending the ban on landfilling biodegradable municipal waste to include biodegradable non-municipal waste, and potentially other waste streams, could increase the costs of managing those wastes due to the cost of alternative processes and the need for additional testing for example. Any increase in the costs of managing the waste is likely to result in additional costs for businesses and local authorities. We are interested in any evidence you may be able to share on the costs of alternative treatments for any of the specific waste streams detailed in this Call for Evidence.

In addition, as with any policy that raises the cost of or limits waste treatment options, there is a risk that extending the ban would lead to an increase in flytipping. We would welcome any evidence of where there has been an increase in flytipping.

There may be wider implications of reducing waste to landfill. For example, reducing biodegradable waste to reduce emissions will also reduce the gas available for captured and use, reducing a potential revenue stream for landfill operators. We are therefore interested in any other impacts that could occur as a result of reducing waste, particularly biodegradable waste, to landfill.

6.8 General comments and views on expanding the ban

If there were any comments, opinions or evidence that you would like to provide related to landfilling or the management or residual waste in Scotland, but there were no relevant questions to respond to, we would welcome these here.

6.9 The Residual Waste Plan

The Scottish Government has committed to the development and delivery of a Residual Waste Plan (RWP) to ensure the best environmental outcome for unavoidable and unrecyclable waste and set strategic direction for management of residual waste to 2045.

Waste systems are highly complex and there are a variety of factors that will influence the future volumes, compositions and types of waste that need to be managed in Scotland, and which need to be strategically considered over the long-term.

Recognising the move to a circular economy will have an impact both on the amount and composition of residual waste in the future, it is essential that we:

• manage materials that cannot be avoided, reused or recycled are managed in a way that minimises environmental and societal impacts;
• ensure we have appropriate capacity (incineration and landfill) to manage any residual waste we do produce;
• have a clear strategy to move away from landfill to avoid abandonment, significant costs to the public purse, and minimise environmental and public health impacts.

The RWP will encompass these objectives through a range of actions, including:

• Building on current data to improve our understanding of the current and future residual waste streams.
• Make recommendations on Scotland’s long-term infrastructure requirements to manage waste by publishing an indicative cap to inform planning and investment decisions on future Energy from Waste (EfW) capacity requirements.
• Identifying priority waste streams and actions to reduce the environmental impact of their disposal.
• Considering how other technologies could support management of residual waste as we move to a circular economy.