Solutions for the identification, separation and sorting of batteries and gas cartridges in waste management streams

Synthesis

Disclaimer: The content of this publication is based on the state of knowledge and the regulatory framework in force at the time of publication of the documents

Context of this study

Over the past fifteen years, accidents in waste management facilities have increased significantly, as highlighted by the French Bureau for Analysis of Industrial Risks and Pollution (BARPI) in its 2024 report. The report shows that in 2023, an increase in industrial accidents was observed in France, with the waste sector accounting for 20% of the events recorded in the ARIA database.

The analysis of these events across facilities with a wide range of activities (collection, sorting, recycling, thermal treatment, or storage) indicates that incidents are frequently associated with the presence, within waste streams, of items that are not suited to these treatment pathways. Among these items, batteries and accumulators (B&A), particularly lithium, as well as gas cartridges (gas cylinders, nitrous oxide or helium cartridges, etc.), appear to be major contributors to the increase in observed accident phenomena.

Fires and explosions represent major risks, both for the safety of operators and for the integrity of facilities and environmental protection. They also result in significant economic consequences for operators, due to material damage, operational downtime, restoration costs, as well as impacts on the insurability of facilities, which may lead to increased premiums, coverage restrictions, or even difficulties in obtaining insurance.

In this context, reducing the risks of fire and explosion in waste management facilities is a priority. This requires both regulatory developments and the deployment of operational solutions aimed at limiting the presence of these hazardous wastes in treated streams.

Recent work carried out within RECORD studies, particularly on managing the hazardous nature of lithium batteries during the collection and sorting of municipal and similar waste, highlights the value of technical characterization and detection systems. These systems aim to identify, upstream of treatment operations (manual or automated sorting, shredding, compaction, or incineration), the presence of hazardous items in order to enable their removal from waste streams.

However, although technological solutions are now available to detect these elements in various waste streams, their effectiveness, maturity, and deployment conditions still need to be further consolidated. Therefore, analysing feedback from real-world applications is essential to assess their ability to address the operational challenges faced by waste management systems.

Objectives of the study and methodological approach

The study aims to critically analyse existing and emerging solutions for identifying and separating hazardous items, namely batteries and gas cartridges, within waste management systems, with a view to reducing incidents at treatment facilities.

It focuses in particular on two categories of items:

• batteries, especially lithium-based ones (button cells, lithium-ion batteries), 
• single-use gas cartridges, with a particular focus on nitrous oxide cartridges.

These two categories share common safety challenges for waste management facilities while differing in terms of how they are present in waste streams and the level of structuring of their management systems. Nitrous oxide cartridges are given particular attention due to their rapid proliferation, increasing presence in collected waste, and their significant contribution to incidents involving pressurized containers, linked to their small size, dispersion within waste streams, and uses outside of domestic contexts.

The analysis is based on a combination of complementary workstreams aimed at integrating both technological and operational perspectives. It relies on:

• a literature review of the characteristics of the items and the associated risks in treatment facilities; 
• feedback from field stakeholders (operators, local authorities, professional organizations), providing insight into the real conditions under which incidents occur; 
• a benchmark of technological solutions, analysed in terms of their operating principles, maturity levels, integration conditions, and economic constraints.

Key findings

The work carried out as part of the study highlights several key findings.

--> Nitrous oxide cartridges: a regulatory framework still under development

Beyond waste management issues, the rapid development of misuse of nitrous oxide is associated with significant public health concerns, which are now a major driver of regulatory developments. The regulatory framework is therefore progressively taking shape at the intersection of market placement, waste management, and hazardous substance classification.

To date, these cartridges are considered household packaging and are integrated into the corresponding Extended Producer Responsibility (EPR) scheme, a classification that only partially reflects the risks they generate. Take-back obligations exist for distributors, but their implementation remains limited. 

From a waste perspective, European regulations provide for their classification as hazardous waste when residual gas is present. The revision of the CLP Regulation, applicable from 2027, will classify nitrous oxide as a hazardous substance, which is expected in practice to lead to the reclassification of non-emptied cartridges. However, this evolution raises operational challenges, particularly related to detecting residual gas under real conditions. 

At the national level, several regulatory developments are underway, aiming to better frame uses (restriction or penalisation of recreational uses) and to evolve end-of-life management, notably through a potential transfer to the EPR scheme for chemical products and containers (PCHIM).

At the European level, this classification could also lead to restrictions on market placement under the REACH Regulation, the implementation details of which remain to be defined. 

In this context, the regulatory framework remains in transition. While it tends to better acknowledge the hazardous nature of these products, it does not yet fully address the operational challenges faced by waste management stakeholders.

--> Lithium batteries and nitrous oxide cartridges: significant accident rates across multiple stages of waste treatment

Feedback collected shows that incidents related to the presence of batteries and nitrous oxide cartridges in waste streams are now reported in an increasing number of waste management facilities. Sorting centres and waste-to-energy plants are particularly exposed due to the mechanical and thermal processes involved.

In sorting centres, incidents most often occur when these objects are damaged during handling and treatment processes. In the case of batteries, mechanical stress can lead to internal short circuits likely to trigger fires on sorting lines. 

In waste-to-energy plants, nitrous oxide cartridges can cause incidents when entering incineration furnaces. Subjected to high temperatures, these cartridges may explode due to pressure build-up of the gas within the cylinder. These explosions can cause equipment damage and operational downtime. 

Operators also report incidents during handling or storage operations, for example when cartridges or batteries are present in compacted containers or intermediate storage areas. In such situations, risks may be amplified by mechanical compression phenomena. 

Beyond immediate safety risks, these incidents generate significant economic consequences. These costs are currently largely borne by downstream stakeholders, particularly treatment facility operators and local authorities, even though the origin of hazardous items lies upstream, at the production and use stages.

In this context, the increase in reported incidents highlights a growing challenge for both safety and operational continuity, as well as an uneven distribution of impacts and costs among stakeholders, to the detriment of operators and local authorities.

--> Significant dispersion within waste streams

The analysis of disposal practices reveals a high level of dispersion of hazardous items across different waste streams, which complicates their identification and management upstream of treatment facilities.

Batteries, particularly lithium-based ones, are now embedded in many everyday products, often small and difficult to dismantle, such as button cells. This widespread use leads to their significant presence in waste streams, with many items incorrectly sorted and frequently ending up in residual waste or sorting streams. The diversity of formats and their potential concealment within waste make detection difficult during sorting operations, contributing to their recurrent presence in treatment facilities. 

Nitrous oxide cartridges are characterised by strong dispersion in waste streams, linked to uses primarily occurring outside the home and the absence of clearly identified collection channels. They are frequently discarded in public spaces or disposed of with household waste. Their small size, high numbers, and similarity to other metallic objects make them difficult to detect during sorting operations, explaining their recurrent presence in treatment facilities. 

--> A developing technological landscape to improve detection of batteries and nitrous oxide cartridges in waste streams

The benchmark shows that a large share of solutions relies on automated waste stream analysis systems, combining detection technologies (computer vision, X-ray imaging, or other sensing technologies) with algorithmic tools to identify specific objects or characteristic signatures in waste streams. These systems generally rely on machine learning models or image databases to recognise hazardous items within heterogeneous flows.

In addition to these approaches, other solutions are based on more mechanical or organisational strategies. Some involve dedicated sorting systems or line modifications to isolate high-risk streams (pre-sorting zones, reduced throughput, separation by density or size). Others aim to mitigate risks without necessarily identifying objects precisely, for example through equipment protection systems (early fire suppression, containment, process adaptation) or enhanced operational protocols.

In most cases, detection technologies are designed to be integrated into existing facilities, particularly at conveyor level, to identify potentially hazardous objects and trigger their automatic removal from the waste stream. Ejection systems then allow these objects to be directed towards dedicated treatment routes or secured areas.

Some solutions also aim to intervene earlier in the waste management chain, for example during initial mechanical treatment stages or, more marginally, during collection operations.

Finally, the performance of these approaches remains dependent on the characteristics of waste streams, which are heterogeneous and difficult to analyse systematically. The presence of overlapping items, variability in shapes, and the condition of waste can complicate the identification and handling of certain hazardous objects.

Key learnings

--> A strong technological convergence

The analysis of the identified solutions highlights a strong convergence of technological approaches, mostly based on the automated analysis of waste streams through imaging and data-processing technologies. These systems combine detection devices (optical systems, X-ray technologies, etc.) with analytical algorithms capable of identifying specific objects or characteristic signatures within heterogeneous waste streams.

This convergence reflects the maturity of the technological building blocks involved, which are already widely used in other automated sorting applications. Their adaptation to the detection of hazardous items therefore follows a logic of functional extension rather than the emergence of disruptive solutions. As a result, the proposed technologies rely on similar architectures, with differences mainly related to their integration or the optimisation of their performance.

However, this technological homogeneity limits the sector’s transformation potential. In the absence of breakthrough innovation, the identified solutions appear more as incremental improvements to existing systems than as structural responses to accident-related challenges. Their ability to handle complex situations, particularly where waste items are overlapping or degraded, also remains limited, reducing their effectiveness under real operating conditions.

--> Integration constraints within existing facilities

The integration of these technologies represents a significant operational challenge that limits their deployment potential. Waste management facilities are designed to operate at high throughput rates, with highly optimised treatment lines, making the addition of new equipment complex.

The implementation of detection and ejection systems often requires significant technical adaptations, which may generate additional costs and operational disruptions. Above all, the effectiveness of these technologies strongly depends on the characteristics of the waste streams: detection becomes uncertain when objects are concealed, fragmented or mixed, which corresponds precisely to the most common situations encountered in facilities.

Industrial constraints (dust, vibrations, flow speed) also require the use of robust technologies, sometimes at the expense of precision. These factors highlight a gap between the theoretical performance of solutions and their actual effectiveness under operational conditions.

More broadly, although some solutions aim to intervene further upstream, the majority of identified systems remain positioned at the sorting and treatment stages, that is, at a point where waste has already been mixed. Such positioning limits the ability to address the structural causes of the problem, which are linked to consumption patterns, disposal practices and the lack of source separation.

--> An uncertain economic model

The deployment of these technologies also faces significant economic constraints. The required investments include not only equipment acquisition, but also integration costs, infrastructure adaptation, maintenance and operator training.

In a sector often characterised by limited profit margins, such investments can be difficult to amortise, especially when the targeted objects represent only a minor fraction of the treated waste streams. The expected benefits, mainly linked to accident reduction, also remain difficult to quantify accurately, complicating operators’ decision-making processes.

This situation leads to trade-offs between safety and economic viability and limits the large-scale deployment of the identified solutions. It also highlights an imbalance in cost distribution: downstream treatment facilities directly bear the consequences of incidents, even though their origin lies upstream, in product design, market placement and usage practices.

In this context, the question of financing these technologies more broadly raises the issue of the role of Extended Producer Responsibility (EPR) schemes and the ability of the regulatory framework to internalise the costs associated with the risks generated by these products.

--> Key regulatory challenges

Beyond the existing framework, the analysis highlights significant structural consequences linked to the current limitations of regulation. Regarding nitrous oxide cartridges, their classification within the packaging EPR scheme appears inappropriate considering the risks they generate. In practice, these costs are mainly borne by operators and local authorities, resulting in a transfer of burdens downstream along the value chain.

Furthermore, the presence of numerous market players that are difficult to identify or located outside the national territory (for nitrous oxide cartridges as well as batteries), particularly through online sales platforms, encourages “free-riding” situations. In practice, these actors evade their contribution obligations to Extended Producer Responsibility schemes, limiting the ability of such schemes to finance appropriate collection, treatment and prevention measures.

These economic and organisational imbalances reduce incentives to act upstream in the product life cycle and contribute to maintaining a high level of risk in treatment facilities. They also hinder the deployment of technical solutions, the costs of which cannot be absorbed solely by downstream stakeholders. In addition, the adoption at the European level of the new classification of nitrous oxide as a toxic substance is generating a degree of wait-and-see behaviour among stakeholders, pending clarification regarding implementation content and timelines.

In this context, the planned regulatory developments appear necessary to rebalance the distribution of responsibilities and costs, provided they are capable of encompassing all stakeholders and ensuring effective implementation.

Conclusions

The study highlights an increase in incidents related to the presence of batteries and nitrous oxide cartridges in waste streams, with significant impacts on treatment facilities. In this context, the technological solutions identified provide useful responses to improve the detection and separation of certain hazardous items.

However, their ability to fully address the identified challenges appears limited, at least in the short term. Their effectiveness is highly dependent on operational conditions and waste stream characteristics, while their deployment remains constrained by technical and economic factors. Furthermore, these systems are most often implemented at a stage where waste is already mixed, which may limit their capacity to prevent all risk situations.

At the same time, limitations in the regulatory and organisational framework (particularly regarding the allocation of responsibilities, financing mechanisms, and the consideration of actors outside the formal scope) contribute to maintaining a high level of risk upstream of treatment facilities.

In this context, technological solutions appear as relevant but insufficient levers, which alone cannot fully address accident-related challenges. Their deployment would benefit from being part of a more comprehensive approach, combining regulatory developments, greater accountability of stakeholders, and preventive actions aimed at reducing the presence of such items in waste streams.