Towards closed-loop recycling
Jade-Ashlee Cox and David Jesson, of the Faculty of Engineering and Physical Sciences, University of Surrey, UK, argue for a different approach to recycling.
Declining ore quality, speculation over peak oil, the availability of rare earth elements – in many quarters, there is a significant worry over the supply of key resources. The possibility of mining landfill has gone beyond speculation and is seen as a viable route to extract both high yield and valuable materials. However, it is often overlooked that there is a resource stream at our front doors. Some of this is recycled but much still goes to landfill (presumably to be mined in years to come). In some places, the message seems to be ‘recycling is solved’, as if all that can be done is being done.
In practice, Defra estimates that around 44% of Municipal Solid Waste (MSW) is recycled and 56% goes to landfill, incineration or energy from waste, but the situation is more complicated than these numbers suggest. For example, looking at the composition of waste for Surrey, a county with a population of more than 1.1 million, there are many materials in the waste stream, with aggregation of categories leading to opportunities for further recycling being missed. Paper and card combines daily newspapers, glossy magazines, junk mail, brown envelopes from the tax man, greasy paper takeaway bags and boxes. Worse, there are 16 different plastics in use for packaging, with some of these being relatively easy to reprocess and others less so.
In terms of disposal, packaging is possibly one of the most difficult areas to get right and is definitely a big problem for re-processors. Manufacturers and suppliers make a virtue of showing how they are reducing the mass of their packaging, which no one could object to as it reduces the mass transported and the fuel used to do so. However, polymer or foil laminated pouches and low-density polyethylene are currently difficult to recycle, especially when compared to glass or polypropylene.
Furthermore, given the efforts that are being put into achieving greater efficiency in extraction, refining and processing, with an increasing emphasis on the minimisation of waste, is it enough simply to ensure that the material doesn’t go to landfill (avoiding spiralling gate fees)? Or should the maximum value possible be extracted from the available resource?
In local government circles, waste management has some new regulations to consider – the Waste (England and Wales) Regulation 2011 (as amended), or WEWR. The WEWR, which aim to promote high-quality recycling and move us towards becoming a recycling society, require any organisation that collects waste to undertake a variety of assessments to determine the most suitable collection method. From January 2015, these assessments (including practicability, necessity and waste hierarchy tests) must be carried out to ensure that the MSW collected is processed to best effect. Most importantly, there is an expectation that waste collected complies with the waste hierarchy, which is more difficult than might be expected.
The WEWR are complicated and there is much uncertainty around how to comply with them, particularly when we consider the complexity of the waste supply chain. For instance, the waste hierarchy isn’t always the most appropriate tool, considering who has responsibility for the different levels – Local Authorities have little control over prevention (although campaigns to reduce food waste have been relatively successful). Some materials do not really fit with the hierarchy – Grade C wood, for example (comprised of flat-pack furniture made mostly from MDF, chipboard and plywood), is problematic because it is not possible to recycle or compost under current Environment Agency guidance. Further, due to the low quality of the material, preparation for reuse and upcycling by householders is minimal. The only plausible option besides disposal is other recovery – energy from waste.
A new road map
The task at hand is a challenging one, when you consider the number of players who have distinct roles and responsibilities for the collection and disposal of household waste. When it comes to collection and disposal agreements, these can be managed in-house by the Local Authority or carried out by a third-party contractor. Materials are then sent for sorting and from there on to a range of re-processors, where tracking the material and understanding its end destination becomes extremely difficult.
The Surrey Waste Partnership (SWP) took on this challenge and found that data collection along the supply chain was key to creating a successful model. Material capture, rejection rates, material destinations (national and international), transport type and facility energy consumption were considered together with secondary data, such as greenhouse gas emission inventories and fuel conversions.
Collection practices, waste composition and onward treatment facilities vary widely across the SWP and so three scenarios were considered:
- the current system
- optimised commingled
- optimised source-segregated
The assessments investigated the compliance of the current management systems to understand whether or not a separate collection was required in order to:
- produce more closed-loop recyclates
- assess practicability, and environmental and economic issues
- be compliant with the waste hierarchy
The results were, in some ways, surprising. Source-segregated collections were not necessary for paper and card, metals or plastics to generate more closed-loop recycling, and in seven out of the eight districts who submitted case studies to the programme, the environmental emissions were on average 5% higher than their current system. In the case of glass, while closed-loop recycling tended to be higher when collected separately (possibly as a result of the option to split glass into clear, green and brown), it was not necessarily practicable to do so, and led to a significant increase in both environmental and economic impacts (an increase of 9% and 12% respectively).
In most instances, the impact of total recycled material for commingled collections had a greater positive effect on the environment (8% reduction in emissions compared with the current system), as opposed to its source-segregated counterpart, as less waste overall was being treated residually. Fundamentally, recycling on this scale must be treated as a system and the optimum performance of the system may mean that individual parts do not achieve their full potential.
The implication of this work is that, while there are still market outlets for the materials being produced through a commingled system, separate collections in their current form would not improve the environmental and economic performance of Surrey’s waste management sector. It also indicates that optimisation, rather than reform, could substantially improve sustainability. In turn, this leads us back to the waste hierarchy – it is best to reduce the use of something or, if possible, design it out completely, but in itself that is not a practicable answer to the whole question.
As ever, the boundary conditions must be considered – the assessment carried out here is for an average recyclate that will, in due course, turn into something else. It certainly doesn’t consider all that nifty reuse that many do as a matter of course, turning old paper coffee cups into plant pots for seedlings, for example.
Sustainability is complex – it is a journey, not a destination. What is true today might not be true tomorrow. All we ever know for sure is that there is always something else that we can do, but in doing it we must be careful not to unbalance the system and cause negative impacts elsewhere. The WAWR have the potential to cause a lot of problems for Local Authorities, particularly those that have returned to commingled recycling collections. However, there are also a lot of opportunities for those seeking a new resource stream.