Commingled versus Separation

Clear, brown and green container glass are increasingly being mixed before recycling in the UK, creating uncertainty for the glass container industry, further exacerbated by the new commingled collection methods and materials recycling facilities (MRFs).

The majority of container glass produced in the UK is clear, with a high level of clear exports, mostly through whisky bottles. Production of green glass is relatively low (around 300,000 tonnes a year) but high volumes of green are imported as wine bottles (around 600,000 tonnes). The chemistry of glass means that recycled green glass cannot be used to make new clear glass bottles. These factors create a fundamental imbalance between what is collected and the markets available.

The problem is being compounded by local authorities increasingly mixing glass colours in kerbside collection schemes, and more recently commingling such collections in MRFs.

The number of UK glass banks has been static for many years, and density is around half of that found in other EU countries. Some figures are even showing that the number of glass banks in the UK is dropping.

Why are glass recyclers worried about putting the material through MRFs?

There is concern in the glass sector about quality from MRFs, not only for container manufacture but for fibre manufacture also. Good quality recycled glass is declining as more and more local authorities and waste management companies become reliant on MRFs. The material coming from some MRFs is only suitable for low grade applications such as replacement aggregate. By degrading recycled glass in this way means the environmental benefits associated with closed-loop recycling will be lost.

Could more front-end sorting at MRFs help improve quality?

Some companies are looking at additions to MRFs, especially at the front end but this also brings with it cost implications. Who will pick up the cost? For glass manufacturers the raw material prices are relatively low compared to recycled glass, and from a commercial perspective companies are going to want to pay more when an alternative collection method already exists in the form of bring banks that deliver high quality colour-separated glass material at a reasonable price but is less favoured because participation rates are not as high. There has always been a value for the material collected and a higher price is paid for clear over mixed and green glass so there has always been a financial incentive.

Is quality suffering because MRFs are operating over-capacity?

Over capacity is one reason why some MRFs are operating at levels they were not originally designed for. However, in some cases, it is more a case of adding in other materials - where for instance an MRF is designed to take paper, plastic and metal, and then adding in glass and textiles. Somes MRFs are not designed for five materials, but were designed for three and therefore the equipment required for the additional materials has been added as an afterthought.

What about over-compaction?

Some of our Members have raised the issue of compaction on vehicles, with some giving examples of compaction rates rising from 7% to 70%. This is then fed into the MRFs and adds to the capacity issue. Compacting more also means that materials are broken and tangled together. Trying to untangle materials and retrieve quality output once compaction has taken place is almost impossible and adds to the processing requirement.

What about having a Quality Standard agreed across the recycling chain?

Quality Standards aready exist with regard to glass: BSI: PAS 101 Recovered Container Glass: Specification for quality guidance for good practice in collection and BSI: PAS 102 Specification for processed glass for secondary end markets. Both of these were commisioned by WRAP and are available through WRAP. These Standards are accepted by the glass industry and MRF-produced glass should strive to meet these Quality Standards.

If a blank slate was produced what would be the ideal way to achieve the best quality recyclate glass?

From a glass point of view, the bring bank system - which has been operating in the UK for the last 30 years - is best. Not only does it work well here but in other countries and could be made to work for flats. It has been proven in many studies that closed-loop recycling is the best use of recycled glass. It should not be forgotten that glass is amazing - it can be recycled endlessly back into bottles and jars. Other uses of glass waste not suitable for container manufacture includes water filtration systems, shot blasting, added to bricks and ceramics, in aggregates and turned into decorative products such as pavings.

By not separating glass colours and not growing glass bank systems, the UK is in danger of heading in the wrong direction and perhaps irrecoverably. The unique nature of the UK market is not being recognised in the way we have developed our recycling legislation and glass collection infrastructure.

Getting a Balance: Click here for more information on the problems glass recycling in the UK faces caused by colour imbalance.

For more information on the glass industry in the UK visit the British Glass website.

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