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Both eyes on the prize

Commercial and industrial (C&I) waste is generated from a wide variety of sources, and typically contains a broad selection of materials, including metals, plastics, wood, paper and card. Sorting visually similar materials, such as different polymers, from each other has been largely resolved using optical sorting systems. But separating different forms of the same material - such as wood from paper - has proved far more of a challenge.

TiTech has developed an optical sorting system that solves this problem by using twin near infra-red (NIR) sensors to examine different parts of the spectrum. This dual-sensor system has been installed for the first time in the UK at Wastebeater’s C&I MRF in Belfast, Northern Ireland.

The twin-sensor system is particularly good at identifying materials that are traditionally difficult to sort because they are very similar to one another, such as wood and paper

During the past five years, Wastebeater’s MRF has witnessed significant changes in the composition of the C&I waste stream. The waste entering the plant has become much lighter, and now contains greater quantities of plastic film, paper, card and rigid plastics. This has had serious implications in terms of materials sorting because the original technology was not extracting all the potential value from the waste.

Wastebeater managing director Kieran Byrne says: “We knew there was a strong market for clean recycled materials, so we wanted to develop a sorting process that would allow us to derive high-value, high-purity fractions from the waste. We investigated all the possibilities and decided that optical sorting would be the most effective.”

The process that Wastebeater designed using optical sorting was so advanced that there was no model to follow in the UK; this made developing the plant more challenging. But TiTech was able to demonstrate how its technology worked in a number of applications at different sites, including C&I waste sites in Europe, and the results it could achieve for different fractions.

During the first phase, four TiTech systems were installed to sort the 2D fraction of the plant’s waste stream and target film and paper. The TiTech team worked closely with Wastebeater during an initial six-month bedding-in period to make sure the new systems were delivering optimum performance.

In 2010, TiTech was asked to install a second phase, this time to recover materials from the 3D fraction such as heavy paper, wood and mixed plastics. Three further sorting systems were supplied, with one unit targeting paper, one unit targeting wood and the third unit providing a clean-up on the wood line while also extracting plastics.

Targeting wood from the 3D fraction was a new application for TiTech in the UK. The installed systems incorporate the company’s latest twin NIR sensing technology. This can gather greater amounts of information about what is on the belt, providing a highly accurate assessment of the materials that are passing through. The twin-sensor system is particularly good at identifying materials that are traditionally difficult to sort because they are very similar to one another, such as wood and paper.

The dual-sensor system is so accurate that it provides Wastebeater with at least 98% purity of recovered wood. In addition to providing the MRF with increased levels of saleable products, TiTech technology has helped the plant to make significant cost savings, as Byrne confirms.

“We are now processing up to six times as much waste per hour while achieving significantly higher recycling rates compared with more traditional labour-intensive operations. This new system has further enhanced our competitive edge in the UK recycling industry,” he says.
Steve Almond is a sales engineer at TiTech UK

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