The amount of waste from liquid crystal displays (LCDs) is increasing at an alarming rate. By the end of last year over 100 million LCD television sets had been sold worldwide, but with no viable recovery techniques or safe disposal options available, the riddle of how to recover and re-use these materials remains unsolved.

With disposal in landfill or incineration no longer acceptable in most European countries, new solutions are needed. The scale and urgency of the problem was stressed by speakers at LCD Recycling – Problem or Opportunity?, an event held in York, UK, on 13 July 2010.

‘Liquid crystal displays are a fixture of modern life, appearing in everything from pocket calculators and mobile telephones to widescreen televisions’, said Dr Avtar Matharu of the Department of Chemistry at the University of York. ‘But the liquid crystals they contain are potentially hazardous and technological advances are so rapid that society is already discarding millions of LCD screens each year in favour of new types of light emitting diode displays.’

Speakers emphasised that recyclers need to act now and invest in the most appropriate technology to help recover and recycle materials from LCDs.

However, no one has yet been able to develop a suitable automated production process for safely dismantling them, relying instead on manually recovering materials, which is costly and labour intensive.

‘Factory workers in China are able to dismantle around 10 units per hour, producing well sorted items’, explained Martin Goosey of the Innovative Electronics Manufacturing Research Centre in Loughborough, UK. ‘On the other hand, automated shredders can process 5.4Mt per hour, however, recyclers then end up with a mixture of materials that are of a low quality.’

Obstacles ahead

An additional ‘purification process’ could be developed, continued Goosey, but the cost of developing and then implementing this extra step would be too high to make LCD recycling economically viable.

But the most pressing concern for recyclers is how to safely remove and dispose of
mercury, used in the fluorescent tubes that form the backlights in these displays.
Mercury is useful in lighting because it contributes to the bulb’s efficiency and life expectancy, but the Restriction of a Hazardous Substances Directive states that
it is illegal to expose people to more than five milligrams of the chemical. Each
fluorescent lamp can contain between 5-10mg of mercury.

‘They are extremely fragile and easy to smash and breaking one backlight bulb will exceed a factory’s hazardous emissions limit’, said Karl Williams of the Centre for Waste Management at the University of Central Lancashire, UK.

Williams added that, although the amount of mercury contained in each fluorescent tube might seem small when measured in milligrams, the large volume of LCD televisions estimated as being sold makes the issue a serious environmental concern.

Expanding solutions

Delegates at the event could be forgiven for thinking that LCD recycling is a ‘problem’, rather than an ‘opportunity’, but, during his second presentation, Matharu highlighted some of the work he and his colleagues had been undertaking as part of the University’s Government-commissioned Reflated project.

Matharu has been working on a recycling technique to transform LCD panels into dressings and human tissue-regenerating medicine.

‘The technique recovers the chemical compound polyvinyl-alcohol (PVA) from polarising films in waste panels’, he explains. ‘To do this we heat them in water in a microwave, then wash them in ethanol to extract the PVA in a porous, “expanded” foam.

‘This expanded version allows us to incorporate bioactives’, continued Matharu, ‘so we are effectively creating a bioactive sponge which then could be used to aid wound healing.’

Mathura is hoping that the technique will be made available to recyclers worldwide when the research project concludes next year.

Though delegates were hoping for more answers to the problem of LCD recycling, the complexities of the issue meant that more study is needed.