Waste wisdom

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Waste management may not sound dangerous but inherently hazardous processes are plentiful in this sector. How to mitigate the several safety challenges faced by the industry?

Whether waste is processed to facilitate recycling, or shredded down to create a fraction that can be used as an energy source – to substitute fossil fuels – the activities associated with handling materials in this matter are often extremely complex. And with this complexity come inherent hazards, which responsible operators must carefully manage to protect personnel and the environment.

For people outside of the industry, this may come as a surprise – ‘rubbish’ hardly sounds dangerous. However, the wealth in waste means that more materials are being processed than ever before, in increasingly larger plants, complete with heavy industrial machinery.

Over the five-year period 2012/13-2016/17, the fatal injury rate to waste workers was 6.8 fatalities per 100,000 – around 15 times greater than the rate across all industries during the same timeframe. The safety challenges are, therefore, vast.

Material-specific challenges

Specific waste streams present safety challenges of their own. It is widely acknowledged, for example, that Waste Electrical and Electronic Equipment (WEEE) such as refrigerators and computers, comprise various potentially toxic substances, including cadmium and mercury, which must be handled
by authorised transfer stations to prevent seepage into the general waste stream and, consequently, a danger to public health.

However, with approximately 50 million tonnes of e-waste created globally each year – and increasingly stringent legislation such as the WEEE Directive regulating its compliant treatment – the illegal trade of such waste does still occur. The sad fact is that some people simply want to cut corners, especially if it means greater access to the level of high-value recyclates, such as gold and copper, within these products.

Of course, this is one very specific example. But the important thing to note is that even general household waste, for example, can pose multiple hazards for the people charged to handle it. And this isn’t just the case if operators cut corners.

Electronic equipment such as refrigerators and computers contain potentially toxic substances, which can be dangerous to health. Photograph: iStock/pic_studio

Improved safety by design

In line with a commitment to the waste hierarchy, most Municipal Solid Waste (MSW) and Commercial & Industrial (C&I) waste generated in the UK is now sent for specialist treatment in plants such as Materials Recycling Facilities (MRFs). Engineering innovations mean such plants can achieve maximum environmental compliance, often with high degrees of automation. But plants contain industrial machinery that must be safely operated to protect the wellbeing of staff and the wider communities.

Multi-tonne shredders, for example, can now process virtually all waste streams – even seemingly ‘unshreddable’ materials such as cars. This process, admittedly, sounds risky. However, many safety mechanisms are now, thankfully, being designed into such machines as standard. For instance, touchscreen control panels are commonplace, should the operator need to explore and diagnose a fault, without the need for machine ingress. 

But modern safety challenges have prompted further machinery and process innovation.

Noise concerns

The issue of noise risk is currently growing in the UK, for instance, and the existence of Noise Action Week in May evidences the efforts being deployed to address the matter. Defra’s official support for this initiative perhaps further stresses the need for greater noise considerations within the environmental sector.

The Control of Noise at Work Regulations 2005 govern the protection of employees’ hearing, so ear defenders have long been essential within industrial waste plants.

However, savvier firms have started to demand more, keen to cap the number of decibels that their plants operate at. As a result, facilities are now being designed to run below the first dB(A) action point. Because some waste shredders can now function below 80 decibels, for example – especially those with quiet electric drives rather than gas-guzzling diesel engines – hearing protection is not necessary.

Not only does this shield operators from the debilitating effect of prolonged exposure to excessive noise, it also supports morale, sustains productivity and, in the simplest of commercial terms, saves money on ear defenders.

It also helps operators navigate planning constraints and community complaints, as plants need no longer disrupt neighbouring residents.

Some firms are starting to cap the number of decibels that their plants operate at, to reduce the noise risks. Photograph: iStock/vm

Fire risks

The risk of fire is also significant within this industry – in fact, an article in The Guardian last summer reported on typically 300 fires per year at UK recycling plants.

The storage of waste is part of the problem. The Environment Agency dictates that sites with environmental permits for waste handling must also have a fire prevention plan. This document must summarise all possible fire risks – including self-combustion – and the mitigation measures implemented to manage them. The maximum height of a waste pile is 4m, for example, but there are further pile-size stipulations according to material type, particle size and whether the fraction is loose or baled.

Sprinkling systems are extremely important for obvious reasons, operators need to do their utmost to keep plants tidy and dust-free, and a thorough cleanse of the floor and all machinery is advised at the end of each day. But innovative machinery features can further help avert otherwise catastrophic incidents.

Carefully positioned UV, infrared, heat and spark detectors on a shredder’s hopper and discharge conveyor can, for example, now sense when a fire is likely to begin. In the event of a significant temperature increase, extinguishing nozzles, positioned in the same place as the sensors and thus pointing directly at the fire risk, can automatically spray water onto the targeted area. This means that, if the risk is within the shredder, the materials can be cooled and/or the fire put out before anything is discharged from the machine. If the problem is on the conveyor, the nozzles prevent hot, glowing fractions from entering the pile of output material, where a fire could otherwise propagate. Alarms can even be activated to alert the operator to start a manual extinguishing process, and/or notify the fire brigade.

Explosions are somewhat different. These can be caused if a ‘foreign object’ such as an aerosol tin bursts due to heat or compression, or if a small electrical spark creates enough of an ignition when it reacts with high volumes of dust. To prevent such scenarios, more responsible equipment manufacturers are again reducing risk by design. Rotor speeds have been slowed, for instance, to reduce the creation of dust, and lower tip speeds mean the potential for a spark is also lessened. Anti-explosive Atex-specification motors and electronics can be installed too.

Ergonomic considerations

As with many workplaces, ergonomics is also important. Waste and recycling machinery is therefore now being designed to ensure operators can service and maintain equipment quickly, safely and in an upright position, without the need to hunch or over-stretch. This is of paramount importance given the prevalence of musculoskeletal disorders affecting industry ill health (see chart 1). Shredders can now automatically stop if unexpected objects are detected, with the machine then ejecting the material so that the operator can simply open the door and retrieve the problematic item, without the need to enter the shredder’s cutting chamber. Again, this development is crucial, given statistics that show that of the 14 fatal injuries in industry in 2016/17, contact with machinery was the second most common cause (see chart 2).

A safety mindset

Of course, safety challenges stretch far beyond the implementation and operation of shredding and recycling machinery. A holistic safety mindset is required within the world of waste, and the Health and Safety at Work Act only sets the minimum baseline. Defra and the Environment Agency are working more closely to police and clamp down on unscrupulous waste sites, while the HSE will investigate breaches of safety legislation, whether general or specific to this industry.

But the driver to implement safer practices shouldn’t just be to stay on the right side of regulation. Standards vary internationally and in less-developed parts of the world, safety isn’t as heavily legislated. However, as plant designs and waste handling technologies are increasingly exported globally, this will hopefully raise the bar when it comes to the safety norm.

Marcus Brew is managing director, UNTHA UK


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