Controlling Legionella in Paper Mill Water Systems, Pulp & Papermaking Processes

Controlling Legionella in Paper Mills

Pulp and paper mills incorporate many processes that use water as part of their operation and this can increase the risks associated with Legionella bacteria and Legionnaires’ disease. Here we review guidance issued by PABIAC, the Paper and Board Industry Advisory Committee, supported by the Health & Safety Executive, dealing with the control of Legionella and other bioaerosols in paper mill water systems.

What are my legal responsibilities?

In the UK, under health and safety law, all employers and business owners are responsible for assessing potential dangers in their workplace and then taking practical precautions to control those risks to protect their employees and others. Part of this risk assessment process should include a consideration for the safety of water systems in relevant buildings, processes or elsewhere on sites and properties controlled by the employer. An Approved Code of Practice has been developed and issued by the Health and Safety Executive (HSE) on this topic. This is known as ACOP L8, titled ‘Legionnaires’ disease. The control of legionella bacteria in water systems’.

It’s important to note that the HSE’s ACOP L8 has a special legal status which means that if you are prosecuted for a breach of health and safety law, and it is proved that you did not follow the relevant provisions of this ACOP, you would need to demonstrate to a court that you complied with the law in some other way… otherwise you could be in trouble.

Pulp and paper mill water systems

However, not all water systems are identical and some may pose specific risks or create issues not seen in other scenarios. A good example of this covers the water systems in use in pulp and paper mills. These mills are concerned with creating paper products.

PABIAC, the Paper and Board Industry Advisory Committee, has developed a 23-page guide to help those responsible for controlling legionella and other micro-organisms within paper mill water systems. The guide provides further insight into the scope, background, and requirements for control measures in these circumstances.

It’s interesting to note that the Health & Safety Executive was involved in writing the report in conjunction with PABIAC. The HSE endorse the guidance given as it follows a sensible and proportionate approach to managing health and safety in pulp and paper mill environments.

What does the PABIAC guide cover?

Rather than covering water systems in general, the PABIAC guide looks at all the water systems and elements used in the pulp and papermaking process with a specific focus on the control of legionella and other bioaerosols. All sources of water in a typical paper mill including those that are stored, used, and present in aerosol form (with the potential for inhalation) are highlighted in the guide.

Various methods for processing paper are also mentioned. These include spraying, tanks, and atomisers. The report also highlights the difference between water sources and processes specifically used to make paper. It points out the guidance does not cover other water systems that would be present in any building, providing hot and cold water for use. These systems are already covered in detail in the HSE’s own guidance document HSG274.

How could paper mills be at risk of developing legionella bacteria?

The report points out that no UK outbreak of Legionnaires’ disease has ever been associated with papermaking. It also points out there are three elements of the pulp and paper product manufacturing process that could be identified as higher in risk:

  1. The use of recycled water.
  2. The possibility water spray (aerosol) could be created during the process.
  3. The chance of low-flowing or stagnant water sitting within the system.

Any or all these elements could produce a greater risk of Legionella bacteria multiplying to potentially dangerous levels, and so increasing the risks from Legionnaires’ disease.

HSE research revealed legionella DNA present

Although no outbreaks of Legionnaires’ disease have been associated with UK papermaking the HSE’s research revealed legionella DNA existed in nine paper mills that took part in the project. This did not mean living bacteria were present, however. That said, the research also indicated certain process waters were found to have higher numbers of legionella by qPCR than source waters.

Which conditions are ideal for legionella growth in paper mills?

Water that is stagnant and warm provides good conditions for the growth of Legionella bacteria which can multiply rapidly if left unchecked. Furthermore, various parts of the papermaking process include processes whereby water could be aerosolised (sprayed into the air). This significantly increases the chances of someone inhaling water droplets that are contaminated with Legionella and possibly becoming ill.

Are paper mill workers at greater risk?

Furthermore, while anyone could contract Legionnaires’ disease via inhalation of or exposure to the bacteria, certain groups within the workers at paper mills could be deemed to be at greater risk of falling ill. Drinking, smoking, having a compromised immune system, and being 45 years of age and over are all factors that can increase risk levels.

Are most UK paper mills already doing the right things to control legionella?

Efficiency in every area of the pulp and paper production process is vital in making sure maximum productivity is achieved. For this to occur, the various machines used in the papermaking process must always be clean and suitably maintained. If slime (biofilm) is left to build up in the water systems, it could jeopardise the efficiency of the equipment and the quality of the finished product. Since mill owners and operators will want to maintain optimum productivity and quality, most paper mills are already likely to be taking measures to prevent such build-up occurring.

Who’s responsible for managing the risk?

However, there is still a requirement for those in charge of paper mills to ensure the risks from Legionella bacteria are identified and controlled effectively. The duty holder has the responsibility of handling this and may be the employer, owner or a director of the business. If they are suitably qualified and knowledgeable, they may appoint themselves as the responsible person for handling all elements of this task. Alternatively, they could hire or appoint someone who is suitably competent to handle the day-to-day elements involved in managing the risk.

Making sure a legionella risk assessment is in place

Since there is likely to be a reasonable risk from legionella (and potentially Legionnaires’ disease) within a paper mill environment, those responsible for managing these risks must conduct a thorough legionella risk assessment to comply with the law. This assessment should be comprehensive and cover all process water systems and any other water systems present on the site.

Potential areas of legionella risk in paper mills

We have previously highlighted the dangers inherent in contaminated aerosols or mist caused by water sources and uses within a paper mill. Other potential causes for concern include water that is used or stored at a temperature of between 20-45 degrees Celsius. This is the temperature at which Legionella bacteria can most readily multiply.

Other risks involve the build-up of rust, algae, biofilm, and sludge within water pipes, tanks, cooling towers and other process systems that use water.

Any water that is stored or recirculated within the system, as is common in paper mills, would also be highlighted as a potential risk factor. All these elements – and any others that may be applicable – should be highlighted in the legionella risk assessment.

Suitable steps to manage those risks should then be identified and control measures implemented and monitored to ensure they remain effective.

Minimise, maintain, and avoid

Minimise, maintain and avoid are the key elements that should be considered as priorities when assessing how best to control the risks posed by legionella contamination of water supplies and other water systems in a paper mill. For example, minimising the presence of aerosols and water sprays would significantly reduce the chances of someone inhaling the bacteria with the potential to develop Legionnaires’ disease.

Proper maintenance procedures should also be laid out to ensure all pipework, tanks, dead legs, and machinery is regularly cleaned and disinfected. This may include appropriate water treatment and the removal of little used outlets and dead-legs that are no longer used. Little or unused outlets and dead-legs present a greater risk from legionella and other bacteria being able to form in pipes filled with stagnant water.

Prepare a written scheme for the control of legionella

The legionella risk assessment should identify any areas of risk along with the best steps to take to minimise them. It should also identify suitable control measures, regular tasks, testing procedures and good maintenance practices. This can then be referred to whenever necessary to ensure the risk factors are kept as low as possible.

It’s essential you keep accurate records of what you do

A full record of any checks, maintenance activities, inspections, and water treatment programmes should also be kept and monitored to ensure the control systems in place are effective and remain so. This is a legal requirement, along with keeping the legionella risk assessment up to date, providing details of who has responsibility, and who is involved in implementing the activities set out in the written scheme of control.

In short, keeping extensive records of what you do will help provide a full picture of the current risk factors present at any paper mill. Any tests undertaken, along with who performed them and the results should also be kept. Again, risk assessments for undertaking these tests must also be performed to keep all those involved in the process safe from harm.

The Health & Safety Executive provides ample guidance on the responsibilities of those who are involved in the legionella risk assessment process. The guide from PABIAC aims to work in conjunction with the existing advice from the HSE including their ACOP L8 and guidance HSG274. In doing so, it helps to ensure those operating pulp and paper mills understand where the risks from water systems, legionella and other bioaerosols lie and how they can best be managed to minimise workplace risk.

International legionella and water safety specialists

Our teams of water safety specialists support those responsible for the control of waterborne pathogens including Legionella bacteria in the workplace, helping them to protect their people and meet their health and safety obligations in this specialist area. We deliver professional water safety legionella risk assessments, water testing, independent compliance auditing, City & Guilds training and other environmental risk management services that help keep staff and others safe.

If you have questions about any of the issues raised above or you would like to speak with one of our legionella specialists please call us today on 0330 223 36 87 or contact us here.