The art of choosing the right clean water technology

Why implement new technologies?

Most drinking water plants around the world are using conventional water treatment processes that have changed little over the past 100 years. These technologies have served us well, but utilities are facing new operating challenges. Communities and regulators have higher expectations for water quality, reliability, and cost effectiveness. Source water quality is often becoming degraded, and new micro pollutants and contaminants of concern are being identified.

When we talk about “New technologies” we are often talking about technologies that have been around for 20-30 years, and have been tested, implemented, and validated by utilities elsewhere. New technologies can help meet stricter water quality regulations, improve reliability and reduce operational risk. Sometimes this will increase customer water bills, but often the whole cost of ownership of new technologies will be even cheaper than the legacy technologies.

What technologies are utilities and companies looking to at the moment?

We see a lot of interest in membranes at the moment, especially in Scandinavia. There is a need to provide a robust barrier against pathogens such as cryptosporidium. Polymeric membranes have improved considerably in the last 10-15 years, and for many applications ceramic membranes provide unparalleled performance. Pesticides, herbicides, pharmaceuticals and other emerging contaminants are also really important issues, so processes like advanced oxidation, activated carbon and ozone are also very relevant. \nWe also see an increased interest in ion exchange because surface water sources are becoming degraded over time with higher organic loads due to local, regional, and global environmental changes. Basically, we see an increased interest across the whole range of water treatment technologies. \n

Why is it so important to make the right decision and how to make it?

Choosing the right treatment technology is a big decision as water treatment plants are expensive long-lived assets. Technology selection locks in not just large capital investment, but also ongoing operating cost profiles. There are certainly plenty of examples where technology decisions have been made or implemented poorly.

There are many factors that influence whether a technology decision is correct – both technical and non-technical. The rules of chemistry and physics are the same all over the world, but source water characteristics can vary dramatically from one valley to the next. Drinking water companies have different business drivers and operational competencies, and industry stakeholders including regulators, contractors and consultants will have different experiences that shape perceptions and attitude to risk.

In Japan, planning for new water treatment plant upgrades is a 10-year systematic process, designed to reduce risk. In many cases, this will start with a multi-stage pilot programme. Piloting validates that the technology can work with the particular local conditions, but when done well can also provide key design inputs to reduce implementation costs and risks. It can also be a valuable opportunity for operations teams to start to build awareness and confidence.

As with other complex decisions, practice makes perfect. In South East Asia, for example, rapid population growth means that a plant built in 2020 might need updates in 2025, and in 2030 they might need to rebuild and expand. Because of their experience and familiarity with implementing new technology, these drinking water companies can often make faster and better decisions.

Singapore’s Public Utilities Board is one of the best examples. They have carefully honed their ability to scour the world for new technologies, test them, and then implement at scale. If we look to Europe or the US, the situation is quite different. It has not been necessary to rebuild and expand at the same speed as in South East Asia, and therefore drinking water companies may have little experience and need to rely more on the experience of others.

So, in this context, choosing the right partner to help make the technology decision is crucial. As with any large projects, local relationships, understanding, and capacity are important. It is also important to have people on the team who have lived through implementation of the technologies elsewhere. That could be engineers who have seen first-hand what works and what doesn't and can help guide the process to avoid making the same missteps again. To make these teams work we need to value diversity and look to specialists who have deep experience in working along the whole journey from piloting, design, construction, commissioning, and handover.

Can you come up with some examples where new technology has been implemented successfully?

Sure. Ramboll is currently working in Florida, where we are piloting the Suspended Ion Exchange technology, also known as SIX®. This is the first time this technology has been applied in the US. The raw water characteristics are ideal for ion exchange, with high levels of dissolved organic carbon. The SIX technology will provide cleaner water, operational cost savings, and unlock additional capacity within the current assets. The Ramboll team includes engineers from the Netherlands who have had lead roles in earlier implementations of SIX in Europe, as well as experienced engineers from the Ramboll US business. Working with our local partners, we are able to guide the City through their pilot evaluation process and give them confidence that they can realise the benefits. Another great example is South West Water, a leading water utility in the United Kingdom. In November 2020, South West Water completed the new Mayflower Water Treatment Works, which treats 90 million litres per day of drinking water from surface water sources. This is actually the first drinking water plant in the world to use suspended ion exchange, ceramic microfiltration, GAC and UV disinfection. The innovative process train will ensure a more efficient water production at a lower cost than conventional technology. Implementation was very challenging for South West Water, because it was their largest project for many years, indeed it was actually the first new water treatment plant they had constructed in more than 30 years. However, they did their research and tests, and now they have a fantastic asset that will provide their customers with high quality water for many years. We can also look to Yorkshire Water, who were the first major utility in Europe to implement ion exchange for DOC removal. Yorkshire Water implemented the MIEX® technology at three large drinking water plants from 2009-2011. The implementation presented some challenges for the operations teams as they had to shift from managing large quantities of low value chemicals, for example coagulants, to small volumes of high value consumables such as ion exchange resin. Managing the process required a different skillset and a modified approach to risk management. It took several years for Yorkshire Water to fully operationalise this. But they have now done this successfully, and it is a measure of the success of the technology that they have implemented a fourth plant using the same technology and are now planning further projects.

About Antony Gibson, chemical engineer and consultant at Ramboll Water

Antony Gibson joined Ramboll in January 2020 and is a leading expert in the implementation of advanced drinking water technologies. He has more than 20 years’ experience and in recent years, has worked extensively with the implementation of ion exchange, membrane filtration and reverse osmosis desalination in large drinking water plants globally.