With a Water ‘Special Measures’ Bill in the pipeline, Howard Marles, of Curio Group, explains how new technologies like ozone and granular activated carbon have opened a new frontier in water treatment.
Two years ago, the UK held its first micropollutants conference, marking a pivotal moment in raising awareness about the hidden yet pervasive issue of micropollutants in the nation’s waterways.
Since then, there has been growing recognition that the UK may follow Europe’s lead in tackling this environmental challenge.
Now, with a renewed focus on water quality and government promises to introduce more robust legislation, it appears that the UK’s water industry is finally transitioning from awareness to concrete action.
Micropollutants present a complex challenge due to the vast array of substances they encompass, from common pharmaceuticals and antibiotics, cleaning detergents and microplastics to steroid hormones and pesticides.
Among these, PFAS – often referred to as ‘forever chemicals’ – have gained particular notoriety due to their persistence and bioaccumulation in both the environment and the human body as well as their tendency to induce resistance and effectiveness.
Safely removing these chemicals is a key focus of the EU’s revised Urban Wastewater Treatment Directive, which is likely to influence future UK legislation, satisfying a growing public desire to instigate environmental improvements.
Currently, the Environment Agency is actively sampling and testing water at sites in the Midlands where micropollutant removal technologies are due to be trialled. The results of these full-scale trials, along with insights from European experiences, are expected to inform the regulations in the forthcoming Water Bill.
However, uncertainty remains regarding which specific pollutants will be targeted, the required removal rates, and the timeline for implementation.
Given this context, it’s crucial to consider the nature and advantages of different solutions for removing micropollutants. The challenge of course lies in the broad scope of what exactly constitutes a ‘micropollutant’. The EU categorises these into priority substances, specific localised pollutants, and ‘contaminants of emerging concern’.
The latter group particularly concerns itself with endocrine-disrupting chemicals (EDCs), which have recently been identified as pollutants of particular concern in effluent. In time, the removal of microplastics may also be required. The challenge therefore is emerging and multi-faceted.
Switzerland, historically known for its stringent environmental regulations, has been a pioneer in using ozone and granular activated carbon (GAC) to tackle this broad spectrum of micropollutants.
The Neugut plant was the first in Switzerland to implement these measures, and its success in removing a wide range of micropollutants has led to the widespread adoption of these technologies across the country.
Ozone is a powerful oxidising agent, capable of breaking down most complex chemical compounds. Its fast reaction time also allows it to handle large volumes of wastewater efficiently.
In the example of the Swiss plants, when combined with granular activated carbon filtration, it has been shown to achieve a removal rate of up to 90%, well above the 80% target, which is also the benchmark in the EU. The ability to adjust ozone dosages based on specific treatment needs also makes it highly scalable, flexible, and adaptable to future regulatory requirements.
In the UK, Severn Trent Water is testing ozone treatment facilities similar to those used in Switzerland. As part of their “Green Recovery – Bathing Rivers” initiative, they are installing ozone treatment units at multiple wastewater treatment plants.
These ‘plug-and-play’ pilots are designed to allow engineers to trial different ozone solutions tailored to their specific wastewater treatment needs. Specialisation in ozone application is the key to success, with follow-up laboratory samples informing the technical and economic assessments for eventual full-scale implementation.
It is recognised that ozone is likely to be just one of several innovative solutions in the armoury of addressing what is essentially a new and evolving frontier in water treatment. For instance, research at Cranfield University is exploring nanobubble technology for treating organic micropollutants, while electrochemical treatment is also being investigated.
Nevertheless, ozone is still likely to form the bedrock of the solution best suited to the UK given its success on the continent. However, its exact implementation will be a matter of trial and refinement, particularly given the ongoing research and development in experimenting with innovative combinations of other removal agents such as hydrogen peroxide, GAC, and even ultraviolet radiation.
With water companies increasingly being encouraged to invest in solutions to these problems, the key will be to capitalise on the expertise already gained from the European experience.
Given the degree of operational complexity in the optimal use of ozone, its integration into the UK’s water and wastewater treatment infrastructure must be driven by a collaborative and iterative process. In time, its widespread implementation also offers a genuinely transformative prospect for the nation: the return of safe and clean waterways to their natural state.
More information and updates on the Severn Trent project can be found at:
creatingbathingrivers.co.uk
