Conventional treatment works

The history of water treatment in the North West

The North West is an area steeped in rich history and awash with unique landscapes – from the rolling hills and glistening lakes to the bustling and densely populated cities, this corner of the UK is truly unique.

For this reason, the water that flows through the region presents a host of opportunities and, similarly, challenges – the task that we have in delivering water of the highest quality is deeply connected to the unique nature of the area.

In this article, we explore the history of the water in the North West, the unique challenges we face, and delve further into why conventional treatment processes, such as wastewater treatment works, are sometimes a necessity and the preferred option.

A background to water treatment in the region

Both Manchester and Liverpool boomed during the industrial revolution and their infrastructure developed to support their growing populations.

Manchester, a small market town until the late 18th century, quickly became the natural distribution centre and marketplace for the rapidly developing textile industry. The Office for National Statistics shows an increase in the population numbers in the city from 328,000 in 1801 to 2.35 million a century later in 1901.

Little over 35 miles west, Liverpool expanded its small ship building industry during the industrial revolution to become one of the world’s leaders in global trade. In less than 30 years between 1851 and 1880, Liverpool’s population doubled.

A brief history of sewage treatment in the North West

In the 19th century, sewerage systems in some parts of the rapidly industrialising North West, particularly around Liverpool and Manchester, were so poor that water-borne diseases such as cholera and typhoid were rife.

In 1848 James Newlands, a Scottish engineer appointed by the Borough of Liverpool, began a programme of sewer construction – ten years before Joseph Bazalgette commenced a similar project in London in response to the ‘Great Stink’ of 1858 – and over the next 20 years almost 150 miles of sewers were built to carry sewage away from the city and into the Mersey Estuary.

Further inland sewers were constructed to pipe wastewater to ‘sewage farms’, such as at Davyhulme on the outskirts of Manchester, where sewage was deposited on the land. However, this continued to pollute the newly built Manchester Ship Canal, so in the early years of the 20th century contact bacteria beds filled with gravel were constructed to filter the sewage. Contact bacteria beds are ‘beds’ filled with gravel or some other media, where bacteria and other micro-organisms can grow. When the sewage comes into contact with the gravel, the bacteria breaks down the sewage.

In 1914, Edward Ardern and William Lockett discovered what is known as the Activated Sludge Process at Davyhulme. An Activated Sludge Process is very similar to the process of the contact bacteria beds – to filter the sewage. It is a type of waste water treatment process – the sewage is aerated and agitated in order to promote the growth of micro-organisms that break down the sewage and remove pollutants. By 1936 the entire works had been converted to this process. This approach quickly spread worldwide, becoming the standard for sewage treatment.

Development and expansion of environmental legislation during the late 20th century drove further advances in sewage treatment.

As a result, brand-new sewers were constructed along the length of both banks of the River Mersey to stop the sewage flowing directly into the rivers and to carry it to new wastewater treatment works at Sandon Dock, Bromborough, and Birkenhead. Improved waste water treatment processes were also provided at Davyhulme and other facilities throughout the North West.

But it’s not just the treatment processes that have advanced, there’s also new legislation that’s come into play that takes into account how we manage wildlife and the environment.

Legislation to provide further environmental protection have pushed the boundaries of sewage treatment even further, challenging the limits of available technology in order to meet increasingly tighter environmental standards. We’re proud to have taken steps to advance our treatment processes, whilst looking after and reducing our impact on the wider environment.

Kendal Wastewater Treatment Works is a perfect example of how we have adopted our treatment process to protect the environment and wildlife that live in it.

Kendal Wastewater Treatment Works discharges into the River Kent – the river is a Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC), what does that mean? It describes an area that is of particular interest due to the rare species that live in it, or important environmental features that may lie in its boundaries. Therefore, the area or habitat needs to protect these sensitive species and habitats.

The River Kent has nationally important populations of white-clawed crayfish, as well as one of the largest populations of fresh-water pearl mussels in England. Consequently, the wastewater discharged from the works into the river needs to be treated to the highest possible standards.

In addition to this, Kendal is a large town on the border of the Lake District National Park, one of the North West’s premier tourist hotspots, and so the treatment works not only needed to meet the highest standards but must do so at times of increased visitor numbers during the peak seasons.

Increased visitors means an increase in phosphorus and ammonia levels in the water, which has a negative impact on the environment and the wildlife that live in it. To meet these challenges, we installed an innovative plant at the site that biologically removes phosphorus and ammonia to very low levels in a more sustainable and cost-effective way.

Instead of using traditional methods which would been expensive and involve large amount of concrete; these innovative plants allow us to get to the low levels that are needed to protect the wildlife and the river in a way that is better for the wider environment and for our customers.

We’ve taken a look at the history of our treatment processes, but what does the future hold?

When looking to reduce our impact on the environment, we work to incorporate a systems thinking approach. What does that mean? We look at how different techniques can work together in practice. We make sure we choose the right technique in the right area, whether that be a conventional treatment process - like our wastewater treatment works - or a nature-based solution – like SuDS, wetlands or potential partnership opportunities - or a combination.

We look at how we can adopt the best process for the environment, our customers and communities; by looking at how the holistic drainage system can be more efficient and in turn enhance the service we provide to our customers.

To fully understand if a systems thinking approach will be suitable to embed in our operations we look into the infrastructure and review the entire drainage area, we look at how our networks of pipes are connected, and how the wastewater flows to the treatment works, then how they can be improved to be more sustainable.

We also identify potential partnership opportunities, as discussed below, introduce and increase monitoring capabilities, and implement artificial intelligence to help control the prediction system. For example, we can use artificial intelligence to predict an increase in rainfall, which would therefore mean we would need to store and treat, more water at the treatment works.

An example of where using different techniques has worked in practice is in Cumbria, where we could see high levels of phosphorus entering the rivers – this could have been from agriculture or wastewater sources. By working in partnership with the farmers, and by implementing new techniques, we were able to reduce the levels of phosphorus entering the rivers, allowing the wildlife to thrive. These techniques include putting fences along a riverbank to prevent cattle manure from entering the river or putting roofs on slurry stores to prevent the slurry being washed into the river by the rain. Working with farmers has meant that the catchment water quality can be improved without the need for intensive processes at wastewater treatment works, giving a more holistic, environmentally friendly approach.

In the future, we would like to move away from having just a conventional treatment process, such as waste water treatment works, and have a more holistic approach, with nature based solutions wherever possible.

Conventional treatment works and Catchment Systems Thinking

And we’re using new ways of working to look after our environment too. We can also apply the principles of systems thinking to water catchment areas – leading to a Catchment Systems Thinking (CaST) approach. By utilising CaST we can understand the needs of the environment and ensure that we address existing and emerging challenges in a holistic and integrated way, providing sustainable and cost-effective solutions.