With sewage sludge as an agricultural fertiliser to farmland coming under greater public and media scrutiny, the issue is rising further up the water companies’ agenda and the possibility of tighter legislation is undoubtedly in prospect.

Ahead of an upcoming free -to-attend webinar on 8 October on Sludge Drying Solutions for AMP 8 and beyond, and a forthcoming presentation at the European Biosolids Conference in Manchester on 21 October, Dale Foster, Business Development Manager at HUBER Technology UK explains how the company’s sludge drying technologies, expertise and capababilities can help water companies to optimise a key section of their sludge treatment processes.

Dale Foster: For anyone working in the UK wastewater treatment sector, HUBER Technology’s name is pretty much synomous with sludge screens technology. With almost 1000 installations across the UK water companies, we’re generally seen as the market leader.

However, what they may not be aware of are the benefits our technology solutions provide in another key part of the wastewater treament process, namely sewage sludge drying.

HUBER offers three types of drying technologies - belt, solar and disc drying with another option soon to be launched. An established tecnology which has been in extensive use in Europe and beyond for many years, HUBER dryers are being used to process nearly two million tons of sludge per year globally – quite a compelling figure.

While there is still no clear line of sight on how the UK water sector is proposing to tackle this particular biosolids challenge, we’re already talking to customers about their requirements and how we can help.

Currently, the gestation period that dryers will take is typically around two to three years from conceptual design up to delivery on site and then becoming operational.

So the fact that our drying technology is a proven solution is clearly an important aspect of their thinking and the reason they are coming to us, the key point being that it does not need to undergo lengthy trials prior to implementation.

In terms of thermal sludge drying, belt drying is a proven technology, which might not be the case with pyrolysis and gasification and other 'downstream' technologies..

Ten years ago the water companies were warned that their sludge strategies would need to factor in the very real prospect of limitations on the availability of land banking coming down the line – this is already the case and public pressure may hasten further restrictions. At the moment there are two primary end uses – as an energy source and as agricutural fertilizer – and currently 90 per cent plus goes to land spreading.

Currently sludge is de-watered to maybe, 20 to 25% dry solid which means there's still a lot water in it 70%-plus – and the end product requires a lot of storage capacity.

Given that spreading to land in future may be limited to to the growing season, the water companies will be faced with the challenge of ensuring they have significant storage capacity for sludge for the no-growing season and an undoubted need to significantly reduce volumes.

This is where our sludge drying technology comes into its own, with the ability to dry sludge to ≥90% dry matter.

For water companies faced with the prospect of storing tonnes of sludge with a 75% water content in big bags for a period of many months, our belt drying technology will shrink that down to dried sludge in the form of cake with ~10% water content which is also virtually odour free.

In addition,  there are no ATEX requirements and explosive atmospheres to deal with within the HUBER® BT Belt Dryer - another massive plus for the water companies.

At the moment, the majority of the companies send sludge which has beeen initially dewatered at Hub sites on to their major sludge treatment facilities for further processing. With the pending launch of the HUBER® HPS Cold Air Dryer, which we believe will provide low cost, small footprint drying at smaller more remote hubs, plus the BT Belt Dryer having the ability to efficiently dry huge volumes of sludge treatment centres this offers new choices to our clients.

Dependent on a few factors the modular design of the HUBER® BT Belt Dryers have the capacity to dry 3-4,000 tonnes per annum up to ~50,000 tonnes with many working examples of multiple dryer streams for much larger throughputs.

I’d also like to rebut the myth that the belt drying process is energy-intensive - something I’ll be talking about at the European Biosolids conference in November.

Our belt drying technology is ideally suited to be used at wastewater treament sites with thermal hydrolysis plants which use biogas from anaerobic digestion to power Combined Heat and Power (CHP) engines – the water companies can simply tap into the heat they are already generating from anaerobic digestion. Again, HUBER have got several options available to harness and make use of that heat by incorporating the sludge drying process into what they’re already doing.

At the end of the day, they have got massive potential to make the most of their existing infrastructure - sludge drying will help them to maximise those benefits.

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Click here for Registration for HUBER Technology UK’s free-to-attend webinar on 8 October on Sludge Drying Solutions for AMP 8 & beyond by HUBER UK Business Development Managers Dale Foster and Adrian Heneghan, looking at the challenges and opportunities available when considering a sludge drying project.

Click here for more information about the Conference Programme: European Biosolids & Bioresources Conference & Exhibition at Old Trafford in Manchester which runs from 10^th to 12^th November 2025.