At Dryden Aqua Ltd. clean water begins with a secondary raw material that many people would regard as waste: used glass bottles. The company produces AFM® (Activated Filter Media) from green and brown recycled glass. AFM® is an activated, biofouling-resistant, glass-based filter medium used in drinking water treatment, swimming pools, aquaculture, and industrial and municipal water applications.
“We want to make clean water available to everyone,” says Jamie McBride, Operations Director at Dryden Aqua.
Jamie McBride grew up in the British glass recycling industry; his family background and decades of experience in cullet processing have shaped his perspective – from traditional cullet recycling to the high-precision production of AFM®. “The quality of the filter medium depends on the feedstock – and therefore on the ability to process recycled glass with the utmost precision.”
The idea goes back to Dr Howard Dryden, founder of Dryden Aqua. As a marine biologist, he studied the conditions under which marine mammals were kept in artificial enclosures. Filtration was often inadequate, the systems had to be heavily chlorinated, and sand as the conventional filter medium had a fundamental weakness: biofilm can form on its surface. His aim was to develop a filter medium that cleans water more efficiently while creating better conditions for humans, animals and the environment.
Only the right glass becomes feedstock
Dryden Aqua receives waste glass from all over Scotland. Green and brown glass are essential, as both have the specific properties required for the subsequent activation process. Sorting systems therefore remove flint glass, metals, ceramics, stones, porcelain and other contaminants before the glass is turned into a high-quality filter medium.
“Our standards are extremely high because we are talking about water – drinking water,” McBride emphasises. “The purity of the material is crucial right from the start.”
During pre-processing, metal separators remove ferrous and non-ferrous metals such as caps, lids and other metallic residues. The MSort AX Twin then performs the first sorting stage, separating flint glass from the green and brown glass fraction. At Dryden Aqua, the MSort AX is used for wet sorting from a particle size of 6 millimetres. MSort AF sorting systems are used for the second cleaning stage. They sort dry material in the 4 to 60 millimetre grain size range and remove contaminants such as ceramics, stones and porcelain in particular. The material is fed evenly, analysed by sensors according to colour and shape, and separated with high precision. The result is a clean, high-quality green and brown glass fraction, internally referred to as “Gramber”.
This fraction forms the basis for the filter medium. Dryden Aqua offers it in different grain sizes – from particularly fine grades of 0.25 millimetres for demanding filtration tasks to coarser grades of up to 6 millimetres.
Technical precision and decades of partnership
For Dryden Aqua, sorting is a decisive quality step. McBride therefore compares the sorting plant to a kidney: just like the organ in the human body, it extracts unwanted substances from the material stream. The collaboration between Dryden Aqua and today’s STEINERT MSort goes back a long way. Jamie McBride describes a relationship with MSort, and previously with Mogensen, that has existed for almost 30 years. During this time, the focus has been on jointly developing a production logic tailored to Dryden Aqua’s specific requirements.
“At Dryden, we had to make a million mistakes to find one or two solutions,” says McBride. “That is true pioneering work, true research and development. For that, you need partners who work with you – and who do not immediately dismiss every idea as crazy.”
This attitude defines the partnership between Dryden Aqua and STEINERT: technical precision on the one hand, and openness to development work on the other.
“Dryden Aqua does not see sorting as a standard process, but as a decisive quality step for a highly sensitive product. That is exactly what makes this collaboration so special: we can discuss ideas with Jamie McBride, explore technical possibilities and develop solutions that contribute to the high purity of the recycled glass,” says Eddie Lüth, Sales Manager at STEINERT MSort.
“We have taken the best technology from various industries and integrated it into our plants in Scotland and at our headquarters in Switzerland,” says McBride. “This enables us to consistently decontaminate the glass and achieve very high colour quality and colour purity. That is precisely the starting point for manufacturing our AFM®.”
From recycled glass to a contribution to clean water
What Dryden Aqua is creating is an example of how recycling, water treatment and industrial precision can work together. Used glass bottles are turned into a high-performance filter medium. A sorting task becomes a central element of product quality. And a long-standing collaboration gives rise to a process that supports Dryden Aqua’s vision: making clean water accessible to as many people as possible.