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.
“The quality of the filter medium depends on the feedstock, and therefore on the ability to process recycled glass with the utmost precision,” said Jamie McBride, Operations Director at Dryden Aqua.
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 emphasised. “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 STEINERT 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 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,” said 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,” said Eddie Lüth, Sales Manager at STEINERT MSort. “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.”
