Johnson Matthey’s site in Skopje, Macedonia, is working to minimise the volumes of waste produced by its processes

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Johnson Matthey's site in Skopje, Macedonia, which opened in 2010, manufactures catalysts for both heavy duty and light duty vehicles. As emission control legislation continues to tighten in Europe, the factory is keeping busy and in common with other Johnson Matthey sites, is working to minimise the volumes of waste produced by its processes.

An autocatalyst is a ceramic cylinder with thousands of very fine channels running through it. The inside of these channels are coated with very tiny particles of platinum group metals and it is these metals that perform the clever chemistry that converts harmful pollutants created by the engine into less harmful gases. In preparing the coating, various solid and liquid raw materials are combined and it was in this part of our production process that the Macedonia site found an opportunity for waste reduction.

During the preparation of the coating, precious metals are dissolved in acid and the excess acid from this process creates a side stream which is then treated or 'cleansed' by a scrubber system to ensure that it can be disposed of safely. Large volumes of effluent were being produced and so the team at Macedonia decided to explore whether there was room for improvement.

To provide an answer, a condenser was installed and commissioned to tackle this side stream. As a result, fewer reagents were required to treat the waste and less acid was needed to be treated by the scrubber, minimising the risks to health and safety. Finally, there was less effluent water to be disposed of. The new system has proved itself.

A further project is underway to recycle the condensed acid back into the process. With lower consumption of acid, the cost of raw materials is expected to be reduced. The projects have a short payback period, reduce the volume of effluent produced and contribute to health and safety on site – efficiency and environmental gains adding up to a big win.