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Odour Control in the Production of Malted Barley

Simpsons Malt protecting the environment with Forbes scrubber system.

For over 150 years Simpsons Malt has been manufacturing specialist high quality malted barley. The company supplies to a large number of whisky distilleries throughout Scotland, as well as to the brewing and food industries at large.

The company’s largest site, Tweed Valley Maltings in Berwick on Tweed, produces an impressive 236,000 tonnes of malted barley annually.


Chitted malt (barley) is transferred into giant stainless steel Germinating and Kilning Vessels (GKVs). Humidified air is passed through the bed of malting barley to create the perfect conditions for the barley to germinate.

After 4-6 days, the wet air is replaced with heated air. The malt is dried (White Malt) and cured to required specifications, both in terms of moisture levels and colour, where it is used to produce some of the finest single malt whisky in the world.

Some of the white malt receives a second treatment process; peat is burnt in large burners and the hot, peat-infused smoky air is drawn through the white malt to give it a distinctive peaty characteristic. This malt is then used in the production of those peat flavoured malts synonymous with the western isles of Scotland.

Previously the peaty / malty scented air, together with fine particulate, was vented straight to atmosphere. Needing to increase production Simpsons recognised their responsibility concerning discharges of odours and dust laden air generated from their process, and that cleaning before discharge to the environment was required before extra processing commenced.


Forbes supplied a complete wet Venturi scrubber system. The scrubber fans now draw the heated air from the kiln, through the malting chamber and into the scrubber. Inside the scrubbing vessel, the scrubbing liquor and peaty gas stream are brought together in turbulent contact, within the venturi throat, where the odour-causing particulates are forced into the atomised liquor.

The result; no more unacceptable odours discharged from the GKV and a more pleasant environment for employees and neighbours alike.

The scrubber vessel was manufactured in polypropylene and reinforced with GRP. With a throughput air flow rate of 23000 m3/h, the Simpsons Malt scrubber system’s duty is 97% particulate removal at 5 micron.

Along with the scrubber system itself, Forbes supplied all vents, ducting and fans, access ladders and handrails which were manufactured at our own Kelso steelworks.

The scrubber has delivered the specified duty and has permitted continuous production of peaty flavoured malt and allowed us to meet the increased demand for this specialist ingredient regardless of weather conditions.


  • Wet Venturi Scrubber System with Odour reduction
  • Air flow rate of 23000 m3/h through the scrubber
  • 97% particulate removal at 5 micron
  • Supply of complete system, including ducting, fans, pumps and all steelwork


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