Reducing Roast House particulate emissions by 84%

Our Tivetshall St Margaret Maltings in Norfolk is home to our state-of-the-art Roast House, which produces our high-quality crystal and roasted malts.

Historically, in producing our darker roasted malts such as Chocolate Malt, Black Malt and Roasted Barley, it created excessive amounts of thick, dark smoke that was emitted into the atmosphere, but tended to fall to ground level.

One of our five roasting drums at our Tivetshall Maltings

To combat this, a smoke abatement plant from Swedish company Centriair was commissioned in 2019 after multiple on-site trials, which indicated that its technology would result in a significant reduction in smoke emissions.

The Centriair system uses two different approaches to reduce the particle size and the strength of odour emissions. Those two approaches are as follows:

Hi Scrubber

This is a high-energy, direct impact wet scrubber that uses nozzles to spray and recirculate water at high pressure into the emission gas stream.

This knocks the bigger particles and fibres out of the emission stream. Furthermore, it creates small water droplets that adhere to the small particles in the gas and enlarges them. This increases the particle size and improves separation performance.

The high intensity scrubber also brings water soluble hydrocarbons out of the gas, which further reduces the odour strength of the emission, while the scrubber tank is where tars and solids are removed.

Air Centrifuge System

The air centrifugal separators do the smaller particle separation of the emission gas stream, using a rotor that is turning at up to 3,000rpm and produces a gravitational strength of 1,500G.

This effectively removes the smaller particles from the emission stream to give a clearer emission stream discharge with removal of particulate down below one micron size.


The installation was extensively tested by a third-party Environment Agency (EA) approved contractor and results met EA guidelines, achieving an average of 84% reduction in particulate.

Since then, no neighbour smoke-related complaints have been received.

For more information on our sustainability efforts, visit our dedicated Sustainability page here.