Sand filtration system gives final polish to wastewater following AD installation at maltster

The sand filtration system installed at Muntons site in Suffolk (Image credit: Tom Owens Open Point Ltd).

Hydro International has installed a sand filtration solution to cope with increased wastewater capacity following the completion of new anaerobic digestion facilities at the Suffolk production headquarters of Muntons, one of the UK’s leading maltsters.

Muntons’ £5.4m Anaerobic Digestion (AD) plant generated one million kilowatt-hours of electricity in its first ten months of operation at the site in Stowmarket. Muntons commissioned Hydro International to supply, install and commission a DynaSand® filter to treat additional wastewater capacity at the site, which produces some 120,000 tonnes per annum of ale, lager and food malts, supplied to customers all over the world.

The DynaSand® will provide tertiary effluent treatment, helping to ensure that Muntons meets its strong environmental commitment to protecting water quality discharged into the River Gipping, which runs along the perimeter of the Stowmarket site. The DynaSand® sand filter has been retrofitted alongside an existing filtration unit to meet Environment Agency consents of 30mg/l of Total Suspended Solids (TSS) with daily capacity of up to up to 1500m3.

The low-maintenance design and durability of the DynaSand® were important considerations, said Environmental Manager Ryland Cairns: “Muntons stands strongly by its ethos of ‘practical sustainability’ and the Hydro International solution was chosen for its ease of operation and its reliability. These were essential considerations for ensuring we continue to meet consents and protect the local aquatic environment.

“Wastewater treatment at Muntons’ Stowmarket site is split between two distinct effluent types,” he explained. “High volumes of effluent with a low Chemical Oxygen Demand (COD), at around 2,000 mg per litre, come from the steeping of the barley grains and are treated by our existing aerobic plant.

“Lower volumes of high COD washwater from the malting process, at about 30,000 mg per litre, are treated via the new anaerobic digestion facility prior to subsequent aerobic treatment. The DynaSand® filter provides the final polishing of water following the aerobic process and before it is discharged into the river.”

By keeping waste treatment on site and using a biogas process to generate electricity, Muntons’ AD plant will save 3,000 tanker movements per annum, produce up to 3,000 tonnes of high quality biofertiliser, and contribute to 25% of on-site electricity demand.

Hydro International supplied a DS500 continuous upflow vertical sand filter with a two metre sand bed. The system removes fine Total Suspended Solids from industrial and municipal effluents in a small footprint, low – power, low – maintenance design.

Keith Hayward, Sales and Marketing Manager for Hydro International’s European Wastewater division said, “Muntons is a company that demonstrates a true commitment to putting sustainability into action and we are proud to have worked with them. The project is another great example of our proven capability in industrial and commercial water treatment and control.”

For more information on Hydro International’s DynaSand® filtration technologies visit