Lime Storage & Handling Application for Sludge Conditioning

Ashford Sewage Treatment Works, Braunton Road, Ashford, Barnstaple, North Devon

Customer: South West Water

System type:  Lime supply & dosing to active sludge

Material:  Hydrated lime

System Description: 1-off Storage silo. Metering, transfer & injection conveyors. 1-off mixing tank

Silo Size:  35 tonnes

Mixing Tank Size: 4.5 m3 volume

Installed: 2009

Sludge Volume: 60,000 PE equivalent


These sewage works are on the edge of the River Taw – an area of outstanding natural beauty and a very sensitive environment, with a walking & cycling route alongside. Ashford is also a regional sludge centre. The client required an effective and reliable method to store and handle hydrated lime, used to condition active sludge. SKE offered a comprehensive solution for bulk storage & handling of the lime powder.

SKE designed the complete powder handling system to fit the limited space, and supplied it in green paint to lessen visual impact. The SKE system uses the unique ‘Sodimate’ mechanical arch breaker to deliver powder from the silo. This obviates problems of compaction or contamination encountered with vibratory or air pad type arch breaking. Furthermore the accurate metering & injection with spiral auger type conveyors mean that the equipment produces a reliable 2% strength slurry mix, which is then added to the sludge.

Gavin Lincoln, Senior Engineer with SW Water is completely satisfied with this installation. At time of writing, further SKE plant for lime & soda ash handling are currently being installed for this Water Authority.