Lime Dosing Application

Assynt Water Treatment Works, Evanton, Easter Ross, Scotland

Customer: Scottish Water

System Type:  Lime supply & lime slurry mixing

Material:  Hydrated lime

System Description: 2-off Silos, 4-off transfer conveyors, 2-off mixing tanks with weight hoppers

Silo Size:  14 tonnes each

Mixing Tank Size: 3.8 m3 volume each

System Operation: Lime powder storage. Lime addition to water in 2-off duty/duty mixing tanks

Installed: 2009

Water Flow Rate: 24.6 Ml/day maximum



Assynt is newly constructed water works located in remote woodland. The plant abstracts water from nearby Loch Glass, and this water receives thorough treatment before distribution to 22,000 customers in this Scottish Highlands area, north of Inverness.

As a critical part of the treatment process, it is necessary to dose lime slurry to the water supply, for PH adjustment, SKE Solutions produced a design of plant to store and mix the lime powder that was optimised for this site. The 2-off silos use a unique ‘Sodimate’ mechanical discharge system that ensures a very high reliability of powder transfer by eliminating powder arching in the silo cone. Each silo can provide powder to either of the 2-off weigh hopper/mixing tank systems, giving maximum flexibility and best utilisation of the plant. Hence if one silo is empty, the other can be utilised to feed to both mixing systems.

This is a clean, professional installation which gives highly reliable service in delivering lime to the potable water supply. The flexibility in the format adds further benefits in terms of high site reliability.