Lime Powder Dosing Application

Carmoney Water Treatment Works, Eglinton, County Londonderry

Customer: Northern Ireland Water

System Type:  Lime storage & supply

Material:  Hydrated Lime

System Description: 2-off Silos feeding to 2-off mixing tanks, with a shared 2-way conveyor

Silo Size: 30 tonnes each

Mixing Method: Load cells below 2-off 1m3 mixing tanks

Installed:  1995

Water Flow Rate: 20 Ml/day


This potable water treatment plant educts 20 million litres of water each day from the Faughan River, and processes it to a standard approved by the NIEA Drinking Water Inspectorate, for consumption in this area to the east of Derry City. The water is contaminated with peat and aluminium sulphate. An important stage of the process of cleaning the water requires PH adjustment using hydrated lime powder. There are 2-off large SKE lime silos, SKE powder conveying systems and mixing tanks. These are installed indoors to ensure reliable long term operation. There is a 2-way transfer conveyor above the two mixing tanks which allows lime from either silo to be fed into either of the two mixing tanks. The lime is then mixed to a strength of 1% before dosing pumps add it to the water main.

This system has been in operation for more than 20 years, and is still providing very reliable service at this site. There is also an SKE sludge conveyor used to transport sludge removed from the water at a later stage in the processing – this equipment is explained in a separate report.