Powdered Activated Carbon Dosing Application

Dorisland Water Treatment Works, Carrickfergus, County Antrim

Customer: Northern Ireland Water

System Type:  PAC supply & mixing

Material:  Powdered activated carbon

System Description: 1-off Silo, 1-off powder transfer system 1-off hopper & eductor

Silo Size:  24 tonnes

Mixing Method: hopper plus eductor

Installed:  2004

Water Flow Rate: average 20 Ml/day, max 50 Ml/day


This site has been in use for more than a Century. Major refurbishments were carried out from 2000. Water is supplied here from 7 local reservoirs. Treated water is supplied to over 30,000 people in the local area, and as far away as Belfast. This site also has an SKE Solutions Lime Plant, in the building behind the silo.

This system was necessary to supply Powdered Activated Carbon to treat the water supply to resolve seasonal odour and taste issues, particularly from algae & MCPA herbicide. The silo is mounted outdoors. It has a unique ‘Sodimate’ mechanical arch-breaker system, which ensures reliable feeding of powder, whereas alternative vibration motor or air pad systems create issues with powder compaction & contamination. The powder is fed into the building, where a hopper & eductor system mixes the PAC with water in the main pipeline at 4.25 mg/l, before being dosed to the water supply. The PAC retains these contaminants, and then it is removed later in the process.