Rotork preferred for innovative new water treatment plant

Rotork valve actuators preferred for innovative new water treatment plant

Residents of the picturesque area of north Wales west of Wrexham will soon benefit from an improved water supply from the Dee Valley Water Plc. A new 4Mld (million litres a day) water treatment plant is being built at Pendinas to simultaneously treat the water from three reservoir sources and meet the latest EU requirements for manganese removal.

The new plant will run automatically under PLC control - combined with an innovative intelligent MCC - using a touch screen SCADA programme. Rotork electric actuators have been installed for the operation of the valves throughout the plant, the majority being butterfly valves fitted with the latest Rotork IQT intelligent quarter-turn actuators.

The new plant, which replaces an existing single stage filtration works on the site, is being designed, constructed and commissioned by Biwater Treatment Ltd, who are responsible for all civil works and M & E installations. The treatment process consists of blending from the three sources, flash mixing and flocculation, pH control with lime, coagulation with aluminium sulphate, dissolved air flotation, first stage rapid gravity filtration, second stage pressure filtration for manganese removal and gas chlorination. Filter backwash water is processed through a washwater recovery plant and the supernatant is returned to the head of works, whilst the sludge is stored for periodic off-site tankering.

Rotork actuators control the flow of water throughout the plant. Initially, two IQM modulating actuators regulate the inlet supply to the dissolved air flotation. Each of the four first stage filters is equipped with five lQT actuators to control inlet, outlet and daily backwash and air scour operations. A similar lQT actuated valve configuration operates the three secondary pressure filters.

Keith Jones, Dee Valley Water's project manager, comments: "Rotork is the preferred supplier for valve actuators at Dee Valley Water sites. At Pendinas they are being controlled for the first time by a new, compact and intelligent MCC panel that has been designed and built to our own specification."

"The MCC starters communicate with the PLC to give, as examples, early warning of failure and to download operating parameters automatically should overloads be replaced. Biwater's SCADA software programme also stores data on operating trends to further assist with plant utilisation and maintenance planning."

Alarms from the normally unmanned site will be signalled by telemetry to the Dee Valley Water operations centre at Packsaddle. The plant itself is equipped with an emergency generator to keep it running during a power failure, supported by a battery back-up to ensure the fail-safe operation of key valve actuators.

When completed, the ?3.8million project will maximise the available water resources to provide a reliable, quality water supply to consumers.