For Brechin Waste Water Treatment Works in Tayside, Verder proposed two Verderflex VF65 peristaltic pumps for discharging from the settling tanks, to replace a Sewpas air system.
In June 2001, MacLeod Consulting in Dundee asked Verder to put forward an alternative pumping solution at Brechin Waste Water Treatment Works in Tayside. Verder visited the site and discovered that the existing pumping system used a Sewpas air system. The application required a 2m suction lift, discharging primary sewage sludge into settling tanks 10m away to feed a filter press.
Discussions with site personnel and the consultants indicated that this system was very old and was unreliable when pumping sludge that contained more than 5% solid content.
As a solution, Verder proposed a design that incorporated two Verderflex VF65 peristaltic pumps, one for each of the settling tanks, with each pump able to act as a standby for the other.
These units were chosen because they can handle up to 80% solid content and can self-prime to a depth of 9.5m.
Verder specified inverter drives for the pumps and hose burst detection sensors to shut the system down in the event of a hose rupture.
Following discussions with the client, Verder were also asked to include a turbidity detection system, to monitor the sludge density between 1% and 12%.
A Dr Lange Solitax turbidity control was chosen and programmed to shut the pumps down when the sludge density read 1.5% or less.
Following approval of the design, the new system was installed in August 2001.
The pumps are specified to discharge 8.2 cubic metres/h, but this can be adjusted by the inverters to suit the current sludge density.
The system is linked to a control panel that includes a series of timers, enabling the pumps to start, run and rest for predetermined times dependent on application conditions.
Since installation, the new system has operated trouble-free and provides Scottish Water with a far more reliable and flexible pumping solution.