Plant & Works Engineering
Investigation into the Deragger II's Energy Savings
Published:  13 May, 2016

The Deragger II product has been successfully installed in multiple sites
throughout Scottish Water to eliminate pump blockages caused by wet wipes and
other non-dispersible products. No thorough tracking of the measurable benefits
other than blockage reduction have been taken. The purpose of this paper is to
demonstrate the other measurable benefits of the product.


The Deragger II was first installed back in April 2011 at Ross point SPS in Fife.
Since then around 100 other sites within Scottish water have been retrofitted
successfully with the Deragger II. The product has eliminated the blockages at all
of these sites saving huge amounts on reactive callouts to unblock pumps.
In Early 2014 Deragger II's were installed on a trial basis and jointly between
Scottish Water Energy Team and ID Systems at this and another 4 sites. This was
with the intention of establishing their effectiveness as a means of reducing
energy, along with preventing pumps from choking. The Deragger II's were set up
to monitor and data log only. No blockage prevention was turned on at this point.

The Site

Annfield SPS is the main pumping station in Leith, Edinburgh. The effluent is
pumped from the wet well to Seafield STW. There is a very flat sewer collection
network due to the low-lying drainage network at close to sea water level. The flat
sewer is conducive to the settlement of rag in the sewer followed by wash in.
Furthermore, SW customers in the area are at risk of flooding should the sewer
become backed up due to the low lying nature of their basements. The station
consists of 2 off 100kW Flygt 3312 N Pumps fitted in a dry well setup delivering
around 260L/s of flow. The Pumps are controlled in a duty standby configuration
from an MCC housed above the dry well. The pumps are started via Ralspeed Soft
Starters. The flow was measured via an ABB Magmaster Magnetic Flowmeter. This
outputs a 4-20mA signal that correlates to L/s. This 4-20mA signal is wired to
telemetry and logged on open enterprise.

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