Location

Inverness, Scotland

Application

Potable water production

Capacity

40 MLD (10.6 MGD)

Construction

Earth Tech Engineering Ltd

End-user

Scottish Water (previously “The North of Scotland Water Authority”)

Source

Surface water

Start-up

2001, extension 2006

system design

The backwash waste from the secondary UF system is discharged to sewer whilst the secondary permeate is blended with the primary permeate. Waste from CEB is neutralised prior to discharge. 


background

In 2001, Scottish Water installed a new 34 MLD (9 MGD) water treatment plant for potable water supply to the town of Inverness and surrounding area. The raw water source is a blend from Loch Ashie (7 MLD) and Loch Duntelchaig (27 MLD). Major goals of the plant included:
  • Micro-organism barrier
  • Color removal
  • Minimize the waste flow
 
Prior to the construction of the full scale plant, tests have been carried out to confirm coagulation combined with ultrafiltration (UF) is capable of achieving these goals.

Pilot trials showed that membrane technology is an appropriate and cost-effective solution to reach the goals. Because of the limited sewer capacity, the waste volume had to be minimized. By introducing a secondary ultrafiltration most of the waste stream of the primary is reused with the result that the total waste stream is minimal. In 2006, the plant was expanded to 40 MLD (10.6 MGD).


water quality

 PARAMETER UNIT  FEED  PERMEATE 
 Temperature  °C
 1 -25
 Turbidity  NTU
0.2 – 4.0  < 0.1 
 Color °Hazen  2 - 25  < 5 
 Coli forms l-1
 0 – 20,000
 E Coli l-1
0 – 10,000
 Cryptosporidium
 l-1
0 – 100


scope of supply

7+2 UF skids including 768 Xiga 40 membrane modules

Plant automation

Engineering & commissioning


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