Anglian Water


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Introduction

Nitrate levels in many Anglian Water groundwater sources have been increasing in recent years. To overcome this problem, Anglian Water selected ACWA’s NitreatTM technology to reduce nitrate levels on all high nitrate sites where blending with other low nitrate water sources was not an option or would not reduce the nitrate levels sufficiently.

The NitreatTM system is based on true counter current continuous ion exchange utilising a unique multiport valve for distribution of feed and regeneration flows to multiple resin vessels. Unlike other similar systems NitreatTM does not require a turntable as the resin vessels remain stationary.

ACWA developed a standard design that could be utilized for all sites, which incorporated two Ion exchange skids that are capable of handling 100% of the flow to cater for maintenance of the plant. The resin regeneration and backwash take place in-situ without interruption to the nitrate adsorption process, thereby eliminating the need for long periods of shutdown or extra cost. The system offers a high degree of flexibility as it can cope with large variations in flow and nitrate levels and produces far less quantities of waste regenerants compared with conventional plants.

The treated water from the NitreatTM plant typically has a nitrate level concentration of less than 5mg/l as NO3 and when blended with untreated water provides a final water with a nitrate level concentration below 43 mg/l as NO3.

Design Information

The following table indicates the flow, Influent nitrate level and final effluent nitrate quality achieved from each of the NitreatTM plants presently in operation or under construction for Anglian Water, there are others in the design phase.

Project Name Works Flow(m3/hr) Nitrate LevelInfluent flowmg/l Nitrate LevelBlended dischargemg/l maximum Project Status
Lyng Forge 129.2 92.50 43.00 In Service Feb 06
Isleham 237.5 110.50 43.00 In Service Apr 06
Birchmoor 122.9 98.00 30.00 In Service May 06
Ringstead 250.0 102.00 43.00 In Service Oct 06
Westerfield 142.1 120.00 43.00 In Service Dec 06
Riddlesworth 333.3 105.00 43.00 In Service Jul 07
Nunnery Lodge 235.8 90.00 43.00 In Service Mar 08
Moulton 191.7 73.60 43.00 In Service Feb 08
Caister & Bixley 416.7 62.50 36.00 In Service Apr 09
Lower Links 116.7 56.40 43.00 In Service Mar 08
Eriswell 140.4 75.00 18.5 In Service July, 09
Fring 291.7 95.8 43.00 In Service Aug, 09

Due to the success of the operational plants in terms of performance and reliability, Anglian Water are assessing reducing the number of skids down from two to one on future schemes.

Description

Each system comprises:

  • Variable speed Booster Pumps, associated pipework & valves
  • In-Line Strainers on feed line
  • 2 No 100% Ion exchange skids complete with indexing valve, ion exchange resin vessels, pipework and valves
  • Salt Saturator, pipework and valves
  • Duplex Base Exchange Water Softener
  • Softened Water Storage Tank
  • Duty / Standby Regeneration Pumps, pipework and valves
  • Effluent Storage Tank
  • Interconnecting pipework & valves
  • MCC and interconnecting cabling
  • Instrumentation and Controls
  • Access ladders, platforms and handrailing

Project Details

Client: Anglian Water

Industry: Nitrate Removal

Application: Nitreat TM

Technologies

Ion Exchange
Ion Exchange