Control on Treated Water quality

Positive control due to constant & continuous operation

Relatively lower control

Chemical Regeneration

Nil

Required

Whether System continuous

Yes, 24 Hrs. operation without any need of regeneration

No, intermittent operation & normally not possible to achieve more than 20 Hrs. / day of treated water generation

Operating Cost

Low

High

Maintenance Cost

Almost nil

High

Space requirement

Low

Atleast 10 times including Chemical handling

Capacity expansion

Easy as system is modular type

Difficult

Effluent Generation

Nil, as CEDI reject stream is recycled to 2nd Pass RO

High

Nature of Effluent

None

Acidic / Alkali causing erratic load on plant ETP

Whether any advantage by Boiler blowdown reduction

Yes, atleast by ½ w.r.t. to normal level due to improved water quality in terms of Silica & Conductivity (thus reduction in heat loss due to reduced blowdown). This will give reduced treated water consumption & thus lower plant capacity with consequential benefits in capital & operating costs.

Normal

Nature of Operation

Largely PLC controlled with minimal human interface

Mostly manually operated, but PLC controls can be provided

Manpower required

Low in number due to PLC control

High in number due to manual control and regeneration requirement

Effect on Turbine operation

Improved life due to better quality of treated water and also reduced maintenance cost as reduced level of Silica etc. will lower the deposits on the Turbine rotor

Due to relatively low control on silica etc., the maintenance cost is higher