Demineralisation Plant Reverse Osmosis Plant
Ion Exchange Ion Exchange and Membrane
Regenerant agent – Acid and Caustic Regenerant agent – Brine
Other chemicals – neutralisation media Other chemicals used – usually none, can need some chemical cleaning
Features/Benefits Features/Benefits
Good process Water Excellent Water
High water production cost Low Water production cost
Affects pH value No significant pH alteration
Uses aggressive chemicals Uses brine solution
Chemicals cause corrosion to plant No aggressive chemicals used
High Maintenance Low Maintenance
Effluent problem Effluent discharged directly to drain
Handling of aggressive chemicals No aggressive chemicals used
Based on plant sized at 3.5m3/hr produced flow rate, costs in £.
Total Capital Costs
Cost 23.0K 21.5K
If the proposed site does not have experience in handling aggressive chemicals then bulk handling facilities will have to be provided for De-mineralisation system at an extra cost as below:
Cost 2.6K Acid system None – non aggressive
Cost 1.7K Caustic system None – non aggressive
Total 27.3K 21.5K
Running Costs (Typical)
The running cost of both plants is dependent upon the water analysis therefore two examples are included;-
Raw Water analysis
- Total dissolved solids = 600ppm, total hardness 300ppm.
- Total dissolved solids = 300ppm, total hardness 200ppm.
Assumed regenerants costs;-
- Acid – 28% HCl @ 24p/litre
- Caustic – 32% NaOH @ 35p/litre
- Salt – 18p/kgs
Power 3.7 kW/Hr 6.4 kW/Hr
Demineralisation Plant Reverse Osmosis Plant
Regenerant costs; required to produce 1 cubic metre of treated water.
Based on raw water analysis 1
HCl = £0.79 Salt = £0.14
NaOH = £1.89
Based on raw water analysis 2
HCl = £0.40 Salt = £0.09
NaOH = £0.95
Raw Water volume required to produce 1 cubic metre of treated Water
1145 Litres 1330 Litres
Labour costs to produce 1 cubic metre of treated Water
1.20 minutes 0.17 minutes
Major plant items required per 5 years of running
1.8K 1.9K
Demineralisation resin Membranes and softener resin
Consumable items required to operate and maintain per year
1.1K 0.7K
As you can see from above, the relevant costs associated with De-mineralisation are high, making Reverse Osmosis more efficient and cost effective. Reverse Osmosis can produce superior quality water than a standard De-mineralisation Plant. Aggressive chemicals are not used in a Reverse Osmosis Plant; therefore costly Bulk Chemical Handling is not required. Another advantage is that the Reverse Osmosis Plant does not require any regeneration so quality water is available to supply to service almost instantaneously on demand. In our opinion Cleaner, greener and more Efficient.
Pre-Treatment to Reverse Osmosis
Reverse osmosis plants require a softened water feed either by a base exchange softener or chemical dosing. Low output Reverse Osmosis Plants rely on the usually use a softened water supply to stop the formation of scale on the membrane. Larger plants with outputs of 6m3/hr or more would normally have anti-scalent dosing which is lower in both capital and running costs.
We believe that Reverse Osmosis Plants are the ideal water purification Plant with obvious advantages over standard ion exchange plants.
Taking all of the above into consideration we believe Reverse Osmosis is the best option on the market today. For any further information please do not hesitate to contact us.
Caroline
Industrial Water Equipment