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Feedwater Limited
Tarran Way West
Tarran Estate
Moreton
WIRRAL
CH46 4TU
Telephone:
+44 151 606 0808
Fax:
+44 151 678 5459
Registered in
England & Wales
Number 1274270 |
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Case Study
ACTIV-OX® Chlorine Dioxide Treatment of Creamery Condensate
Background
This large integrated creamery and dairy complex processes 1.4 to 1.6 million litres of milk per day. After initial separation the skimmed milk is evaporated in a 5- (or 8-) effect thermo-compression evaporator followed by spray drying to yield 80 to 85 tonnes of skimmed milk powder per day.
The German-manufactured evaporator was designed so that the condensate from |  |
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the 5th effect could be recovered and re-used. This was the normal practice until some 7 years ago when, for operational reasons, recovered condensate use was discontinued and towns mains water was used for boilers, cooling water and CIP make-up.
This raised operating costs because of:
- Reduced boiler feedwater temperature
- Reduced cooling tower cycles of concentration
- Increased mains water usage
- Increased effluent volume
As part of its ongoing commitment to reducing its customers' total water and energy bills, Feedwater proposed the re-introduction of condensate recovery using ACTIV-OX, its patented chlorine dioxide dosage system, to inhibit bacterial activity.
The objectives of the programme were to:
- Reduce the use of mains water
- Increase boiler feedwater temperature
- Improve boiler feedwater quality
System
To achieve the objectives it was proposed that condensate from the 5th effect of the evaporator, after collection in a holding tank, would be passed initially through a triplex multi-media filter system (with cascade backwash) capable of 23m3/hour. From the filter system the condensate would be treated with 0.5ppm chlorine dioxide before passing to storage and then used to supply the boiler and cooling tower systems.
Stored treated condensate would be further dosed with chlorine dioxide to 0.5ppm before use in the CIP system. Chlorine dioxide is the biocide of choice for the food industry becuase it provides long-term disinfection, does not produce chlorinated organic derivatives and its biocidal action is unaffected by pH.
The ACTIV-OX system provides a hands-free automatic dosing system without the requirement for reaction chambers or holding tanks containing concentrated chlorine dioxide solutions.
Results
- Mains water consumption down by 500m3/day
- Boiler feedwater temperature increased by 10-15oC
- Boiler feedwater softening requirement reduced by over 95%
- Boiler blowdown reduced by 60%
- Cooling tower bleed-off reduced by 45%
- Chlorine dioxide maintained at 0.4ppm to storage tank
- Chlorine dioxide maintained at 0.4ppm to CIP systems
- TVC analyses on CIP water consistently zero
- Increased efficiency of CIP operations owing to warmer water
- Effluent volume reduced
Conclusions
The use of ACTIV-OX has provided a safe, controllable and effective means of treating evaporator condensate with chlorine dioxide so that it can be re-used in the plant.
It is calculated that overall savings from lower mains water use, higher boiler feedwater temperature and reduced salt usage will be £100,000 per year, giving a payback on investment in less than 12 months.
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