The bacteria are well controlled because of the double-pass reverse osmosis system


Safe water supply for the sterilisation centre secures operational reliability 

EUROWATER has supplied a water treatment plant for demineralised water for the new sterilisation centre at the regional hospital in Viborg, Denmark. The water quality after the double-pass reverse osmosis system is purified water and this is used as rinsing water in decontamination washers and as make-up water for autoclaves.​

The purpose of medical equipment re-treatment is to minimise infections acquired in hospitals. According to the national infection control guidelines on hygiene from Statens Serum Institut (Health protection institute under the auspices of the Danish Ministry of Health), poor water quality can influence both cleaning efficiency and instrumentation materials. This can have direct consequences for the patient. Either because of living microorganisms in rinsing water used for non-sterilized equipment, or because of endotoxin on sterilized equipment derived from Gram-negative bacteria in the water supply to the steam autoclave.

The right water quality

The sterilisation centre has a crucial and central role for the operations of the regional hospital in Viborg. Therefore, ensuring the right water quality helps to maintain stable operations that benefit both patients and employees.
 
In a re-treatment unit, water is used for many purposes: Dissolving various soaps and detergents, dissolving and washing off dirt, flushing instruments, as a heat conductor during disinfection in the automated re-treatment and as a medium for steam sterilisation.
 
In Denmark, there is no tradition of using demineralised water in all processes. Typically, softened water is used in the phases before thermal disinfection, and purified water is used in the final rinse of the instrument washers. The same model is used in Viborg.
 

Water treatment plant for demineralised water

The complete project for the sterile centre at the regional hospital in Viborg includes the construction of water treatment plants for demineralised water and distribution facilities with associated distribution system. The project has been put out to tender and was won by technical contractor Henning Mortensen a/s. As a subcontractor, EUROWATER has solved the following jobs:

  • Delivery and installation of production plant
  • Delivery of components for distribution facilities
  • Supply of control and supply board
  • Validation and qualification
  • Commissioning and adjustment
  • Planning
  • Training of technical personnel

"We are very pleased. The project has gone according to plan. The sterilisation centre is running as it should, and the desired water quality is available

Thorkild Vestergaard, Project manager and mechanical engineer at Regional Hospital Viborg

 

Pipe system in hygienic design according to pharmaceutical standards

Production plant

The production plant for demineralised water comprises two units so that there is redundancy in case of shutdown of one plant. Two membrane systems of the double-pass reverse osmosis system type have been delivered, which in practice are two reverse osmosis systems connected in series and built on a common frame with piping, pumps, instrumentation, etc. Each system has a capacity of 1,000 l/h.

The systems are based on standard systems of the type DPRO B1 3/3, but the systems have been adapted to deliver the desired water quality. The permeate piping system including conductivity meter, valves and sampling taps is thus in hygienic design in accordance with pharmaceutical standards.

The water quality after the systems is approx. 1.4 µS/cm, well below the 4.3 µS/cm requirement. The bacteria are also well controlled since the water is treated through membranes in two stages, each of which is a hygienic barrier.

Proper pre-treatment of the inlet water is an absolute condition for continuous, trouble-free operation. A softening plant removes calcium, which would otherwise clog the membranes. The softening plant also supplies softened water to a large number of smaller washing facilities in the hospital.

The plant supplies minimum the desired water quality corresponding to purified water in accordance with the European Pharmacopeia:

  • Nitrate ≤ 0.2 ppm
  • Heavy metals ≤ 0.1 ppm
  • Total germ count ≤ 100 cfu/ml (cfu = colony-forming unit)
  • Conductivity ≤ 4.3 μS/cm (at 20 °C)
  • TOC ≤ 500 ppb.

The water quality also meets the autoclave feed-water requirement, since the water is used to ensure a high vapour quality for the purpose.

Distribution facilities

The demineralised water is collected in a pharmaceutical buffer tank of 2,500 litres. In its own factory, EUROWATER has manufactured the desired buffer tank fitted with spray ball for cleaning, rupture disc, instrumentation and breather filter.

In addition to the tank, components are also supplied to the distribution facilities including valves, instrumentation, heat exchangers and pumps. When the individual equipment requires water, water is pumped around to the individual draw-off points and returned to the tank.

Hot-water sanitising of the distribution system can be performed manually as well as automatically.

 

 

 

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