December 15, 2003

By: Holly Rebekah
Website: http://www.water-purification-filters.com

Purified water for the Höchst industrial park

In mid-April, the world's largest distribution system for purified water was handed over ready for operation to the client, Infraserv GmbH & Co. Höchst KG, Energy Division, at the Höchst Industrial Park. The system was installed in one year by Axiva, the technology services provider and plant construction company spun off from the former Hoechst Group. The system supplies purified water round the clock to 17 pharmaceutical production units. The total cost of the investment was some DM 20 million.

Frankfurt am Main, May 22, 2000. When it rains over the Höchst Industrial Park, the important distinction between clean and pure water is most evident. Outdoor pipes with walls just a few millimeters thick separate wind and weather from purified water, i.e. from water with a high degree of purity, one of the most important ingredients in pharmaceutical production. Because most drug rejects are due to deficient water quality in the production process, pharmaceutical manufacturers specify extremely high purity requirements for purified water.

At the start of the system in the Höchst Industrial Park is a central purified water production plant, where well water of drinking-water quality is treated to a purity that meets pharmacopeia quality standards. Immediately after the plant was commissioned, the following analytical values were determined for the water: specific conductivity < 0.3 µS/cm, TOC < 100 ppb. The temperature of the water was between 10 and 22°C. The heavy metal content (according to the German Pharmacopeia , DAB) amounted to < 0.1 mg/l and the nitrate content (DAB) to < 0.2 mg/l.

The central production plant for purified water by itself would have served hardly any of the pharmaceutical production units at the Höchst Industrial Park. The great technical challenge for Axiva's engineers was to distribute the purified water throughout the four-square-kilometer industrial park in compliance with the relevant pharmaceutical guidelines. To ensure that water quality is maintained, bacterial growth must be prevented throughout the entire system. This task is accomplished by the purified water distribution system, which – with 13 kilometers of sterile pipeline in all – is the largest of its type in the world. On leaving the production plant, the purified water passes via a ring main to four decentralized buffer tanks with capacities of 75 and 200 cubic meters. These tanks – some located inside buildings and some outdoors – have an equalizing function at times of peak water demand. Each of these tanks supplies purified water via a secondary ring main to five of the total of 17 production units. In the ring mains some 500 cubic meters of purified water are constantly in circulation – even when there is no water demand – to ensure microbiological quality. 13 sterile pumps are used to ensure constant circulation. Five redundant pairs of pumps provide high fail-safe security.

Most of the purified water distribution system is installed aboveground on pipe bridges and routes that criss-cross the Höchst Industrial Park east-west and north-south. As a result of this, weathering effects could cause the quality of the welded joints to deteriorate. The system installers have avoided these risks with a very high degree of prefabrication and consistent use of automated welding. The purified water is therefore protected throughout the distribution system.

To ensure that water quality is maintained, the purified water is not only continually circulated but also ozonized at several points in the system – the know-how comes from Axiva and Infraserv. The ozone generators operate on the principle of catalytic water electrolysis. For this process, the specific conductivity of the purified water must be less than 20 µS/cm. Flow-through electrolysis cells ensure in-situ ozonization of the purified water, i.e. neither oxygen nor cooling water are required. The advantages of this form of ozonization are minimal operating costs and absolute safety.

The unique feature of this purified water supply system installed by Axiva is that it is the first system in the world to operate solely with electrolysis cells. "We have certainly pioneered the way for a future time when only electrolysis cells will be used for this type of system," enthused Dr. Michael Ewers, Axiva project manager, stressing the groundbreaking nature of the system.

These ozone stations, some of which are housed in containers, ensure permanent ozonization of the water at 13 decentralized points. Even if all the connected production units withdraw their maximum required quantity of purified water, an ozone concentration of at least 20 ppb is ensured. If necessary, the system can be sanitized with an ozone concentration of at least 200 ppb without additional equipment.

The entire system is controlled by a central Siemens PCS-7 process control system that consists of two operator stations and five process stations. These are linked to each other by an Industrial Ethernet in the form of fiber-optic cable. Production-unit consumption data and in-line test values for water quality are fed into the process control system. Altogether, the control system processes data from 260 measuring points in 20 buildings spread over several square kilometers.

Most of Aventis' pharmaceutical production activities at the Höchst site are among the 17 production units using the purified water distribution system constitute. All consumers are connected to the system by a free outlet to their feed tank. The distribution system is operated by Infraserv Höchst but use of the purified water from the feed tank onwards is the responsibility of the production units.

With this FDA-compliant system, Axiva scientists and engineers, in collaboration with Infraserv, have solved a fundamental logistics problem – how to maintain water quality in the supply line. Unlike supplying cars or tubes of cream, the distribution of purified water under constant threat of bacterial contamination is a highly complex task. But the effort has paid off. It can rain and snow all it likes at the Höchst Industrial Park from now on – the distribution of purified water will not be affected.

Author Notes:

Holly Rebekah contributes and publishes news editorial to http://www.water-purification-filters.com.  Get educated on the benefits of water purification systems and different water filters available.