Since 2008 Vinnolit operates in the Chemical Park Knapsack with PVClean the first commercial-scale plant for the recycling of process waste water of a suspension PVC plant. By ultra filtration and water recycling, the water consumption per year could be reduced by 200,000 cubic meters. The Vinnolit project PVClean "Optimising Process Water Handling in S-PVC Production” was supported by the North Rhine-Westphalian Ministry of Environment and funded by the EU Commission under the LIFE III program.

LIFE (L'Instrument financier pour l'environment) is the only support of the EU, which only provides financial support to environmental and conservation projects. The aim of this project is to reduce the effects of climate change and the decline of biodiversity in Europe. PVClean is one of three North Rhine-Westphalian environmental projects that were funded by the LIFE Environment Programme in 2005, with around 2.7 million euro. The project started in December 2005 and was completed successfully in December 2008.

Idea: The S-PVC process at the site Knapsack was to be optimized, regarding to water consumption and sewage flow, by a new recycling process.

At the S-PVC production the polymerization is discontinuous in liquid phase. The water, applied for polymerization, is separated in the following reprocessing and accrued as waste water to the treatment plant before. This untreated sewage flow can not be used again, because it still contains a small amount of PVC. With a return of this sewage flow, the high quality requirements to Vinnolit´s suspension PVC can not be achieved, since only a few particles in the water approach of the polymerization lead to a significant impairment of quality. After the separation of the PVC particles from the waste water, this may be reused and the separated PVC particles may be reprocessed and fed to the product stream again.

Development: In preliminary tests in laboratory and pilot plant scale the basic feasibility was demonstrated. By dint of a ceramic membrane with a pore diameter of 50 nanometer (1 nanometer = 0.000001 mm) an almost complete separation of the PVC particles succeeded in continuous operation for several months. The purified water was collected and reused for polymerization in pilot plant and field tests. The maintaining of the high quality standards for S-PVC has been demonstrated. While several earlier attempts of process water recycling failed, Vinnolit has now developed a method to filter the disturbing PVC micro-particles out through an ultra filtration process, so that the treated water can be recycled into the production.

Implementation: Based on the development, Vinnolit built a membrane system on large scale in Knapsack, which was put into operation in 2008. The waste water gets now treated by a newly developed membrane filtration plant. The amount of waste water is reduced by up to 50 percent through the refeeding of treated waste water, almost free of PVC, to the polymerization process. Furthermore the fresh water consumption in the production process is reduced significantly. About 200,000 cubic meters of fresh water are saved per year by the new technology.

The procedure sets new standards in water consumption in suspension PVC production:

Worldwide, almost 35 million tons of PVC are used annually for pipes, window frames, floor coverings, automotives, packaging, credit cards or medical applications for instance. With a share of about 90 percent, the suspension process is the world's most important procedure for PVC production. By dint of the new recycling process, the required amount of fresh water and similarly the amount of waste water are reduced by half. Thus, the environmental performance of the whole process is improved significantly.

With PVClean a new standard in water consumption of the PVC procedure was set, which is also provided to other PVC producers by the sale of licenses by the Vinnolit technology center VinTec. The procedure is not only able to get integrated in new plants, but - as in Knapsack - into existing production environments, too. Particularly for PVC producers in arid countries it is a opportunity to use the scarce resource fresh water economically.

For more information, see the Layman's Report (2009, pdf file for download) and our press release.