The paper-making process is one of the most water-intensive industrial production processes. This is because, without the physical properties of water, it would not be possible for a consistent structure to be achieved when the constituents of paper are processed in a sludge. A high level of water consumption is inevitable in the processing of natural raw materials (wood, cellulose, vegetable fibers) and also in the process of recycling waste paper. This creates a high level of waste water for processing. The residues in the waste water are a problem particularly in the case of de-inking: the process of recycling printed waste paper.
This demonstrates the tremendous advantages of a decanter from GEA Westfalia Separator Group, both in terms of competitive advantages by way of reducing costs in the paper industry and also for environmental protection by minimizing pollutants.
In addition to the above-mentioned constituents, further chemical substances are also added depending on the desired paper quality – for instance whiteners, inks or dust-inhibiting agents – which have to be removed from the waste water at the end of the production process.
During preclarification and post-clarification, primary, secondary and flotation sludges are produced which are dewatered individually or together by the decanter. Because of the high dry substance, the storage and disposal costs are reduced, the volume of fresh water is minimized, and expensive chemical substances can be reused on several occasions – a factor which likewise has a positive impact on the economic balance. The dewatered sludge can either be dumped, dried or incinerated.