Improved paper quality and runability by iological process water recovery in closed water circuits of recycle mills

摘要

Reduction of effluent discharge leads to process water accumulation of anionic trash, waxes, secondary stickies, pitch odorous components, salt, calcium hardness etc. This can have a negative impact on the paper making process as well as on the product especially if the target is to achieve zero discharge. The paper gives an overview of the problems that may occur, their causes and mechanisms, as well as the possibilities to cope with them. One method that can deal with most kinds of contamination at one time is the in line biological treatmet. The mechanisms are given to show its effectiveness to remove both organic as well as inorganic process water impurities. In a full scale operating example, these facts are being confirmed and the first results are very positive, in terms of quality improvement and machine runability. Investment and especially operating cost are expected to be much lower than physical/chemical methods to achieve similar results.