| 摘要 |
During the manufacturing of bleached, mechanic pulp the pulp is led, after defibration (1) to a pulp drying machine (3), a bleaching tower (7), a place of screening (9) and a dehydrator (10). Waste from the pulp drying machine (3) is divided in a semi-permeable membrane device (4) in a concentrate (5) containing high-molecular substances and a permeate (6) containing low-molecular substances as well as unused bleaching-agent. The concentrate (5) is led away and destroyed whilst the permeate (6) is recirculated to the process, e.g. to the bleaching tower (7). The bleaching chemicals (2) are added to the defibration (1) as well as fresh water (12). The screening backwater (8) is used in the normal manner in order to stop the concentration of pulp. Through the harmful, high-molecular substances being eliminated as a concentrate the use of fresh water can be reduced down to the corresponding amount and the back water system almost completely eliminated. Environmental waste is reduced to a minimum. The process is also suitable for the fabrication of ground wood.<IMAGE> |
