Process for treating wastewater from a bleach plant
US6425974B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1999 |
| Grant date | Jul 30, 2002 |
| Priority date | — |
| Expiry date | Nov 8, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S162/08
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
The process according to the present invention relates to the treatment of wastewater discharged from a bleach plant and more particularly treatment of bleach plant alkaline wash filtrate from treatment-steps and/or delignification/bleaching-steps of pulp. Further improvements of known processes are needed for solving the problems associated with the recovery of alkaline filtrates into the chemical recovery system. According to the process of the present invention, alkaline wash filtrate from treatment-steps and/or delignification/bleaching-steps of pulp is treated in a process by the following steps: i) treating at least a part of the alkaline filtrate in order to produce an alkaline concentrate enriched in high molecular weight dissolved organic compounds and a stream depleted in organic compounds, where the share of the alkaline concentrate to the total amount of the alkaline filtrate corresponds to a volume reduction factor (VRP) in the range of from about 2.0 up to about 7.5; ii) withdrawing the depleted stream; iii) collecting at least a part of the alkaline concentrate from step i) and using the concentrate as wash or dilution water in brownstock washing fiberline with a dil…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.