| 摘要 |
Lignin is flocculated and batched off from a sulfide-free black liquor discharged out of a pulp digestion step by water disposal techniques, and organic matters remaining in the filtrate are removed to recover water, acids and caustic soda. A mineral acid and, if necessary, diluting water is added to the black liquor to control its pH to 1 to 7, and a flocculant is added to the black liquor to filtrate out flocculating lignin. Further, ozone is brought into contact with the filtrate to oxidize and break down organic matters in the filtrate and remaining organic matters are adsorbed onto activate charcoal for removal. |
