Extended delignification during oxygen bleaching of modified kraft pulp

1986 ◽  
Vol 1 (4) ◽  
pp. 12-17
Author(s):  
Olof Samuelson ◽  
Urban Öjteg
Keyword(s):  
1991 ◽  
Vol 24 (3-4) ◽  
pp. 427-430 ◽  
Author(s):  
J. Nevalainen ◽  
P.-R. Rantala ◽  
J. Junna ◽  
R. Lammi

Conventional and oxygen bleaching effluents from hardwood kraft pulp mills were treated in laboratory-scale activated sludge processes. The main interest was the fate of organochlorine compounds in the activated sludge process. In the treatment of conventional bleaching wastewaters the BOD7-reduction was 80-91 % and in oxygen bleaching wastewaters 86-93 %. The respective CODCr removals were about 40 % and about 50 %. The AOX reductions were on average 22 % and 40 % in the treatment of conventional and oxygen bleaching effluents, respectively. The reductions of chlorinated phenols, guajacols and catecols were usually more than 50 % in both reactors. Very little accumulation of AOX into the sludge was observed. The stripping of AOX from aeration unit was insignificant.


2004 ◽  
Vol 5 (9) ◽  
pp. 485-489 ◽  
Author(s):  
Ana P.M Tavares ◽  
Jose A.F Gamelas ◽  
Armindo R Gaspar ◽  
Dmitry V Evtuguin ◽  
Ana M.R.B Xavier

2005 ◽  
Vol 33 (3-6) ◽  
pp. 57-64 ◽  
Author(s):  
Jose A.F. Gamelas ◽  
Ana P.M. Tavares ◽  
Dmitry V. Evtuguin ◽  
Ana M.B. Xavier

Holzforschung ◽  
1994 ◽  
Vol 48 (4) ◽  
pp. 355-359 ◽  
Author(s):  
Lai Yuan-Zong ◽  
Funaoka Masamitsu ◽  
Chen Hsin-Tai
Keyword(s):  

2003 ◽  
Vol 239 (1-2) ◽  
pp. 157-168 ◽  
Author(s):  
A. Gaspar ◽  
D.V. Evtuguin ◽  
C. Pascoal Neto
Keyword(s):  

1993 ◽  
Vol 47 (5) ◽  
pp. 635-644 ◽  
Author(s):  
Hiroshi Ohi ◽  
Masanao Tajiri ◽  
Yuzo Iwanaga ◽  
Masato Suzuki ◽  
Tetsuo Aoyagi ◽  
...  

1993 ◽  
Vol 13 (2) ◽  
pp. 237-259 ◽  
Author(s):  
Per Larsson ◽  
Olof Samuelson
Keyword(s):  

TAPPI Journal ◽  
2012 ◽  
Vol 11 (6) ◽  
pp. 31-38
Author(s):  
TATIANA M. PÓVOAS ◽  
DINA A.G. ANGÉLICO ◽  
ANA P.V. EGAS ◽  
PEDRO E.G. LOUREIRO ◽  
LICÍNIO M. GANDO-FERREIRA ◽  
...  

We conducted a comparative evaluation of different treatments for the bleaching of eucalypt kraft pulps beginning with OP stages. The treatments tested were (1) an acid chelation stage with DTPA (OQP sequence); (2) a hot acid stage (AOP sequence); and (3) a chelant addition into the alkaline oxygen stage ((OQ)P and A(OQ)P sequences). The latter strategy was also studied for environmental reasons, as it contributes to the closure of the filtrate cycle. The OQP sequence leads to the highest brightness gain and pulp viscosity and the lowest peroxide consumption caused by an efficient metals control. Considering that the low biodegradability of the chelant is a problem, the A(OQ)P sequence is an interesting option because it leads to reduced peroxide consumption (excluding OQP) while still reaching high brightness values and similar brightness reversion to OQP prebleaching, with only a viscosity loss of 160 dm3/kg. Therefore, a hot acid stage could be considered when a separate acid Q stage is absent in a prebleaching sequence of Eucalyptus globulus kraft pulps involving OP stages.


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