Effects of electrostatic precipitators ash leachate (EPAL) from recovery boilers on the biological treatment of effluent of kraft pulp mills

2019 ◽  
Vol 659 ◽  
pp. 905-911 ◽  
Author(s):  
Rafles Anselmo da Mata ◽  
Claudio Mudadu Silva ◽  
José Cola Zanuncio ◽  
Laura Barron Materazzi
Keyword(s):  
Biological Treatment ◽  
Kraft Pulp ◽  
Pulp Mills ◽  
Recovery Boilers ◽  
Kraft Pulp Mills ◽  
Electrostatic Precipitators

The influence of anoxic conditioning of sludge on enhanced AOX (adsorbable organic halogen) removal in aerobic biological treatment systems

1997 ◽  
Vol 35 (2-3) ◽  
pp. 77-84 ◽  
Author(s):  
Liu Hua-Wu ◽  
Steven N. Liss ◽  
D. Grant Allen
Keyword(s):  
Activated Sludge ◽  
Biological Treatment ◽  
Kraft Pulp ◽  
Pulp Mills ◽  
Batch Experiments ◽  
Bleached Kraft Pulp ◽  
Organic Halogen ◽  
Kraft Pulp Mills ◽  
Aox Removal ◽  
Activated Sludge Systems

The increasingly stringent limits on the discharge of adsorbable organic halogen (AOX) from bleached kraft pulp mills have resulted in a need to optimize the performance of biological wastewater treatment systems with respect to the removal of these compounds. To investigate whether anoxic conditioning of sludge can enhance AOX removal in activated sludge systems, a series of batch experiments was conducted where reactors were seeded with various proportions of activated and anoxic-conditioned sludges. AOX removal was found to be significantly enhanced through the addition of anoxic-conditioned sludge to activated sludge, resulting in overall AOX removal of up to 75%. The extent of enhancement ranged from 3 to approximately 10% as the conditioning time was increased from 5 to 20 days. The benefit then declined as the conditioning times increased further beyond 20 days and up to 30 days. The effect of conditioning time on COD removal followed a similar trend as for AOX removal. An optimal AOX removal was achieved when the proportion of conditioned sludge within the biomass was 30%. A good correlation between the enhanced AOX removal and increasing levels of facultative bacteria developed in the conditioned sludge was observed. The addition of sulphate into the sludge during conditioning further increased the enhancement of AOX removal when compared to sludges conditioned under nitrogen.

Combustion behaviors of lignin-lean black liquor and lignin

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 451-458 ◽  
Author(s):  
LIMING ZHAO ◽  
HONGHI TRAN ◽  
KIRSTEN MAKI
Keyword(s):  
Kraft Pulp ◽  
Black Liquor ◽  
Volatile Content ◽  
Pulp Mills ◽  
Heating Value ◽  
Lignin Removal ◽  
Recovery Boilers ◽  
Attractive Option ◽  
Kraft Pulp Mills ◽  
Combustion Behaviors

For kraft pulp mills that have thermally limited recovery boilers, lignin removal from black liquor has become an attractive option for increasing pulp production by allowing more black liquor to be processed through the boiler. This study systematically examined the combustion characteristics of lignin-lean black liquor and precipitated lignin from three kraft mills using a thermogravimetric combustor. The results confirm that adding lignin-lean black liquor to its original black liquor decreased the heating value and the degree of swelling of the mixed liquor. The effect on liquor swelling, however, was insignificant for mixed liquors that contained less than 20 wt% of lignin-lean liquor. As with other biofuels, the combustion of precipitated lignin was found to occur through three main stages: drying, volatile burning, and char burning. During the volatile burning stage, hardwood lignin swelled significantly, softwood lignin did not swell much, and mixed hardwood and softwood lignin was somewhere in between. Although the char content in lignin was about half of the volatile content, it took 10 times longer for the char to burn compared to the volatiles.

The solubility of calcium carbonate  in green liquor handling systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (10) ◽  
pp. 595-602
Author(s):  
ALISHA GIGLIO ◽  
VLADIMIROS G. PAPANGELAKIS ◽  
HONGHI TRAN
Keyword(s):  
Calcium Carbonate ◽  
Systematic Study ◽  
Kraft Pulp ◽  
Thermodynamic Simulation ◽  
Solubility Data ◽  
Pulp Mills ◽  
Persistent Problem ◽  
Green Liquor ◽  
Kraft Pulp Mills ◽  
Salt Systems

The formation of hard calcite (CaCO3) scale in green liquor handling systems is a persistent problem in many kraft pulp mills. CaCO3 precipitates when its concentration in the green liquor exceeds its solubility. While the solubility of CaCO3 in water is well known, it is not so in the highly alkaline green liquor environment. A systematic study was conducted to determine the solubility of CaCO3 in green liquor as a function of temperature, total titratable alkali (TTA), causticity, and sulfidity. The results show that the solubility increases with increased temperature, increased TTA, decreased causticity, and decreased sulfidity. The new solubility data was incorporated into OLI (a thermodynamic simulation program for aqueous salt systems) to generate a series of CaCO3 solubility curves for various green liquor conditions. The results help explain how calcite scale forms in green liquor handling systems.

Toward Production of Bioethanol Using Pulp Rejects from Kraft Pulp Mills as Raw Materials

2013 ◽  
Vol 67 (11) ◽  
pp. 1248-1251
Author(s):  
Masanori Kishino ◽  
Ken Orihashi ◽  
Akira Harada
Keyword(s):  
Kraft Pulp ◽  
Raw Materials ◽  
Pulp Mills ◽  
Kraft Pulp Mills

Activated Sludge Treatment of Kraft Mill Effluents from Conventional and Oxygen Bleaching

1991 ◽  
Vol 24 (3-4) ◽  
pp. 427-430 ◽  
Author(s):  
J. Nevalainen ◽  
P.-R. Rantala ◽  
J. Junna ◽  
R. Lammi
Keyword(s):  
Activated Sludge ◽  
Kraft Pulp ◽  
Activated Sludge Process ◽  
Chlorinated Phenols ◽  
Pulp Mills ◽  
Main Interest ◽  
Sludge Treatment ◽  
Kraft Pulp Mills ◽  
Activated Sludge Processes ◽  
Oxygen Bleaching

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.

State of the art methods for combined water and energy systems optimisation in Kraft pulp mills

2021 ◽  
Author(s):  
Elvis Ahmetović ◽  
Zdravko Kravanja ◽  
Nidret Ibrić ◽  
Ignacio E. Grossmann ◽  
Luciana E. Savulescu
Keyword(s):  
Kraft Pulp ◽  
State Of The Art ◽  
Energy Systems ◽  
Pulp Mills ◽  
Art Methods ◽  
Kraft Pulp Mills

Fate of phosphorus in the recovery cycle of the kraft pulping process

TAPPI Journal ◽  
2020 ◽  
Vol 19 (3) ◽  
pp. 139-148
Author(s):  
MARYAM SADEGH MOUSAVI ◽  
NIKOLAI DEMARTINI
Keyword(s):  
Kraft Pulp ◽  
Pulp Mill ◽  
Field Studies ◽  
Kraft Pulping ◽  
Pulp Mills ◽  
Recovery Cycle ◽  
Green Liquor ◽  
Green Liquor Dregs ◽  
Kraft Pulp Mills ◽  
Negative Effect

The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magne-sium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.

Excess heat from kraft pulp mills: Trade-offs between internal and external use in the case of Sweden—Part 1: Methodology

Energy Policy ◽  
2008 ◽  
Vol 36 (11) ◽  
pp. 4178-4185 ◽  
Author(s):  
Inger-Lise Svensson ◽  
Johanna Jönsson ◽  
Thore Berntsson ◽  
Bahram Moshfegh
Keyword(s):  
Kraft Pulp ◽  
Pulp Mills ◽  
Excess Heat ◽  
Trade Offs ◽  
Kraft Pulp Mills
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