Membrane treatment of alkaline bleaching effluent on a kraft pulp - - PowerPoint PPT Presentation

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Membrane treatment of alkaline bleaching effluent on a kraft pulp - - PowerPoint PPT Presentation

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FEDERAL UNIVERSITY OF VIOSA DEPARTMENT OF FOREST ENGINEERING LABORATORY OF PULP AND PAPER Membrane treatment of alkaline bleaching effluent on a kraft pulp mill Rafael Quezada, Claudio Mudadu Silva, Leif Nilsson Christian Hoffstedt and Niklas

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Membrane treatment of alkaline bleaching effluent on a kraft pulp mill

FEDERAL UNIVERSITY OF VIÇOSA DEPARTMENT OF FOREST ENGINEERING LABORATORY OF PULP AND PAPER

Rafael Quezada, Claudio Mudadu Silva, Leif Nilsson Christian Hoffstedt and Niklas Berling

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Outline

  • Introduction
  • Objectives
  • Results

– Membrane treatment of alkaline bleaching effluent – Effects of the (EPO) membrane filtration on the effluent treatment plant – Membrane permeate recycling to the bleaching plant – Membrane retentate send to black liquor evaporation

  • Conclusions
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SLIDE 3

EVAPORATORS RECOVERY BOILER CAUSTICIZING 1,3 – 6,0 4 – 10 15 – 30 4 – 7 0,5 – 2,0 1,0 – 2,0 2,0 – 4,0

Volume (m3/adt)

Water consumption Bleaching area: 45.000 m3/d Total: 65.000 m3/d WOODYARD

COOKING

BLEACHING

DRYNG MACHINE

Effluent generation

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Module

Membrane

(EPO) filtrate Retentate Permeate

Membrane treatment

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D (EPO) D D

ClO2

NaOH D D

(EPO)

D

Pre–O2

Pulp Acid effluent Alkaline effluent (EPO) filtrate

Bleaching sequence

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Evaluate the membrane treatment of (EPO) filtrates from a kraft pulp mill Specific objectives

a) Compare three configurations of membrane to treat alkaline (EPO) filtrate of a kraft pulp mill using pilot plants and determine the best

  • peration conditions;

b) Study the effect of the (EPO) filtrate membrane treatment on the effluent treatment plant; c) Evaluate the feasibility of recycling of the UF permeate within the bleaching plant; d) Evaluate the feasibility to send the UF retentate to the black liquor evaporation sector

Objectives

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SLIDE 7

Membrane treatment of alkaline bleaching effluent

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Membrane configuration selection (UF, UF + NF, NF) Optimal condition determination Long-term operation

Membrane treatment – Experimental set-up

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Membrane treatment – Pilot plants

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  • The nanofiltration membranes require a pre-

treatment to reduce temperature and neutralize pH;

  • In order to select the best option it was considered

not only the selectivity but also the costs and

  • peration simplicity;
  • The selected configuration was ultrafiltration;
  • The best condition for higher permeate flux (over

200 L/m2h) was 3,0 m/s of cross-flow velocity and 7 bar of TMP, for a COD removal and color of 58% and 91%, respectively.

Membrane treatment

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Effects of the (EPO) UF on the effluent treatment plant

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SLIDE 12

ClO2

NaOH D D

(EPO)

D

Pre–O2 Pulp

Acid effluent Permeate Retentate

ETP

Scenario 1

Effects on the ETP

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SLIDE 13

ClO2

NaOH D D

(EPO)

D

Pre–O2 Pulp

Acid effluent Permeate Retentate

Scenario 2

ETP

Effects on the ETP

Chemical recovery process

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SLIDE 14

Reference

Biological treatment Tertiary treatment

Scenario 1

Effluent with (EPO) UF permeate

Scenario 2

Effluent without (EPO) filtrate. UF permeate is recycled

Effects on the ETP – Lab. simulation

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Parameter

Scenario 1 Scenario 2

Softwood Hardwood Softwood Hardwood

COD reduction efficiency +10,1% + 9,8 % + 6,0 % + 8,1 % Final color

  • 9,8 %
  • 8,0 %
  • 8,3 %
  • 8,0 %

Biological sludge production 0 % 0 %

  • 20,3 %
  • 17,1 %

Energy consumption 0 % 0 %

  • 20,3 %
  • 17,1 %

Coagulant dosage

  • 30 %
  • 37 %
  • 40 %
  • 40 %

Tertiary sludge production

  • 28 %
  • 35 %
  • 44 %
  • 46 %

Effects of the UF on the Effluent Treatment Plant (+) Increase; (-) decrease

Effects on the ETP

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Membrane permeate recycling to the bleaching plant

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  • Software simulation (WinGEMS);
  • Steady state model approach;
  • Hot water on the EOP-press is stepwise replaced with permeate

from the membrane filtration unit all washing liquor on the press is permeate;

  • Same efficiency assumed at different filtrate concentrations

although a different filtrate composition can be expected when recycling the permeate on the EOP-press.

EPO permeate available (m3/adt) Hot water used on EPO- press (m3/adt)

Softwood 8,4 5,8 Hardwood 6,2 5,4

Permeate recycling

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50 100 150 200 20 40 60 80 100 CaCO3 g/Adt Hot water on EOP-press replaced with permeate (%)

(EPO) Stage (EPO) Filtrate Supersaturation limit

50 100 150 200 250 300 20 40 60 80 100 CaCO3 g/Adt Hot water on EOP-press replaced with permeate (%)

(EPO) Stage (EPO) Filtrate Supersaturation limit

Hardwood campaign Softwood campaign

Permeate recycling – CaCO3 formation

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50 100 150 200 250 20 40 60 80 100 Mg(OH)2 g/Adt Hot water on EOP-press replaced with permeate (%)

(EPO) Stage (EPO) Filtrate

20 40 60 80 20 40 60 80 100 Mg(OH)2 g/Adt Hot water on EOP-press replaced with permeate (%)

(EPO) Stage (EPO) Filtrate

Softwood campaign Hardwood campaign

Permeate recycling – Mg(OH)2 formation

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UF retentate send to black liquor evaporation

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Parameter Hardwood Softwood Weak black liquor (kg/h) Retentate (kg/h) CI (%) Weak black liquor (kg/h) Retentate (kg/h) CI (%) Na 26380 10,28 0,04 35596 11,74 0,03 Ca 65 0,43 0,66 33 0,37 1,13 K 361 0,28 0,08 3379 0,29 0,01 Mg 25,5 0,34 1,33 36,6 0,95 2,59 Mn 8,0 0,16 1,96 4,0 0,05 1,24 Ba 1,59 0,003 0,18 0,22 0,001 0,39 Al 12,7 0,22 1,72 8,8 0,23 2,63 Si 76,3 0,11 0,14 40,2 0,34 0,84 P 55,0 0,06 0,10 16,1 0,06 0,34 Cl 239 0,83 0,35 576 1,25 0,22 SO4 7415 3,55 0,05 4147 1,79 0,04 CI= Concentration increment of the element on the weak black liquor after adding the (EPO) retentate

Retentate reuse

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  • The treatment of the (EPO) filtrate by tight UF allows an

increase on the COD removal efficiency by 10% in the biological treatment plant. It also decreased the color on the treated effluent by approximately 9%;

  • The recycle of the resulting UF permeate in the bleaching

area is the best option available for the reuse of this current;

  • It can increase the efficiency of COD reduction in 8%, and

20% reduction in the generation of biological sludge, 45%

  • f tertiary sludge and 40% less coagulant.
  • Water economy: 200 L/s (17.280 m3/d)

Conclusions

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  • In the hardwood and in the softwood case, 100%

replacement of hot water on EPO-press is possible (5,4 m3/adt and 5,8 m3/adt)

  • Small CaCO3(s)-formation in EOP-filtrate above 50%

replacement of hot water due to high carbonate content according to equilibrium calculations

  • Supersaturation calculations indicate that the

precipitations will not start to form when replacing 100% of the hot water with permeate

  • It is expected that the relation of S/Na2 remain unchanged

after the addition of the retentate to the black liquor stream, therefore the recovery boiler chemical performance will not be affected

Conclusions

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SLIDE 24

Rafael Quezada Reyes

Rafael.Reyes@ufv.br

Membrane treatment of alkaline bleaching effluent on a kraft pulp mill

FEDERAL UNIVERSITY OF VIÇOSA DEPARTMENT OF FOREST ENGINEERING LABORATORY OF PULP AND PAPER

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  • Membrane configuration selectivity
  • PCI modules
  • Cost information
  • Industrial design
  • Membrane performance experiment
  • Characterization of filtrates, permeate and retentate
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SLIDE 26

Rafael Quezada Reyes

Rafael.Reyes@ufv.br

Membrane treatment of alkaline bleaching effluent on a kraft pulp mill

FEDERAL UNIVERSITY OF VIÇOSA DEPARTMENT OF FOREST ENGINEERING LABORATORY OF PULP AND PAPER

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Pressão Diâmetro Poros

Suspended Solids Water Monovalent Ions Virus Multivalent ions Bacteria

MICRO FILTRATION

0,1 - 10 m 70 - 350 KPa

ULTRA FILTRATION

0,02 - 0,1 m 170 - 850 KPa

NANO FILTRATON

500 - 20.000 Da 500 - 1500 KPa

REVERSE OSMOSE

<500 Da 3500 - 5000 KPa Mudado, 2008

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SLIDE 28

lenght (m) 1,22 2,44 3,66 Area (m2) 0,88 1,75 2,63

PCI – B1 Module

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Membrane PCI – ESP04 Temperature 70 – 75° C Press Above 8 bar pH 11 – 11,5 Permeate recuperation 98 – 99% Permeate flux 90 l/m2.h Area 7.971,6 m2 Lines 3 Steps/Line 7 Modules/steps 146

Investment: $15.000.000 USD Energy: $1.200.000 USD/year (1.485 kW) Membrane: $920.000 USD/year Cleaning: $250.000 USD/year

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Permeate 7 Retentate 7 R1 R2 R3 R4 R5 R6 P1 P2 P3 P4 P5 P6

(EPO) filtrate

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Volumetric concentration factor (VCF) Permeate flux, L/m2.h

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Raw material Parameter Na Ca K Mg Mn Ba Al Si P Cl SO4 Units mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L Eucalyptus Permeate (198 L/s) 666

0,95 12,7 0,09 0,01 0,2 4,8 163,7

Retentate (2 L/s)

1428 59,9 39,18 47 21,71 0,391 30,5 14,9 7,69 115 492,8

D0 filtrate

575 26 33 3,1 1 0,05 0,37

  • (EPO) filtrate

625 2,6 7,3 0,6 0,15 0,02 0,26

  • D1 filtrate

ND ND ND ND ND ND 0,004

  • D2 filtrate

381 5,25 4,5 1,1 0,08 0,04 0,31

  • Water

150 1,2 1,6 0,3 0,01 0,01 0,31

  • Pine

Permeate (198 L/s) 694,5 1,36

9,34 0,07 0,005 0,14 8,1 142,7

Retentate (2 L/s)

1630 51,4 40,56 131,8 6,94 0,119 32 46,6 7,6 173 248,3

D0 filtrate

95,2 31,9 31,1 10,5 0,51 0,33 0,45 7,2

  • 790

(EPO) filtrate

603 8,51 11,8 2,2 0,1 0,07 0,2 8,2

  • 250

D1 filtrate

89,7 32,5 34,6 15,9 0,45 0,36 0,69 25,3

  • 370

D2 filtrate

105 15,1 5,1 4 0,09 0,06 0,21 9,3

  • 230

Water

162 3,22 0,6 0,5 0,03 0,01 0,22 4,3