EPA-R2-73-086
FEBRUARY 1973 Environmental Protection Technology Series
Color Removal from
Kraft Pulp Mill Effluents
by Massive Lime Treatment
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3* Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards*.
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EPA-R2-73-086
February 1973
COLOR REMOVAL FROM KRAFT PULP MILL
EFFLUENTS BY MASSIVE LIME TREATMENT
By
John L. Oswalt
Joseph G. Land, Jr.
Project 12040 DYD
Project Officer
George Webster
Office of Water Programs
Environmental Protection Agency
Washington, D.C. 20460
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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EPA Review Notice
This report has been reviewed by the Office of
Research and Monitoring, EPA, and approved for
publication. Approval does not signify that the
contents necessarily reflect the views and policies
of the Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for use.
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ABSTRACT
A demonstration plant was installed and operated to determine effectiveness and feasibility
of using massive lime treatment (that is, 20,000 ppm lime) to decolor kraft putp mill
effluents. The two most highly colored effluents and mixtures of those treated in the
demonstration plant were: (1) the almost black effluent from the caustic extraction stage
of pulp bleaching, and (2) the light reddish-brown effluent from the final unbleached pulp
washing stage. Objectives of the project were to determine:
effectiveness of color removal
design and performance of massive lime system equipment
effects on normal pulp mill operations
effects on pulp quality
operating costs
Impact of the massive lime system on a hypothetical 1000 tons-per-day bleached kraft pulp
and paper mill is described. Using all the iime normally available in such a mill would allow
massive lime treatment of four million of the mill's twenty-nine million gallons of effluent.
Such treatment would remove 72% of the total mill effluent's color, reducing final effluent
color to approximately 740 APHA units at an estimated cost of $1.80 per ton of pulp
(depreciation, insurance, and taxes included).
This report was submitted in fulfillment of Project Number 12040 DYD under the partial
sponsorhip of the Water Quality Office, Environmental Protection Agency.
II!
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TABLE OF CONTENTS
SECTION PAGE
I Conclusions 1
I! Introduction 3
III Description Of Initial Demonstration Plant Equipment 7
IV Operating Problems And Modifications To Original Equipment 13
V Operation And Performance Of The Equipment 23
VI Effectiveness Of The Massive Lime Process 31
VII Impact Of The Massive Lime System On Normal Pulp Mill Operations 41
VIII Considerations For Design Of A Color Removal Plant 51
IX Benefits And Operating Costs For A Typical Mill 59
X Acknowledgments 67
XI References 69
XII Glossary 71
XIII Appendices 75
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No.
FIGURES
PAGE
1. Massive Lime Process 5
2. Causticizing Process For A Kraft Pulp Mill 6
3. Massive Lime Demonstration Plant-Original Equipment Flow Diagram 8
4. Primary Clarifier Sample Lines 9
5. Flue Gas Dispersing Arrangement In Carbonator 10
6. Experimental Clarifier 15
7. Primary Clarifier Internals ^
8. Design Of Carbonator Spargers 18
9. Flue Gas Control 19
10. Massive Lime Demonstration Plant-Final Equipment Flow Diagram 21
11. Primary Clarifier Maximum Rise Rate Versus Untreated Effluent Color 25
12. Calcium Content In Effluent To And From The Carbonator Clarifier
Versus Untreated Effluent Color 27
13. Massive Lime Sludge Filter Performance 28
14. Solids Content Of Filter Cake From Sludge Filter Versus
Untreated Effluent Color 29
15. Material Balance For Massive Lime Plant Treating 100% Bleach
Caustic Extraction Stage Effluent 37
16. Material Balance For Massive Lime Plant Treating 50% Bleach Caustic
Extraction Stage Effluent And 50% Unbleached Decker Effluent 38
17. Material Balance For Massive Lime Plant Treating 100% Kraft
Unbleached Decker Effluent 39
18. Material Balance For Normal Pulp Mill Liquor Preparation And
Spent Liquor Recovery System 42
19. Material Balance For Pulp Mill Liquor Preparation And Spent Liquor
Recovery System Using Massive Lime System Sludge For Causticizing 43
20. Volume Of Effluent Treated Versus Lime Requirements For
Massive Lime Process 52
21. Sludge Filter Area Versus Effluent Color 56
VI
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TABLES
No. PAGE
1. Calcium Losses From Carbonator Clarif ier 26
2. Color And Organic Carbon Content Of Mill Effluents 31
3. Color Load Produced By Pulp Mill Sources 32
4. Analytical Tests On Bleach Caustic Extraction Stage Effluent Before
And After Massive Lime Treatment 32
5. Analytical Tests On 50/50 Mixture Of Caustic Extraction Effluent And
Decker Effluent Before And After Massive Lime Treatment 33
6. Analytical Tests On Unbleached Kraft Decker Effluent Before And
After Massive Lime Treatment 33
7. Color And Organic Carbon Removal 34
8. Effects Of Massive Lime Treatment On BOD 35
9. Contribution Of Effluent Sources To Total Mill Effluent Color
With No Massive Lime Treatment 59
10. Contribution Of Effluent Sources To Total Mill Effluent Color
With Massive Lime Treatment Of Bleach Extraction Stage And
Decker Effluents 60
11. Increased Pulp Mill Operating Costs Resulting From
Massive Lime Treatment 63
12. Pulp Mill Savings Or Credits Resulting From Massive Lime Treatment 63
13. Annual Depreciation, Insurance, And Taxes 64
14. Summary Of Effects Of Massive Lime System On Operating Costs
For Hypothetical Mill Producing 1000 Tons Of Bleached Pulp Per Day 65
VII
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SECTION I
CONCLUSIONS
The massive lime treatment demonstration plant was operated at International Paper
Company's Springhill, Louisiana, mill from February 15, 1970, until August 14, 1971.
Results presented in this report led to the following conclusions:
1. Effectiveness of Massive Lime System
Massive lime treatment will remove more than 90% of the color bodies
contained in effluent from the bleach caustic extraction stage and the final
unbleached pulp washing stage. These two effluents contain 65 to 75% of
of the total color load produced in the manufacture of bleached kraft pulp.
Using all the lime normally available for a typical bleached pulp mill (that is
matching the quantity of massive lime sludge produced in effluent treatment
with the mill's ability to utilize the sludge for causticizing cooking liquor),
approximately 14% of the mill's total effluent can be treated for color removal.
Treatment of the most highly colored effluents, the bleach caustic extraction
stage effluent and unbleached decker effluent, will remove 72% of the mill's
total color load. Final total effluent color discharged from the mill can be
reduced from 2630 to approximately 740 APHA units of cclor.
Another benefit of massive lime treatment is a 20 to 40?/o reduction in BOD5
of the effluents treated.
2. Design and Performance of Massive Lime System Equipment
Foaming and carryover of solids from the primary clarifier was the most
serious problem encountered with the demonstration plant as originally
designed. It is imperative that equipment throughout the system be designed
to prevent air entrainment and eliminate or control foaming.
For effluents having a color of 5000 APHA units or more, sludge settling rate
and filter rate vary inversely with the concentration of organic compounds in
the effluent to be treated. Therefore, for a given flow rate, the primary
clarifier and sludge filter sizes must vary with the concentration of organic
compounds in the effluent.
3. Effects on Normal Pulp Mill Operations
Using massive lime system sludge in the pulp mill's liquor causticizing operation
will dilute the cooking liquor, causing its concentration to be approximately
15% lower. Therefore, the volume of liquors handled throughout the pulp
mil! processes will increase, and increased capacity in most of the chemical
preparation and recovery equipment will be required.
Lime kiln fuel requirements increase approximately 6.4% for a given pulp
production, and increased kiln capacity is required.
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Organic compounds carried with massive lime sludge into the mill's cooking
liquor system intensified foaming problems.
Buildup of chlorides or other materials caused by use of massive lime sludge
for causticizing cooking liquor had no apparent effect in the chemical
recovery cycle,
4. Effects on Pulp Quality
There were no apparent effects on bleachability of the pulp or on finished
product quality.
5. Cost
For a typical 1000 tons-per-day mill using the massive lime system to treat
four million gallons of effluent per day, costs would be approximately $1.80
per ton of bleached pulp. This cost is based on current typical raw material
and utilities cost It includes the cost of depreciation, insurance, and taxes
for the increased capital investment for a new mill's color removal system
and expanded capacities elsewhere in the mill necessitated by installation
of the massive lime system.
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SECTION II
INTRODUCTION
The kraft pulping process, used for approximately 90% of the United States' chemical wood
pulp production, produces highly colored liquid effluent. During the 1950's the National
Council for Stream Improvement (NCSI) now known as the National Council for Air and
Stream Improvement (NCASI), conducted many experiments to develop a color removal
process for pulp mill effluents. NCSI's work led to development of a process called "The
Massive Lime Treatment for Color Removal from Kraft Waste Pulping Liquors." This process
was patented in 1964 and assigned to NCSI (Reference 1). Laboratory work by NCASI,
(References 2 and 3), International Paper Company (References 4 and 5), Western Kraft
Corporation (Reference 6), and probably others showed the massive lime process removed
90 to 97% of the color bodies and 35 to 50% of the BOD from pulp mill effluent. Pilot plant
operations conducted by West Virginia Pulp and Paper Company in 1970 (Reference 7), and
by Western Kraft Corporation in 1964 (Reference 6) confirmed the laboratory results.
A larger scale evaluation was needed to: (1) evaluate possible effects of the massive lime
process on normal pulp mill operations, (2) evaluate possible effects on pulp and paper
quality, (3) obtain reliable design criteria for the system and the equipment, and (4) deter-
mine the cost of such treatment. Discussions were held in late 1966 between FWPCA and
International Paper Company on the possibility of a demonstration project. Subsequently
International Paper Company submitted a proposal to the FWPCA to construct, operate,
and evaluate a demonstration color removal plant designed to handle up to 530 gpm of pulp
mill effluent. On June 11,1968, International Paper Company accepted an FWPCA Research
and Development Grant to evaluate and demonstrate the massive lime process, and if this
method of color removal was successful, to determine the best design criteria for future
installations.
The demonstration plant was constructed at International Paper Company's mill at Springhill,
Louisiana. The plant started operation in February 1970 and operated until August 14, 1971,
except for shutdowns due to equipment breakdowns, natural gas shortages, and equipment
alterations.
Primary Sources Of Kraft Pulp Mill Effluent Color
The kraft pulping process solubilizes and removes lignin from wood in a pressure vessel
(digester) at approximately 100 psi and 340°F. This process is called "cooking." Lignin
reacts with chemicals added to the digester in a cooking liquor (white liquor) which is
primarily water, sodium hydroxide, and sodium sulfide. Highly colored lignin and other
organic chemical compounds formed during the cooking process contribute a dark reddish-
brown color to the unbleached pulp. Much of this type pulp is used in grocery bags,
corrugated boxes, and other products where the pulp's color is acceptable. For still other
paper products however, the pulp is bleached to various degrees of whiteness.
Practically all lignin and other materials dissolved during the cooking process are recovered
and used by the mill as fuel for its boilers. The small portion of these highly colored soluble
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materials which are not recovered for use as fuel eventually leave the mill in its liquid effluent.
The main source of colored effluent in a kraftpulp mill producing unbleached pulp is the
final stage of pulp washing. This effluent is called the "unbleached decker effluent" because
it is discharged from a machine known as the unbleached pulp decker.
If the pulp is bleached, additional lignin is solubilized and removed from the pulp. Bleaching
is usually accomplished in multi-stage processes with most of the remaining lignin removed
in the "caustic extraction stage"normally the second step in the bleaching process. Effluent
from the caustic extraction stage is almost black. This caustic extraction stage effluent is the
main source of colored effluent in a kraft pulp mill producing bleached pulp.
Color compounds in the kraft pulp mill effluent have been identified by Holzer (Reference 8)
as sulfur dyes derived from phlobotannins. Investigations by the Empire State Paper Research
Institute, as reported in NCASI Technical Bulletin No. 239 (Reference 9), indicate the color
is due largely to lignin and its degraded products.
Massive Lime Process
Early work on color removal processes had shown most of the color could be removed by
treating the pulp mill effluent with chemicals such as alum and lime. However, a voluminous
sludge was produced which would not densify on settling. Efforts to concentrate the sludge
using filters, centrifuges, and other methods were unsuccessful.
The significant difference between the massive lime process evaluated in this project and
earlier processes is in the amount of lime used. In earlier work lime usage was closely related
to the stoichiometric requirements whereas the massive lime process utilizes a large excess of
lime to produce a heavy and readily settleabfe sludge.
A flow diagram for the massive lime process is shown in Figure 1. Part of the total effluent
to be treated is used for slaking the lime which is to be used. Then, the remaining colored
effluent is treated with a heavy dose of the slaked lime (approximately 20,000 ppm lime
based on weight of the effluent). The mixture is allowed to react for 5 to 30 minutes.
During this period color bodies react with calcium ions. The mixture of lime and liquor then
enters the primary clarifier where the slaked lime and the insoluble calcium-organic com-
pounds are separated from the treated effluent. Clarified, decolored effluent is then treated
with carbon dioxide to precipitate dissolved calcium compounds as calcium carbonate. This
calcium carbonate settles in the carbonator clarifier, is removed, and then combined with
sludge from the primary clarifier in the sludge storage tank. Clarified, decolored effluent
with most of the calcium compounds removed overflows from the carbonator clarifier.
Sludge having a solids content of 18 to 22% is pumped to a rotary vacuum filter and concen-
trated to about 50% solids. Filtrate from the vacuum filter is returned to the massive lime
treating system because of its high content of dissolved and suspended solids. Sludge at
approximately 50% solids is removed from the process and the lime in the sludge is recovered
by using the sludge in the mill's caustSeizing process (process in which the mill produces the
white liquor used for cooking).
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Figure 1
MASSIVE LIME PROCESS
Lime
Colored
Effluent
Decolored Effluent
Sludge
Figure 2 is a flow diagram for the causticizing process. Green liquor which is fed to this
process is a water solution of inorganic chemicals, primarily sodium carbonate and sodium
sulfide, which have been recovered by burning concentrated spent cooking liquor in a
reduction furnace. Sludge from the massive lime process is mixed with green liquor causing
reactions which convert sodium carbonate to sodium hydroxide and calcium hydroxide to
calcium carbonate. The precipitated calcium carbonate is settled from the mixture and the
resulting clarified liquor is the white liquor used for cooking. The calcium carbonate is
washed with water to recover soluble sodium salts and is then burned in a lime kiln to
convert the calcium carbonate to lime.
Lime produced in the kiln can be recycled to the massive lime process. Carbon dioxide
from the lime kiln flue gases can be used for the carbonation step of the massive lime process.
Color bodies removed from the massive lime process with the sludge are to a large extent
soluble in caustic. Most of the color compounds dissolve in the white liquor as it is produced
in the causticizing process. Therefore, white liquor produced with this process is black.
Color compounds which are not dissolved in the white liquor remain with the calcium, go to
the lime kiln, and are burned. Color compounds dissolved in the white liquor eventually are
burned in the mill's chemical recovery furnace.
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Figure 2
CAUSTICIZING PROCESS FOR A KRAFT PULP MILL
Green Liquor
Fuel
Kiln
Lime and/or Sludge from Massive Lime Process
Steam
Causticizer
(Reaction Tank)
*
IMhitB 1
Clarifier
White Liquor
(for cooking)
Lime
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SECTION 111
DESCRIPTION OF INITIAL DEMONSTRATION PLANT EQUIPMENT
The major manufacturers of equipment for kraft pulp mill caustic plants had little or no
experience in the clarification of water using excessive calcium hydroxide or the concentra-
tion of the sludge resulting from this clarification. They expressed little confidence in the
reliability of such a system, and were reluctant to recommend equipment for the project.
Neither International Paper nor the inventors of the massive lime process had any significant
experience outside the laboratory in determining type and size of equipment necessary to
accomplish the objectives. However, International Paper did have personnel experienced in
clarifying pulp mill liquors, and treating water for solids removal.
International Paper Company engineers and the inventors reviewed data from several reports
covering laboratory experiments and small pilot plant trials with the massive lime process.
Based on these reports, the equipment for this project was decided upon. The demonstration
plant was designed to treat 530 gpm of waste water using 20,000 ppm lime (CaO). Figure 3
is a flow diagram showing the original equipment installed. The following is a brief descrip-
tion of the major items of equipment which were installed.
Slaker
Both lime and liquid (colored effluent for the massive lime process) were added continuously
into the slaker tank. The lime pellets disintegrate and react with water in the liquid to form
calcium hydroxide. A sloping trough equipped with an oscillating rake was used to remove
heavy solids (dregs) which settled to the bottom of the slaker. A mixture of liquid and slaked
lime overflowed through a weir.
The slaking of lime to calcium hydroxide occurs slowly at normal ambient conditions;
however, as temperature is raised the reaction becomes much more rapid. Therefore, temper-
ature was normally controlled to approximately 210°F for slaking.
A typical lime-green liquor type slaker with a capacity for slaking 75 tons of lime per day
was installed. This unit was equipped with liquid flow control, temperature control, and a
dregs removal rake. Lime feed to the slaker was controlled by a variable speed screw
conveyor from the lime storage silo. The two types of effluent to be treated in the demon-
stration plant (unbleached decker effluent and caustic extraction stage effluent) were piped
into the system so that either flow could be treated individually, or a mixture of the two
could be treated. Only part of the total effluent flow was needed for slaking, therefore
a by-pass was provided so the remainder would go directly to the reaction tank.
Reaction Tank
The agitated reaction tank, 10 feet in diameter and 8 feet high, was equipped with level
control operating on the discharge of the pump to the primary clarifier. A minimum of five
minutes retention time was provided by the reaction tank.
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£fflu«nt from
Unbleached Docker
CO
Figure 3-MASSIVE LIME DEMONSTRATION PLANT
Original Equipment Flow Diagram
Effluent from
Bleach Caustic
extraction Stage
*--J- Variable Speed Screw
Green Liquor Slaker
(For Mill's Caustic/zing
Process)
| <- Suterbilt Pump
Gas Scrubber
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In the reaction tank, slaked lime and the effluent to be treated were mixed and reaction
occurred between the calcium ions and the organic compounds in the liquid.
Primary Clarif ier
From the reaction tank, the slurry is pumped to the primary clarifier, a large tank in which
the separation of settled solids and supernatant liquid was accomplished. The clarifier has
(Da center well used as the entrance for the slurry, (2) a rotating rake to convey settled
solids to (3) a collection well from which settled solids were removed, and (4) a launder
through which the clarified liquid flowed from the tank.
The primary clarifier installed in the demonstration plant was designed for a rise rate of one
gallon per square foot per minute, with a retention time of three hours. The tank was 26 feet
in diameter and 26 feet high. Clarified liquid overflowed from six three-foot wide weirs,
which were equally spaced around the periphery of the tank. A consistency regulator was
provided to control the density of sludge discharged from the unit.
When installed, the entrance into the center well was an open ended pipe which discharged
above the liquid surface in the center well. The center well was 3 feet in diameter and
extended 3 feet below the liquid level in the clarifier.
As shown in Figure 4, four sample lines at different elevations were provided on the side of
the clarifier.
Figure 4
PRIMARY CLARIFIER SAMPLE LINES
CO
IS
!_£.
J
Launder Orifice
Top
3rd
2nd
Bottom
Tank
Sample Lines
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Carbonator Clarifier
Overflow from the primary clarifier flowed by gravity to the dual purpose carbonator
clarifier. It was designed so that carbon dioxide (lime kiln flue gas) was introduced into the
clarifier's center well along with the incoming liquid. Originally, the flue gas was added five
feet below the surface of the liquid from a circular section of 6-inch diameter pipe having
1/2-inch diameter holes drilled on 4-inch centers (Figure 5). The center well, designed to
give a retention time of about 20 minutes, was 15 feet in diameter by 12 feet high with a
liquid depth of 10 feet. A loosely fitting cover was provided to minimize the escape of foam
created by action of undissolved flue gases.
Figure 5
FLUE GAS DISPERSING ARRANGEMENT IN CARBONATOR
SECTION
PLAN
ORIGINAL DESIGN
Overall dimensions of the carbonator clarifier tank were 30 feet in diameter by 24 feet high.
Rise rate between the center well and the outside wall was designed to be one gallon per
square foot per minute. Retention time was slightly more than three hours. Clarified liquid
overflowed from six three-foot wide weirs equally spaced around the periphery of the tank.
Also, as in the primary clarifier, a rotating rake and collection well were provided at the
bottom for sludge removal. Sludge from the carbonator clarifier was initially pumped to the
mill's existing unfiltered lime mud storage tank (a tank in the mill's normal lime recovery
system where a calcium carbonate sludge is collected). A consistency regulator was installed
to control density of sludge discharged from the unit.
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A positive displacement, constant volume pump capable of supplying 650 cubic feet of flue
gas per minute was installed to provide gas for the carbonator.
Sludge Storage Tank
A tank large enough to hold a two-hour surge was installed between the primary clarifier and
the sludge filter. This tank's capacity was large enough to allow for backwashing or acid
cleaning on the filter, or minor repairs on the filter and causticizing system.
A consistency regulator was provided so that a sludge of uniform consistency could be
delivered to the sludge filter.
Sludge Filter
The purpose of the sludge filter was to thicken the mud from approximately 18 to 22%
solids to approximately 50% solids. For this a sludge filter of the pre-coat type was installed
(similar to existing rotary vacuum drum filters, used as lime mud concentrators for feed to
the mill's lime kiln). This filter had an 8-foot diameter by 8-foot wide face. Sizing was
based on an assumed capacity of 1000 pounds (dry basis) of sludge per day per square foot
of filter area. A Nash pump with vacuum break set at 22 inches was installed to provide the
necessary vacuum.
A screw conveyor was installed to transfer filter cake from the sludge filter discharge to the
pulp mill's slaker in the cooking liquor causticizing process.
Location
An area near the mill's reburned lime storage silo and near one of the existing lime siakers
was cleared and used for erection of the massive lime process slaker, reaction tank, mud filter,
and vacuum pump. The filter was located above the new slaker. Another area 150 feet from
the silo was cleared for the clarifiers. The sludge storage tank (to receive sludge from the
primary clarifier) was located near the filter. A control room was built as an extension to
the existing slaker control room.
A small surge tank with an overflow line to the sewer was located on the ground floor of the
bleach plant to receive caustic extraction stage effluent from either or both of two bleaching
lines. TKis surge tank was some 2200 feet from the slaker and was serviced by a pump with
volume and head characteristics sufficient to deliver the desired flow to the system.
The pump used to supply unbleached decker effluent was tied into the decker seal pit. The
decker seal pit was located some 750 feet from the slaker.
Flow indicators and controllers were located in each of the above lines so flow to the system
could be controlled independently.
There were two separate systems in the mill's caustic room for slaking, causticizing, clarifying
white liquor, and storing white liquor. That part of the system which furnished white liquor
11
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to the bleached pulp mill digesters was isolated for studying effects of using the massive lime
system filter cake on the liquor and pulping systems.
Once the demonstration plant started operating, the need for changes in some of the original
equipment became obvious. Significant changes were made in some parts of the plant.
Problems which made the changes necessary, changes that were made, and a description of
the equipment finally used in the demonstration plant are discussed in Section IV.
12
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SECTION IV
OPERATING PROBLEMS AND MODIFICATIONS TO ORIGINAL EQUIPMENT
The massive lime process demonstration plant was completed in January 1970 and turned
over to the mill operating department February 1, 1970. The first two weeks of February
were used to check out the mechanical and electrical dependability of the equipment, and
to check and calibrate instruments and automatic equipment. Also during this period, the
people who were to operate this system were trained.
It was immediately apparent that there were serious operating problems with the system as
initially installed. Reliable data on performance of the massive lime process could not be
obtained until equipment modifications were made to solve these operational problems. The
modifications were not completed until January 1971. Major operating problems were:
foaming and carryover of suspended solids from the primary clarifier
scaling and mechanical problems with the carbonator system
poor pH control in the carbonator
Foaming Problems In Primary Clarifier
The demonstration plant started operation on February 15, 1970, treating bleach caustic
extraction effluent. Soon after start-up, the surface of the primary clarifier was covered with
foam. This foam soon built up enough to overflow into the launders, and at times overflowed
the outer wall of the clarifier. It was impossible to observe the liquid overflow from the
primary clarifier due to coverage of the entire surface by this tenacious foam. Performance
of the clarifier was completely unsatisfactory as long as the foam persisted because of exces-
sive carryover of suspended solids.
Suspended solids (primarily calcium hydroxide) carried over from the primary clarifier varied
from 1500 ppm to 7500 ppm. This condition existed regardless of the type of effluent
being treated.
The carbonation system did not have enough capacity to carbonate both the soluble calcium
hydroxide and the insoluble calcium hydroxide from the primary clarifier. Therefore
excessive calcium hydroxide in sludge from the carbonator clarifier caused foaming and
operational troubles in the mill's causticizing process mud filter and in the lime kiln.
Foam in the primary clarifier usually had the consistency of shaving cream. Sometimes there
were large bubbles,' 1/2 to 6 inches in diameter, indicating the presence of entrained air.
Commercial defoamers were tried, but their use was costly and not completely effective.
Since the foam was believed to be caused by entrained air, sources of air were eliminated
where possible. Leaking packing glands on pumps were repaired. Speed was reduced on
agitators which could have been whipping air into the liquid, and splashing of entering
liquid was eliminated by submerging entrance piping in all tanks.
13
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These changes eliminated the large bubbles of foam but did not eliminate the very persistent
foam having the consistency of shaving cream. It was determined that this foam was caused
by minute gas bubbles released from the waste water as temperature was increased in the
reaction tank by addition of the slaked lime slurry to the effluent. Speed of the reaction
tank agitator was not fast enough to whip air into the liquid, but it was fast enough to keep
the minute air bubbles from escaping.
There was nothing practical that could be done to prevent the temperature increase and the
resulting release of air bubbles. Therefore, the next approach was to collect the foam and
either destroy it or remove it from the clarifier.
A small experimental clarifier was designed, built, and installed adjacent to the reaction tank
(Figure 6) and in parallel with the primary clarifier. Thick foam collected and overflowed
from the experimental clarifier until a small Yarway shower was installed at the top of the
clarifier's center well. The shower was positioned so that its conical spray covered most of
the open top of the center well. Liquid used for the spray was the same as the untreated
effluent going to the reaction tank. The shower delivered 4 to 5 gpm at 20 psi.
Cylindrical and conical center wells were tried (Figure 6). Both appeared to work, but the
conical design may have been slightly more effective. Therefore, when the primary clarifier
was modified a conical center well was installed. Overflow from the experimental clarifier
was through 8 holes on a horizontal line. These orifices were sized so that liquid level in
the tank would be 2 inches above their center line at 18 gpm outflow and 4 inches above
their center line at 25 gpm. The orifices discharged into a collection launder and flowed
from there to the sewer. This orifice type of overflow launder was essential to allow visual
observation of the outflow even if the surface of the clarifier was covered with foam.
Observation of the outlet stream from the orifices showed the effect of many operating
variables on the condition of the effluent. Some of the observations were:
1. When the unit was performing statisfactorily effluent was not turbid.
2. When clarifier's surface was covered with foam, the lower 2/3 of the stream
was not turbid, but the upper 1/3 was very turbid from entrainment of the
floating foa/.i which contained suspended solids.
3. When the overflow became slightly turbid because of improper operation or
overloading the clarifier, conditions should be changed for better operation
or concentrated suspended solids would soon overflow. There were condi-
tions under which the top half of the stream would be only slightly turbid
and the bottom half would have a heavy concentration of sludge.
When the unit was operating satisfactorily, liquid from the bottom sample port (Figure 4)
contained essentially the same percent settled solids as underflow from the pilot unit. Liquid
from the second sample port was very turbid, and that from the third sample port was only
slightly turbid. If liquid from the second sample port became muddy, mud would soon be
overflowing the unit.
During the experiments with the small clarifier, flow to the regular clarifier and carbonator
was maintained at 250 gpm (± 10). Operation of the primary clarifier was as disappointing
as ever.
14
-------
Figure 6
EXPERIMENTAL CLARIFIER
3" I 5.7
1
i - ,
r *
|
1 T
1
t
1
/ .1
|
7 1
1
i
1
1
l
1
I
i
I
3'-0" D
i
|
1
1
l
ameter
V- Ml
\ T
r-7" \\--ix
< *
< - Fabricated
Carbon Ste
r-o"
DETAIL "A"
1X1X%2$.X2-
Fabricated from ]
Carbon Steel Plate
3" I 5.7
\
t
9
CM
E *?
CS
'-
CNI .
Magnetic .'
Flow ^-,
Meter fe
i
j
4
4
-jt
i
s^
«
T
_
2" Diameter Pipe
M-
l j
-HXI
-tX!
-M
ir p
*» r
i
1
i 1
j !
K
H
~
1
h
1
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I I
1 .a
i |
rlll "
1 Deflectipn Plate "|
i 6'-0" inside dimension '
___! . -i
s. 4" Diameter
xv Drain
X
/! x
/ \"
/
/' 1
^ i
U3
^ Jo,
6"
9
b
,->
\
DETAIL "B"
- See Detail "A" and "B"
for two types of Center
Well used.
3" Gate Valve 3" Diameter Pipe
ELEVATION
15
-------
High molecular weight polymer settling aids were tried with little or no improvement in
settling rate or clarity of the overflow in either the experimental clarifier or the primary
clarifier.
Based upon experience gained with the experimental clarifier changes were made in the
primary clarifier during the latter part of 1970. Figure 7 illustrates the final configuration
of the primary clarifier.
In the experimental clarifier, the velocity of the clarified overflow through the launder
orifices had a tendency to pull suspended particles (suspended in the foam) from the liquid
surface due to induced eddy currents. To reduce this velocity and the localized conditions
that created eddy currents, 6 radial launders from the conical internal to the peripheral
launder were added. Even when a light foam or scum covered the surface of the clarifier,
the clarity of the overflow could still be observed with the new arrangement. Also, there
was very little entrainment from the surface in the outflow.
The most important changes made in the primary clarifier were: installation of the spray
showers to control foam, changes in the launders to provide low velocity outflow through
orifices instead of overflow from weirs, and installation of the conical center well. These
changes (plus the elimination of air which was accomplished earlier) eliminated the foaming
and carryover problems of the primary clarifier under normal operating conditions. Foam
still rose within the new center well but was destroyed by the sprays; however, whenever
level controls in the reaction tank allowed liquid level to drop low enough for air to be
pulled into the system foaming was still a problem.
Since essentially three changes in the primary clarifier were made simultaneously, it was not
proven which of the changes had the greatest effect. It is possible that with foam controlled
through use of the Yarway showers and submerged inlet, the original clarifier design may
have been adequate especially at low flow rates (100 to 250 gpm).
Scaling And Mechanical Problems With Carbonator System
Openings in the original carbonation system (Figure 5) rapidly scaled up, limiting the flue
gas flow to the carbonator. The holes were enlarged but scale still formed rapidly to restrict
gas flow.
After consulting with people who had successfully carbonated waters with high calcium
content, design of the carbonator was changed. A header was built above the reaction
chamber cover with drops to which spargers were attached. These spargers connected to
the header with 1 1/2-inch pipe were inverted cones with scalloped bottoms located 5 feet
below the liquid level. Each sparger could be removed without affecting the operation of
the others. Figure 8 shows the final sparger design and Figure 5 shows the original arrange-
ment. While the system shown in Figure 8 worked satisfactorily, better equipment and
arrangements for distribution of flue gases for carbonating solutions are probably available.
Before modifications were made, mechanical breakdowns and electrical overloads caused
the flue gas blower to be out of operation most of the time. The mechanical troubles were
primarily rapid deterioration of seal rings, bearings, and associated parts due to the abrasive
action of particles in the flue gases.
16
-------
Figure 7
PRIMARY CLARIFIER INTERNALS
2" Supply to
Yarway Showers
6"
-------
Figure 8
DESIGN OF CARBONATOR SPARGERS
6" Pipe
DISTRIBUTION RING
114" (b Pipe with Cap
00
t?
111
VA AA L\L
\
VIEWA-A
12GAT-304SS
SKIRT DETAIL
18
-------
The electrical overloads were attributed to the back pressure type flow control originally
installed in the system.
The valve controlling the flue gas flow to the carbonator was changed from a back pressure
type control to an atmospheric relief control (Figure 9). The back pressure control would
overload the blower, reduce flow and cause condensation of water vapor which led to some
of the maintenance problems with the blower. Since a pressure only slightly above the hy-
draulic depth of the spargers would supply sufficient flue gas for carbonation, atmospheric
relief control was better suited to the system. The change eliminated the overload problem,
but did not reduce the mechanical breakdowns.
The mechanical breakdowns were attributed primarily to use of a blower not suited for this
type application. Therefore the original positive displacement flue gas blower was replaced
by a converted Nash vacuum pump. There were no electrical or mechanical problems with
the Nash pump during its 8-month period of operation.
Figure 9
FLUE GAS CONTROL
Lime
Kiln
Stack
Filter
Original
Blower
Original Design
(Back Pressure Control)
Vent
Lime
Kiln
Stack
Filter
Nash Pump
/
V
V
V
V
V
i
\
Carbonation Chamber
» *>
*
Final Design
(Atmospheric Relief Control)
19
-------
Poor pH Control In The Carbonator
The carbonator ciarifier pH control as originally installed was unsatisfactory. The pH sensor
was located in the clarifier's overflow launder indicating pH some 3 hours or more after car-
bonation. To correct this fault, a line was run on a 45°angle from inside the reaction chamber
to a sample jug outside the ciarifier where the pH sensor was relocated. This arrangement
gave better pH control.
Other Changes
In addition to the equipment changes which have already been discussed, several other
changes were made. The pipe for conveying liquid from the primary ciarifier overflow to the
carbonator ciarifier was replaced with an open trough. This was done to allow easier cleaning
since the pipe scaled rapidly, restricting flow to the carbonator ciarifier.
Mud from the carbonator ciarifier originally was put into the mill's unfiltered mud tank.
Since this gave problems in operation of the mill's regular mud processing system, the carbon-
ator ciarifier mud was put into the massive lime system sludge storage tank. This resulted in
somewhat improved dewatering on the sludge filter. The original system was used only during
the period when there was excessive carryover of calcium hydroxide from the primary ciarifier.
Therefore, inadequate capacity for carbonating in the carbonator ciarifier and the resulting
presence of calcium hydroxide in the carbonator ciarifier mud may have contributed to the
problems encountered with the original system.
Filtrate from the sludge filter initially was put into the carbonator ciarifier. However, after
experimenting with addition of the filtrate to the primary ciarifier; reaction tank, and slaker,
the reaction tank was chosen as the best point in the process at which the filtrate could be
recycled. Addition of filtrate to the slaker was undesirable because of the increased steam
consumption required to heat the filtrate.
Finally, the sludge filter was changed from precoat operation to continuous belt operation.
This change gave a slight increase in the filter's capacity. Water content of the filter cake
was essentially the same with either type of operation.
The Final Plant
Figure 10 is a flow diagram showing the massive lime process demonstration plant as finally
operated. The most important changes made in the plant were those made in the primary
ciarifier. These changes, completed in January, 1971, allowed the primary ciarifier to produce
a clarified effluent and enabled the process to be evaluated as planned. Appendix A is a
chronological list of changes made to the original plant, and reasons for the changes.
20
-------
Effluent from
Unbleached Decker
Figure 10-MASSIVE LIME DEMONSTRATION PLANT
Final Equipment Flow Diagram
Effluent from
Bleach Caustic
Extraction Stage
Consistency VT-4
Regulator
Green Liquor Slaker
(For Mill's Causticizing
Process)
L±>
Pump
Gas Scrubber
-------
SECTION V
OPERATION AND PERFORMANCE OF THE EQUIPMENT
After January 1971, when the major operating problems were solved by equipment changes,
it was possible to start evaluating both the equipment's performance and the effectiveness of
the massive lime process. The following operating schedule was decided upon and followed
for the remainder of the project.
1. 100% bleach caustic extraction effluent 4 weeks
2. Increasing amounts of kraft decker effluent 3 weeks
3. 50% bleach caustic extraction effluent + 50% kraft decker effluent 4 weeks
4. Decreasing amounts of bleach caustic extraction effluent 3 weeks
5. 100% kraft decker effluent 5 weeks
a. Reuse of final effluent with carbonation.
b. Reuse of final effluent without carbonation.
6. Compare precoat with continuous belt-type operation on the sludge filter.
The above schedule was followed and sufficient reliable data on the operation were obtained
to predict the impact of this process on the pulping operation and to develop significant
information for design purposes.
This section discusses important operational parameters and the performance of individual
items of equipmentoverall effectiveness of the massive lime process is discussed in
Section VII.
Slaker
A temperature of 210°F was found to be the most desirable operating temperature. At
temperatures much above 210°F, boiling and foaming occurred in the slaker. At temperatures
much below 210°F, incomplete slaking of the lime occurred with an increase of rejected
material from the slaker.
Once liquid in the slaker reached 210° F, heat evolved from slaking was sufficient to maintain
the temperature provided the ratio of incoming effluent to reburned lime was maintained at
the proper level. A ratio of 6 gallons of liquid to five pounds of lime was required for typical
operating conditions. If temperature of either stream changed however, a change in the ratio
or other adjustment was of course required to maintain the heat balance. If the reburned
lime feed screw became plugged or partially plugged, temperature in the slaker would drop,
and the slaker's temperature controller would add steam. This proved to be a good indication
of the condition of the lime feed screw conveyor.
The normal temperature of bleach caustic extraction stage effluent entering the system
ranged from 135 to 145°F and the decker effluent ranged from 115 to 125°F.
23
-------
Reaction Tank
Proper operation of the reaction tank was essential to avoid foaming problems in the primary
clarifier. Agitation in the reaction tank had to be sufficient to prevent settling of the sus-
pended solids. To avoid foaming problems, however, it was essential that; (1) all liquor inlets
be below the liquid level of the tank, (2) the tank's agitator be run at the minimum speed
that would prevent settling, and (3) the agitator be positioned to avoid air entrainment.
Liquid had to be maintained at a level which would not create problems with air entrain-
ment (for example, improper liquid level could cause air entrainment by causing splashing
of inlet streams, by changing the agitation, and by causing the discharge pump to suck air).
To reduce lime losses from the system, filtrate from the sludge filter (which contained con-
siderable suspended matter) was pumped into the reaction tank. This tank was the best place
for re-admission of these suspended solids.
Primary Clarifier
Several factors affected efficiency of the primary clarifier. Among those factors were: (1)
air entrainment or foam, (2) entrance into and design of the center well, (3) design of the
overflow into the launders, (4) temperature, (5) composition of the suspended or settleable
solids in the slurry, (6) flow rate, and (7) rate of withdrawal of the settled solids. Many of
these factors are interrelated.
The first three of the above factors are discussed in Section VI and the original primary
clarifier design was modified based on a better understanding of those factors. The last four
factors-temperature, composition of solids, flow rate, and withdrawal rate-were evaluated
with the modified clarifier.
Temperature of the mixture entering the primary clarifier was varied from 150 to 180°F,
while treating bleach caustic extraction effluent, and from 136 to 175°F while treating kraft
decker effluent. These variations had little if any effect oh settling rate of the sludge, but as
temperature to the clarifier was raised, more gas bubbles were released. Samples of the flow
to the clarifier showed a definite increase in the volume of foam produced at higher temper-
atures.
The composition of the solids in the primary clarifier slurry was one of the main determin-
ants of settling rate. Differences in solids composition are mainly a function of the color of
effluent being treated and the quantity of lime used in the treatment. When an excess of
lime was not used, precipitated organic compounds (such as color bodies) formed a volumi-
nous floe which was light and settled very slowly. Even when great excesses of lime were
used, settling rate was significantly slower and the settled sludge was less dense as the
quantity of organic material increased.
The maximum flow rate (rise rate) at which the primary clarifier could produce a clear
effluent was found to be a function of the color of effluent being treated in the system.
Figure 11 is a graph of the relationship between rise rate and effluent color.
24
-------
Figure 11
PRIMARY CLARIFIER MAXIMUM RISE RATE VERSUS
UNTREATED EFFLUENT COLOR
2000 r-
1600
H
J[ 1200
|
1
"» 800
CD
cc
I
ir
400
I
I
0 4000 8000 12,000 16,000 20,000 24,000 28,000
Color of Effluent Before Massive Lime Treatment
(APHA Color Units)
The rate at which settled solids were removed from the clarifier had an effect on both clarity
of the unit's overflow and on performance of the sludge filter. Solids content of sludge
removed from the clarifier increased as residence time of the settled sludge in the clarifier
increased. However, if withdrawal rate was too low for a given flow rate to the clarifier, the
sludge bed within the clarifier would deepen until it eventually overflowed the tank. If
withdrawal rate was too high, solids content of the sludge would be low and the sludge filter
would then be overloaded.
Conditions inside the clarifier were determined by observation of samples taken from four
sample lines on the side of the clarifier (Figure 4). Under good operating conditions when
the overflow was clear, the following conditions existed; solids content at the bottom sample
line was 8 to 10%: solids content at the second sample line was 1 to 3%: the appearance of
samples from the third sample line was very cloudy: and samples from the top sample line
were hazy. If color of the effluent increased significantly or lime feed became erratic, the
following conditions were normally noticed. Solids from the bottom sample line remained
about the same; solids in the sample from the second sample port increased to 4 to 8%; the
sample from the third line became muddy; the sample from the top line became very cloudy;
but the overflow wouJd remain clear to slightly hazy. If the upset condition continued for
as long as 4 hours, mud would be present in the overflow. Flow to the system had to be
decreased, or withdrawal of settled sludge increased, to correct such upset conditions. Once
the sludge bed had risen above the third sample point, it took several hours at a lower flow
rate or lower color load to lower the bed to a good operating level.
25
-------
Carbonator Clarifier
The main factors affecting solubility of calcium hydroxide appeared to be concentration of
sodium and chloride ions, temperature and pH. All of these factors also seemed to affect the
size and rate of calcium carbonate crystal formation upon carbonation.
The reaction of carbon dioxide (from flue gas) with calcium hydroxide in the solution precip-
itated calcium carbonate in two physical forms. One of these was a heavy crystalline calcium
carbonate which settled rapidly. The other was a very fine precipitate of colloidal nature
which would not settle in a beaker in 24 hours. Work done by C. L. Davis and others at
interstate Paper Company, Riceboro, Georgia, indicates that recirculating some of the
settled calcium carbonate to the carbonation chamber aids formation of the heavy precip-
itate and reduces the colloidal calcium carbonate (Reference 10). This recirculation was not
tried during this project.
Settled sludge (mostly calcium carbonate) was withdrawn periodically from the carbonator
clarifier because the underflow pump and controls were too large to handle the small volume
on a continuous basis. This withdrawal took place when sludge concentrations of 20 to 25%
were reached.
Table 1 shows calcium removal in the carbonator clarifier was not a function of temperature
and pH. Data in the table are grouped to show periods of high, medium, and low concentra-
tions of color, sodium, and chloride in the influent to the massive lime system.
Table 1
CALCIUM LOSSES FROM CARBONATOR CLARIFIER
Overflow From
Untreated Effluent From Pulp Mill
Color,
APHA
Units
26,250
24,800
19,800
19,050
18.600
10,950
10,500
10,200
8900
8600
1280
1125
730
525
470
Na, ppm
1993
1840
1610
1560
1300
1060
890
983
910
820
545
480
608
560
520
d, ppm
1813
1723
1308
1409
1145
846
634
796
614
704
67
63
72
79
85
Carbonator Clarifier
pH
12.0
11.9
12.2
11.7
12.3
11.2
11.6
12.2
12.2
12.0
12.3
11.2
11.8
11.8
12.5
Temp, °F
165
167
162
163
159
159
154
158
153
157
151
146
145
140
148
To
Carbonator
Clarifier
663
390
336
362
400
512
468
476
464
484
498
534
477
504
514
Ca ippm)
Removed
by
Clarifier
382
92
88
126
188
291
198
263
336
238
465
444
452
430
476
From Clarifier
Total
281
298
248
236
212
221
270
213
128
246
33
90
25
74
38
Soluble
61
52
100
40
44
116
21
28
57
30
14
82
20
20
7
26
-------
Figure 12 shows the concentration of calcium in waters to and from the carbonator clarifier
as a function of the original waste water color. Data for these curves were obtained from
samples taken under stable conditions when effluent from the primary clarifier was essentially
non-turbid and pH in the carbonator was stable. The data indicate that the presence of large
amounts of color, sodium ions, and chloride ions affect the calcium content of streams to and
from the carbonator clarifier, reducing the efficiency of calcium recovery for higher colored
effluent. This is possibly the result of the formation of colloidal calcium carbonate.
Figure 12
CALCIUM CONTENT IN EFFLUENT TO AND FROM THE CARBONATOR
CLARIFIER VERSUS UNTREATED EFFLUENT COLOR
1200 r
1000
O
u
CD
O
a
a.
o
o
800
400
O
200
Flow to Carbonator Clarifier
Overflow from Carbonator
Clarifier
_L
_L
J_
J
4000 8000 12,000 16,000 20,000 24,000
Color of Effluent Before Massive Lime Treatment
(APHA Color Units)
28,000
Sludge Filter
Volume and percent solids of material going to the sludge filter were regulated and flow
through the green liquor slaker was controlled based on the quantity of material going to the
sludge filter. With this type control, it was essential that overflow from the sludge filter
(back to storage tank) be avoided.
The quantity of insoluble organic material in the sludge was probably the most influential
parameter governing the dewatering ability of the sludge filter. Even with the weight of
inorganic material present being several times more than that of the organic solids, the or-
ganics made the sludge slick and slimy and had a tendency to blind over the filter face. As
the ratio of organic to inorganic solids was reduced (as lower color effluent was treated),
the dewatered cake lost some of its tendency to seal over the filter surface. The cake became
more porous, and volume of the discharged cake increased as effluent color decreased. The
27
-------
sludge filter was initially operated as a precoat filter and was later changed to continuous belt
operation for comparison. Capacity of the filter for both types of operation is shown in
Figure 13 as a function of the color of effluent being treated by the system.
Figure 13
MASSIVE LIME SLUDGE FILTER PERFORMANCE
1200
JT 1000
>
8
:§
"i soo
3
600
400
Continuous Belt Filter
OL
J_
4000 8000 12,000 16,000 20,000 24,000
Color of Effluent Before Massive Lime Treatment
(APHA Color Units)
J_
28,000
Dewatered filter cake formed from sludge having a high ratio of organics to inorganics was
thinner and more dense than cake formed from sludge with lesser amounts of organics. Al-
though filter cake with high organics content was thin, it had very low porosity. Such filter
cake was drier (contained less water) than filter cake with lower organic solids content
(Figure 14).
A slightly drier cake could be discharged from the filter at slower drum speeds with very
little effect on capacity of the filter. Drier solids were beneficial in reducing water load and
steam requirements in the pulp mill cooking liquor system.
Deposits built up on the wires which formed the filter face during precoat operation and on
the fibers of the belt upon which the cake was formed when the filter was operated as a belt
filter. This build-up restricted the flow of liquid through the filter and reduced the filter's
capacity. Back washing of the wire or cloth was necessary about every 6 hours of continu-
ous operation. Back washing did not remove all of the deposits, but did remove enough in
about 5 revolutions of the washer to allow the filter to perform satisfactorily. Soon after
back washing, vacuum in the filter built up to 22 inches of mercury (the maximum). A
vacuum break was set at this negative pressure to protect the filter drum, hose connections,
and associated piping.
28
-------
Figure 14
SOLIDS CONTENT OF FILTER CAKE FROM SLUDGE FILTER VERSUS
UNTREATED EFFLUENT COLOR
4000 8000 12,000 16,000 20,000 24,000
Color of Effluent Before Massive Lime Treatment
(APHA Color Units)
28,000
About every two days, scale built up until back washing alone did not provide sufficient
cleaning of the mesh or cloth for good operation. When this occurred inhibited muriatic
acid was used for cleaning. The acid was slowly poured onto the rotating face of the filter.
The entire surface of the wire or cloth was treated. After acid cleaning, the filter was
thoroughly back washed to remove solids and residual acid before starting up. The entire
acid cleaning procedure required 45 to 60 minutes. (Note: The acid is harmful to human
skin and clothing. Fumes from the acid are harmful to the eyes, nose, and throat. Protec-
tive clothing, face shields, and absorbent respirators should be used by personnel handling
this acid.)
Immediately after back washing and particularly after acid cleaning, solids content of the
filtrate sometimes reached 7%. This would decrease to 0.5 to 1% solids just prior to back
washing. This filtrate with its suspended and dissolved solids was too valuable to waste.
Therefore it was recirculated to the reaction tank.
29
-------
SECTION VI
EFFECTIVENESS OF THE MASSIVE LIME PROCESS
Before the massive lime plant started operating, analytical tests were made at regular intervals
on green liquor, white liquor, lime, lime mud, black liquor, and unbleached pulp. Also, the
bleach caustic extraction stage effluent and unbleached decker effluent were analyzed regu-
larly to obtain a history of the variation in concentration of components. These same tests
were made during the operating period. A comparison of data from the two periods indicated
no discernable change in mill operating conditions, although normal fluctuations occurred
during both periods.
Appendix B describes the analytical tests used in this project while detailed operational test
data are given in Appendix C.
Sources of Color In Kraft Pulp Mill Effluents
The color and organic carbon content is different for effluents from various processes within
a mill. Data for some of the effluents are shown in Table 2. As seen from data in this table,
the two most highly colored effluents are from (1) the pulping and recovery area (including
the unbleached decker) and (2) the bleach caustic extraction stage. The ratio of color to
organic carbon also is different for different effluents.
Table 2
COLOR AND ORGANIC CARBON CONTENT OF MILL EFFLUENTS
APHA Total Organic Ratio of Color
... Color Units Carbon, ppm to TOC
Effluent source
Pulping and recovery area 2566 370 6.9 :1
Chlorination stage of bleaching 1388 358 3.9:1
Bleach caustic extraction stage 21,550 1446 14.9:1
Paper mill 346 104 3.3 : 1
Combined mill sewer1 2401 316 7.6:1
Stabilization basin (combined mill
sewer in holding basin for 4 months)1 2181 217 10.0:1
Contains all of the individual effluents from the mills.
Variations of ± 50% were observed in color in the combined mill discharge. Variables of at
least this extent were noticed in each of the individual process discharges.
To convert the color data to a weight basis each color unit was assumed equal to 1 ppm.
That is, a 10,000 color unit liquid was assumed equal to 10,000 ppm of color present. Using
this procedure, the color discharged from pulping and bleaching operations (as pounds per
ton of bleached pulp) was calculated, and the results are shown in Table 3 for periods when
either pine or hardwood pulp was being produced. The color loads listed in Table 3 do not
include losses from the evaporation process, the recausticizing process, or the cooking
31
-------
process. Brown stock washing and bleaching processes are included. Data in Table 3 show
that the bleach caustic extraction stage produces the greatest load of color bodies of any of
the pulp mill effluents.
Table 3
COLOR LOAD PRODUCED BY PULP MILL SOURCES
Effluent source
Pulp mill general
Chlorination stage
Caustic extraction stage
Rest of bleaching process
Total
Pine Pulp
Color.
Ib/Ton Percent
Hardwood Pulp
Color,
Ib/Ton Percent
680
100.0
32
93
354
36
515
6.2
18.1
68.7
7.0
100.0
Paper mill color losses on samples with pH adjusted to 7.6 and allowed to settle seldom ex-
ceeded 10 pounds of color per ton when producing bleached paper which contained only
small amounts of tinting dyes. However, color far exceeded this amount when making deeply
colored papers.
Performance Of The Massive Lime Process
The demonstration plant was used to treat bleach caustic extraction stage effluent, unbleached
decker effluent, and various combinations of the two effluents. Tables 4, 5, and 6 summarize
the analytical tests made on these effluents before and after treatment. Appendix C gives the
daily averages from which the overall ranges and averages shown in Tables 4, 5, and 6 were
determined.
Table 4
ANALYTICAL TESTS ON BLEACH CAUSTIC EXTRACTION STAGE
EFFLUENT BEFORE AND AFTER MASSIVE LIME TREATMENT
(Data f'om period: February 8 to March 10, 1971)
Flow rate, gpm
APHA color units
Suspended solids, ppm
Dissolved sol ids, ppm
Total carbon, ppm
Inorganic carbon, ppm
Total organic carbon, ppm
Ca, ppm, total
soluble
Cl, ppm
pH
BOD5, ppm
Feed to
Massive Lime Process
Av
170
21,546
27
5748
1520
75
1446
43
Min
100
13,000
10
4580
1125
25
1050
23
Max
250
29,000
60
79OO
1925
125
1850
70
Primary
Clarifier Overflow
Av
_
1459
185
_
_
_
490
Min
_
1095
20
_
_
_
_
240
Max
_
1815
880
_
937
1471 1035 2051
10.0 8.6 11.0
353 288 444
Discharge from
Massive Lime Process
Av Min Max
1265
195
5409
448
81
373
222
105
1430
12.5
264
565
10
3860
290
10
260
44
28
1085
11.7
198
2000
410
6910
680
250
530
324
264
1872
13.2
342
32
-------
Table 5
ANALYTICAL TESTS ON 50/50 MIXTURE OF CAUSTIC EXTRACTION
EFFLUENT AND DECKER EFFLUENT BEFORE AND AFTER MASSIVE
LIME TREATMENT
(Data from period: April 7 to May 15, 1971)
Flow rate, gpm
APHA color units
Suspended solids, ppm
Dissolved solids, ppm
Total carbon, ppm
Inorganic carbon, ppm
Total organic carbon, ppm
Ca, ppm, total
soluble
Cl, ppm
pH
, ppm
Feed to
Massive Lime Process
Primary
Clarifier Overflow
Discharge from
Massive Lime Process
Av
395
10,043
44
3129
847
53
798
30
614
10.2
300
Win
300
5350
10
2220
550
25
525
18
463
9.4
246
Max
500
17,500
100
3800
1225
100
1150
48
_
815
11.4
390
Av
522
76
_
469
_
_
_
_
Min
-
230
10
108
_
Max
-
1070
420
-
790
-
Av
-
451
196
3343
309
64
245
193
70
605
12.2
223
Min
-
185
40
2440
140
10
110
85
20
518
11.2
186
Max
-
800
510
4420
620
150
470
394
169
765
13.2
276
Table 6
ANALYTICAL TESTS ON UNBLEACHED KRAFT DECKER EFFLUENT
BEFORE AND AFTER MASSIVE LIME TREATMENT
(Data from period: May 29 to July 2, 1971)
Feed to
Primary Discharge from
Massive Lime Process
Av
542
900
101
1098
283
15
268
22
277
71
9.7
138
Min
525
455
20
610
110
10
100
11
160
35
9.0
96
Max
550
2360
710
1490
740
30
720
36
525
221
10.9
192
Clarifier Overflow Massive Lime Process
Av
225
73
509
_
Min Max Av
_ _ _
135 295 234
10 390 631
18991
- - 146
21
126
420 599 169 '
1451
525
- - 73
- - 12.0
- - 75
Min
160
101
12001
40
10
60
24 1
71
362
35
11.2
50
Max
335
1501
2870 '
250
70
240
558 '
5461
675
110
12.8
117
Flow rate, gpm
APHA color units
Suspended solids, ppm
Dissolved solids, ppm
Total carbon, ppm
Inorganic carbon, ppm
Total organic carbon, ppm
Ca, ppm, total
soluble
Na, ppm
Cl, ppm
PH
BODj, ppm
1Data shown include periods with and without carbonation. Average data for periods either with or without
carbonation are"
With Carbonation
75
1638
78
Suspended solids, ppm
Dissolved solids, ppm
Ca, ppm, total
soluble
51
Without Carbonation
22
2488
514
505
33
-------
Color Removal
Color removal ranged from 90 to 97%, with the overall average being between 94 and 95%
removal. Data showing color removal and organic carbon removal achieved when various
mixtures of effluents were treated are given in Table 7.
Table 7
COLOR AND ORGANIC CARBON REMOVAL
Composition of
Treated Effluent
Bleach Caustic Kraft
Extraction Decker
Stage Effluent, Effluent,
100
67
60
50
33
20
0
0
0
33
40
50
67
80
1001
1002
Effluent Color
(APHA
Before
Treatment
21,546
14,325
12.125
10,043
6612
4660
16401
9002
Color Units)
After
Treatment
1265
745
594
451
331
298
1401
2342
Color
Removal,
94.2
94.8
95.1
95.5
95.0
93.6
91.51
74.02
Organic Carbon
Content (ppm) Organic Carbon
Before After Removal.
Treatment Treatment %
1446
1016
905
798
569
450
270 ]
2682
373
253
248
245
183
173
1201
1262
74.2
75.1
72.6
69.3
67.8
61.5
55.61
53.02
Very little paper mill white water reuse in decker pulp washing and make-up water.
Practically all water used in decker system was white water from paper mill.
A little over 3 months before conclusion of the massive lime project, the mill substantially
increased reuse of paper machine white water in the decker system. Practically all wash
water, dilution water, and make-up water used in this system was paper mill white water.
When this was done there was a significant reduction in color removal when treating un-
bleached decker effluent in the massive lime system (last line of Table 7).
The reduction in color removal efficiency when using a maximum flow of paper mill white
water was probably due to papermaking dyes which were not insolubilized by treatment
with calcium hydroxide. Precipitation of colored organic compounds by alum present in
the paper mill white water may have caused some color bodies to remain with the pulp thus
reducing the decker effluent's color.
Organic Carbon Removal
Organic compounds account for most of the BOD as well as most of the color present in pulp
mill waste waters. Data on organic carbon content of effluent before and after massive lime
treatment are given in Table 7. From 55 to 75% of the incoming organic carbon was re-
moved by the massive lime treatment, with percent removal generally increasing with higher
colored effluent.
BOD Reduction
BOD removal varied from 25 to 45%, with the lower efficiency being from waters containing
34
-------
the most color and organic material (bleach caustic extraction effluent). The absolute
amount of BOD removed decreased very little with large decreases of BOD in the untreated
samples. Reasons for this type behavior were not determined. BOD determinations were
not made on daily samples as were many of the other tests. Therefore, the BOD data are
not as complete or as reliable as the other data.
Table 8 shows average BOD determinations on various waters treated in the massive lime
plant.
Table 8
EFFECTS OF MASSIVE LIME TREATMENT ON BOD
BOD5 (ppm)
Before After
Source of Sample Treatment Treatment Removed Removal, %
100% bleach caustic extraction stage effluent 353 264 89 25.3
50% extraction stage effluent/50% decker effluent 300 223 77 25.7
100% unbleached decker effluent 138 75 63 45.7
Other Considerations
Although the massive lime process reduces color, organic carbon, and BOD in the waste
waters treated, the discharge from the massive lime plant is hot and highly alkaline. It will
have to be cooled and at least partially neutralized before being discharged from the mill.
Temperature can be reduced by many methods. If there is sufficient storage capacity be-
tween the massive lime plant and the receiving stream, natural evaporation will do an
acceptable job.
Neutralization can also be accomplished in many ways. Two of these which are available
in a pulp and paper mill are:
1. additional carbonation after the massive lime system with flue gases
from the lime kilns or power boilers.
2. dilution or combination of this effluent with waste waters having a
low pH, such as the bleach plant chlorination stage effluent or the
paper mill effluent.
Mineral solids such as sodium chloride, sodium sulfate, and sodium carbonate are greater in
the discharge from the system than in the original waste water.
Material Balances Around System
Data obtained from operation of the demonstration plant were used to calculate material
balances around the system. Results of material balances for treatment of bleach caustic
35
-------
extraction effluent, kraft decker effluent, and a 50/50 mixture of these two effluents are
recorded in Figures 15, 17, and 16, respectively. The following assumptions were used in
calculating the balances:
1. Composition of reburned iime is; 85.0% calcium oxide, 13.3% inerts,
1.7% soluble sodium compounds (as sodium carbonate), and the
remainder is inactive material too light or fine to be removed at the
slaker.
2. Organic compounds which combine with calcium do so at a ratio of
1 part calcium to 8 parts organic material.
3. All organic compounds which are reacted with calcium leave the
system with the sludge.
4. There are no losses from the system except at the slaker, the carbonator
clarifier overflow, and in sludge discharged from the filter.
5. The filtrate from the sludge filter with its dissolved and suspended solids
is a constant in the material balances.
6. The ratio of weight of organic carbon to total organic compounds is that
which is found in NCASI Bulletin No. 239 (Reference 9) and is different
for the compounds which can be precipitated and those which can not
be precipitated.
Insoluble organic compounds = 0.4647 carbon.
Soluble organic compounds = 0.3431 carbon.
36
-------
Figure 15
MATERIAL BALANCE FOR MASSIVE LIME PLANT TREATING 100% BLEACH CAUSTIC
EXTRACTION STAGE EFFLUENT
CaO 141,667lbs
Ma2C03 2824 Ibs
Inerts 22,T76 Ibs
Fteburned Lime
Untreated Effluent
(21,550 APHA Color)
( Water 8,301,983 Ibs
\ CaC03 902 Ibs
\ Organic compounds 30,115 Ibs
Dregs
6667 Ibs
Water
CaC03
Ca(OH)2
Ca-Organics
Soluble Organic:
NaOH
8,257,527 Ibs
3566 Ibs
180,782 Ibs
21,648 Ibs
10,872 Ibs
2131 Ibs
15,509 Ibs
CO
CO,
Carbonator
Clarifiar
4520 Ibs
~> Decolored Effluent
Water 8,051,117 Ibs
CaCO3 4445 Ibs
Soluble organics 10,601 Ibs
N»2CO3 2753 Ibs
Sludge to Grten Liquor
Caustic/ling System
Sludge Filter
Water
CaC03
Ca(OH)2
Ce-Organics
Soluble Organic;
NaOH
Inerts
208,260 Ibs
6796 Ibs
175,102 Ibs
21,648 Ibs
271 Ibs
53 Ibs
15,509 Ibs
Sludge Storage
Tank
Basis: 1,000,000 gallons of effluent to be treated
-------
Figure 16
MATERIAL BALANCE FOR MASSIVE LIME PLANT TREATING 50% BLEACH CAUSTIC EXTRACTION STAGE
EFFLUENT AND 50% UNBLEACHED DECKER EFFLUENT
CaO 141,667lbs
Na2CO-i 2824 Ibi
Inert. 22,176 Ibs
Rfburned Lime
Untreated Effluent
(10,043 APR A Color)
( Water 8,316,508 Ibs
< CaCO3 625 Ibs
I Organic compounds 15,887 Ibs
Dreg,
6667 Ibi
Water
CaC03
Ca(OH)2
Ca-Organics
Soluble Organic!
NaOH
Inerts
00
Sludge to Green Liquor
Catiitlcizing Systtm
Water
CaC03
Ca(OH)2
Ca -Organics
Soluble Organic:
NaOH
Inerts
230,706 Ibs
9594 Ibs
176,477 Ibs
11,157 Ibs
164 Ibs
59 Ibs
15,509 Ibs
8.271,536 Ibs
3289 Ibi
182,937 Ibi
11,157 Ibi
5960 Ibs
2131 Ibs
15,509 Ibs
CO?
Carbonator
Clarifier
4981 Ibs
-> Decolored Effluent
Water 8.042,866 Ibs
CaCO3 2425 Ibs
Soluble Organ! ; 5786 Ibs
Na2C03 2745 Ibs
Sludge Filter
Sludge Storage
Tank
Basis: 1,000,000 gallons of effluent to be treated
-------
Figure 17
MATERIAL BALANCE FOR MASSIVE LIME PLANT TREATING 100% KRAFT UNBLEACHED
DECKER EFFLUENT
CaO 141,667 Ibs >
Na2CO3 2824 Ibs I
Inerts 22,176 Ibs J
CO
CO
Reburned Lime
Untreated El fluent
(900 APHA Color)
Water 8,326,934 Ibs
CaCO3 458 Ibs
Orflanic Compounds 5,608 Ibs
Dregs
6667 Ibs
Water 8,281,545 Ibs
CaCO3 3122 Ibs
Ca(OH)2 184,641 Ibs
Ca-Organics 2869 Ibs
Soluble Organic: 3058 Ibs
NaOH 2131 Ibs
Inerts 15,509 Ibs
CO2
Carbonator
Clarifiw
5403 Ibs
-* Decolored Effluent
Water 8,018,897 Ibs
CaCOj 727 Ibs
Soluble Organic* 2960 Ibs
Na2CO3 2733 Ibs
\
Sludge to Green Liquor
Causticizing System
Sludg* Filter
Water
CaCOj
Ca(OH)3
Ca-Organic*
Soluble Organics
NaOH
Inerts
264,857 Ibs
12,095 Ibs
177,463 Ibs
2869 Ibs
S8 Ibs
68 Ibs
15,509 Ibs
Sludge Stor,
Tank
IT
Basis: 1,000,000 gallons of effluent to be treated
-------
SECTION VII
IMPACT OF THE MASSIVE LIME SYSTEM ON NORMAL PULP MILL OPERATIONS
Recovery and reuse of lime is an essential step in the massive lime process. This reuse is
accomplished by replacing lime used in the pulp mill's causticizing process (Figure 2) with
sludge (mainly calcium hydroxide and water) from the massive lime system. Use of this
sludge however, changes equilibrium conditions for the mill's causticizing and black liquor
recovery process. Water and organic materials not normally added to the causticizing process
are introduced with the massive lime system sludge. In addition, with the normal causticizing
system, some water is consumed and heat is liberated when lime is added and reacted with
water to produce calcium hydroxide. This does not occur when massive lime system sludge
is used for causticizing.
To determine the effects of these changes on the mill's processes for cooking liquor prepa-
ration and cooking chemical recovery, the material balances shown in Figures 18 and 19
were calculated. Figure 18 shows results of a material balance for the normal mill system,
while Figure 19 shows results of a material balance for the system with massive lime system
sludge used for causticizing. Quantities of materials shown in Figures 18 and 19 are the
amounts required for each ton of unbleached pulp produced. Since pulp mill cooking
chemicals are a complex mixture of various sodium and sulfur compounds (predominantly
sodium sulfide, sodium hydroxide, and sodium carbonate), the sodium compounds have
been expressed as the equivalent amount of sodium oxide (Na20), as is commonly done
within the paper industry.
Many assumptions were necessary to make the material balances. The following are the
major assumptions on which the calculations were based.
1. Total cooking chemical required per ton of unbleached pulp is equivalent
to 836 pounds of sodium oxide. This is equivalent to 675 pounds of
active cooking chemical.
2. When not using massive lime system sludge for causticizing, cooking liquor
(that is white liquor) concentration is equivalent to 0.1366 gram of tola!
sodium oxide per gram of water.
3. Of the total unclarified white liquor entering the white liquor clarifier,
80% of the liquid overflows as clarified white liquor while 20% of the
liquid is discharged from the bottom of the clarifier with the calcium
carbonate mud.
4. Normally 550 pounds of reburned lime are used for causticizing green
liquor, and reburned lime is normally 85.0% calcium oxide, 13.3% inerts,
and 1.7% sodium carbonate.
5. All soluble soda in the reburned lime is in the form of sodium carbonate.
6. Heat required in the normal slaking and causticizing operations is supplied
by the exorthermic reaction of lime with water to produce calcium
hydroxide.
41
-------
Figure 18
MATERIAL BALANCE FOR NORMAL PULP MILL LIQUOR PREPARATION AND SPENT
LIQUOR RECOVERY SYSTEM
Basis: 1 Ton of Unbleached Pulp
CaO 468 Ibs
NajCOj 9 Ibs
Inerts 73 Ibs
Dregs -
23 Ibs
Returned
Lime
Green Liquor
Na2O 1040 Ibs
Water 7797 Ibs
,., ., Wood solids 4348 Ibs
r~ Wo"d Water 4348 Ibs
Slifcw
And
Camticizin
Unclarified N
White Liquor
Na20 1045 Ibs
Water 7647 Ibs
CaCOj 835 Ibs
Inerts 50 Ibs
NO
Wash Water
6652 Ibs
White
Liquor
Clarifier
Settled Mud
Na2O 209 Ibs
Water 1529 Ibs
CaCO3 835 Ibs
Inerts 50 Ibs
Calcium
Mud
Recovery
Na20
Water
CaCO3
Inert!
13 Ibs
384 Ibs
835 Ibs
50 Ibs
Calcium Carbonate Mud
To Lime Kiln
Wash Liquor To
Recovery System
Dissolving Tank
Clarified
White Liquor
Na2O 836 Ibs
Water 6118 Ibs
Digesters
And
Pulp Wiihers
Steam And
Wash Water
23,217 Ibs
Weak Black Liquor
Water 19,200 Ibs
Dissolved solids 3000 Ibs
Unbleached Pulp
Pulp 2000 Ibs
Water 14,667 Ibs
Black Liquor
Evaporators
I
Water
16,200 Ibs
Water 3000 Ibs
Dissolved solids 3000 Ibs
Concentrated Black
Liquor To The
Recovery Furnace
-------
Figure 19
MATERIAL BALANCE FOR PULP MILL LIQUOR PREPARATION AND SPENT LIQUOR RECOVERY SYSTEM
USING MASSIVE LIME SYSTEM SLUDGE FOR CAUSTICIZING
Basis: 1 Ton of Unbleached Pulp
Water
Ca(OH)2
Ca-Organics
CaCO3
Inerts
Massive Lime System
Sludge
I Green Liquor
Steam
Water 313 Ibs
I Na2O
{ Water
1055 Ibs
7910 Ibs
. Wood
Unclarified
White Liquor
Na20 1045 Ibs
Water 8999 Ibs
Na-Organics 58 Ibs
CaCO, 888 Ibs
Inerts 54 Ibs.
Whits
Liquor
Clarifiw
Clarified
/ White Liquor
I Na20 836 Ibs !
_J Water 7199 Ibs
Na-Organics 58 Ibs
T
CO
Settled Mud
Na2O 209 Ibs
Water
CaCO3
Inerts
1800 Ibs
888 Ibs
54 Ibs
Calcium Carbonate Mud
To Lime Kiln
Wash Liquor To
Recovery System
Dissolving Tank
Wood solids
Water
4348 Ibs
4348 Ibs
Dig«ttars
And
Pulp Washers
Steam And
Wash Water
23,319 Ibs
Weak Black Liquor
Water 20,199 Ibs
Solids 3058 Ibs
Concentrated Black
Liquor To The
Recovery Furnace
Unbleached Pulp
Pulp 2000 Ibs
Water 14,667 Ibs
NOTE: The compositon of massive lime system sludge used in this balance is representative of what would be available at the hypothetical mill described in Section IX.
-------
7. Green liquor concentration is such that there are 7.497 pounds of water
present for each pound of total sodium oxide, and the mill normally
operates at the maximum green liquor concentration it can handle.
8. Pulp yield is assumed to be 46%, meaning that 46 pounds (dry basis) of
pulp are produced for every 100 pounds of wood (dry basis) cooked.
9. Wood entering the system is 50% water and 50% "wood solids."
10. Unbleached pulp is discharged from the system (from the pulp washers)
at 12% consistency.
11. The amount of water used to wash the unbleached pulp varies with the
total amount of sodium charged to the digester, so that wash water varies
1.25 gallons for a change in sodium equivalent to one pound of sodium
oxide.
12. Normally, 3000 pounds of black liquor solids are generated per ton of
unbleached pulp, and normal weak black liquor concentration is 13.5%
solids.
13. Concentrated black liquor discharged from the evaporators is controlled
to 50% solids.
Slaker And Causticizer
When using massive lime sludge for causticizing, the amount of green liquor processed through
the pulp mill's causticizing system must be increased approximately 13.6 gallons per ton of
pulp, an amount equivalent to an increase of 15.1 pounds of sodium oxide per ton of pulp.
This increase is necessitated by two factors. First, the calcium-organic compounds entering
the system with the massive lime sludge will react to consume sodium (calcium combined
with the organics will be replaced with sodium). Second, sodium compounds previously ob-
tained from the reburned lime are not available from the massive lime system sludge and
must be replaced with sodium compounds obtained by increasing green liquor flow.
The slaking reaction (conversion of calcium oxide to calcium hydroxide) in the normal liquor
making process consumes 149.7 pounds of water per ton of pulp. This does not occur when
massive lime system sludge is used for causticizing. As a result, a more dilute white liquor is
produced when using massive lime system sludge.
To equal the causticizing ability of 550 pounds of reburned lime, 1540 pounds of massive
lime sludge at 49.6% solids were required. Average temperature of the sludge was 125°F.
Therefore, to heat the sludge and green liquor to causticizing temperature 313 pounds of
steam were used. Condensation of this steam in heating the liquor also reduced white
liquor concentration. The amount of steam required was calculated by assuming green
liquor concentration was approximately 18% solids, the heat capacity of green liquor was
approximately 0.93 BTU/lb -°F, and the heat capacity of massive lime sludge solids was
approximately 0.2 BTU/tb -°F:
44
-------
(7910 Ib water in green liquor) (210 - 185°F change in temp) (0.93 BTU/lb-°F) = 231.2 Ib of steam to
X - X
(0.82 ib water/pound green liquor) (970 BTU/lb steam) heat the green ''qu°r
(776 Ib water in sludge) (210 - 125°F change in temp) x (1.0 BTU/lb-°F) = 68.0 Ib of steam to
._- '. heat water in the
(970 BTU/lb steam) , .
sludge
(764 Ib sol ids in sludge) (210 - 125°F change in temp) (0.2 BTU/lb-°F) = 13.4 Ib of steam to
(970 BTU/lb steam) * heat sludge solids
Total steam required = 313lb
Net effect of all the above factors is to increase water input to the causticizing system by the
following amounts:
113 Ib due to increased green liquor flow
776 Ib entering with sludge
150 Ib not consumed in slaking reaction
313 Ib from condensation of steam used for heating.
1352 Ib = total increase (or 162 gallons) per ton of pulp
This increased water input caused white liquor produced by the system to contain a signifi-
cantly lower concentration of cooking chemicals.
Foaming problems were created in the slakers, causticizers, clarifiers, and mud washers when
massive lime sludge was used for causticizing. Foam overflowed these vessels and tanks
causing excessive losses of soda and lime until corrective action was taken. Addition of de-
foamer to liquor discharged from the slaker controlled the foam (0.5 pound of defoamer per
ton of pulp was required).
White Liquor Clarifier
The overall increase in volume of liquid conveyed to the white liquor clarifier was 162 gallons
per ton or 17.7%. This means that to do a comparable job of white liquor clarification, the
white liquor clarifier's size (surface area) must be increased 17.5 to 20% when using massive
lime system sludge for causticizing.
For the material balances shown in Figures 18 and 19, it was assumed that all settleable solids
from the white liquor clarifier go to the mud washer, and all organics, from the massive lime
sludge go with the white liquor to the digesters. Since the cooking liquor chemicals and wash
liquor eventually are recycled to the green liquor, this assumption represents the net effect
after equilibrium conditions are established.
White liquor made by causticizing green liquor with filter cake from the massive lime process
is black in color, approximately 15% weaker in concentration, and has a higher chloride
content than normal white liquor.
The black coloration of the liquor has little or no effect on the cooking of wood chips. Black
coloration is caused by basically the same organic compounds that are found in normal weak
black liquor used to make up the necessary liquor volume in batch digesters. The black color
45
-------
however, does interfere with the normal analytical tests used for determination of white
liquor composition, since visual observation of the color change of pH indicators is normally
used to determine end points for the titration. Instead of titrating to visual color changes
electrical pH meters should be used for this analysis.
Mud Washing
The volume of mud handled in the mud washing system increased about 16% and solids to
the mud washing system increased by 57 pounds per ton of pulp or 6.4%. Therefore the lime
mud filter capacity would have to be increased 6.4%.
To keep the system in balance, water for mud washing would be decreased 16 gallons per ton
of pulp. This decrease should result in greater soda losses from the mill when using the
massive lime sludge; however, loss of this soda was not considered in the balances shown in
Figures 18 and 19.
Lime Kiln
Solids handled in the lime kiln will be increased by 57 pounds per ton of pulp or 6.4%. This
requires an increase in kiln capacity as well as an increase in fuel consumption.
A rotary lime kiln with 70% solids feed will require approximately 9,000,000 BTU per ton of
reburned lime. Therefore, fuel consumption will increase an amount equal to 576,000 BTU
per ton of reburned lime when the massive lime system is used. This results in an increase in
fuel consumption equal to:
(576,000 BTU) (550 Ib reburned I ime) = 158,400 BTU per ton of pulp
(2000 Ib of reburned lime) (1 ton of pulp)
Digesters And Washers
Because of significantly lower concentration of cooking chemicals (approximately 15%
lower) in the white liquor, the volume of liquor required to furnish the cooking chemicals
to the digester is greatly increased. In the case of batch digesters, this means less weak black
liquor would be used for volume make up. In the case of continuous digesters, the actual
cooking chemical concentration in the digester is reduced. Therefore larger liquor circu-
lating pumps and possibly somewhat larger cooking vessels may be required for continuous
digester systems.
Flow to the pulp washers will increase by 134 gallons per ton of pulp. This may not require
larger washers but will require an increase of 5.8% in their hydraulic capacity (liquor removal
ability) and pumping capacity. Discharge of black liquor solids from the washers will increase
from the normal 3000 pounds to 3058 pounds of solids per ton of pulp. Also, the concen-
tration of solids in the weak black liquor will decrease from 13.5 to 13.1%.
46
-------
Evaporators
The flow of weak black liquor to the evaporators will increase from 22,200 pounds to 23,257
pounds per ton of pulp. Discharge of strong black liquor from the evaporators will remain at
50% solids, but the discharge of strong black liquor will increase from 6000 to 6116 pounds
per ton, while solids discharged in the strong black liquor will be increased to 3058 pounds
per ton.
The amount of evaporation required will increase from 16,200 pounds to 17,141 pounds per
ton of pulp. With an evaporator efficiency of 4 pounds of evaporation per pound of steam,
this increases steam requirements by 235 pounds per ton of pulp. This amounts to an increase
in evaporator capacity of 5.8%.
Recovery Furnace
Concentrated black liquor is burned in the mill's recovery furnaces where inorganic chemicals
are recovered and heat produced by the burning is used to generate steam. Recovery furnaces
are generally sized to process 3000 pounds of black liquor solids per ton of pulp and to pro-
duce 3.5 pounds of 850 psi steam per pound of black liquor solids.
Since organic solids removed from bleach plant waste waters are similar (derived from lignins)
to normal black liquor solids these solids were assumed to have the same handling character-
istics and heating value as normal black liquor solids. If so, the recovery furnace size must be
increased 1.9% to handle the increased flow of concentrated black liquor.
This increase in solids can also be expected to increase steam production by 203 pounds of
steam per ton of pulp. This steam will essentially offset the additional steam required for
evaporation, but will also generate 10.4 kw of electricity in a turbine when reducing the
pressure from 850 psi to 60 psi gauge.
Effect On Chloride Concentration
Small amounts of chloride ion enter the mill's liquor system from the wood, sodium sutfate,
and lime normally added to the process. Therefore green liquor normally contains 800 or
more ppm chloride ion. Massive lime treatment of bleach caustic extraction stage effluent
containing 1430 ppm chloride will cause an addition of the equivalent of approximately 20
ppm chloride to the green liquor stream each cycle. This addition would have a tendency to
increase chloride concentration to an equilibrium level where chloride losses would equal
the amount of chloride added. The amount of chloride introduced with the massive lime
sludge is probably,small enough to have little effect on corrosion or other detrimental condi-
tions in the liquor system.
Effect On Pulp And Paper
Analyses of pulp and paper showed very little if any difference in the final quality of these
products. No appreciable difference was observed in bleachability or bleaching of the pulp.
Also, no differences were evident in the pulp's performance on the paper machine and there
47
-------
were no differences in customer's reactions to the finished product. Using massive lime
process sludge as a replacement for reburned lime apparently does not affect finished
product quality, however it is possible that long term effects on pulp mill processes or on
pulp quality, which did not show up in the demonstration plant project, might be observed
in a full-scale installation.
Chemical Losses From The Pulp Mill
A fairly good chemical recovery system in a kraft pulp mill requires a chemical make-up of
approximately 125 pounds of sodium sulfate per ton of pulp produced. An equally well
closed system on the lime cycle requires 20 pounds of new lime makeup per ton of pulp.
Considering that these losses are proportional to the quantity of materials carried through-
out the cycle, additional losses due to use of the massive lime process sludge are calculated
below.
(1055 - 1040 Ib change in Na2O concentration in green liquor) x (125 tb Na2S04 makeup/ton of pulp) = 1.8 Ib of Na2SO4
,._. ,.-... , ,. , additional losses
(1040 Ib of Na-jO in normal green liquor)
per ton of pulp
(955 - 898 Ib change in solids to lime kiln) x (20 Ib lime makeup/ton of pulp) = 1.3 Ib of lime additional losses per ton
(898 Ib solids to lime kiln normally) of pulp
Reuse Of Treated Effluent
Reuse of treated effluent as the scrubbing liquid in the lime kiln flue gas scrubber (see
Figure 2) was evaluated using decolored unbleached kraft decker effluent from the demon-
stration plant. At a flow rate of 550 gpm to the massive lime system, there was insufficient
flow to meet the make-up water requirements for the Springhill, Louisiana mill. Clarified
effluent, either carbonated or uncarbonated, was pumped from the carbonator clarifier
overflow to the sump feeding the lime kiln's venturi scrubbers. However a 1,000,000
gallons-per-day massive lime treating plant would supply the lime requirements for causti-
cizing enough cooking liquor to produce 281 tons of pulp per day and the same plant would
discharge enough treated water to supply a caustic room-lime kiln complex for a 1220 tons-
per-day pulp mill.
Soluble organic compounds affected surface tension of the scrubbing liquid sufficiently to
cause severe foaming in the lime kiln dust collection system. If foaming was not controlled,
the overflow and spillage caused excessive losses of lime and soda. Spray showers were unable
to control the foam, so defoamer at the rate of 20 ppm was used. The defoamer added to
this liquid and the defoamer added to the white liquor system controlled foam throughout
the liquor making and consuming operations. Except for the foaming problem, treated
effluent performed as well as water from any other source for flue gas scrubbing and caustic
room make-up.
With a massive lime system large enough to provide all the lime required for green liquor
causticizing, more water would be treated than could be used for make-up in the caustic
room-lime kiln complex. Only 22.5% of the treated water could be utilized, so the rest
of the treated water would be available for some other reuse or discharge to the mill sewer.
Reuse of this water in the brown stock washing system was not tried. If the total hardness
48
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of the treated effluent can be controlled at less than 100 ppm as calcium carbonate, the
water could be used on the brown pulp washers. Addition of defoamer and pitch dispersants
would probably be required to make treated decker effluent usable in the washing system.
Reuse of treated effluent would result in the following savings:
1. Retain most of the sodium compounds which are normally lost in
the massive lime system.
2. Somewhat reduce the amount of heat required for heating brown
stock washer wash water.
3. Save the cost of procuring, treating, and delivering the same
quantity of fresh water.
4. Save the cost of disposing of a like quantity of waste water.
Reuse of treated bleach caustic extraction stage effluent would probably present more
problems than reuse of treated unbleached decker effluent because of the chlorides present
in the bleach plant effluent.
49
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SECTION VIII
CONSIDERATIONS FOR DESIGN OF A COLOR REMOVAL PLANT
The massive lime treatment system should be located adjacent to the mill's normal liquor
making operations. This will minimize conveying of lime to the slaker and conveying of
massive lime sludge from the filter to the causticizing process. New and reburned lime
storage facilities can be utilized by both processes. In case of an interruption in operation
of the massive lime system, lime could be slaked and used in the normal manner for
causticizing.
Calcium scale builds up quite rapidly in pumps and pipe lines after the slaker. This scale
must be removed at least every six months or capacity of the lines will be limited. If possible,
the massive lime system flows should be by gravity from the slaker through the carbonator
clarifier. This would eliminate pumping, and conveying from one unit to the next could be
done through open troughs. The troughs can be easily cleaned without shutting down the
system. If gravity feed is not feasible, piping should be as short as possible with the fewest
possible bends or elbows.
The entire area should be drained to a sump for collection of spills, washup water, and sample
discharges. All of these waste liquids usually contain exceptionally high concentrations of
calcium compounds, so chemical losses would be excessive if these liquids are not returned
to the system. These recovered wastes should be returned to the reaction tank.
The entire massive lime system should be designed to minimize air entrainment at all points,
and to release any gas admitted or generated by the process as soon as possible. This will
reduce foaming which is disastrous to the efficiency of the operation.
Effluent Supply Tank For Massive Lime System
A sump, chest, or tank should be provided to collect colored effluent and serve as a supply
source for the massive lime system. Baffling between the inlet and outlet of the supply tank
can be used to eliminate entrained air. The pump or other means of transporting effluent
from the supply tank to the massive lime treatment should have the capacity and flexibility
to handle most operational surges without allowing air to get into the effluent.
An accurate flow meter should be installed to indicate and record the flow of effluent to the
color removal system.
Slaker And Accessories
Figure 20 shows the relationship between the volume of effluent to be treated and the
quantity of lime which must be slaked for a 20,000 ppm effluent treatment. For a 1000
tons-per-day bleached pulp mill, enough lime would normally be available to treat approxi-
mately 4.0 million gallons of effluent. If a greater volume of effluent is to be treated, the
mill would need increased lime recovery capacity.
51
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Figure 20
VOLUME OF EFFLUENT TREATED VERSUS LIME
REQUIREMENTS FOR MASSIVE LIME PROCESS
c
o
"co
O
c
o
22
*-
100 200 300 400 500
Reburned Lime Used (Tons)
600
700
Since the quantity of lime to be slaked is directly proportional to the volume of effluent to
be treated, this volume must be determined before the slaker can be properly sized. The
maximum quantity of effluent to be treated should be the governing factor in sizing.
A variable speed feed mechanism is needed to meter lime to the slaker. If the volume of
waste water to be treated varies more than ±10% from the design figure, this meter should
be controlled based on the flow of effluent to the system.
To conserve heat, only the minimum quantity of liquid required to slake the lime should be
used in the slaker where a temperature of about 210°F is maintained. Once the system
around the slaker has come to equilibrium, liquid flow to the slaker can be proportioned
and controlled relative to the total liquid flow to the massive lime system.
Final slaker temperature control by direct steam is recommended. Steam is required during
slaker start-up after shut downs exceeding 20 to 30 minutes. A small amount of steam may
also be required as trim control due to variations in effluent temperature or reburned lime
temperature. A steam flow recorder is a good indicator of pluggage problems in the lime
feed mechanism.
The slaker should be equipped with a grit removal device which will discharge into a collection
container for easy removal.
Liquid level in the slaker can be controlled by gravity overflow through an inclined pipe or
trough.
Reaction Tank
The reaction tank should be designed for 10 minutes retention time based on total flow of
52
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waste water to the system plus 15% of that flow. This additional 15% approximates (1) the
flow of filtrate from the sludge filter, (2) seal water from the sludge filter vacuum pump,
and (3) the return of spills, wash-up, etc from the area pick-up sump.
All liquid inlets into the reaction tank should be at or below the liquid surface to minimize
air entrainment caused by splashing. If gravity flow to the primary clarifier can be used, then
an overflow weir can be used to maintain a level in the tank which will avoid splashing of in-
coming liquid, if however, a pump is required to transport the reaction tank mixture to the
primary clarifier, discharge from the pump should be controlled based on the reaction tank
level.
An agitator is required to thoroughly mix the various liquids and sludges for uniform reaction
between organic compounds and the hydrated lime. Agitator should have design character-
istics which will keep suspended solids in suspension without creating a vortex and without
generating foam.
Primary Clarifier
The following items should be considered in design of the primary clarifier.
1. A center well sufficiently large to allow for escape of gases and control of the
resulting foam with spray showers or surface skimmers.
The clarifier's center well should be designed for a rise rate of 0.96 feet per
minute. This allows for a 33% increase in rate due to turbulence before
equalling the observed rise rate (1.28 feet per minute) of air bubbles in
treated effluent.
The center well should extend at least two feet above the water level in the
clarifier. Showers should be positioned one foot above the top of the center
well so that their spray will cover the surface of the well. One and one-half
gallons of shower water per square foot of area should destroy or control
normal foaming conditions.
The center well can be either conical or cylindrical and should extend to at
least 50 to 60% of the liquid depth. Liquid entrance into the center well
should be below the surface and pointed downward. A deflection plate
should be located below the liquid entrance to reduce entrance velocity.
2. A clarifying area sized according to the information given in Figure 11.
The volume of colored waste water that the primary clarifier can handle
is almost entirely dependent on the original color of the liquid. As color
increases, the rate of settling (clarification) decreases. Figure 11 shows
the relationship between color and the maximum clarifier flow rate in
gallons per day per square foot of effective clarification area (total
surface area of clarifierarea of center well at overflow level).
Average color and flow of the effluent to be treated must be known. The
53
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design flow rate should be 25% higher than the expected flow to allow for
normal fluctuations associated with operational demands of increased
production, increased flows, and occasional spillage,
3. A settled sludge removal system.
The bottom rake or sludge removal rake, should be designed to deliver
to the clarifier's outlet well a volume equal to 20% of the flow to the
process. Since the settled solids are very fluid and are easily roused
from a settled condition by even medium velocity changes, peripheral
speed of the removal rake should not exceed 15 feet per minute. A
reputable supplier of such equipment can supply a good design for the
removal rake if given the conditions under which the rake will operate.
Sludge discharged from the clarifier needs to be regulated by both volume
and percent settled solids.
4. A clarified liquid overflow device which will not produce channeling in
the clarifier.
Discharge through orifices into the launders worked well in the modified
demonstration plant clarifier. A similar arrangement should be satisfactory
for any unit.
Carbonator Clarifier
The carbonator clarifier must provide good contact of flue gases containing carbon dioxide
with liquid from the primary clarifier; and it should provide a vessel for settling and with-
drawing the precipitated calcium carbonate.
The carbonator could be an external vessel or an integral part of the clarifier. In this dis-
cussion, it is considered as an integral part of the clarifier.
The bottom of the center well (carbonation area) should extend to a depth not less than
40% nor more than 50% of the liquid depth in the clarifier and the top should extend
1.5 to 2 feet above the liquid level. It is not necessary that the center well be covered.
Foam generated by carbonation is the large bubble type and is easily controlled.
Due to turbulence in the carbonator, the point of liquid entrance into the center well is
not critical.
The flue gas header and diffuser arrangement shown in Figure 8 provides a practical design.
The diffusers or spargers should be equipped with disconnects from the header for easy
removal for replacement or cleaning. A flue gas flow of approximately 0.75 to 1.0 cubic
foot for each gallon of effluent per minute is required.
Based on the work done in this project, the clarifier should be designed for a liquid rise rate
54
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of 1.5 gallons of water per square foot per minute. However, work done by Mr. C. L. Davis
of Interstate Paper Company, Riceboro, Georgia, indicates calcium carbonate crystal growth
can be increased by recirculating part of the sludge to the liquid entering the carbonator.
Such seeding is reported to give more than 90% recovery of the calcium in the water
(Reference 10). As stated in his report, rise rates in the clarifier could be increased by
using this procedure.
The sludge removal rake in the carbonator clarifier does not handle nearly as much sludge as
the one in the primary clarifier. Also, the settled sludge is denser and the rake speed not so
critical. Again, a reputable supplier of such equipment could design a suitable rake when
given the operating conditions.
Sludge removed from the carbonator clarifier can either be pumped to the sludge storage
tank and then to the massive lime sludge filter, or to the causticizing system mud storage
tank which feeds the lime kiln thickener. The calcium carbonate mud improves drainage
properties of the massive lime sludge on the sludge filter if the two muds are mixed in the
sludge storage tank. But, the mixture puts a slightly heavier load of inactive solids on the
slakers, white liquor clarifier, and mud washing equipment in the causticizing system. If
completely carbonated, the carbonator clarifier sludge can be sent to the lime kiln and it
will not interfere with operation of the lime kiln.
Sludge Storage Tank
This tank is to provide surge capacity between the clarifiers and the sludge filter, and to pro-
vide storage space for mud when emergency repairs or breakdowns occur at the massive lime
sludge filter or in the caustic room area. This tank should accommodate 3 hours of sludge
from the massive lime system. For each 1,000,000 gallons of effluent per day to be treated
in the massive lime system, this tank should hold at least 3342 cubic feet of sludge.
An agitator large enough to keep sludge in the tank homogeneous should be provided so a
uniform consistency sludge can be supplied to the sludge filter. The tank should be provided
with a consistency regulator to control solids content of sludge pumped to the sludge filter.
This storage tank should also be used to collect slurry dumped from the sludge filter vat
when back washing or acid cleaning the filter. It will also be used as a collection tank for
slurry that overflows the filter vat when the filter becomes overloaded.
Sludge Filter And Accessories
Surface area required for the rotary vacuum filter used in dewatering sludge reclaimed from
the massive lime process is a function of the color and organics content of the water being
treated. The higher the color of the effluent to be treated, the more difficult and slower the
sludge dewaters. Figure 21 shows the relationship between effluent color and the area of
filter surface required to dewater sludge per 1,000,000 gallons of effluent treated per day.
Since the filter will not operate continuously because of back washing, acid cleaning, emer-
gencies, etc, the area obtained from this graph should be divided by 0.9 for design purposes.
In addition to the running time factor, sufficient surface area should be provided for those
55
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periods of operation when flows or color loads exceed the design capacity due to increased
production, etc. The mud storage tank provides space for short time surges but will not
overcome increases over a long time period. An additional 25% of filter area should be pro-
vided. Therefore total surface area of the sludge filter should be:
Figure 21
(Filter area from Figure 21 -= 0.9) x 1.25
SLUDGE FILTER AREA VERSUS EFFLUENT COLOR
Basis = 1,000,000 gallons of effluent treated per day
1000 r
800 -
§
sr
6OO
< 400
200
Conditions for which data were obtained:
A. One hour after back washing.
B. Filter Speed -7.5 feet per minute.
C. Vat levelAt overflow weir-45% submergence.
_L
Continuous Belt
_L
J_
J
4000 80OO 12,000 18,000 20,000 24,000
Color of Effluent Before Massive Lime Treatment
(APHA Color Units)
28,000
Back washing the filter should be automatically controlled using properly time sequenced
actions for greater efficiency. For best back washing results, shower header sprays should be
no more than 2 inches from the washer face. Sprays from the showers should overlap and
pressure on the shower header should be about 250 psi. High pressure is more essential than
high volume for good back washing.
Acid cleaning should be done mechanically, both for personnel safety and greater cleaning
efficiency. The acid cleaning system should include a storage tank for inhibited muriatic
acid, acid pump, piping, and a small volume overlapping spray header the width of the filter.
The size of the acid storage tank would be governed by capital cost of the storage and the
price of muriatic acid.
The filtercake discharged from the sludge filter can be delivered to the green liquor reaction
tank or slaker by screw conveyor. Capacity and design of this screw depends on the volume
of sludge cake to be moved. When these conditions are known, screw conveyors can be
properly sized.
Except for the limited experimentation with reuse of the kraft decker effluent, the final dis-
56
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position of treated waste water from the massive lime process has not been considered. The
effluent, before discharge into a receiving stream, would have to be further treated for pH
adjustment, temperature reduction, and BOD5 reduction. Methods of treatment and costs
to meet these requirements have not been explored in this project.
Coordination
Probably the most difficult design parameter in incorporating a massive lime system into a
normal pulp mill liquor system is that of predicting variations in the demand for causticizing
chemical due to production variations. Not including mechanical breakdowns or clothing
changes, production rate of an average paper machine can vary ± 25% due to the grade mix
assigned to the machine. This variation directly affects the usage of pulp, and in turn, the
demands on the liquor and recovery system of the pulp making process.
When production increases, total color (organic compounds) generated in the pulp mill and
bleach plant increases. However, the consumption of water does not increase proportinately,
thus the color of the effluents tends to increase. Design of a massive lime plant should
consider these variations. Sufficient storage for green liquor, white liquor, lime mud, re-
burned lime, and massive lime sludge should be provided.
The massive lime system cannot be operated as a water treating plant clarifying a given flow
and a given organic load. It must be able to fluctuate to some extent with variation in the
mill's production.
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SECTION IX
BENEFITS AND OPERATING COSTS FOR A TYPICAL MILL
To illustrate what can be expected from using the massive lime process in a full-scale mill
installation, data presented earlier in this report were used to calculate effects of a massive
lime process on a hypothetical 1000 tons-per-day mill.
Conditions Assumed For Hypothetical Mill
The mill is assumed to be a new kraft pulp and paper mill producing a 75% pine/25% hard-
wood bleached pulp. Bleached pulp production is 1000 tons per day so unbleached pulp
production is 1136 tons per day. The equivalent of 550 pounds of 85% causticizing power
lime is used per ton of unbleached pulp for production of cooking liquor.
Estimated use of fresh water is 20,000 gpm or approximately 29 million gallons per day.
The evaporator, brown stock washer, recovery boiler, and black liquor storage systems have
catch basins for collection and return of leaks and spills. These systems are of sufficient size
to operate efficiently at maximum production with minimum losses.
Total effluent from the mill is approximately 29 million gallons per day. Without massive
lime treatment color of the total combined mill effluent is 2631 APHA units. Color loads
contributed by various individual streams within the mill are shown in Table 9.
Table 9
CONTRIBUTION OF EFFLUENT SOURCES TO TOTAL MILL EFFLUENT
COLOR WITH NO MASSIVE LIME TREATMENT
Source of Effluent
Pulp millgeneral
Paper mill
Bleach chlorination stage
Bleach caustic extraction stage
Remainder of bleaching process
Total
Color Load
(Ib color/bl ton)
31
5
111
460
27
Contribution to
Combined Effluent
Color
(APHA Color Units)
129
21
462
1916
113
634
2631
Effects Of Massive Lime Treatment On Effluent Color
Using data from Figures 16 and 19, the maximum amount of effluent that can be treated in
a massive lime system (20,000 ppm lime treatment) without exceeding the mill's causticizing
requirements is:
(1540 Ib sludge for causticizing per ton unbl pulp) (1136 tons unbl pulp) =
(443,666 Ib sludge per 106 gal. of effluent treated)
A million gallons
59
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Assuming the most highly colored effluents would be treated, then all of the bleach caustic
extraction stage effluent (2,750,000 gallons per day) and approximately 1,250,000 gallons
per day of unbleached decker effluent would be treated for color removal. Combining these
two flows would give an influent to the massive lime system having a color of 14,500 APHA
units. Based on a color removal of 95% (from Table 7), color of this effluent would be
reduced to 725 APHA units after massive lime treatment. This stream would then be com-
bined with mill effluents which had not been treated for color removal. Color of the combined
mill effluent would then be 742 APHA units and color loads contributed by various individual
sources would be as shown in Table 10.
Table 10
CONTRIBUTION OF EFFLUENT SOURCES TO TOTAL MILL EFFLUENT
COLOR WITH MASSIVE LIME TREATMENT OF BLEACH
EXTRACTION STAGE AND DECKER EFFLUENTS
Source of Effluent
Pulp mill-general
Paper mill
Bleach chlorination stage
Bleach caustic extraction stage
Remainder of bleaching process
Total
Color Load
(Ib color/bl ton)
12
5
111
23
27
178
Contribution to Combined
Effluent Color
(APHA Color Units)
742
The net effect of the massive lime treatment is a 72% reduction in color of the combined mill
effluent (2631 units to 742 units).
Equipment Size
Based on design criteria presented earlier in this report, the massive lime plant for treating
four million gallons of effluent per day would require equipment of approximately the
following sizes:
Slaker
Reaction tank
Primary clarif ier
Carbonator clarifier
Sludge storage tank
Mud filter
Flue gas (C02) blower
Designed to slake 400 tons of reburned lime per day
15 feet in diameter by 15 feet high
80 feet in diameter by 26 feet high with a center
well 25 feet in diameter by 12 feet deep
55 feet in diameter by 24 feet high with a center well
(carbonation zone) 35 feet in diameter by 12 feet deep
30 feet in diameter by 20 feet high
2250 square feet of filter area
To deliver 3000 cubic feet per minute at 5 psig
60
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As described in Section VII, use of the massive lime sludge also results in larger equipment
being required in the mill's cooking liquor and recovery processes. Compared with a mill
which does not have the massive lime treatment, the following increases in capacity are
required.
Increased
Capacity, %
Green liquor slaker or mixing tank 17.7
Causticizers and associated equipment 17.7
White liquor clarifier, storage, and associated equipment 17.7
Mud washers, storages, and associated equipment 15.8
Mud filter 6.4
Lime kiln 6.4
Pulp washing accessories 5.8
Evaporators and accessories 5.8
Recovery boilers and accessories 1.9
Labor Costs For Massive Lime System
With the massive lime treatment system located adjacent to the normal liquor making facil-
ities, operation of the two systems can be controlled by the same personnel. Additional
duties imposed by operation of the massive lime system are:
Observe and inspect all equipment to see that it is performing efficiently.
Back wash and acid clean the sludge filter. Back washing is required at
6-hour intervals and requires about 20 minutes. Acid cleaning is required
once every two days and requires about one hour.
Test solids concentration once each four hours.
Test decolored effluent to control loss of lime due to improper carbonation
or carbonate settling.
Observe instrument panelboard for indications of improper operation.
Keep the area clean.
These additional duties necessitated by operation of the massive lime process should require
no more than 8 hours per day for a cost of:
(8 hr) (5.50 $ per hr including fringes, overtime, etc) = $44.00
Maintenance Costs For Massive Lime System
Maintenance costs for the hypothetical mill are estimated to be $50,000 per year
($142.86 per day) more than for a comparable mill operating without the massive lime
treatment system.
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Electricity Costs For Massive Lime System
The color treatment system requires 1500 connected horsepower. With a load factor of
80%, this is estimated to cost $150 per day.
Steam Costs For Heating Slaker
Approximately 20% (or 0.8 million gallons per day) of the influent must be heated to 210°F
for slaking. Some steam is needed to bring the slaker to temperature on startup and some
"trim" steam is required for temperature control. Based on an assumed 2°F rise in the slaker,
achieved by use of steam, cost of the steam is:
(0.8 x 106 gal, effluent) (8.33 Ib per gal.) (2 BTU per Ib) = 13,740 Ib steam per day
(970 BTU per Ib steam)
(13,740 Ib steam/day) (1.05$ per 1000 Ib steam) = $14.42 per day
Lime Losses
As indicated in Figures 15 and 17, calcium carbonate losses from the carbonator clarifier are
4445 Ib and 727 Ib per million gallons for bleach caustic extraction and decker effluents,
respectively. A weighted average of these indicates losses of 13,133 Ib of calcium carbonate
per day. However, when adjusted to compensate for calcium, which is brought into the
system with the influents, the net loss is 10,093 Ib of calcium carbonate per day. Converting
this to tons of new lime (90% calcium oxide) which must be purchased at $25.40 per ton
gives a cost for lime of $79.76 per day.
Sodium Losses
Also, as shown in Figures 15 and 17, significant amounts of sodium compounds which enter
the system with the reburned lime are lost with the carbonator clarifier effluent. The sodium
compounds are essential for cooking and must be replaced by adding sodium sulfate to the
mill's chemical recovery system. Cost of the soda lost is:
(10,987 Ib Na2CO3 lost per day) (142 Ib Na2SO4) (30.40 $ per ton Na2SO4) = $223.74 per day
(2000 Ib per ton) (106 Ib Na2CO3)
Acid Cleaning Massive Lime Sludge Filter
Eight carboys of inhibited muriatic acid are required every two days for acid cleaning the
filter. Cost of this acid is $8.09 per carboy or $32.36 per day. If a bulk system for muriatic
acid is installed, costs could be much less.
Increased Operating Costs Of Normal Pulp Mill Operations
The above costs are only the costs directly related to operation of the massive lime treatment
plant. As discussed in Section VII, use of the massive lime sludge in the mill's causticizing
system affects many of the normal pulp mill operations. Effects which increased costs of
62
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pulp mill operations (based on data from Section VI!) are shown in Table 11. Effects which
decreased net costs of pulp mill operations (based on data from Sections VI and VII) are
shown in Table 12.
Table 11
INCREASED PULP MILL OPERATING COSTS RESULTING
FROM MASSIVE LIME TREATMENT
1.
2.
3.
4.
5.
6.
Effect of Massive Lime Treatment on Pulp Mill Operations
Steam used to heat filter cake and green liquor for causticizing;
313 tb per ton of unbleached pulp produced
Added 0.5 Ib of defoamer per ton of unbleached pulp to
control foaming in the causticizing system
Increased fuel consumption in the lime kiln 158,400 BTU
per ton of unbleached pulp
Increased steam used for evaporating black liquor 235 Ib
of steam per ton of unbleached pulp
Increased sodium losses from the system the equivalent of
1.8 Ib of Na2SO4 per ton of unbleached pulp
Increased lime losses from the system the equivalent of
1.3 Ib of new lime
Raw Material or
Utility Cost
$1.05 per 1000 Ib
of steam
$0.25 per Ib of defoamer
$0.625 per million BTU
$1.05 per 1000 Ib
of steam
$30.40 per ton
$25.40 per ton of
new lime
Increased Pulp
Mill Cost
($ per day)
373.35
141.88
112.46
280.31
31.07
18.74
Table 12
PULP MILL SAVINGS OR CREDITS RESULTING FROM
MASSIVE LIME TREATMENT
Effect of Massive Lime Treatment on Pulp Mill Operations
1. Reduced BOD content of the waste water 2695 Ib per day
2. Increased steam production by 203 Ib per ton of
unbleached pulp
3. Increased production of electricity by 10.4 KWH per ton of
unbleached pulp
Raw Material or
Utility Cost
$0.04 per Ib BOD
$1.05 per 1000 Ib
of steam
$0.007 per KWH
Savings Realized
($ per day)
107.79
242.14
82.70
Capital Costs
Increased capital costs resulting from use of the massive lime color removal process were de-
termined by preparing two capital cost estimates for the hypothetical 1000-tons-per-day mill;
one estimate without the color removal process and one including the color removal process.
Appendix D gives a comparison of capital cost estimates for the two situations. Including
the massive lime process in the hypothetical mill is estimated to increase total mill capital
costs $2,704,000.
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Annual depreciation, insurance, and taxes, shown in Table 13, were calculated based on the
cost estimates given in Appendix D.
Table 13
ANNUAL DEPRECIATION, INSURANCE, AND TAXES
Without Massive With Massive
Lime System Lime System Difference
Total investment required $119,954,000 $122,658,000 $2,704,000
Annual charges for:
Depreciation 7,254,433 7,422.158 167,725
Insurance 183,287 187,429 4,142
Taxes 1.499.425 1,533,225 33,800
Total $ 8,937,145 $ 9,142,812 $ 205,667
Assuming the mill operates 350 days per year, the increase in depreciation, insurance, and
taxes resulting from use of the massive lime color removal system would be:
(205.667$ per year) . $0.588 per ton of pulp
(350 days per year) (1000 tons of pulp per day)
Overall Effects On Costs And Mill Operation
All significant costs incurred or changed as a result of using the massive lime color removal
process are summarized in Table 14. These cost data are based on typical values for a new
mill, and will vary for different situations. Mill size would have a significant effect on the
costs. Also, capital investment required for adding a massive lime color removal process to
an existing mill would probably be quite different from the costs for including a similar
system in a new mill. Some of the reasons for this are; increasing capacity of existing equip-
ment would be more costly than providing the necessary extra capacity in a new installation,
space for new equipment may not be readily available, and available space may be in relatively
unfavorable locations in existing mills.
Costs shown in Table 14 are for a hypothetical mill producing 1000 tons of bleached kraft
pulp which is 75% pine ano 25% hardwood. Using all of the mill's available lime allowed
4,000,000 gallons of the mill's 29,000,000 gallons of effluent to be treated for color removal.
This level of treatment removed approximately 72% of the mill's total effluent color, giving
a final combined mill effluent color of 742 APHA color units. These benefits were achieved
in the hypothetical mill at a cost of $1.80 per ton of bleached pulp. This includes costs of
depreciation, taxes, and insurance for the capital expenditures required as a result of massive
lime treatment.
64
-------
Table 14
Summary of Effects of Massive Lime System on Operating Costs for
Hypothetical Mill Producing 1000 Tons of Bleached Pulp Per Day
Costs of operating massive lime system,
Operating labor
Maintenance
Electricity
Steam
Lime
Saltcake (Na2SO4)
Muriatic acid
Costs of Massive Lime System
$ per ton of
($ per day) bleached pulp
44.00
142.86
150.00
14.43
79.76
223.74
32.36
687.15
0.687
Increased pulp mill operating costs resulting from use of
massive lime process.
Steam to heat filter cake and green liquor
Defoamer
Increased fuel to lime kiln
Increased steam for black liquor evaporation
Sodium losses
Lime losses
373.35
141.88
112.46
280.31
31.07
18.74
0.373
0.142
0.112
0.280
0.031
0.019
957.81
0.958
Credits resulting from massive lime treatment
Reduced BOD load
Increased steam production
Increased production of electricity
Annual depreciation, insurance, and taxes
Total
107.79
242.14
82.70
(432.63)
587.62
$1799.95
(0.433)
0.588
$1.800
65
-------
SECTION X
AC KNOWL EDGM ENTS
The support and recommendations of Mr. Herbert F. Berger, National Council for Air and
Stream Improvement, Pulp and Paper Industry, Southeast Laboratory, Gainesville, Florida,
is acknowledged with sincere thanks.
Mr. John L. Oswalt, Assistant to the Mill Manager, Springhill Mill; Mr. Samuel R. Williamson,
Sr., (retired); and Mr. Ben C. Vercher, Project Engineer, SpringhiM Mill; supervised the
necessary bench scale studies, analytical work, and operational changes to bring the demon-
stration project to a successful conclusion. Mrs. Anna M. Lambert, Mrs. Maria M. Blan,
Mrs. Sharon W. Bush, Mr. John R. Poole, and Mr. Joseph G. Land, Jr., of International
Paper Company's Erling Riis Research Laboratory, Mobile, Alabama, assisted in preparation
of the final report.
Suggestions for the application and design for equipment used in carbonating liquids, by
Mr. Charles L. Davis, Jr., Interstate Paper Company, Riceboro, Georgia, and Mr. Ed Spruill,
Continental Can Corporation, Hodge, Louisiana, were useful in overcoming deficiencies in
performance of original design.
The support of the project by the Water Quality Office, Environmental Protection Agency
and the help provided by Mr. George R. Webster, Mr. Robert Hiller, and Mr. George Putnicki,
the Grant Project Officer, is acknowledged with sincere thanks.
67
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SECTION XI
REFERENCES
1. Berger, H. F.,eta/, "Decolorizing Kraft Waste Liquor," U. S. patent 3,120464
(February 4, 1964).
2. National Council for Stream Improvement, Inc., "Experimental Chemical Treatments
For Kraft Mill Wastes," Technical Bulletin Number 50 (May 1952).
3. National Council for Stream Improvement, Inc., "A Process For Removal Of Color
From Bleached Kraft Effluents Through Modification Of The Chemical Recovery
System," Technical Bulletin Number 157 (June 1962).
4. National Council for Stream Improvement, Inc., "Treatment Of Calcium-Organic
Sludges Obtained From Lime Treatment Of Kraft Pulp Mill Effluents-Part I,"
Technical Bulletin Number 62 (August 1953).
5. National Council for Stream Improvement, Inc., "Treatment of Calcium-Organic
Sludges Obtained From Lime Treatment Of Kraft Pulp Mill Effluent-Part 11/'
Technical Bulletin Number 75 (April 1955).
6. Morgan, Robert J., "The Clarification Of Decker White Water With Lime," Western
Kraft Corp., Albany, Oregon, September 15, 1964.
7. West Virginia Pulp and Paper Company, "Project 513102-Color Removal," Covington
Research Laboratory, Luke, Maryland, March 1960.
8. Holzer, Walter F., "A Study Of The Coloring Matter In Pine Kraft Pulps," Paper Trade
Journal 99 (12):91-103 (September 20, 1934).
9. Luner, P., and C. Dence, "The Mechanism Of Color Removal In The Treatment Of
Pulping And Bleaching Effluents With Lime," National Council of Air and Stream
Improvement, Inc., Technical Bulletin Number 239 (July 1970).
10. Davis, Charles L., Jr., "Lime Precipitation For Color Removal In Tertiary Treatment
Of Kraft Mill Effluent At The Interstate Paper Company, Riceboro, Georgia,"
Interstate Paper Company Mill Project Report to Federal Water Pollution Control
Agency, March 1970.
69
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SECT ION XII
GLOSSARY
Active Cooking Chemical-
Batch Digester-
Black Liquor-
Black Liquor Solids-
BOD-
Brown Stock Washing
Ca-Organics
Clarifier
Causticizing Power
COD-
Continuous Digester-
Consistency
Sodium hydroxide (NaOH) and sodium sulfide (I\la2S)
in kraft pulp mill liquor; usually expressed as the equiv-
alent amount of Na20; also called active alkali.
A large pressure vessel in which a batch of wood chips is
cooked with white liquor to produce pulp; the digester
is filled, capped, brought to temperature and pressure,
held at these conditions for some period then emptied,
a batch cooking process.
Spent cooking liquor from the kraft pulping process,
which contains spent cooking chemicals plus materials
from the wood (mostly lignin) which reacted with white
liquor during the cooking process and dissolved.
The residue left when evaporating a sample of black
liquor to dryness.
Biochemical oxygen demand.
A countercurrent multistage pulp washing process
immediately after cooking; used to remove (wash) from
the pulp the spent cooking chemicals and materials made
soluble during the cook.
Those organic compounds which have combined with
calcium to form insoluble compounds.
Equipment for removing settleable solids from liquids.
Generaliy expressed as a percent causticizing value indi-
cating the percent of a sample of lime which when slaked
will react with Na2C03 to produce NaOH.
Chemical oxygen demand.
A large pressure vessel for cooking wood chips with white
liquor in a manner that allows wood chips (and white
liquor) to be added continuously and pulp to be removed
continuously.
Ovendry weight of pulp in a pulp-water slurry divided by
the total slurry weight; usually expressed as a percentage.
71
-------
Cooking Liquor-
Digester
Dregs-
Green Liquor-
Launder
Pulp Yield-
Reburned Lime
Recausticizing
Recovery Furnace
Slaker-
Slaking
Soda-
Strong Black Liquor-
Liquor which is added to the digester to provide the
necessary chemicals for the cooking process; white liquor.
A large pressure vessel for cooking wood chips (with white
liquor) to produce pulp.
Heavy solids that settle in the slaker and are removed
from the process.
A solution of recovered pulp mill cooking chemicals,
formed by dissolving recovery furnace smelt in water;
primarily sodium carbonate, sodium sulfide, and water.
A trough used to collect and transport liquid.
The percentage obtained by dividing the ovendry weight
of pulp produced by the ovendry weight of wood used
to produce that amount of pulp.
Lime produced from recycled calcium carbonate which
is produced in the causticizing process and removed in
the white liquor clarifier.
Process of reacting green liquor with slaked lime to pro-
duce white liquor; Na2C03 in the green liquor reacts with
Ca(OH)2 to produce NaOH.
The chemical recovery unit in which concentrated black
liquor is burned; heat from this combustion is used to
generate steam; sulfur compounds are reduced to sulfides;
inorganic sodium and sulfur compounds are recovered
from the bottom of the unit as a smelt which is dissolved
in water to form green liquor.
Equipment in which the slaking process occurs.
Process of adding lime to water to convert the calcium
oxide to calcium hydroxide.
Generally used in the paper industry to refer to sodium
compounds present in pulp mill liquors.
Black liquor which has been increased to approximately
50% black liquor solids or more by evaporation of water
from weak black liquor.
72
-------
Weak Black Liquor The dilute (approximately 10 to 15% solids) black liquor,
before evaporation; obtained from the brown stock wash-
ing operation.
White Liquor Highly alkaline chemical solution used to digest (cook)
wood in the kraft (sulfate) pulping process; formed by
the reaction of green liquor with slaked lime; active
chemicals are primarily NaOH and Na2S.
73
-------
SECTION XIII
APPENDICES
PAGE
A. Chronological List Of Modifications Made To Massive Lime Demonstration Plant 77
B. Description Of Analytical Testing Techniques Used 83
Tests On Liquid Effluents 85
Tests On Pulp Mill Liquors 87
Tests On New And Reburned Lime 89
C. Operational Test Data 91
Feed To Massive Lime Process
Table C-1-100% Bleach Plant Caustic Extraction Stage Effluent 93
Table C-2-50% Bleach Plant Caustic Extraction Stage Effluent and
50% Unbleached Kraft Decker Effluent 94
Table C-3-100% Unbleached Kraft Decker Effluent 95
« Effluent From Primary Clarifier
Table C-4-While Treating 100% Bleach Plant Caustic Extraction
Stage Effluent 96
Table C-5-While Treating 50% Bleach Plant Caustic Extraction Stage
Effluent and 50% Unbleached Kraft Decker Effluent 97
Table C-6-While Treating 100% Unbleached Kraft Decker Effluent 98
Effluent From Carbonator Clarifier
Table C-7-While Treating 100% Bleach Plant Caustic Extraction
Stage Effluent 99
Table C-8-While Treating 50% Bleach Plant Caustic Extraction Stage
Effluent and 50% Unbleached Kraft Decker Effluent 100
Table C-9-While Treating 100% Unbleached Kraft Decker Effluent 101
Green Liquor Analyses, Table C-10 102
White Liquor Analyses, Table C-11 103
Typical Operator's Daily Report
Table C-12-Massive Lime System Flow Rates 104
Table C-13-Massive Lime System Operating Data And Analyses 105
Table C-14-Primary Clarifier Conditions At Sample Points 106
D. Capital Cost Estimates 107
Table D-1Estimated Capital Costs For Hypothetical
1000 Tons-Per-Day Mill 108
Table D-2-Capital Costs Affected By Inclusion Of Massive Lime
Color Removal Process 109
75
-------
APPENDIX A
CHRONOLOGICAL LIST OF MODIFICATIONS MADE TO
MASSIVE LIME DEMONSTRATION PLANT
77
-------
CHRONOLOGICAL LIST OF MODIFICATIONS MADE TO
MASSIVE LIME DEMONSTRATION PLANT
CD
DATE
1. 3/1/70
2. 3/6/70
CHANGE
REASON FOR CHANGE
3. 4/15/70
4. 4/28/70
5. 5/11/70
6. 5/12/70
7. 6/8/70
Started putting flow of mud from carbonator
clarifier into the mill's mud washer instead of
into the unfiltered mud tank.
Changed the flow of carbonator clarifier mud
again; this time put it into the massive lime
system sludge storage tank.
Filtrate from the sludge filter was put into the
primary clarifier instead of into the carbonator
clarifier.
Started putting filtrate from the sludge filter
into the reaction tank.
Started putting filtrate from the sludge filter
into the massive lime system slaker. This also
required increased heat (steam) input into
the slaker.
Installed new flue gas distribution system in
the carbonator clarifier.
Extended center well of primary clarifier
to a depth of 10 feet below the liquid level
(it originally extended only two feet below
liquid level).
Calcium hydroxide carryover from the carbonator
clarifier caused the mill's mud filter to glaze over.
The change made on 3/1/70 caused a problem in
settling of the mill's regular calcium carbonate
mud, and a foaming problem which resulted in
turbid wash liquor.
A significant quantity of solids were going through
the sludge filter and being carried with the filtrate.
The change made on 4/15/70 resulted in consider-
ably impaired settling rates in the primary clarifier.
Settling rate remained impaired.
Scaling problems with original system made it
unsatisfactory.
To try to eliminate excessive carryover of
suspended solids from the primary clarifier.
-------
DATE
CHANGE
REASON FOR CHANGE
8. 7/6/70 Removed four feet of the eight-foot extension
added to the primary clarifier center well 6/8/70.
9. 9/10/70 Enlarged and levelled overflow weirs in primary
clarifier and in carbonator clarifier.
10. 9/10/70 Changed flue gas flow control from back
pressure control to atmospheric relief control
11. 9/10/70 Relocated pH control of the carbonator so pH
of the center well could be measured almost
immediately.
12. 9/10/70 The pipe transferring liquid from the primary
clarifier to the carbonator clarifier was
replaced with an open trough.
13. 10/16/70 Installed experimental clarifier in parallel with
primary clarifior.
14. 10/22/70 Tried adding high molecular weight polymer
settling aids.
15. 1/14/71 Installed conical center well, radial launders,
and Yarway foam suppressing showers in the
primary clarifier.
16. 1/14/71 Replaced the original flue gas blower with a
Nash pump.
Excessive carryover continued after center well had
been extended on 6/8/70.
To achieve a more even distribution of overflow from
the weirs and hopefully less carryover of suspended
solids.
Excessive back pressure was causing electrical
overloads on the flue gas blower.
Original pH measurement of the clarifier overflow
gave a 3-hour lag in measurement so response to
changes was too slow and control was not good with
the original system.
Scaling problems were encountered with the pipe and
a trough should be easier to clean.
To provide a small-scale means of studying way to
eliminate the foaming and suspended solids carryover
problems of the primary clarifier. To evaluate new
launder and center well design.
To see if carryover of suspended solids could be
eliminated.
To eliminate foaming and carryover problems of the
primary clarifier.
Severe maintenance problems had been experienced
with the original type of blower.
-------
DATE
CHANGE
REASON FOR CHANGE
17. 1/14/71 Changed flow of filtrate from sludge filter so it
again went to the reaction tank.
18. 7/9/71 Changed sludge filter from precoat operation to
continuous belt operation.
With the flow going into the slaker, steam
consumption in the slaker was high.
To compare the two methods of operations.
00
-------
APPENDIX B
DESCRIPTION OF ANALYTICAL TESTING
TECHNIQUES USED
83
-------
Tests On Liquid Effluents
1 . Procedures for the following tests which were used during this project are described
in the book, Standard Methods For The Examination Of Water And Wastewater,
Twelfth Edition, published by American Public Health Association, Inc., New York,
October 1967.
Page Numbers
APHAcolorl 127-129
Total Solids Content 244 - 245
Suspended Solids Content 245 - 246
Dissolved Solids Content 246 - 247
Biochemical Oxygen Demand (BODS) 415 - 421
Chemical Oxygen Demand (COD) 510 - 514
1 A Klett-Summerson colorimeter Model 900-3 was used
for color comparison instead of Nessler tubes.
2. Procedures used to determine total carbon (TC), total organic carbon (TOO, and
total inorganic carbon present in the effluents are described in the FWPCA manual
Methods for Chemical Analysis of Water and Wastes, U. S. Dept. of Interior,
November 1969, p 211.
3. Laboratory Massive Lime Treatment
a. Collect a 3-liter sample of effluent.
b. To a 600-ml portion of the sample add 60 grams of lime (20,000 ppm)
and heat with stirring until the lime is slaked.
c. Add the 600-ml portion to the remainder of the 3-liter sample while
stirring at maximum rpm with a Phipps and Bird variable speed stirrer.
d. After 2 minutes at high speed, reduce stirrer speed to 50 rpm for 5 minutes,
then stop the stirrer and allow the sludge to settle.
e. Start time when the stirrer is cut-off.
f. Record sediment height at 5, 10, 15, 20, and 30 minutes.
g. Remove supernatant liquid for carbonation (step j) and test as desired.
h. Filter the residue through Whatman No. 41 filter paper on a Buchner funnel
to collect the settled sludge.
i. Dry the collected sludge in an oven at 105°C, weigh, and save for testing as
desired.
j. Bubble C02 through sample (from step g) of supernatant liquid until pH
11.0 is reached.
k. Filter carbonated sample through Whatman No. 41 filter paper on a Buchner
funnel.
85
-------
I. Save filtrate for testing as desired.
m. Dry calcium carbonate mud in oven at 105°C, weigh, and save for testing
as desired.
4. Sodium Content
Sodium was determined using a Beckman DU-2 flame spectrophotometer.
5. Calcium Content
a. Pipette a 25-ml sample into a crucible and acidify with HCI.
b. Evaporate to dryness.
c. Place in muffle furnace at 600° F for 10 to 15 minutes.
d. Cool, then dissolve residue in concentrated HCI.
e. Place HCI solution in muffle furnace at 600°F for 10 to 15 minutes.
f. Cool, then dissolve residue in 6N HCI.
g. Evaporate to dryness, then place in muffle furnace at 600° F for 10 to
15 minutes.
h. Repeat steps f and g.
i. Dissolve the residue in hot distilled water.
j. Filter the solution through Whatman No. 41 filter paper into a 100-ml
volumetric flask and make to the mark.
k. To a 25-ml sample of the filtrate add calcium indicator powder and 6 to
8 drops of calcium buffer.
I. Titrate with 0.001M E DTA.
m. Calculate Ca concentration by % Ca = ml titration x 0.0160
25
6. Chlorides Concentration
a. Pipette a suitable volume of liquid into an Erlenmeyer flask.
b. Neutralize with dilute H2SO4 or NaOH solution.
c. Add 1 ml of 2% potassium chromate solution.
d. Titrate with 0.0142N AgN03 to the first color change.
e. Calculate chlorides concentration by;
ppm chlorides = ml titration x 498
ml of sample
86
-------
Tests On Pulp Mill Liquors
1. Analysis of Cooking Chemicals in Green Liquor And White Liquor
To determine total sodium compounds (total alkali) which are in an active form
(NaOH or Na2S) or which can be converted (Na2C03) to active cooking chemicals;
a. Pipette 5 ml of the liquor sample into a 250-ml Erlenmeyer flask.
b. Add approximately 100 ml of distilled water and 2 or 3 drops of Methyl
Orange indicator.
c. Titrate to the Methyl Orange end point with 1N HCI.
d. Record the ml of acid used in the titration as the value, A.
e. Calculate total alkali as the Na2 O equivalent by;
Total Alkali, as gpl Na20 = 6.20 A
To determine the NaOH and Na2S contents;
a. Pipette a 25-ml sample of the liquor into a 250-ml volumetric flask.
b. Fill to the mark with 10% BaCI2, shake, and let settle for 15 minutes.
c. Pipette 50 ml of the supernatant liquid into a 250-ml Erlenmeyer flask and
titrate to the phenolphathalein end point.
d. Record ml of 1N HCI used in this titration as the value, B.
e. Continue to titrate with 1N HCI to the Methyl Orange end point.
f. Record the total ml of 1N HCI used in titrating to both end points as the
value, C.
g. Calculate NaOH and Na2S content as the Na20 equivalent by;
NaOH, as gpl Na20 = 6.2 [B - (C - B)]
Na2S, as gpl Na20 = 12.4 (C - B)
Na2CO3,asgpl Na2O = 6.2 {A - C)
2. Unreduced Na2SO4
a. Pipette 10 mi of liquor into a small beaker.
b. Dilute with distilled water and add 10 ml of concentrated HCI.
c. Boil on a hot plate until the solution is clear, then filter through qualitative
filter paper.
d. Add 10 ml of 12% BaCI2 to the filtrate and iet stand on hot plate without
boiling until precipitate has settled.
e. Filter through a weighed Gooch crucible containing a suitable filter pad to
retain the precipitate.
87
-------
f. Wash, dry, and weigh the crucible.
g. Calculate unreduced Na2SO4 by:
Unreduced Na2 S04/ as gpl Na2 0 = 26.61 (wt of precipitate)
3. Settling Time For Clarifier Sludge
a. Collect representative sample.
b. Agitate sample to get uniform slurry.
c. Fill 3-liter beaker and start timing.
d. Measure and record temperature.
e. Record height of sediment at 5,10,15, 20, and 30 minutes.
4. Tests for sodium content, calcium content, chlorides concentration, and COD
were made using the procedures described for testing Liquid Effluents.
88
-------
Tests On New And Reburned Lime
1. Available Lime
a. Weigh 1 gram lime and add approximately 25 ml water.
b. Boil 5 minutes.
c. Cool, add 40 grams sugar, stopper, and shake every 15 minutes for 2 hours.
d. Filter through Whatman No. 42 filter paper on a Buchner funnel and wash
with 100 ml of 10% sugar solution.
e. Titrate filtrate with 1N HCI to a phenolphathalein end point.
f. Calculate:
% Available Lime = 2.804 (ml Titration)
2. HCI Insolubles In Lime And Lime Mud
a. Weigh a 25-gram sample into a beaker.
b. Bring volume to approximately 500 ml with distilled water.
c. Slowly add an excess of concentrated HCI and bring to boil.
d. Filter through a weighed Gooch crucible containing an asbestos filter pad,
wash with hot water, dry, and reweigh.
e. Save filtrate for sodium, analysis which can be run using procedure as
described for testing Liquid Effluents.
f. Calculate:
Wt % Insolubles = Wt Residue x 100
Wt of sample
3. Causticizing Value
a. Weigh 212 grams of soda ash and 112 grams of lime.
b. Heat 1800 ml of distilled water to approximately 160°F in a 2-liter beaker.
c. Slowly add the soda ash and lime from step (a.) to the heated water.
d. Boil contents for 1 hour.
e. Remove the container from the hot plate and allow precipitate to settle
to a height of 2 inches.
f. Pipette 5 ml of supernatant liquid into an Erlenmeyer flask.
g. Titrate with 1N HCI to phenolphthalein and Methyl Orange end points
recording ml of acid to titrate to the first end point as P and that to the
second as M.
89
-------
h. Calculate:
% Causticizing Value = M - 2(M - P)
0.01 M
4. Tests for sodium content were made on liquid from 3 above using procedures
described previously in tests for Pulp Mill Liquors.
-------
APPENDIX C
OPERATIONAL TEST DATA
91
-------
Table C-1
100% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT
FEED TO MASSIVE LIME PROCESS FEBRUARY 8 - MARCH 10, 1971
Date,
1971
2/08
2/09
2/10
2/12
2/13
2/14
2/15
2/16
2/17
2/18
2/19
2/20
2/21
2/22
2/23
2/24
2/27
2/28
3/01
3/02
3/03
3/04
3/05
3/06
3/07
3/08
3/09
3/10
Flow
Rate,
gpm
200
100
100
250
250
150
150
150
150
150
150
150
200
200
150
150
150
150
150
200
225
200
200
175
175
175
150
150
APHA
Color
Units
15,300
16,500
18,150
18,150
18,150
16,500
23,600
16,500
23,600
23,200
23,200
19,050
21,400
28.250
29,000
26,750
24,200
22,600
22,000
20,000
24,800
21,000
20,400
24,200
23,600
23,600
21,000
18,600
Suspended
Sol ids.
ppm
40
10
20
10
50
40
40
60
0
20
30
20
20
20
30
30
10
10
30
20
30
20
20
10
40
30
50
30
Dissolved
Solids,
ppm
5180
4850
4820
4790
4580
4630
6070
5030
5870
6210
6080
4840
4220
7060
7220
7900
6710
5940
6370
5590
-
-
-
-
-
-
-
-
Total
Carbon,
ppm
1125
1350
1475
1450
1450
1125
1750
1250
1725
1550
1525
1225
1425
1750
1750
1925
1725
1375
1500
1450
1700
1475
1475
1700
1600
1700
1600
1400
Inorganic
Carbon,
ppm
50
100
100
50
75
75
50
75
50
75
75
50
75
125
100
75
75
75
100
100
25
75
75
100
100
75
25
75
Organic
Carbon,
ppm
1075
1250
1375
1400
1375
1050
1700
1175
1675
1475
1450
1175
1350
1625
1650
1850
1650
1300
1400
1350
1675
1400
1400
1600
1500
1625
1575
1375
Ca,
ppm
46
31
37
57
67
34
48
37
56
60
40
24
29
42
48
58
40
BO
41
38
69
52
35
30
43
36
30
39
Cl,
ppm
1268
1145
1155
1145
1035
1175
1604
1254
1530
1520
1510
1308
1409
1782
1892
2051
1820
1693
1594
1534
-
-
-
-
-
-
-
-
pH
10.9
11.0
9.8
10.3
10.0
9.8
9.8
9.8
10.0
10.0
10.3
9.9
8.6
10.4
9.8
10.3
10.2
10.2
10.2
10.4
9.8
10.4
10.1
10.1
9.4
9.9
9.8
9.7
BOD5
ppm
_
336
-
-
342
348
-
-
444
-
288
-
-
-
360
-
93
-------
Table C-2
50% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT AND
50% UNBLEACHED KRAFT DECKER EFFLUENT
FEED TO MASSIVE LIME PROCESS APRIL 7 - MAY 15,1971
Date,
1971
4/07
4/08
4/09
4/10
4/11
4/12
4/13
4/14
4/15
4/16
4/17
4/18
4/19
4/20
5/01
5/02
0/03
5/04
5/05
5/06
5/07
5/08
5/09
5/10
5/11
D/12
5/13
5/14
6/15
Flow
Rote,
gpm
400
400
450
450
500
500
500
400
500
450
450
400
300
300
300
300
300
400
400
450
450
450
350
350
350
400
400
400
300
APHA Suspended
Color
Units
10,200
8000
16,500
17,500
8300
8900
11,700
9300
8300
8600
12,900
12,900
12,700
10,200
7300
5350
8300
10,500
9400
8900
9100
10.200
10,050
10350
9300
10500
10.050
8600
6750
Solids,
ppm
50
70
30
100
50
70
70
20
60
70
50
70
60
10
10
10
0
10
20
40
30
0
20
30
40
30
40
50
70
Dissolved
Solids.
ppm
2930
2940
3260
2990
2490
3150
3370
3050
2750
3030
3760
3800
3710
3720
2900
2220
2980
3480
2920
2920
2920
2920
2920
2920
2920
2920
2920
2920
2920
Total
Carbon,
ppm
900
875
1000
925
825
775
925
875
800
950
1000
1075
1025
1025
750
650
825
1225
775
700
825
875
900
725
750
750
750
650
550
Inorganic
Carbon,
ppm
75
50
25
25
25
25
50
50
25
75
75
50
75
50
75
50
50
75
25
50
25
50
75
75
100
75
75
50
25
Organic
Carbon,
ppm
825
825
975
925
800
750
875
825
775
875
925
1025
950
975
675
600
775
1150
750
650
800
825
825
650
650
675
675
600
525
Ca,
ppm
18
30
21
27
28
34
47
29
39
23
27
24
23
36
25
27
24
25
28
26
29
27
38
29
31
44
42
38
29
a.
ppm
594
553
577
557
508
598
815
687
674
704
594
463
604
634
684
583
583
583
583
583
583
583
583
583
583
PH
10.2
10.5
11.4
10.5
10.0
10.2
9.4
10.3
10.1
10.3
9.9
10.2
9.6
10.8
10.8
10.2
10.8
10.4
10.6
10.2
9.8
9.9
10.0
9.7
9.8
10.0
9.8
9.8
10.2
BOD5,
ppm
-
-
294
-
-
270
-
-
-
-
-
-
-
-
390
-
-
-
-
-
-
-
246
-
-
-
94
-------
Table C-3
100% UNBLEACHED KRAFT DECKER EFFLUENT
FEED TO MASSIVE LIME PROCESS MAY 29 - JULY 2, 1971
Date,
1971
5/29
5/30
5/31
6/01
6/02
6/03
6/04
6/05
6/06
6/07
6/08
6/10
6/15
6/16
6/17
6/18
6/19
6/20
6/21
6/22
6/23
6/24
6/25
6/26
6/28
6/29
6/30
7/01
7/02
Flow
Rate,
gpm
525
525
525
525
525
525
540
540
540
540
540
540
530
550
550
550
550
550
550
550
550
550
550
550
550
550
550
550
550
APHA
Color
Units
1020
860
730
700
605
525
470
675
800
890
1270
730
970
2360
970
960
885
1125
830
590
470
455
910
940
1100
1320
660
1100
1180
Suspended
Solids,
ppm
60
140
50
40
70
50
120
60
130
120
60
50
120
20
60
200
710
170
0
100
120
100
50
40
40
30
30
60
20
Dissolved
Solids,
ppm
1190
960
970
780
610
680
870
1040
990
1120
1490
1030
1040
1340
1200
1040
1490
1200
1040
1180
1470
1250
1230
1280
1180
1300
880
1220
770
Total
Carbon,
ppm
275
200
230
170
160
180
160
130
320
110
350
260
350
740
350
340
310
350
270
180
230
160
340
350
400
430
290
Inorganic
Carbon,
ppm
25
25
20
20
10
10
10
10
0
10
20
10
10
20
20
10
10
30
10
10
10
10
20
20
20
10
10
-
-
Organic
Carbon,
ppm
250
175
210
150
150
170
150
120
320
100
330
250
340
720
330
330
300
320
260
170
220
150
320
330
380
420
280
-
-
Na,
ppm
370
320
250
260
310
260
230
185
270
300
300
246
250
525
233
340
265
255
235
190
160
178
320
305
305
275
240
300
360
Ca,
Rpm
12
24
18
17
27
15
29
19
23
22
19
14
21
18
26
33
26
29
17
36
30
23
12
16
12
19
24
22
33
Cl,
ppm
65
65
60
75
79
85
100
110
79
50
50
50
40
35
59
50
50
95
90
85
40
40
221
79
74
45
35
PH
10.0
9.7
9.8
9.3
9.2
9.3
9.2
9.2
9.3
10.5
10.9
10.0
10.2
10.8
10.0
10.4
9.2
9.0
9.4
9.8
9.0
9.4
10.1
10.1
9.7
9.5
9.0
9.5
10.0
BOD5,
Ppm
-
114
-
138
-
150
150
-
-
-
-
-
-
96
126
-
-
-
192
-
95
-------
Table C-4
EFFLUENT FROM PRIMARY CLARIFIER WHILE TREATING
100% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT
FEBRUARY 8 - MARCH 10,1971
APHA Suspended
Oato. Color Solids, Ca,
1971 Units ppm ppm
2/08 1530 130 472
2/09 1270 30 492
2/10 1270 30 330
2/12 1365 380 403
2/13 1455
2/14 1245
2/15 1455
2/16 1095
2/17 1245
2/18 1365 880 917
2/19 1605 810 896
2/20 1410 40 387
2/21 1815 60 334
2/22 1695
2/23 1770 460 757
2/24 1815 30 260
2/27 1455 50 366
2/28 1500 30 346
3/01 1170 50 398
3/02 1365 20 395
3/03 1605 60 396
3/04 1530
3/05 1320 220 592
3/06 1410 200 424
3/07 1500 100 512
3/08 1650
3/09 1695 80 400
3/10 1240 140 592
96
-------
Table C-5
EFFLUENT FROM PRIMARY CLARIFIER WHILE TREATING
50% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT AND
50% UNBLEACHED KRAFT DECKER EFFLUENT
APRIL 7-MAY 15, 1971
APHA Suspended
Date, Color Solids, Ca,
1971 Units ppm ppm
4/07 365 42u 107
4/08 400 20 492
4/09 - 120 240
4/10 356 80 422
4/11
4/12 -
4/13 510
4/14 445 0 380
4/15 400 30 384
4/16 500 100 572
4/17 780
4/18 1070
4/19 1020
4/20 675 10 479
5/01 970 30 432
5/02 240 30 454
5/03 350 20 468
5/04 620 20 468
5/05 700 20 447
5/06 390 40 513
5/07 565 - -
5/08 390 100 750
5/09 430 40 630
5/10 415 30 514
5/11 455 60 504
5/12 455 80 570
5/13 525
5/14 320 140 459
5/15 230 130 553
97
-------
Table C-6
EFFLUENT FROM PRIMARY CLARIFIER WHILE TREATING
100% UNBLEACHED KRAFT DECKER EFFLUENT
MAY 29-JULY 2,1971
APHA Suspended
Date, Color Solids, Ca,
1971 Un'ts ppm ppm
5/29 185 10 461
5/30 230 10 514
5/31 135 10 537
6/01 175 10 497
6/02 200 20 497
6/03 160 10 510
6/04 160 70 439
6/05 160 20 506
6/06 185 80 496
6/07 215 160 491
6/08 220 60 424
6/10 180 200 437
6/15 230 40 488
6/16 285 10 497
6/17 240 10 495
6/18 255 20 516
6/19 230 130 515
6/20 255 130 550
6/21 230 220 534
6/22 230 75 510
6/23 230 390 535
6/24 230 200 565
6/25 240 50 494
6/26 295 10 530
6/28 270 0 558
6/29 255 10 . 565
6/30 255 10 597
7/01 295 10 522
7/02 285 0 538
98
-------
Table C-7
DECOLORED EFFLUENT FROM CARBONATOR CLARIFIER WHILE TREATING
100% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT
FEBRUARY 8 - MARCH 10, 1971
Date.
1971
2/08
2/09
2/10
2/12
2/13
2/14
2/15
2/16
2/17
2/18
2/19
2/20
2/21
2/22
2/23
2/24
2/27
2/28
3/01
3/02
3/03
3/04
3/05
3/06
3/07
3/08
3/09
3/10
APHA
Color
Units
1350
1070
1240
1290
940
640
565
1020
1125
1245
1320
1365
1650
1050
1180
1605
1530
1605
1245
1815
2000
655
1280
1357
1695
750
1695
1130
Suspended
Solids,
ppm
210
10
420
30
-
370
150
-
20
230
370
140
-
200
260
90
170
340
140
-
170
-
-
190
-
Dissolved
Solids,
ppm
5240
5230
4240
5260
4900
4540
5750
3860
5160
5380
4880
5830
4400
6100
6910
6080
6670
6500
6100
5140
-
-
Total
Carbon,
ppm
380
360
480
380
390
310
290
500
370
350
460
340
500
390
420
460
440
380
380
650
660
350
680
590
650
350
610
420
Inorganic
Carbon,
ppm
20
20
130
10
30
50
10
160
0
0
60
20
130
20
30
10
30
20
20
150
220
20
150
190
230
10
250
110
Organic
Carbon,
ppm
360
340
350
370
360
260
280
340
370
350
400
320
370
370
390
450
410
360
360
500
440
330
530
400
420
340
360
310
Total
Ca,
ppm
66
_
215
179
132
309
264
242
166
192
212
256
260
322
228
298
_
230
212
Soluble
Ca,
ppm
36
30
^_
159
-~
84
260
83
_
166
127
168
176
156
96
58
46
52
46
44
Cl.
ppm
1248
1096
1095
1085
1095
1135
1355
1215
1479
1530
1530
1449
1308
1711
1793
1872
1780
1600
1594
1594
1474
_
_
_
PH
12.6
12.8
12.4
12.9
13.2
12.7
13.0
12.4
12.9
12.9
12.6
12.6
11.7
12.4
12.3
12.3
12.8
12.8
12.8
12.2
11.9
12.7
12.5
11.8
11.9
12.9
12.1
12.3
BOD5
ppm
198
312
258
342
246
227
99
-------
Table C-8
DECOLORED EFFLUENT FROM CARBONATOR CLARIFIER WHILE TREATING
50% BLEACH PLANT CAUSTIC EXTRACTION STAGE EFFLUENT AND
50% UNBLEACHED KRAFT DECKER EFFLUENT
APRIL 7-MAY 15, 1971
APHA Suspended
Dote,
1971
4/07
4/08
4/09
4/10
4/11
4/12
4/14
4/15
4/16
4/17
4/18
4/19
4/20
5/01
5/02
5/03
5/04
5/05
5/06
5/07
S/08
5/O9
5/10
5/11
5/12
5/13
5/14
5/15
Color
Units
415
470
800
428
400
390
445
400
605
445
415
470
700
335
445
635
675
365
295
455
455
535
510
470
295
295
185
Solids,
pom
290
_ .
150
210
240
40
60
60
220
300
_
210
100
_
_
510
130
410
130
Dissolved
Solids,
ppm
3170
2850
2760
2440
2850
4360
3670
3790
3400
3880
4420
3960
3060
2760
2860
2820
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
Total
Carbon,
ppm
250
350
460
450
290
200
280
220
550
220
260
290
400
360
380
620
380
180
310
290
290
360
250
270
140
240
190
Inorganic
Carbon,
ppm
40
90
60
50
50
10
20
20
140
30
20
30
120
.
110
130
150
110
20
10
80
90
100
90
120
30
40
10
Organic
Carbon,
ppm
210
260
400
400
240
190
260
200
410
190
240
260
280
250
250
470
270
160
300
210
200
260
160
150
110
200
180
Total
Ca,
ppm
100
202
-
212
216
184
116
132
246
-
-
-
213
109
124
280
134
128
-
245
249
423
221
250
-
384
87
Soluble
Ca,
ppm
22
21
-
33
94
156
74
60
30
-
-
-
28
24
40
21
41
57
-
69
83
115
130
142 .
160
67
Cl,
ppm
594
594
577
557
518
598
637
765
-
55
594
604
684
614
614
614
614
614
614
614
614
614
614
pH
12.3
12.1
12.6
12.7
12.3
12.7
12.5
12.6
12.0
12.9
12.8
12.8
12.2
12.3
11.4
11.6
12.0
12.2
12.3
11.5
11.5
11.2
11.4
11.6
12.5
12.2
12.1
BOD5.
ppm
-
252
276
186
210
192
100
-------
Table C-9
DECOLORED EFFLUENT FROM CARBOIMATOR CLARIFIER WHILE TREATING
100% UNBLEACHED KRAFT DECKER EFFLUENT
MAY 29-JULY 2, 1971
APHA Suspended
Date,
1971
5/29
5/30
5/31
G/01
6/02
6/03
6/04
6/05
6/06
6/07
6/08
6/10
6/15
6/16
6/17
6/18
6/19
6/20
6/21
6/22
6/23
6/24
6/25
6/261
6/28 l
6/29 1
6/301
7/01 1
7/02 l
Color
Units
255
255
175
175
200
160
160
185
215
215
220
160
230
285
240
248
240
285
255
240
240
240
240
285
255
255
255
270
335
Solids,
ppm
65
20
85
110
60
150
60
100
115
60
65
20
35
90
60
10
150
25
110
90
70
100
70
0
30
10
20
10
60
Dissolved
Solids,
ppm
1620
1540
1640
1600
1340
1390
1640
1520
1620
1430
1780
1920
1990
1950
1850
1200
1750
1460
1590
1530
1570
1780
2870
2400
2560
2250
2540
2270
Total
Carbon,
ppm
220
200
140
170
100
90
70
40
215
140
190
140
180
250
200
100
120
160
80
90
80
90
140
220
180
150
190
Inorganic
Carbon,
ppm
70
60
30
30
20
10
10
10
10
10
40
30
30
10
30
30
10
10
10
10
10
20
10
10
10
0
10
-
-
Organic
Carbon,
ppm
150
140
110
140
80
80
60
215
130
150
110
150
240
170
70
110
150
70
80
70
70
130
210
170
150
180
N?:,
oprn
625
525
500
510
560
514
520
455
533
560
655
608
540
645
475
570
480
475
465
415
530
362
675
570
540
475
415
500
600
Total
Ca,
ppm
44
50
44
52
71
73
31
99
59
31
33
25
24
109
98
83
85
9Q
146
119
130
210
93
504
516
536
558
494
474
Soluble
Ca,
ppm
22
43
15
17
50
20
7
63
21
13
14
20
12
65
82
74
42
82
73
85
103
174
66
502
502
534
546
486
458
Cl,
ppm
-
65
75
75
90
104
85
100
110
79
45
55
89
35
60
89
75
75
99
75
90
85
75
50
50
75
74
45
35
PH
11.4
11.6
11.4
11.7
12.4
11.8
12.5
12.5
12.1
12.4
12.3
11.8
12.7
11.9
11.8
11.5
11.3
11,2
11.5
12.0
12.1
12.4
12.1
12.7
12.7
12.7
12.8
12.5
12.0
BOD 5,
ppm
-
-
-
-
90
-
-
78
-
-
65
76
-
-
-
-
-
-
50
52
-
-
-
-
-
117
-
Effluent was not carbonated during this period.
101
-------
Table C-10
GREEN LIQUOR ANALYSES
Sodium Compound!, gpl at Na2O
Period
6/15/69-8/11/69
11/3/69-1/20/70
4/20/70 - 6/2/70
6/2/70-8/3/71
Av
Max.
Min
Av
Max.
Min
Av
Max.
Min
Av
Max.
Min
Na2C03
-
-
75.6
83.7
67.5
76.5
82.0
67.5
73.6
79.4
66.9
NaOH
-
-
21.1
26.0
13.6
23.0
28.5
17.4
20.1
22.3
16.7
Na2S
-
-
34.7
37.2
29.1
34.4
37.8
31.0
35.9
37.2
34.7
Total
-
-
131.4
137.1
128.4
133.9
139.5
130.8
129.5
136.4
123.4
Unreduced
Na2S04 at
NajO, gpl
2.66
3.57
1.82
3.30
4.60
2.47
3.48
5.22
2.16
2.96
4.12
1.54
APHA
Color,
Units
-
-
-
-
-
-
1723
3390
250
Ca,
ppm
11
20
10
8
13
5
16
33
10
16
21
13
Cl.
ppm
-
-
818
906
654
940
1273
677
906
1097
704
COD,
ppm
32,242
38,512
27,480
33,907
38,520
29,540
31 ,237
36,723
26.660
29,018
32,300
23,308
""~~ Carbon, ppm ^""""
Inorganic
-
10,400
_
-
9394
1 1 ,492
7480
10,378
12,996
8500
Organic
_
-
4200
_
-
2360
3910
1283
2914
5950
1363
Total
-
14,600
-
11,753
12.775
8840
13,292
15,219
1 1 ,928
o
Ni
-------
Table C-11
WHITE LIQUOR ANALYSES
Period
6/15/69-3/11/69
11/3/69- 12/16/69
1/20/70-1/26/70
4/20/70 - 6/2/70
_, 6/2/70-8/3/71
O
00
Sodium Compounds, gpl as N
Na2CO3 NaOH Na2S
Av
Max.
Min
Av
Max.
Min
Av
Av
Max.
Min
Av
Max.
Miri
-
-
25.3
31-.0
20.5
-
22.9
26.7
19.2
23.4
26.6
19.8
-
71.5
76.3
62.8
_
75.0
78.1
72.5
75.1
78.1
71.3
-
36.2
40.9
32.9
-
35.4
37.2
33.5
34.4
37.8
32.2
la2O
Total
-
133.0
135.1
130.4
_
133.5
138.3
130.2
132.3
135,8
127.7
Unreduced
Na2SO4 as
Na2O, gpl
2.86
4.64
2.02
2.98
5.56
1.52
3.26
4.52
2.18
3.21
5.04
2.42
APHA
Color, Ca,
Units ppm
26
64
8
21
29
16
_ _
18
30
15
3045 26
5000 64
1500 11
Cl,
ppm
-
_
_
-
906
951
1296
675
964
1339
805
COD,
ppm
31,670
40,832
25,120
32,368
34,860
29,700
-
30,814
32,481
25,294
28,927
34,980
22,972
Ci
Inorganic
-
_
-
-
2425
3420
1326
3136
3424
2550
jrbon, ppn
Organic
-
_
-
1311
1505
989
1094
1700
678
i
Total
_
-
_
-
-
3735
4788
2881
4230
4919
3674
-------
Table C-12
TYPICAL OPERATOR'S DAILY REPORT
MASSIVE LIME SYSTEM FLOW RATES
Date: 2/21/71
Tim*
7A
8
9
10
11
12N
1
2
3
4
5
6
7
8
9
10
11
12MN
1
2
3
4
5
6
Bleach
Effluent,
9pm
200
200
200
200
200
200
200
200
200
200
200
200
Decker
Effluent,
gpm
0
0
0
0
0
0
0
0
0
0
0
0
Effluent To
Slaker,
gpm
50
50
50
50
50
50
50
50
50
50
50
50
Slaker
Steam,
100 Ib/hr
4
4
0
4
2
5
0
5
5
0
8
5
Lime Mud
to Filter.
gpm
53
58
45
85
85
80
70
70
35
37
32
36
Flue Gat
(C02)
cu ft/min
150
150
150
150
150
150
150
150
150
150
150
150
.
Lime
Feed,
Tone/Day
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
Slaker
Temp,
°F
212
212
212
212
212
210
212
210
212
212
212
212
-------
Table C-13
TYPICAL OPERATOR'S DAILY REPORT
MASSIVE LIME SYSTEM OPERATING DATA AND ANALYSES
Date: 2/21/71
Time
7AM
SAM
9AM
10AM
11 AM
12N
1 PM
2PM
3PM
4PM
5PM
6PM
7PM
8PM
9PM
10PM
11 PM
12MN
1 AM
2AM
3AM
4AM
BAM
6AM
Effluent Feed
pH
9.0
10.1
9.6
9.4
9.5
9.1
9.6
9.7
9.8
9.6
9.4
9.5
Temp,°F
134
134
134
136
136
132
134
132
130
128
126
124
Reaction Tank
Titration.ml1 .ON HCL
Phenol
9.2
9.0
8.8
8.5
9.7
8.6
8.0
9.7
8.5
7.8
9.7
8.7 '
MQ2
9.5
9.3
9.1
9.0
10.1
8.8
8.3
10.1
9.0
8.2
10.1
9.1
Temp°F
165
165
164
166
167
164
163
163
162
161
160
158
Primary Effluent Clarifier Overflow
Pheno1
15.4
15.7
15.8
19.0
21,5
20.0
18.5
18.0
17.1
15.8
18.5
20.0
ration, ml 0.1 N HC
MO2
17.4
17.0
17.0
20.3
23.0
21.5
20.0
19.0
18.1
17.0
20.0
21.5
pH
12.4
12.4
12.3
12.4
12.4
12.5
12.5
12.4
12.3
12.4
12.4
12.3
L
Temp, °F
161
161
161
163
164
161
159
158
157
156
155
153
Carbonator Clarifier
Overflow
Titration. ml 0.1 N HCL
Pheno1
9.2
9.2
9.2
9.2_J
9.2
9.2
9.0
9.1
9.0
9.3
10.0
10.3
MQ2
13.2
12.9
13.2
13.6
13.4
13.7
13.0
13.1
13.0
13.3
13.8
14.0
PH
11.4
11.4
11.4
11.5
11.4
11.5
11,5
11.4
11.4
11.3
11.4
11.3
Primary
Clarifier
Underflow,
% Sol ids
19.2
18.4
20.0
19.0
16.8
16.4
17.2
17.2
17.5
18.0
16.0
17.0
Carbonator
Clarifier
Underflow,
% Solids
21.2
N.T.
16.3
N.T.
21.1
N.T.
18.4
N.T.
22.7
N.T.
18.3
N.T.
Lime
Mud to
Filter,
% Solids
19.2
20.4
19.0
18.0
18.8
18.0
18.0
18.5
17.5
17.5
17.0
17.5
Lime
Mud from
Filter,
% Solids
50.6
52.0
52.0
50.0
50.0
51.6
52.4
52.0
51.0
50.5
50.0
51.5
1-r-
Titration to phenolphthalein end point.
Titration to methyl orange end point.
-------
Table C-14
TYPICAL OPERATOR'S DAILY REPORT FOR MASSIVE LIME SYSTEM
PRIMARY CLARIFIER CONDITIONS AT SAMPLE POINTS1
Time
Sludge
Percent Solids
Bottom
2nd
3rd
Appearance
Top
Overflow
8:00 AM
12:00 Noon
4:00 PM
8:00 PM
12:00 Midnite
4:00 AM
19.2
20.0
16.8
17.2
17.5
16.0
12.0
12.0
8.4
8.8
9.3
10.0
0.4
1.2
5.6
4.5
4.0
3.6
Clear
Hazy
Moddy
Muddy
Very Cloudy
Very Cloudy
Clear
Clear
Very Cloudy
Hazy
Hazy
Hazy
Clear
Clear
Hazy
Clear
Clear
Hazy
o
O)
COMMENTS: Backwashed filter at 7:05 AM, Backwashed filter at 2:15 PM. Increased mud flow from primary clarifier at 2:45 PM,
Backwashed filter at 9:10 PM. Decreased mud flow to filter at 11:10 PM. Backwashed filter at 4:45 AM.
OPERATOR:
7:00 AM-3:00 PM
3:00 PM- 11:OOPM
11:OOPM -7:00 AM
See Figure 4.
-------
APPENDIX D
CAPITAL COST ESTIMATES
107
-------
Table D-1
ESTIMATED CAPITAL COSTS FOR HYPOTHETICAL 1000-TONS-PER-DAY MILL
Water treating and waste disposal
Power plant
Pulp mill
Paper mill
Electrical facilities
Service facilities
Outside piping
Water supply and site facilities
Fire protection
Subtotal
Sales and use tax
Contingencies
Engr., tools and temp, bldgs.
Total
tstimateo capital Viosts, $
Without Massive
Lime System
$ 4,387.000
22,942,000
29,814,000
26,827,000
950,000
2,247,000
1,290,000
5,399,000
300,000
$ 94,156,000
3,672,000
4,707,000
17,419,000
$119,954,000
With Massive
Lime System
$ 5,771.000
23,376,000
29,997,000
26,827,000
950,000
2,247,000
1 ,320,000
5,490,000
300,000
$ 96,278,000
3,755,000
4,814,000
17,811,000
$122,658,000
Difference
$ 1 ,384,000
434,000
183,000
30,000
91,000
$ 2,122,000
83,000
106,000
393,000
$ 2,704,000
108
-------
Table D-2
CAPITAL COSTS AFFECTED BY INCLUSION OF MASSIVE LIME
COLOR REMOVAL PROCESS
Water treating and waste disposal:
Primary waste treating equipment
Secondary waste treating system
Color reduction system
Power plant:
Turbine generator
Recovery boiler
Turbine and evaporator condenser cooling tower
Black liquor evaporator equipment
Black liquor oxidation equipment
Desoaping equipment
Pulp mill:
Brown stock washers
Caustic plant equipment
Lime recovery equipment
Outside piping:
Pipe, valves and fittings for
Process
Steam and condensate
Oil piping
Labor
Water supply and site facilities:
Railroad facilities
Process sewers
Piling
Subtotal
Sales and use tax
Contingencies
Engineering, tools and temporary buildings
Total
Without Massive
Lime System
$ 760,000
1,550,000
3,470,000
9,325,000
300,000
2,111,000
310.000
202,000
2,356,000
1,489,000
2,230,000
151,000
66,000
57,000
420,000
387,000
211,000
1,389,000
$26,784,000
Estimated Capital Costs, $
With Massive
Lime System
$ 715,000
1,535,000
1,444,000
3,566,000
9,500,000
310,000
2,234,000
328,000
214,000
2,358,000
1,609,000
2,291,000
161,000
70,000
60,000
433,000
401,000
228,000
1,449,000
$28,906,000
$
Difference
(45,000)
(15,000)
1,444,000
96,000
175,000
10,000
123,000
18,000
12,000
2,000
120,000
61,000
10,000
4,000
3,000
13,000
14,000
17,000
60,000
$ 2,122,000
83,000
106,000
393,000
$ 2,704,000
»U.S. GOVERNMENT PRINTING OFFICE:1973 514-153/195 1-3
109
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
' -tffo.
j. Arcf. rj'iy - * rr
w
COLOR REMOVAL from KRAFT PULP MILL EFFLUENTS by
MASSIVE LIME TREATMENT
/. AutboT(s) Oswalt, John L.
Land, Joseph 6., Jr.
Organization
INTERNATIONAL PAPER COMPANY
Springhill Mill
Sprlnghlll, Louisiana 71075
5, R ortD,
6.
8. Pftformir- Qigar utica
tO.
#12040 DYD
11. Contract/GramA?:,.
Grant 135-01-(R-l)(68)
13. Type > Repo. md
Period Covered
IS. Supplementary Motes
Environmental Protection Agency report
number% EPA-R2-73-086, February 1973.
/(?. Abstract A demonstration plant was installed and operated to determine effectiveness
and feasibility of using massive lime treatment (that is, 20,000 ppm Lime) to decolor
kraft pulp mill effluents. The two most highly colored effluents and mixtures of these
treated in the demonstration plant were: (1) the almost black effluent from the caustic
extraction stage of pulp bleaching, and (2) the light reddish-brown effluent from the
final unbleached pulp washing stage. Objectives of the project were to determine:
Effectiveness of color removal, design and performance of massive lime system equipment,
effects on normal pulp mill operations, effects on pulp quality, operating costs.
Impact of the massive lime system on a hypothetical 1000 tons-per-day bleached kraft
pulp and paper mill is described. Using all the lime normally available in such a mill
would allow massive lime treatment of four million of the mill's twenty-nine million
gallons of effluent. Such treatment would remove 72% of the total mill effluent's
color, reducing final effluent color to approximately 740 APHA units at an._estimated
operating cost of $1.80 per ton of pulp (depreciation, insurance, and taxes
included).
17a. Descriptors
*Pulp & Paper Industry, *Effluents, *Waste Water Treatment, *Color Reactions, *Lime,
*Pilot Plants, *0peration and Maintenance, *Cost Analyses, Pulp Wastes, Foaming,
Floculation, Sedimentation Rates, Chemical Precipitation, Water Reuse, Biochemical
Oxygen Demand, Calcium Carbonatefeasibility Studies,*Capital Costs.
17b. Identifiers
*Massive Lime Process, *Color Removal, *Bleach Caustic Extraction Effluent, *Kraft
Decker Effluent, *Recarbonation.
I7c. COWRRField&Gtoup 05D
IS. Availability
19. S- luityC'ass.
(Report) .
; 20. Security CJass.
21. r .of
Pages
22. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 2O240
Abstractor
Institution
------- |