WATER POLLUTION CONTROL RESEARCH SERIES • 12O4O EZZ O4/7O
Dilute Spent Kraft Liquor Filtration
through Wood Chips
13.S DEPARTMENT OF THE INTERIOR • FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
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DILUTE SR&rf^**ABTRER)UOR FILTRATION
THROUGH WOOD CHIPS
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEPARTMENT OF THE INTERIOR
By
Department of Wood and Paper Science
School of Forest Resources
North Carolina State University
Box 5*»88
Raleigh, North Carolina 27607
Program #120^0 EUG
Grant #WPRD 115-01-68
April 1970
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FWPCA Review Notice
This report has been reviewed by the
Federal Water Pollution Control Admin-
istration and approved for publication,
Approval does not signify that the
contents necessarily reflect the views
and policies of the Federal Water Pol-
lution Control Administration.
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ABSTRACT
The principal objective of this project was to determine if contact
between effluent from a Kraft pulp mill and pine chips would reduce
the water pollution characteristics of the waste liquor.
The experimental work was divided into two phases: 1) a small scale
laboratory investigation of contacting dilute waste liquor with chips;
2) a pilot-scale investigation of filtering waste liquor through a
column and a pile of chips.
It was found that contact of alkaline waste liquor, or even distilled
water, with pine chips extracted organic matter from the chips which
had a considerable BOD^. This extract corresponded to a pollution load
of about 3~11 Ibs. 6005 per ton of dry wood. Alkalinity, pH, and inten-
sity of color of the waste liquor were somewhat reduced by the contact.
These reductions are, however, too small to have any practical appli-
cation in effluent treatment. It can, in general, be concluded that
contact of alkaline waste liquor, or water, with wood chips extracts
soluble organics and adds pollutional materials to the effluent stream.
This report was submitted in fulfillment of Grant No. 115-01-68 between
the Federal Water Pollution Control Administration and the Department
of Wood and Paper Science, School of Forest Resources, North Carolina
State University at Raleigh, North Carolina.
Key Words: Water pollution, waste water, BOD-extraction, Kraft pulp
mi 11, wood ch ips.
i i i
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TABLE OF CONTENTS
Page No.
Abstract i i i
List of Figures vi i
List of Tables ix
I. CONCLUSION ]
II. RECOMMENDATION 3
III. INTRODUCTION 5
IV. EXPERIMENTAL 7
A. Analytical Procedures 7
B. Laboratory Experiments 7
C. Pilot-Scale Experiments at Mill Site 8
V. DISCUSSION OF RESULTS
A. Laboratory Experiments — Treatment of Diluted Spent
Kraft Pulping Liquor from the Decker Effluent
by Contact with Pine Chips 11
B. Pilot-Scale Treatment of Diluted Spent Kraft Pulping
Liquor (Effluent) by Contacting It with Pine Chips. 16
C. Practical Aspects 20
Acknowledgment 29
References 31
Appendix 33
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FIGURES
Figure
Page No.
Change in biochemical oxygen demand (BOD) of a waste
Kraft pulping liquor of pH 10, resulting from
filtering the liquor through a column of pine
chips
Change in biochemical oxygen demand (BOD) of a waste
Kraft pulping liquor of pH 10.5 resulting from
filtering the liquor through a column of pine
chips
21
Reduction
initial
through
Reduct ion
initial
through
in pH of a waste Kraft pulping liquor of
pH 10, resulting from filtering the liquor
a column of pine chips
22
23
in pH of a waste Kraft pulping liquor of
pH 10.5 resulting from filtering the liquor
a column of pine chips
VI I
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TABLES
Table Page No.
1. Properties of a waste liquor from a Kraft pulp mill
after stirring contact at 25°C with different amounts
of pine chips 12
2. Properties of waste liquors from a Kraft pulp mill
after stirring contact at 25°C with different amounts
of pine chips 13
3- Analytical data for waste Kraft pulping liquor and dis-
tilled water after stirring separately with pine chips
for 1 hour at 25°C \k
k. Analytical data for waste Kraft pulping liquor and dis-
tilled water after stirring contact separately with
pine chips for 1 hour at 75°C 15
5- Analytical data for waste Kraft pulping liquor stirring
treatments for 1 hour at 25°C with original pine chips,
and with the previously treated chips 17
6. Properties of waste Kraft-pulping liquor resulting from
recycling of the liquor through pine chips in an open
column (laboratory experiments) 18
7. Properties of waste Kraft pulping liquor before and after
gravity flow of the liquor through a column of pine
chips (preliminary mill pilot-scale experiments). ... 19
8. Change in biochemical oxygen demand of waste Kraft pulping
liquor of pH 10-10.5 resulting from filtering the
liquor through a column of the pine chips 25
9. Changes in properties of waste Kraft pulping liquor by
contacting the liquor with pine chips through spraying
the liquor over a small chip pile (pilot-scale experi-
ments) 26
i x
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Dilute Spent Kraft Liquor F i 1 ^ration
Th rough Wood Ch i ps
CONCLUSION
Contact between pine chips and dilute alkaline effluent from a Kraft
pulp mill extracted a considerable amount of biochemical oxygen de-
manding matter from the chips. The pH, electrical conductivity, as
well as the alkalinity of the waste liquor were somewhat reduced by
contact with the chips. The intensity of color of the waste liquor
diminished. It is believed that the change in color is caused
mainly by the reduction in pH. The pine chips acted as a good filter-
media for the waste liquor. Fibers present in the waste liquor were
almost quantitatively removed by filtering the liquor through a
chip column or chip-pile. However, the fibers retained on the sur-
face of the chip-column, or pile, hindered penetration of the liquor
through the chips.
It can, in general, be concluded that contact of waste liquor from
a Kraft pulp mill with wood chips would extract enough BOD from the
chips to increase the pollution load of the effluent. Even water
extracted a considerable amount of BOD from wood chips. This means
that liquid drainage from a mill's chip storage area should be con-
sidered as a pollutional waste. The change in pH, alkalinity, and
the color reduction obtained by contacting waste liquor with wood
chips were too small to achieve practical benefits through industrial
application of the system.
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I I. RECOMMENDATION
It is recommended that contact between pulp and paper mill alkaline
effluent and wood chips should be avoided and that drainage, result-
ing from rainfall and other water sources, from a wood chip storage
area should be considered a pollutional waste.
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III. INTRODUCTION
The prime objective of this project was to determine if contact
between waste liquor from a Kraft pulp mill, that produces un-
bleached pulps from southern pine, and the wood chips from which
the pulp is subsequently made, reduces the water polluting pro-
perties of the waste liquor. The suggestion was based in the
fact that wood sawdust, or chips, will absorb alkali from water
to reduce its pH, and that wood and cellulose are good adsorbents
for phenols and tannins. The experimental work was divided into
two phases. The first of these was a laboratory investigation
to determine changes in the water polluting characteristics of
the waste liquor after contact with pine chips. The second phase
involved pilot-scale investigations by filtering waste Kraft
pulping liquor through pine chips at the plant site of the co-
operating company, Albemarle Paper Corporation at Roanoke Rapids,
North Carolina.
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IV. EXPERIMENTAL
A. Analytical Procedures
Standard analytical procedures (1) were used for testing the pol-
lution characteristics of the liquors. These were applied in the
laboratory and pilot-scale experiments.
jp_H_was measured with a calibrated Beckman pH meter.
Bjochemjca I_oxy3_en_ demarid_(j3prjr)_ was determined according to the
"me~thl>d described in the 12th edition of "Standard Methods for
the Examination of Water and Waste Water" (1). The seeding used
was domestic sewage taken from Raleigh City sewage treatment
plant. The dissolved oxygen content was measured with polaro-
graphic DO-Analyzer (Wes ton and Stack, Inc., Model 300) after
calibrating the instrument with solutions which had been analyzed
according to the Winkler-Method (1).
Tp.La.L Alj
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or any other evidence of degradation. The waste liquor used for
the experiments was effluent from the mill's decker-operation,
which increases the consistency of the pulp after the low consis-
tency screening operation. In this mill the decker-operation also
acts as a final washing stage. It was found that if the waste
liquor was kept in closed polyethylene carboys of 5 gallons at
^°C, it could be stored for one to two months without any change
in pH or BOD. In the laboratory tests BOD analyses were completed
in the test waste liquor, prior to use, after storage periods not
exceeding 3 weeks.
Small scale experiments were performed by the mechanical stirring
of 100 to AOO grams of wet chips, with a moisture content of 50%,
in a three liter beaker containing one liter of waste liquor or
water. The tests were made at room temperature (about 25°) and
at an elevated temperature of 75°C. In the control experiments
no chips were added. Samples of the liquors were taken before
and after the treatments. The pollutional characteristics of
the samples were determined following filtration of the sampled
liquors through filter paper. The experiment was designed to
reflect realistic ratios of chips used to waste liquor discharged
by a mill. The total waste liquor from a Kraft mill amounts to
about 1-2 gallons per pound of dry chips used. In the metric
system this would be 60-120 grams of dry chips per liter.
A few experiments were made utilizing a glass column packed with
chips. The dimension of the column was 1.5 inches in diameter
and about 36 inches in length. The column contained 500 grams
of chips with a moisture content of about 50%. This quantity of
chips filled the column to a depth of about 30 inches. In each
test 1500 ml of the waste liquor was recirculated through the
column by a constant volume pump delivering about 500 ml/min.
The time of treatment was varied. Liquor samples were taken at
different time intervals and analyzed for pH, BOD,, and suspended
solids. '
C. Pilot-Scale Experiments at Mill Site
Preliminary experiments were made by filtering effluents from
the mill's decker operation through a pine chip column. This
was contained in a 55 gallon steel drum. The weight of the chips
was 1^*3 Ibs. on a wet weight-basis, or about 70 Ibs. as oven-
dried chips. The effluent was distributed over the top of the
chip column by utilizing four paper machine headbox showers which
distributed the effluent in a relatively uniform manner. The
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four overlapping sprays covered 90% of the area on the top of
the column. The flow rate of the effluent was kept at 5 and
3 gal/min. Samples of the effluent, before and after contact
with the chips, were taken at different time intervals.
Additional experiments employing a longer column were completed.
This column was constructed from 55 gallon drums which were
welded together endwise. For one experiment a 10 ft. depth of
chips was employed using 575 Ibs. of chips. For the second
experiment a 6 ft. depth of chips was used employing 3^0 Ibs.
of chips. The chip moisture content in both instances approxi-
mated 50%. The flow rate of the decker effluent through the
column was kept at 1.5 and 2 gal/min. and the liquor was dis-
tributed on the top of the column by the four overlapping sprays.
A piece of Fourdrinier wire was placed over the top of the col-
umn in order to filter out the fibers present in the waste liquor
and to prevent plugging of the chip column with fibers. Samples
of the liquor were taken before and after contact with the chips
at different time intervals and analyzed for pH and BOD_.
A small experimental chip pile was also constructed which was
12 feet in diameter at the base, 4 feet in diameter at the top
and 6 feet high. The pile contained about A.5 tons of wet pine
chips (kkOO Ibs. of oven-dried chips). The chip pile was placed
on a 3 mil. polyethylene sheet and arranged in such a way that
all the effluent would drain to one point for sampling of the
liquor. Effluent from the mill's decker operation was sprayed
on the top of the pile, utilizing the same spray arrangement as
for the column experiments. The flow rate was 12 gal/min. The
first chip pile constructed was essentially washed away after
one week. A second pile equal to the first one was therefore
constructed with the base of the pile restrained by a foundation
of 1" x 5" boards. Samples of liquor were taken at various time
intervals before and after contact with the chips and analyzed
for pH and BOD_.
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V. DISCUSSION OF RESULTS
A. Laboratory Experiments — Treatment of Diluted Spent Kraft
Pulping Liquor from the Decker Effluent by Contact with Pine
Chips
a) Stirring tests in beaker. Table 1 shows the results of
the tests. As the liquor changed on exposure to air, the
analysis of a liquor, which was stirred without chip contact
for the same period of time as the other test liquors, are
included. The most notable changes in the characteristics
of the waste liquor by contact with the chips were a decrease
in pH, an increase in the content of the volatile matter
(organics), and an increase in the biochemical oxygen demand
(6005). The amount of inorganic matter was not significantly
changed. The electrical conductivity decreased, as expected
from the pH-reduction, as a result of the treatment. Contact
of liquor with the chips reduced the intensity of the color
of the waste liquor but increased its colloidal nature. The
change in color could be caused by the change in pH. It is
well known that the color of spent Kraft pulping liquor is
highly dependent on pH. Although a noticeable color change
of the effluent occurred, it was not possible to quantitatively
measure the degree of change because the residual color was
still too intense to measure accurately.
Analytical data for stirring experiments at 25°C performed
on 100 and 200 grams of wet chips, with two new samples of
decker effluent, are given in Table 2. The results verified
the findings of the former experiments. Organic matter was
extracted from the chips by the waste liquor. The BOD-
demand of the liquor was thereby considerably increased and
the pH and the alkalinity of the liquor was significantly
reduced. This was obviously a result of neutralization of
the liquor by the extracted wood-acids. The data showed
also that the BOD of the waste liquor was reduced by contact
with the air. This was probably caused by air-oxidation
of sulfides in the waste liquor to their respective oxidation
products.
Tables 3 and 4 show the results obtained by contacting pine
chips with waste liquor and with distilled water by stirring
at about 25°C and at 75°C.
The findings confirmed earlier results and showed also, that
even distilled water extracts biochemical oxygen demanding
materials from wood chips. At room temperature (about 25°C)
11
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Table 1. Properties of a waste liquor from a Kraft pulp mill after stirring contact at 25°C with
different amounts of pine chips
Chi p-Liquor
Ratio
(g. chips/
1 i ter 1 iquor)
0
50
100
200
Time
of
Sti rring
(hours)
—
1
k
0
1
k
0
1
k
0
1
4
pH
8.8
8.8
8.7
8.8
7.5
6.9
8.8
7.0
6.6
8.8
6.9
6.5
Electrical
Conduct i vi ty
(mho/cm')
450
410
370
350
Vo 1 a t i 1 e
Matter
(g/li ter)
0.36
0.56
0.99
1.14
1 norgani c
Matter
(g/li ter)
0.15
0.18
0.14
0.19
Five day
Biochemi cal
Oxygen Demand
(ppm)
225
315
330
310
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Table 2. Properties of waste liquors from
different amounts of pine chips
a Kraft pulp mill after stirring contact at 25°C with
Waste
1 iquor
Sample
1
Sample
1 1
Chip-Liquor Ratio
(g. dry chips/
1 i ter of 1 iquor)
0
50
100
0
0
50
100
Time
of
St i rring
(hours)
4
k
k
0
k
k
k
PH
9-0
7.9
7.7
10.8
10. k
9.3
8.0
Alkal inity
(mg/1 i ter)
(CaC03)
456
381
374
717
700
600
535
Dissolved
sol ids
(g/liter)
0.7
0.9
1.4
1.3
1.5
1.7
1 norgan i c
Matter
(g/liter)
0.21
0.23
0.26
0.39
0.36
B iochemi cal
Oxygen Demand
(ppm)
90
255
315
435
355
540
750
Change in
6 iochemi cal
Oxygen Demand
(ppm)
...
+ 165
+225
-100
+ 185
+395
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Table 3. Analytical data for waste Kraft pulping liquor and distilled water after stirring separately
with pine chips for 1 hour at 25°C
Type
of
Liquid
Waste
1 i q uo r
Waste 1 iquor
centri f uged"
Waste 1 iquor
Waste 1 iquor
centri f uged"
Water
Water
centri f uged"
Ch ip-Li quor
Ratio
(g.dry chips/
liter) pH
0 9.7
0
50 7.7
50
50 5- ^
50
Dissolved
Solids
(g/li ter)
1.2
1.1
1.6
1.5
0.3
0.2
1 norgani c
Matter
(g/1 i ter)
0.4
...
0.4
0.4
0.05
-0.06
Biochemi cal
Oxygen
Demand
(ppm)
250
250
410
415
75
90
Change in
Biochemi cal
Oxygen
Demand
(ppm)
...
+ 160
+ 165
+ 75
+ 90
Extracted
BOD5
from the Chips
(ibs.BOD/Ton
of Dry Chips
6.4
3.0
'llltra-centrifuging was performed after the treatments.
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Table 4. Analytical data for waste Kraft pulping liquor and distilled water after stirring contact
separately with pine chips for 1 hour at 75°C
Type
of
Liquid
Waste
1 iquor
Was te 1 iquor
centri f uged"
Waste
1 iquor
Waste 1 i quo £
centri f uged
Water
Water
centri f uged'
Chip-Liquor
Ratio
(g.dry chips/
liter) pH
0 9.5
0
50 7-6
50
50 6.0
50
Di ssol ved
Solids
(g/1 iter)
1.4
1.1
1.7
1.4
0.5
0.3
1 norgan i c
Matter
(g/1 iter)
0.5
0.4
0.5
0.4
0.04
0.03
Change in Extracted
Biochemical Biochemical BODr
Oxygen Oxygen from the Chips
Demand Demand (ibs.BOD/Ton
(ppm) (ppm) of Dry Chips)
300
280
400 +100 4
380
105 4
95 +100
'Ultra-centrifuging was performed after the treatments
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the amount of the extracted BOD^ was, after 1 hour's treatment,
about twice as high for the alkaline waste liquor (pH 9-7) as for
distilled water. The amounts of BOD,- extracted from the chips
were, on the basis of 1 ton of dry cnips, about 6.4 Ibs. and
about 3-0 Ibs., respectively. A one-hour stirring treatment at
75°C showed no difference in the amount of extracted BODc between
water and the alkaline waste-liquor. It amounted to about k Ibs.
of BODr per ton of dry chips. Removal of colloidal matter from
the liquors by ultra-centrifugation did not significantly change
the BODc of the liquors. Two successive treatments of pine chips
with the alkaline waste liquor at room temperature (about 25°C)
extracted a total amount of BOD^ equal to about 11.2 Ibs. per ton
dry chips. This can be seen from Table 5-
b) Recycling tests through chip column. Results from recycling
of waste liquor in a small column of pine chips are given in
Table 6. The data showed that this treatment gave generally the
same pH reduction as did the stirring experiments. The chip
column was a very effective filter as it removed almost all the
fiber and the other suspended solids present in the waste liquor.
The effect on BOD of filtering the waste liquor through the chip
column was less apparent than shown by the stirring experiments.
This can be explained by a more extensive air oxidation of the
waste liquor during the recirculation treatment.
B. Pilot-Scale Treatment of Diluted Spent Kraft Pulping Liquor
Effluent by Contacting It with Pine Chips
The preliminary experiments of passing effluent from a pulp
decker operation through a column of chips on the plant site
of Albemarle Paper Company in Roanoke Rapids, North Carolina,
were inconclusive with respect to changes in pH and BOD of the
waste liquor. The reason for this was that the chip column
became plugged with fiber rather quickly, and the experiments
had to be discontinued after a very short period of time. The
pH and BOD changes of the effluent on contact with the chips
tend to show, however, the same trends that were observed in
the laboratory. The results from the mill experiments are
shown in Table 7-
Further mill experiments on filtering effluent through a column
of chips, were performed with columns of the same diameter as
used in the first test, but with 2.k times as many chips. In
these tests to overcome the problem of fibers clogging the
column, the 1 iquor was first filtered. The flow rate of waste-
liquor through the column was also reduced. The exact experi-
mental conditions and analytical data for a set of duplicating
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Table 5- Analytical data for waste Kraft pulping liquor stirring treatments for 1 hour at 25°C
with original pine chips, and with the previously treated chips
Biochemical
Treatment
St i rri ng
Sti rring
Chip-Liquor Ratio
(g. dry chips/1 i ter)
0
50
(origi nal
pine chips)
Dissolved
Sol ids
pH (q/liter)
9.5 0.9
7.7 1-3
Inorgan i c
Matter
(q/liter)
0.3
0.3
Oxygen
Demand
(ppm)
400
580
Chanqe in
Biochemical
Oxygen
Demand
(ppm)
+ 180
Extracted
BODj-
from the Ch
ips
(ibs.BOD/Ton
of Dry Chi
7.2
ps)
Sti rring
50
(Previous ly stir
treated chips)
8.0
1 .1
0.3
500
+100
k.O
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Table 6. Properties of waste Kraft-pulping liquor resulting from recycling of the liquor through
pine chips in an open column (lab experiments)
oo
Temp.
(°0
20
20
75
Chip-Liquor Ratio
(g.dry chips/liter)
0
170
170
170
0
170
170
170
0
170
170
170
170
Time of
Liquor
Cycle,
(mi n . )
0
3
3
3
0
3
3
3
0
3
3
3
3
Time of
Treatment,
(mi n. )
0
10
30
70
0
30
180
330
0
5
10
15
20
pH
10.3
9-5
8.8
7.6
10.3
8.8
7.1
7.1
9-2
8.2
7-7
7.5
7.5
Suspended
Solids
(mg/1)
350
5
—
—
—
_ _ ••»
—
—
—
—
Biochemical
Oxygen
Demand
(ppm)
350
375
290
270
290
310
260
205
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Table 7- Properties of waste Kraft pulping liquor before and after gravity flow of the liquor
through a column of pine chips (preliminary mill pilot-scale experiments)
Temp.
(°O
30
30
Flow
Rate
(Gal/lbs.
Dry Chips/Hr.)
4.3
4.3
2.6
2.6
2.6
E lapsed
Time of
Effluent
Flow,
(mi n)
10
45
5
45
130
Total Amount
of Liquor
Contacted by
the Chips
(Gal/lb.
Dry Chips)
0.7
3.2
0.2
1.9
5.5
PH
Before
Contact
10.0
9-6
9.6
9-6
9.6
pH
After
Contact
9.5
9.4
9.0
9.3
9-5
A pH
0.5
0.2
0.6
0.3
0.1
BOD5
Before
Contact
(ppm)
375
310
330
395
370
BODr
After
Contact
(ppm)
320
410
460
395
410
A 6005
(ppm)
- 55
+ 100
+ 130
0
+ 40
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experiments are given in Appendix Table 1 and the results are
demonstrated in Figures 1-**. It can be seen that biochemical
oxygen demanding materials were extracted from the chips by
the alkaline liquor. The bulk of this material was leached
out of the chips when 3"^ gallons of waste liquor, per pound
of dry chips, had passed through the column. The BOD-results
obtained at the end of the second experiment (Fig. 2) can be
explained by channeling of liquor through the column. The
reduction of pH of the waste liquor followed in general the
BOD changes (Figs. 3 and k) : decreasing with time of effluent
flow until the reduction became constant at about 0.2 - 0.3 pH
units. This constant reduction in pH was probably due to the
absorption of carbon dioxide from the atmosphere.
Table 8 shows the approximate increases in biochemical oxygen
demand of the waste liquor by filtering it through the chip
column, after different amounts of liquor had passed through.
The magnitude of the BOD increase corresponds with the BOD in-
creases found in the laboratory stirring-experiments, when the
effect of air-oxidation of the liquor is taken into consideration.
In order to investigate what happens when a stored chip-pile is
sprayed with the decker effluent for a long period of time, two
small experimental piles were built. The results from these
spraying experiments are given in Table 9. The piles acted as
a good filter medium for fibers and other suspended matter in
the waste liquor. This resulted however, in a partial plugging
of the surface of the piles and therefore limited contact of
waste liquor with the chips. It can be concluded from the
experiment that, after the bulk of soluble organics were ex-
tracted from the chips, the changes in BODc were not very clear
and were in most cases i ns ign i fi cant. A biological slime did
form on the pile surface with time. It is likely that the pile
acted partially as a biological trickling filter towards the
end of the second experiment. The pH reduction was somewhat
higher than would be expected from the results of the previous
experiments.
C. Practical Aspects
Interest in spraying of stored chips with water or mill effluent
for wood preservation has been growing since it was reported in
the literature (2) that spraying of stored round-wood-piles with
a Kraft mill effluent prevents wood losses and simultaneously
reduces the BOD,- of the mill effluent 60-65%. Recently pub-
lished data (3) shows, however, that spraying of chips, which
20
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300
150 200 250
TIME-min
i i
300 350
400
i
0.55 1.25 1.95 2.65 3.35 4.05
AMOUNT OF LIQUOR CONTACTED BY
THE CHIPS-gal/lb dry chips
4.75
Figure 1. Change in biochemical oxygen demand (BOD) of a waste
Kraft pulping liquor of pH 10, resulting from filtering
the liquor through a column of pine chips
21
-------
125
175 225 275 325
TIME-min ,
375 425 475
0.55 1.25 1.95 2.65 3.35 4.05 4.75
AMOUNT OF LIQUOR CONTACTED BY
THE CHIPS-gal/lb dry chips
5.45
Figure 2. Change in biochemical oxygen demand (BOD) of a waste
Kraft pulping liquor of pH 10.5 resulting from
filtering the liquor through a column of pine
ch i ps
22
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1.2
o 0.8
I-
o
ELAPSED
60 120
TIME OF LIQUOR FLOW-min
i i
180
0.71 1.42 2.13
AMOUNT OF LIQUOR FILTERED THROUGH
THE CHIPS-gal/lb dry chips
Figure J>. Reduction in pH of a waste Kraft pulping liquor of
initial pH 10, resulting from filtering the liquor
through a column of pine chips
23
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X
Q.
l.2r-
2 0.8
o
ID
0.4
I
60
ELAPSED TIME
I
OF
120
LIQUOR
L_
ISO
FLOW-mi n
L_
0.71 1.42 2.13
AMOUNT OF LIQUOR FILTERED THROUGH
THE CHIPS-gal/lb dry chips
Figure 4. Reduction in pH of a waste Kraft pulping liquor
of initial pH 10.5 resulting from filtering the
liquor through a column of pine chips
-------
Table 8. Change In biochemical oxygen demand of waste Kraft pulping liquor of pH 10-10.5 resulting
from filtering the liquor through a column of the pine chips
vn
Elapsed Time
of
Experiment Effluent Flow
Number (Hours)
1
2
1 3
4
5
6.0
1
2
II 3
" 4
5
6
7
8
Total Amount of Liquor
Fi 1 tered Through
the Chips
(gal/lb. of dry chips)
0.71
1.42
2.13
2.84
3-55
4.25
0.71
1 .42
2.13
2.84
3-55
4.25
4.93
5.65
Increase in BODr
of the Total Waste Liquor
Passed Through the Chips,
(Ibs/ton dry chips)
2.4
3.7
4.5
5-0
5.4
5.6
2.0
2.8
3.2
3-5
3.8
4.20
4.80
5-50
-------
Table 9. Changes in properties of waste Kraft pulping liquor by contacting the liquor with pine
chips through spraying the liquor over a small chip pile (pilot-scale experiments)
Fow Rate
Temp.
(°C)
30
IJ ;V
30*
1 1 •!;
II ;';
II ...
11 .'.
(Gal
Dry Ch
0.
0.
0.
0.
0.
0.
0.
0.
/lb.
ips/Hr)
16
16
16
16
16
16
16
16
Elapsed Total Amount
Time of Liquor
of Contacted
Effluent by the Chips
Flow
(gal/lb.
(hrs) dry
0.
24
168
168
336
504
1176
1344
1
,one
Week)
/one
week)
(seven ,
weeks )
(eight 2
weeks)
ch i ps )
0.02
3-9
27-2
27.2
54.4
71.6
90.4
17.6
pH
Before
Contact
with the
Ch i ps
10.2
9.5
9.6
9-9
9.8
10.2
9-6
—
PH
After
Contact
wi th the
Chips
9-1
8.4
8.1
9-0
8.9
9.3
9-2
—
ApH
1.1
1.1
1.5
0.9
0.9
0.9
0.4
—
BOD5
Be f o re
Contact
with the
Ch ips
(ppm)
330
240
190
290
275
300
210
250
BOD5
After
Contact
with the
Chi ps
(ppm)
410
150
180
290
290
320
215
210
Changes
in
BOD5
(ppm)
+80
-90
-10
0
+ 15
+20
+ 5
-40
"The chip pile surface became partially plugged with fibers and the flow of the liquor through
the chip pile was thereby considerably reduced.
-------
are stored for relative long periods of time (1 year), does not
preserve the wood against degradation. Spraying of chips for a
short time, j_.e_. , one month or less, could, according to the
literature source (3), offer an economic means of wood protection.
Our data show, however, that spraying of stored chips with an
alkaline liquor may be a substantial source of water pollution,
because organic materials with a 6005 of about 5~10 Ibs. per
ton of dry chips could be extracted from pine chips. Even water
extracted a considerable amount of biological oxygen-demanding
material from chips. This means that liquor drainage from a
chip storage area should be considered as a pollutional waste,
and preferably should be treated in the mill's waste treatment
plant. The pH changes and color reduction of alkaline waste
liquor by filtering it through pine chips are too small to
have any practical application in treatment of waste water.
27
-------
ACKNOWLEDGMENT
We wish to thank Mr. F. W. Gladstone and his technical staff at
Albemarle Paper Company at Roanoke Rapids, North Carolina, for
supplying us with the pine chips and waste liquors and for providing
valuable technical assistance with the pilot-scale experiments.
29
-------
REFERENCES
12th Edition of Standard Methods for the Examination of Water
and Waste Water. Publ. by APHA, AWWA & WPCF (1965).
Mi ddlebrooks , E. J., e_t_ a\_. : "Spraying of Stored Pulpwood with
Waste Water," Tappi 5J_ (7) 93A (1968).
Djerf, A. C. , and Volkman, D. A.: "Water Spray Wood Storage,"
Paper Trade Journal 153 (10) 51 (March 1, 1969).
31
-------
APPENDIX
Page
Table 1. Properties of waste Kraft pulping liquor before
and after gravity flow of the liquor through
a column of pine chips (pilot-scale experi-
ments) 35
33
-------
Appendix Table 1
Properties of waste Kraft pulping liquor before and after gravity
liquor through a column of pine chips (pilot-scale experiments)
flow of the
Temp.
(°C) D
12
12
12
12
12
12
13
13
13
13
13
13
14
14
15
15
15
15
14
13
13
13
13
12
Flow
(Gal/
ry Chi
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
Rate
Ib.
ps/Hr)
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
El apsed
Time of
L i q uo r F 1 ow
(mi n . )
1
15
30
45
60
75
95
105
120
135
150
165
185
195
210
225
240
255
275
285
300
315
330
345
Total
of L
Fi Ite
rh rough
(Ga
Dry
_
0
0
0
0
0
2
2
2
2
2
3
3
3
3
3
3
4
Amount
quor
red
the Chip
1/Lb
Chips)
_ _ _
.18
.35
.53
.71
.89
.12
.23
.41
.59
.77
.94
.18
.30
.47
.65
.82
.00
.24
.35
.53
.70
.88
.06
s pH
Before
Contact
9-9
9-8
0.9
9-9
10.0
10.0
9-9
9-9
9-8
9-9
9-9
10.0
10.0
10.0
10.3
10.0
PH
After
Contac
9-0
9-2
9-3
9-5
9-5
0.3
9-5
9-4
9-5
9-5
9-4
9-5
9-7
9-7
—
—
—
10.0
—
—
—
9-8
(Conti
t ApH
0.9
0.6
0.5
0.4
0.5
0.7
0.4
0.5
0.3
0.4
0.5
0.5
0.3
0.3
—
—
—
0.3
nued)
Before
Contact
(ppm)
380
350
320
310
460
340
350
350
350
370
420
410
450
450
530
510
620
560
520
490
490
450
450
440
6005
After
Contact
(ppm)
670
600
520
480
330
520
460
440
430
470
440
430
580
492
510
600
680
540
530
560
500
480
470
450
. ABODr
(ppm)
+290
+250
+200
+ 170
+ 130
+ 180
+ 110
+ 90
+ 80
+ 100
+ 20
+ 20
+ 130
+ 40
- 20
+ 90
+ 60
- 20
+ 10
+ 70
+ 10
+ 30
+ 20
+ 10
-------
Appendix Table 1 (continued)
UJ
ON
Flow Rate
Temp. (Gal/lb.
(°C) Dry Chips/Hr)
10
10
10
10
10
10
11
11
11
11
120
12
13
13
]k
14
14
15
15
15
15
15
13
13
13
13
13
13
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
El apsed
T i me of
Liquor Flow
(mi n . )
1
15
30
45
75
90
105
120
135
150
165
180
195
210
225
240
255
270
285
300
330
360
375
390
405
420
438
450
Total Amount
of Liquor
Filtered
Through the Chips pH
(Gal/Lb Before
Dry Chips) Contact
_ _
0.
0.
0.
0.
1 .
1.
1.
1.
1.
1.
2.
2.
2.
2.
2.
3.
3.
3.
3.
3-
4.
4.
4.
4.
4.
5.
5.
_ _
18
35
53
89
06
23
41
59
77
94
12
30
47
65
82
00
18
35
53
88
23
41
49
77
95
13
30
10.5
10.5
10.4
10.5
10.5
10.5
10.4
10.4
10.3
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
PH
After
Contact
9-5
9-7
9-8
9-9
10.2
10.2
10.1
10.1
10.0
10.2
10.2
10.2
10.2
10.2
10.2
10.2
10.2
ApH
1.0
0.8
0.6
0.6
0.3
0.3
0.3
0.3
0.3
—
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
BOD5
Before
Contact
(ppm)
330
560
380
410
420
400
400
430
440
470
460
410
480
430
550
490
580
550
560
600
590
420
430
450
420
400
440
420
BOD5
After
Contact
(ppm)
660
680
550
580
520
400
470
470
450
430
480
460
510
500
460
490
600
540
620
630
610
470
500
490
490
470
490
480
ABODr
(ppm)
+ 340
+ 120
+ 170
+ 170
+ 100
+ 60
+ 70
+ 40
+ 10
- 40
+ 20
+ 50
+ 30
+ 70
- 90
0
+ 20
- 10
+ 60
+ 30
+ 20
+ 50
+ 70
+ 40
+ 70
+ 70
+ 50
+ 60
-------
BIBLIOGRAPHIC:
School of Forest Resources, North Carolina State University,
Dilute Spent Kraft Liquor Filtration Through Wood Chips, Final
Report FyPCA Grant No. WPRD 115-01-68, April, 1970
ABSTRACT
The principal objective of this project was to determine if
contact between effluent from a Kraft pulp milt and pine chips
would reduce the water pollution characteristics of the waste
I iquor.
The experimental work was divided into two phases: 1) a
small scale laboratory investigation of contacting dilute
waste liquor with chips; 2) a pilot-scale investigation of
filtering waste liquor through a column and a pile of chips.
It was found that contact of alkaline waste liquor, or even
distilled water, with pine chips extracted organic matter from
the chips which had a considerable 8005. This extract corre-
sponded to a pollution load of about 3-11 Ibs. BODj per ton
of dry wood. Alkalinity, pH, and intensity of color of the
ACCESSION NO.
KEY WORDS:
Water Pollution
Waste Water
BOD-extraction
Kraft Pulp Mill
Wood Chips
BIBLIOGRAPHIC:
School of Forest Resources, North Carolina State University,
Dilute Spent Kraft Liquor Filtration Through Wood Chips, Final
Report FWPCA Grant No. VIPRD 115-01-68, April, 1970
ABSTRACT
The principal objective of this project was to determine if
contact between effluent from a Kraft pulp mil) and pine chips
would reduce the water pollution characteristics of the waste
Iiquor.
The experimental work was divided into two phases: 1) a
small scale laboratory investigation of contacting dilute
waste liquor with chips; 2) a pilot-scale investigation of
filtering waste liquor through a column and a pile of chips.
It was found that contact of alkaline waste liquor, or even
distilled water, with pine chips extracted organic matter from
the chips which had a considerable BOD;. This extract corre-
sponded to a pollution load of about 3-11 Ibs. BODj per ton
of dry wood. Alkalinity, pH, and intensity of color of the
ACCESSION NO.
KEY WORDS:
Water Pollution
Waste Water
BOD-extraction
Kraft Pulp Mill
Wood Chips
BIBLIOGRAPHIC:
School of Forest Resources, North Carolina State University,
Dilute Spent Kraft Liquor Filtration Through Wood Chips, Final
Report FWPCA Grant No. WPRB 115-01-fcB, April, 1970
ABSTRACT
The principal objective of this project was to determine if
contact between effluent from a Kraft pulp mill and pine chips
would reduce the water pollution characteristics of the waste
I iquor.
The experimental work was divided into two phases: 1) a
small scale laboratory investigation of contacting dilute
waste liquor with chips; 2) a pilot-scale investigation of
filtering waste liquor through a column and a pile of chips.
It was found that contact of alkaline waste Uquor, or even
distilled water, with pine chips extracted organic matter from
the chips which had a considerable BOD;. This extract corre-
sponded to a pollution load of about 3-11 Ibs. BODJ per ton
of dry wood. Alkalinity, pH, and intensity of color of the
ACCESSION NO.
KEY WORDS:
Water Pollution
Waste Water
BOD-extraction
Kraft Pulp Mill
Wood Chips
-------
waste liquor were somewhat reduced by the contact. These
reductions are, however, too small to have any practical ap-
plication in effluent treatment. It can, in general, be
concluded that contact of alkaline waste liquor, or water,
with wood chips extracts soluble organics and adds poMotional
materials to the effluent stream.
This report was submitted in fulfillment of Grant No. WPRD
115-01-68 between the Federal Water Pollution Control Admin-
istration and the Department of Wood and Paper Science,
School of Forest Resources, North Carolina State University
at Raleigh, North Carolina.
waste liquor were somewhat reduced by the contact. These
reductions are, however, too smalt to have any practical ap-
plication in effluent treatment. It can, in general, be
concluded that contact of alkaline waste liquor, or water,
with wood chips extracts soluble organics and adds pollutional
materials to the effluent stream.
This report was submitted in fulfillment of Grant No. WPRD
115-01-68 between the Federal Water Pollution Control Admin-
istration and the Department of Wood and Paper Science,
School of Forest Resources, North Carolina State University
at Raleigh, North Carolina.
waste liquor were somewhat reduced by the contact. These
reductions are, however, too small to have any practical ap-
plication in effluent treatment. It can, in general, be
concluded that contact of alkaline waste liquor, or water,
with wood chips extracts soluble organics and adds pollutional
materials to the effluent stream.
This report was submitted In fulfillment of Grant No. WPRD
115-01-68 between the Federal Water Pollution Control Admin-
istration and the Department of Wood and Paper Science,
School of Forest Resources, North Carolina State University
at Raleigh, North Carolina.
------- |