PLYWOOD PLANT
GLUE WASTES DISPOSAL
PROGRESS REPORT
February 1968
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PROGBESS REPORT
PLYWOOD PIANT GLUE WASTE DISPOSAL
Prepared by
Danforth G. Bodien
Technical Projects Branch
Report No. PR-2
U. S. Department of the Interior
Federal Water Pollution Control Administration
Northwest Region
Pacific Northwest Water Laboratory
Corvallis, Oregon
February 1968
0c ft of the interior
Edison, W. J. 08817
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ABSTRACT
In the States of Oregon, Washington, Idaho, Montana, and
California, 158 plywood plants generate an estimated 6.2 million
gallons of waste per day from the cleanup of glue mixing equip-
ment and glue spreaders. The waste is toxic and high in pollu-
tional strength. Treatment of these glue wastes varies from plant
to plant but generally consists only of solids separation or the
removal of suspended matter. Further investigations are needed
to determine which treatment methods will solve the pollution
problems caused by the discharge of these wastes.
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TABLE OF CONTENTS
Page
I. INTRODUCTION
A. Problem 1
B. Objectives 2
C. Authority 2
D. Acknowledgments 2
II. SUMMARY
A. Findings 4
B. Conclusions 4
III. PLANT SURVEY 5
IV. PLYWOOD PLANT CHARACTERISTICS
A. Locations and Number 8
B. Production 8
C. Operations 11
V. WASTE CHARACTERISTICS
A. Waste Quantity 18
B. Waste Quality 28
VI. DISPOSAL OF WASTE
A. Methods in Use 33
B. Incineration of Waste 36
VII. PROPOSED STUDIES 40
VIII. SELECTED REFERENCES 41
IX. APPENDIX
A. Definition of Terms 43
B. Plywood Plant Locations 47
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LIST OF FIGURES
No.
1 Plywood Plant Flow Diagram 12
2 Average Glue Waste Flows (Plant 1) 20
3 Daily Average Glue Waste Flows (Plant 2) .... 22
4 Daily Average Glue Waste Flows (Plant 3) .... 23
5 Daily Average Glue Waste Flows (Plant 4) .... 24
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LIST OF TABLES
No. Page
1 Number of Plants by Types of Plywood 6
2 1966 Plant Production by Type and Grade of Plants
Surveyed ,
3 Number and Percentage of Plants Surveyed 9
4 1966 Plant Production by Types of Plywood 10
5 Number of Glue Spreaders for Plants Surveyed ... 13
6 Number of Spreader Shifts for Plants Surveyed ... 14
7 Green Ends, Cold Decks, and Log Ponds 16
8 Number and Size of Log Ponds at Plants Surveyed . . 17
9 Characteristics of Plants Used in Discharge Study . 19
10 Glue Waste Discharge Measurements 25
11 Ingredients of Typical Exterior and Interior Glue
Mixes 29
12 Chemical Analysis of Plywood Glue 31
13 Disposal Methods of Plants Surveyed 34
14 Chemical Analysis of Settled Effluent 35
15 Incineration Test of Exterior and Interior Glue . 38
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PROGRESS REPORT
PLYWOOD PIANT GLUE WASTE DISPOSAL
I. INTRODUCTION
A. Problem
The cleanup of glue spreaders at 158 plywood mills throughout
the study area produces a waste that is high in pollutional strength
even though volumes are quite low. At the present time the State
of Oregon rates this waste as their primary pollution problem
based on the number of complaints received.
The glues used in the plywood industry are of three basic types:
the blood soya variety used for interior grade plywood; the phenolic
formaldehyde variety used for exterior grade plywood; and a urea
formaldehyde glue used for hardwood paneling. Each type presents
its own problem and combinations of two or more types of glue present
additional and more complicated problems.
The blood soya glues produce an alkaline waste with a high
oxygen demand. Coagulation of the glue solids may cause large
masses of solids resulting in sewer stoppage. The waste also
supports the growth of Sphaerotilus sp.
Phenolic formaldehyde glues produce a toxic waste which is
alkaline. The waste from this glue also creates color, taste,
and odor problems.
-1-
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The urea formaldehyde glues also produce a toxic waste, but
it is acidic. These glues are used for less than 8 percent of
the plywood production in the study area. For this reason, the
majority of work has been done with the interior and exterior
glues.
B. Objectives
This study is to determine the magnitude and extent of the
problem created by the disposal of glue wastes, review the charac-
teristics of plywood glue wastes, and recommend methods of treatment
for these wastes. The study area includes the States of Oregon,
Washington, Montana, Idaho, and California. Basic information on ply-
wood plants was collected from plants in all five States while field
work has been confined to plants in Oregon that are representative
of those in the industry. This progress report covers the preliminary
phases of the project. A final report will be issued later covering
the entire project.
C. Authority
The Pacific Northwest Water Laboratory of the Federal Water
Pollution Control Administration, Northwest Region, was requested
by the Oregon State Sanitary Authority, letter dated January 19, 1966,
to study methods for disposing of glue wastes from plywood plants.
The Federal authorization for this study was from the Federal Water
Pollution Control Act, as amended.
D. Acknowledgments
Acknowledgment is given the American Plywood Association for
-2-
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their valuable assistance in conducting the survey.
Special thanks to the Borden Chemical Company at Springfield,
Oregon, for their donation of glue ingredients and their assistance
in explaining and defining techniques involved in the preparation
of the mixes.
Thanks are due to the personnel of the many plants visited.
Their interest and cooperation is appreciated.
-3-
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II. SUMMARY
A. Findings
1. Some 158 plywood plants in the study area generate
an estimated 6.2 million gallons of waste per day from the cleanup
of glue spreaders and glue mixing equipment.
2. Water usage at plants varies greatly with no apparent
relationship to amount or type of plywood produced.
3. Both exterior and interior grade glues exhibit high
pH and COD. The exterior grade glue is high in phenol but low in
nitrogen and phosphorus content.
4. Interior and exterior glues each contribute approxi-
mately 50 percent of total waste based on production figures.
5. Most plywood plants utilize some sort of settling tank
which removes the wood chips and some of the glue solids, but some
plants still dump raw waste into rivers, the ocean, and other receiv-
ing bodies of water.
6. Glue solids can be burned at high temperatures with
small percentages of ash being produced.
B. Conclusions
1. Water usage at most plants far exceeds that required
to wash down the spreaders and glue-mixing equipment.
2. Proper maintenance of settling tanks and ponds is
neglected until they become inoperative. This lack of maintenance
leads to low efficiencies.
-4-
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III. PLANT SURVEY
Plywood plants vary with respect to many parameters such as
size, type of waste generated, and waste disposal methods. To gain
an understanding of the plywood industry two methods were employed.
The first involved personal visits to 50 plants; all in the State of
Oregon. The second method consisted of obtaining from the American
Plywood Association (A.P.A.) the information they had collected from
a survey of their plants. This survey was concerned with production,
operations, waste generation, and disposal practices.
To obtain a good response, the A.P.A. had their plant supervisors
personally fill out a questionnaire when they visited each plant in
their district. This method gave a 100 percent return for the plants
belonging to the A.P.A. From the results listed in Table 1 and Table
2, it can be seen that the survey represented about 67 percent of
the plants and 70 percent of the production in the study area; this
appears to have been a representative sample of the industry.
-5-
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TABLE 1
Number of Plants by Types of PlywoodfL/
State
California
Idaho
Montana
Oregon
Washington
Totals
Softwood
Plants
17
4
6
84
22
133
Hardwood
Plants
4
0
0 ,
2
_2
8
Mixed
Plants
1
:r 0
0
6
10
17
Total
Plants
22
4
6
92
34
158
a/
—' 1967 Plywood and Board Products Directory
-6-
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-7-
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IV. PLYWOOD PLANT CHARACTERISTICS
t
A. Location and Number
The location of the 158 plywood plants in the five-state study
area is shown on Plate 1 in Appendix B. The plants are concentrated
in the Willamette and Rogue River Valleys in Oregon and the Puget
Sound area in Washington. Table 3 shows the distribution by state
of the 158 plants. As can be seen, Oregon has 92 plants or approxi-
mately 58 percent of the total. Table 1 gives the breakdown by type
of plywood produced by the plants surveyed. Comparison of the tables
shows that a good cross-section was obtained by the survey.
B. Production
Plywood production for 1966, which was a normal year, is given
in Table 4. These data give the hardwood and softwood production by
states and show that in the study area the softwood makes up 92.1
percent of the total. The production in the State of Oregon in 1966
was 64 percent of the total for the five states in the study area.
Table 2 gives the 1966 production for the plants surveyed. In
this table, the softwood production is further divided into interior
and exterior grades of plywood. The survey shows that the total
production of interior and exterior grades is very similar, being
48.0 percent and 48.4 percent, respectively. Hardwood plywood
production accounts for the remaining 3.6 percent. Since each type
of plywood uses a different type of glue, these data indicate the
relative amounts of the glues used.
-8-
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TABLE 3
a/
State
California
Idaho
Montana
Oregon
Washington
Totals
Number
Plants
22
4
6
92
34
158
Number and Percentage of Plants Surveyed—'
Number Plants % Plants
Surveyed Surveyed
11 50
2 50
4 67
59 64
30 88
106 67
iA.P.A. Survey, 1967
-9-
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TABLE 4
a/
1966 Plant Production by Types of Plywood—
Softwood Production Hardwood Production
Total Production
State
California
Idaho
Montana
Oregon
Washington
Totals
7
/o
(Sq.Ft. 3/8" Basis)
1,277,000,000
293,100,000
456,000,000
7,948,350,000
2,150,600,000
12,125,050,000
92.1
(Sq.Ft. 3/8" Basis)
115,500,000
499,450,000
427,500,000
1,042,450,000
7.9
(Sq.Ft. 3/8" Basis
1,392,500,000
293,100,000
456,000,000
8,447,800,000
2,578,100,000
13,167,500,000
a/
— 1967 Plywood and Board Products Directory
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C. Operations
To help understand the plywood operations, a flow chart of a
complete plant is shown in Figure 1. This flow chart also indicates
sources of solid and liquid wastes.
1. Green End
The green end of a plant involves the storage and handling
of logs through the process of turning them into veneer. Storage of
logs may be through the use of a log pond, cold decks, or a combina-
tion of both. Log ponds at plywood plants usually serve as a disposal
site for the glue wastes. This rids the plant of the glue waste but
usually complicates the pollutional problems caused by the log storage
itself. Cold decking also causes some pollution problems; water
sprayed over the logs to keep them from checking usually finds its
way into the log pond or to another receiving body of water. Table 5
presents data on green ends, log ponds, and cold decks. Of the plants
surveyed, 82.1 percent have green ends. Of these with green ends,
63.2 percent have log ponds and 59.4 percent have cold decks. Table 6
presents more detailed information on the log ponds. The average
size log pond for the plants surveyed was 17 acres with a range from one-
half to 100 acres.
2. Gluing
The first source of glue waste comes from the washdown of
kettles and equipment used to mix the glue ingredients. A typical
plant, which produces 100,000,000 square feet of plywood per year,
approximately 50 percent exterior grade and 50 percent interior
-11-
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TABLE 5
a/
Green Ends, Cold Decks, and Log Ponds—
Plants Surveyed
with
Average
for 5 States
Plants Surveyed
with
State
California
Idaho
Montana
Oregon
Washington
Green Ends (%)
90.9
100.0
100.0
83.1
73.3
Cold Decks
72.7
100.0
100.0
57.6
50.0
W
82.1
59.4
Plants Surveyed
with
Log Ponds (%)
27.3
0.0
16.7
72.9
56.7
63.2
a/
A.P.A. Survey, 1967
-13-
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grade, makes about 11 batches per day of interior glue and 9
batches per day of exterior glue. This amounts to approximately
400,000 pounds of exterior and 350,000 pounds of interior glue
per month. The mixing equipmtnt may not always be washed between
batches, but when it is washed, only a small amount of water is
used. Thus, the waste volume from this phase of the operation is
a small but highly concentrated part of the total waste.
The second source of glue waste is from the spreaders
themselves. Table 7 gives data on the number of spreaders in the
plants surveyed. As can be seen, the average plant has approximately
three spreaders with a range from one to nine. Of more interest
is the number of spreader shifts per day. Table 8 contains data
on spreader shifts for the surveyed plants. The average plant
has slightly over six spreader shifts per day with a range from
one to twenty. These spreaders are usually washed down once per
shift when interior glue is used and at least once per day for
exterior glue. The difference is due to the fact that the interior
glues have a pot life of 6 to 8 hours whereas the exterior glue
lasts almost indefinitely. The accumulation of wood chips in the
pans of the spreaders usually necessitates cleaning the exterior
glue spreaders at least once per day.
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TABLE 7
a
Number of Glue Spreaders for Plants Surveye'
State
California
Idaho
Montana
Oregon
Washington
Number
24
3
10
179
94
Average/
Plant
2.2
1.5
2.5
3.0
3.1
Max./
Plant
4
2
4
9
6
Total 310
Average for 5 States 2.9
Maximum for 5 States
Minimum for 5 States
a/
-A.P.A. Survey, 1967
Min./
Plant
1
1
2
1
1
-16-
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TABLE 8
a/
Number of Spreader Shifts for Plants Surveyed—
State
California
Idaho
Montana
Oregon
Washington
Total
Number
42
8
25
406
185
Average/
Plant
3.8
2.0
6.3
6.9
6.2
Max./
Plant
7
5
11
20
16
Min./
Plant
1
3
4
2
1
Total 666
Average for 5 States 6.3
Maximum for 5 States 20
Minimum for 5 States
-/A.P.A. Survey, 1967
-17-
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V. WASTE CHARACTERISTICS
A. Waste Quantity
1. Measured Waste Discharges
Waste flows were measured at four plants over periods
ranging from 6 weeks to several months. A different scheme was
used at each plant for these measurements due to equipment availa-
bility and accessibility to the waste stream. The plants where
flows were measured will be referred to by number. Pertinent data
on the four plants are in Table 9.
At Plant Number 1, a water meter was placed in the wash-
water line adjacent to one of the four glue spreaders. This meter
was read at various time intervals over a 7-month period. The meter
readings were multiplied by four, and the average flows were computed.
Figure 2 shows these flows for the 7-month period. The average flow
for the 7-month period was 12.9 gpm, and the average flow for the
working days in the period was 18.2 gpm.
At Plant Number 2, a 45-degree V-notch weir and water level
recorder were installed in a ditch between the plant and the settling
pond. This proved to be a bad arrangement as the weir was soon plugged
with glue and wood chips. The weir was removed and an alternate plan
was sought. At this plant, the settling pond effluent was pumped
into the log pond. The pump was controlled by a set of probes. The
recorder was placed on the pond. The pond area was measured and
-18-
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TABLE 9
Characteristics of Plants Used in Discharge Study
Plant
Number
1
2
3
4
1966 Production-'
(Sq.Ft.3/8" Basis)
100,000,000
135,000,000
100,000,000
70,000,000
Exterior
Grade
(%)
50
0
25
75
Interior
Grade
(%)
50
100
75
25
Numbe r
of
Spreaders
4
3
4
2
Spreader
Shifts
Per Day
8
9
9
6
Days
Worked
Per Week
5
5
5
5
a /
— 1967 Plywood and Board Products Directory
-19-
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AVERAGE GLUE WASTE FLOWS
(PLANT I)
AVEKAM n0W.NOV.M-.MC 2», I2.t «.PM.
DECEMBER
1966
JANUARY FEBRUARY
1967 1967
DATE
FI6UME t
-------
the flow was determined. This set up was used for 7 weeks and proved to
be the easiest to maintain. Figure 3 shows the daily average flows
for the period. The average flow for the 7 weeks was 24.4 gpm and
the average flow for the working days was 30.2 gpm.
At Plant Number 3, a 60-degree V-notch weir and level
recorder were installed in a ditch located downstream from the
plant's settling tank. This setup was used for 6 weeks and required
only minor maintenance. Figure 4 shows the daily average flows for
the period. The average flow for the period was 17.9 gpm and the
average flow for the working days was 21.6 gpm.
At Plant Number 4, a 16-inch rectangular weir and level
recorder were installed in the last compartment of the plant's
settling tank. This setup was used for 6 weeks. Figure 5 shows
the daily average flows for the period. The average flow for the
period was 53.2 gpm and the average flow for the working days was
54.0 gpm.
Table 10 compiles the flow data for the four plants. As
can be seen, the average flows vary widely. This variance should
be a result of the spreader shifts per day and the types of glue
used. Plant Number 4, with the fewest spreader shifts per day and
the highest percentage of exterior grade production, should have
the smallest flow but as can be seen it is much higher than the
other three. At Plant Number 4 there is only a small difference
between amount of water used on working and nonworking days further
indicating water is being used when spreaders are not being washed
down.
-21-
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DAILY AVERAGE GLUE WASTE FLOWS
(PLANT 2)
» • *> tZ 24
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JUNE 1967
DATE
FIOUMC 3
-------
DAILY AVERAGE GLUE WASTE FLOWS
(PLANT 3)
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MAY 1967
46 8 10 12 W
JUNE 1967
DATE
FIGURE 4
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DAILY AVERAGE GLUE WASTE FLOWS
(PLANT 4)
22 24 2B 24 30 2 4 6 • K> tt M
DATE
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The flow from Plant Number 1 was much lower than the
other three. This may be due to the manner by which the flow was
calculated. Here, actual amounts of water used for washdown were
measured, eliminating any other discharges which may get into the
waste stream further down the line such as the washdown water from
the glue mixing area.
On two plants the daily maximum and minimum flows were
recorded. The average is shown in Table 10. These are shown as
a percentage of the average flow. The maximum for the two plants
averaged 213 percent while the minimum was 60 percent.
The average discharge for the four plants was 27.1 gpm.
This is about 39,000 gpd. When multiplied by the 158 plants in
the study area, it results in a discharge of 6.2 million gallons
per day of glue waste.
In conclusion, it can be seen that under present conditions
of inexpensive water and little concern over the destination and
pollutional effects of the waste, the flow from different plants
will vary markedly depending on plant practices.
2. Calculated Waste Discharges
Two spreader washdowns have been observed. Both of these
took place at Plant Number 1 where a water meter had been installed
in the wash-water line. The first washdown required 210 gallons,
took approximately 35 minutes, and resulted in an average discharge
of 6 gpm. The second washdown measured 250 gallons, took approxi-
mately 35 minutes, and resulted in an average discharge of 7 gpm.
-26-
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For this calculation assume that 250 gallons at 7 gpm is needed to
wash down a spreader. To flush out lines or troughs, an additional
10 minutes at 7 gpm is added, giving a total of 70 gallons for
flushing. This gives a total of 320 gallons for each washdown. The
average interior plywood plant with six spreader shifts and a wash-
down at the end of each shift would generate 1,920 gallons of waste
per day. To this should be added the contribution from the washdown
of glue mixing equipment. A plant making 10 batches of glue per
day and washing down their equipment after each batch should add
approximately 300-500 gpd of waste. The total glue waste discharge
should then be around 2300 gpd per plant. This is considerably less
than the 18,500 to 76,500 gallons measured at Plants 1-4. This great
difference can be traced to the fact that water is allowed to run in
the waste lines when glue is not being washed off equipment. This
practice has been followed for one or more of the following reasons.
First, some plant personnel feel that by diluting the glue waste their
pollution problems will be reduced. Second, lines have become
plugged on occasion and water is kept running in an effort to prevent
this. Third, forgetfulness and poor plant practices account for
the excess amounts of water consumed.
It is concluded that glue waste discharges could and
should be reduced considerably. This could easily be done through
better in-plant practices and through the development of new
techniques such as the use of steam instead of water for cleaning
-27-
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the metal parts of equipment. Surely, if a disposal method such
as incineration is to be used, the waste should be concentrated
as much as possible.
The problem of plugged lines could possibly be solved
by using better line flushing techniques, minimizing waste line
lengths, by using teflon coated pipes or a combination of these.
If biological treatment is to be employed, some dilution of waste
beyond the quantities calculated may be needed to reduce the
effects of toxic substance on biological organisms. This problem
will be studied further in connection with activated sludge pilot
plant work.
B. Waste Quality
1. Chemical Investigations
Many different glue formulas are used by the plants in
the study area. However, the glues vary only slightly with respect
to their actual ingredients. Table 11 lists the ingredients of
typical interior and exterior glue mixes. The pentachlorophenol
or phenolic formaldehyde resin listed under interior glue is added
only when a toxic mix is required. This toxic mix makes the glue
more resistant to biological degradation.
Because all glues could not be chemically analyzed,
typical exterior and interior glues were chosen. These were
a/ a/
Borden's Cascophen 31— exterior glue and Borden's Casco S-230—
a/
— Use of product and company names is for identification only and
does not constitute endorsement by the Department of the Interior.
-28-
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TABLE 11
Ingredients of Typical Exterior and Interior Glue Mixes
Exterior
Water .
Furafil-7
Wheat flour
Phenolic formaldehyde resin
Caustic soda
Soda ash
Interior
Water
Dried blood
Soya flour
Lime
Sodium silicate
Caustic soda
Formaldehyde doner for thickening
Pentachlorophenolk/
Phenolic formaldehyde resinH/
a/
—Residue from furfural extraction of corn cobs and oat hulls
—May be added to produce a toxic glue
-29-
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interior glue. The Casco S-230 mix contains neither pentachloro-
phenol nor phenolic formaldehyde resin. The ingredients of these
glues were obtained from the producing company and the glues were
mixed in the laboratory. These prepared glues were then chemically
analyzed. Table 12 lists the results of these analyses. As can
be seen, the COD of the exterior glue is much greater than that of
the interior glue. The levels of total phosphates and total
kjeldahl nitrogen, however, are much higher in the interior glue.
These low levels of phosphate and total kjeldahl nitrogen in the
exterior glues may make it necessary to add nutrients for biological
treatment. The phenol concentration of the exterior glue is much
greater than that of the interior glue. While the phenol concen-
trations are quite high (514 mg/kg) they still are in the range of
500 mg/1 found by McKinney et al to be biologically treatable with
proper acclimation.' '
2. Biological Investigations
a. Stream Survey
Biological investigations of a small creek in Western
Oregon were undertaken to determine the effects of plywood glue
wastes on the ecology of a small stream. This creek receives both
a/
interior and exterior plywood glue wastes from Plant Number 1.—
Ten sampling stations were established on the creek.
The aquatic community is being sampled routinely through the
a/
~ Information regarding this plant can be found in Table 9.
-30-
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TABLE 12
Chemical Analysis of Plywood Glue
Analysis and Units Exterior Glue— Interior Glue—
COD, mg/kg 653,000 176,500
TOG, mg/kg 176,000 52,000
Total Phosphate, mg/kg as P 120 260
Total Kjeldahl Nitrogen, mg/kg as N 1,200 12,000
Phenols, ^g/kg 514,000 1,810
Suspended Solids, mg/kg 92,000 59,000
Dissolved Solids, mg/kg 305,000 117,500
Total Solids, mg/kg 397,000 176,500
Total Volatile Suspended Solids, mg/kg 84,000 34,000
Total Volatile Solids, mg/kg 171,500 137,000
—Borden's Cascophen 31 which is similar to Borden's Cascophen 382
b/Borden's Casco S-230
-31-
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collection of bottom-dwelling animals, phytoplankton, and attached
algae. Artificial substrates for the collection of bottom animals
and diatoms were also installed and are being serviced at scheduled
intervals.
Preliminary results from samples that have already
been collected indicate a classical picture of river pollution. The
creek supports a well balanced community of aquatic organisms
upstream from the waste outfall and exhibits extremely degraded
conditions downstream. Pollution-tolerant organisms are in
abundance below the outfall along with large amounts of Sphaerotilus.
Studies of this creek are valuable in showing dramatic
changes in the stream environment due to plywood glue wastes. However,
the large volume of wastes and the normally low stream flow coupled
with a marshy drainage area in the downstream reaches of the creek,
make it difficult to evaluate recovery from the glue wastes.
b. Bioassays
Toxicity bioassays run in accordance with Standard
Methods are being conducted to evaluate the relative acute toxicity
of plywood glue. A series of bioassays, using guppies as test
organisms, were conducted on both interior and exterior glues. The
test solutions were renewed daily to lessen the effects of deoxy-
genation and detoxification. Preliminary results indicate the
Cascophen 382, an exterior glue, is about four times as toxic as
Casco S-230, an interior glue. Median tolerance limits for 96 hours
for Cascophen 382 ranged from 830 to 1200 mg/1 while Casco S-230
ranged from 4200 to 4800 mg/1.
-32-
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VI. DISPOSAL OF WASTE
A. Methods in Use
Many different disposal methods for glue waste are being used
at the present time. These methods vary from no treatment to systems
involving municipal treatment plants. Table 13 lists 23 different
schemes used by the 106 plants surveyed. As can be seen, 77 plants
employ some type of settling tank or pond. The settling tanks
commonly consist of one or more 1,000-gallon septic tanks. These
settling devices remove some of the glue solids and the wood chips.
Table 14 lists the chemical analyses of the settled effluent for three
a/
of the plants used in the discharge survey." Comparison of Table 12
and Table 14 shows a significant increase in the dissolved solids/
suspended solids ratio after the settling operation, indicating a
reduction of suspended solids. A similar comparison also shows
little reduction in phenols, phosphates, and total kjeldahl nitrogen.
The removal of suspended solids is further evidenced by the
filling of settling devices, necessitating their periodic clean out.
This clean out is needed every 1 to 3 months depending on the size
of the tank, number of washdowns, and types of glues used. In these
tanks and ponds, lack of proper maintenance leads to poor efficiencies"
and subsequent problems. Usually, these tanks are not cleaned until
a/
—Information regarding the three plants can be found in Table 9.
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TABLE 13
Disposal Methods of Plants in Survey
Number of Plants Using System
Disposal System
Field Spreading .
Log Pond (N.O.)-
Log Pond, Field Spreading
Log Pond, S.L.R.O.k/
Municipal Sewer
Settling Pond (N.O.)
Settling Pond,
Settling Pond,
Settling Pond,
Settling Tank,
Log Pond (N.O.)
S.L.R.O.
Waste Burner
(Further Disposal Unknown)
Settling Tank, Field Spreading
Settling Tank, Log Pond (N.O.)
Log Pond, Field Spreading
Log Pond, S.L.R.O
Municipal Sewer
Settling Pond (N.O.)
Settling Pond, Field Spreading
Settling Pond, Slough
Settling Pond, S.L.R.O.
S.L.R.O.
Waste Burner
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
Settling Tank,
S.L.R.O.
Other£/
.3
c
M
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M-l O
•H J2
i-l Ctf
(8 T>
U H
1
1
1
1
1
1
2
1
1
1
2
Montana
1
2
1
Oregon
2
4
5
5
3
1
1
8
2
4
1
3
4
1
1
8
1
4
1
Washington
1
1
1
4
3
1
1
12
1
5
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3
1
1
5
7
8
3
2
1
14
7
5
1
4
5
1
1
1
2
20
2
11
1
a/
— Nonoverflow
k/Stream, Lake, River, or Ocean
£/Waste is put in Drums and hauled to Land Disposal
-34-
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TABLE 14
Chemical Analysis of Settled Effluent
Analysis & Units
PH
COD, mg/1
TOG, mg/1
Total Phosphate, mg/1
Total Kjeldahl
Phenol, |ig/l
Suspended Solids, mg/1
Dissolved Solids, mg/1
Total Solids, mg/1
mg/1
.trogen, mg/1
mg/1
mg/1
1
ispended Solids, mg/1
ilids, mg/1
#2 a/
Plant
11.6
1814
772
15
110
1667
148
1479
1627
125
1122
#3 y
Plant
9.4
1917
723
9
64
1790
356
1458
1814
338
1267
#4 y
Plant
10.8
1621
540
12
3
222
330
790
1120
322
919
—'Average of 2 grab samples
2/Average of 3, 24-hour composite samples
£/Average of 2, 24-hour composite samples
-35-
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they are completely filled, resulting in zero or even negative
efficiencies.
Table 13 also shows that 18 plants employ some type of non-
overflow system to dispose of their waste. In this type of system,
rates of evaporation and infiltration exceed the waste input.
Because of the plugging nature of glue solids, evaporation probably
accounts for most of the moisture lost.
Twelve of the plants surveyed dispose of their waste in munici-
pal treatment systems. High pH plus wood chips and glue solids cause
some problems at these plants. Adjustment of pH and the use of
settling tanks or ponds should make the waste amenable to conventional
waste treatment. The settling tank would also help damp out any
slugs of toxic materials such as phenolic compounds which could
upset the balance of a biological system.
Eleven of the plants listed in Table 13 dispose of their waste
without treatment of any sort. The majority of these plants are
located on large bodies of water such as Puget Sound, the Pacific
Ocean, or the Columbia River.
B. Incineration of Waste
Due to the low volume of waste, the high organic content of the
waste, and the availability of existing sources of heat, disposal
by incineration offers a potential solution to the glue waste
problem.
The survey of plants indicated that three plants at the present
-36-
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time are using their waste burners to dispose of their glue waste.
Realizing that waste burners burn rather inefficiently and that
these metal "teepees" will be eliminated in the near future, some
other source of heat is needed. One large corporation is consider-
ing the use of their Dutch ovens. Most plants have this type of
device to generate heat. These ovens burn at temperatures from
1800-2000° F. If sander dust is burned, the temperature can go
as high as 2500°F.
An ash test was made on samples of interior and exterior glue.
These were run at the usual 600°C (1112°F) and at 1000°C (1832°F).
The results of these tests are shown in Table 15. The tests
indicate that at 1000°C (1832°F) very little ash would remain. The
interior glue produced 4.12 and 23.40 percent ash, based on wet
and dry weight, respectively, at 1000°C (1832°F). The exterior
glue produced 6.12 and 15.76 percent ash, based on the wet and
dry weight, respectively, at 1000°C (1832°F). A plant with three
spreaders running six spreader shifts per day and washing down each
shift would generate about 12 pounds of ash per day. This is a
small percentage of the total ash produced in a furnace of this
type.
The ash produced at 1000°C (1832°F) was tested to check
whether it could be redissolved. A small portion was redissolved
in H20 while the majority could not be redissolved with either the
strongest acids or bases.
-37-
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One of the biggest problems in this method of disposal lies in
transporting the glue waste from the spreader to the furnace.
Maintenance of pumps and lines must be low. This problem will be
investigated further as it will be important in many treatment
schemes.
A third problem lies in a potential air pollution problem.
Before incineration can be an accepted method of disposal, it must
be shown that no harmful pollutants are given off from the burning
of this waste.
-39-
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VII. PROPOSED STUDIES
Future work on the project will be aimed at determining
applicable treatment methods for plywood glue waste. Investi-
gations will be made in regard to biological treatment, floc-
culation, sedimentation, and incineration.
Biological treatment will be studied by installing a mechanical
aerator at a plant and by using some bench scale activated sludge
units. These studies will be made with and without the use of
pH control and additional of nutrients. The work with the bench
scale units should give basic information on the treatability of
the waste including some insight into the effect of glue waste
on municipal treatment systems.
Flocculation and sedimentation studies will be made at the
bench scale level. These investigations will include the use of
flocculating agents such as alum, lime, ferric chloride, etc.,
plus the addition of polyelectrolytes. pH control will also be
studied along with this phase of the project.
More work will be carried out on the process of incineration.
This work will mainly concern problems associated with storage and
handling of the waste from the time it leaves the spreader until
it reaches the furnace. These problems could be acute as waste
streams to be treated must be highly concentrated.
Water use and reuse will also be studied in conjunction with
the above-mentioned treatment schemes.
-40-
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VIII. SELECTED REFERENCES
1. Sawyer, Clair N., Chemistry for Sanitary Engineers, McGraw
Hill, New York, 1960.
2. Anon., 1967 Plywood and Board Products Directory, Forest
Industries, Portland, Oregon, 1967.
-41-
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IX. APPENDIX
-------
APPENDIX A
DEFINITION OF TERMS
-------
DEFINITION OF TERMS
COD -- Chemical Oxygen Demand. A measure of the pollutional
strength of sewage and industrial wastes which is based on fact
that all organic compounds, with a few exceptions, can be oxidized
to carbon dioxide and water. COD values give the amount of oxygen
required to perform this oxidation.
Cold Deck -- A method of log storage where logs are stacked
in piles and kept wet to prevent checking by use of sprinklers
located on top of the stack.
Conductivity -- Referred to as specific conductance at a
specified temperature (25°C). The opposite of resistance and
used as a measure of the concentration of total ionized solids
in water. Reported in micromohos (nMHOS).
Dissolved Solids — Solids which are in solution.
Exterior Grade Plywood -- Plywood made with 100 percent
waterproof glue and a high grade veneer.
gpm -- Gallons per minute.
Green End — Portion of plant involving the storage and handling
of logs through the process of turning them into veneer.
Interior Grade Plywood -- Plywood made with a moisture resistant
(but not waterproof) glue.
ug/1 -- micrograms per liter (1000 (j.g/1 = 1 mg/1).
mg/1 -- milligrams per liter (1000 mg/1 = 1 gm/1).
-43-
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mgd -- million gallons per day.
p_H -- The negative log of the hydrogen ion concentration. The
pH scale is usually represented as ranging from 0 to 14 with a pH
of 7 representing neutrality. Acid conditions increase as pH values
decrease and alkaline conditions increase as pH values increase.
Phenols -- (C6H50H) The monohydroxy derivative of benzene,
known as carbolic acid. Phenols are waste products of oil refineries,
coke plants, and some chemical producing facilities. Phenols are
used extensively in the synthesis of phenolic type resins. Concen-
tration of phenols in the order of .01 to .1 mg/1 are detectable by
taste and odor tests.
Sphaerotilus sp. -- Slime-forming bacteria.
Spreader Shift -- One spreader running one shift (8 hours).
Suspended Solids -- Solids that either float on the surface
or are in suspension in water, sewage, or other liquids.
a/
TOG -- Total Organic Carbon. TOG is determined on a Beckman—
Carbonaceous Analyzer that catalytically oxidizes all organic
carbon to carbon dioxide that is measured with an infrared analyzer.
Total Kjeldahl Nitrogen -- Organic nitrogen and nitrogen in
the form of ammonia (Nl^). Does not include nitrogen in the form
of nitrates (N0§) and nitrites (NO^)• Nitrogen and phosphorus
are nutrients necessary for maintaining biological growth.
—'Use of product and company is for identification only and does
not constitute endorsement by the U. S. Department of the Interior.
-44-
-------
Total Phosphate -- Phosphorus in organic and inorganic forms.
Phosphorus and nitrogen are nutrients necessary for maintaining
biological growth.
Total Solids -- The sum of the suspended and dissolved solids,
Total Volatile Solids -- The quantity of solids in water,
sewage, or other liquids lost on ignition of the total solids at
600°C (1112°F).
Total Volatile Suspended Solids -- The quantity of solids in
water, sewage, or other liquids lost on ignition of the suspended
matter at 600°C (1112°F).
Veneer -- A thin sheet of wood turned off a log by a lathe
and used in the production of plywood.
-45-
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APPENDIX B
PLYWOOD PIANT LOCATIONS
-------
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