Draft Report on Waste Pofiles
of the Paper Industry
ENVIRONMENTAL PROTECTION AGENCY • WATER QUALITY OFFICE
-------
DRAFT REPORT ON
WASTE PROFILES
OF THE
PAPER INDUSTRY
by
WAPORA, Inc.
1725 DeSales St., N.W.
Washington, D. C.
for the
Office of Water Quality
Environmental Protection Agency
Covering
Contract #68-01-0012
Contract #68-01-0022
Date: March 5, 1971
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CONTENTS
PAGE
INTRODUCTION 1
MAJOR_PROCESS CATEGORIES
I. Wood Preparation - 5
II. Groundwood Pulp 16
III. NSSC Pulping 22
IV. Kraft and Soda Pulping 27
v. Pre-Hydrolysis .31
VI. Kraft-Sulfit* Bleaching 32
VIII. Kraf t-Sulf ite Bleaching 32
VII. Acid Sulfite Pulping 35
IX. Deinked Pulp 39
X. Paper Making 43
XI. Waste Paperboard 49
XII. Building Products 56
OTHER MILL EFFLUENTS 60
WASTE PARAMETERS (SWRL) 61
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LIST OF FIGURES
PAGE
I. Settling Rate of Barker Screening Effluent ..-13
II. Wet Debarking Flow Diagram 14
III. Groundwood Pulp Flow Diagram 20
IV. Refiner Groundwood Pulp Flow Diagram 21
V. BOD Load of Effluents from NSSC Pulping 24
VI. Suspended Solids Loss from NSSC Pulping 25
VII. NSSC Pulp Mill Flow Diagram 26
VIII. Kraft Pulping Flow Diagram 29
IX. Kraft Recovery System Flow Diagram 30
X. Four Stage Bleaching Flow Diagram 34
XI. Acid Sulf ite Pulping Flow Diagram 37
XII. Magnesium Base Sulfite Recovery System Flow Diagram...38
XIII. Deinking of Waste Paper Flow Diagram 41
XIV- Fordrinier Paper Machine Flow Diagram 45
XV. Waste Paper Board Mill Flow Diagram 54
XVI. Insulating Board, Builing Board and Hardboard Flow
Sheet 58
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LIST OF TABLES
PAGE
I. Major Manufacturing Categories A
II. Leachate From Logs 11
III. Analysis of Debarking Effluents 12
IV. Effluent Characteristics of
Groundwood Pulp Mills 19
V. Analysis of Waste Paperboard
Mill Effluents 53
VI. SRWL Data for Major Industrial
Categories 76
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ABSTRACT
This report includes short descriptions of the major waste waters
discharged from pulp and paper mills previous to any external treatment.
Tte concentration values for BOD^ and suspended solids are included together
with other effluent characteristics. A flow sheet of each major process
is also included together with references as to where the information was
obtained.
Data collected also includes load factors for individual manufacturing
processes with ranges of BOD and total suspended solids lost from each,
together with corresponding typical values. With the exception of processes
for which fiber or cooking liquor recovery processes are operative, little
can be done about these losses since they represent materials that must
be removed from the raw material in order to make a satisfactory product.
The quality and quantity of these is determined by the various raw materials.
used such as wood, waste paper, etc. The values set forth are referred to
as the "Standard Raw Waste Load" (SRWL).
In addition, Tables indicate pH range, color and COD values for the
various wastes where these are available and indications as to what
heavy metals, if any, might be present. Also, notations regarding their
potential toxicity to aquatic life are included together with a listing
of their pollutional characteristics.
In arriving at the SRWL figures experienced judgment of both the authors
and specialists from the industy were employed to evaluate collected data.
Frequently, due to combined sewering many of the industrial figures collected
represented more than one operation and could not be used per se. It
is felt that the data presented represent as sound values as can be obtained
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considering the many variables involved in pulp and paper manufacturing.
We believe that with only minor adjustments the data will meet with
approval of those industrial engineers acquainted with effluent control.
The parameters of pollution as they apply to these spent process
waters are discussed in detail. The limited amount of mass data available
in some process categories is evidence of the unimportance of many of them
to these wastes. The major problems involved with them are caused by suspended
and dissolved organic matter. Strong emphasis is, therefore, put upon
these criteria by tne industry and regulating agencies.
11
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INTRODUCTION
This progress report covers the pertinent information requested by
the Environmental Protection Agency for review prior to the interim report
and conference scheduled for April, 1971. The report includes:
1. A description of the processes used in producing
most of the pulp and paper products manufactured
in the United States. These processes have been
broken down into categories and sub-categories
based on logical sequence in production and technical
judgment on the types of wastes produced.
2. Narrative information on the pertinent waste load constituents
as they apply to each manufacturing process category. This
discussion covers the basis for establishing Standard Raw Waste
Load parameters.
3. Flow diagrams of the processes involved in each major
category. The diagrams show product lines, water flow,
wastewater flow, recirculation patterns and sources of
air pollution and solid wastes produced.
4. A comprehensive Table showing the "Standard Raw Waste
Loads" (SRWL) for the processes described. Included
are the major parameters of concern in wasteloads from
each process, the range of quantities of these (in mg/1
per ton of product) and a typical level of wastes which
might be expected.
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The number of mills included in some of the sampling is not as large
as desirable because either the sewer division in many mills did not allow
process effluent segregation or that surveys available did not concern
themselves with more than overall discharge from individual mills or
segments thereof. There is a feeling among many regulatory agencies
that their concern is for the total discharge rather than individual
process effluents and the data available reflects this.
The delay involved between requests and receipt of information
has also been a limiting factor. Hence, it is felt that further information
will be available relative to SRWL. However, it is doubtful that the figures
presented herein will be substantially changed since both experience and
published summaries strongly support the data presented. Also abundant
information was available for the major chemical pulping processes which
account for a very large percentage of the total production involving
the large units of the industry.
No information was available on a few minor processes. A continued
effort will be made to obtain data regarding them even though they represent
only a small factor in respect to the number of operating mills and tonnage
of product.
More serious is the limited number of parameters of pollution reported.
Inmost cases, this is limited to BOD and total suspended solids. However,
pH, COD and color figures are to be found in operating and research reports
which will allow an estimate to be made.
Little information is to be found on heavy metals or on the effect of
wastes on aquatic productivity, however, those wastes which are potentially
toxic to aquatic organisms are well established. Wastes so involved
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are identified in the Table presented together with a statement relative
to the undesirable qualities of each effluent.
It is not possible to supply detailed data of value for speciality
paper mills because of the very wide variety of products made by most
of them. A large number of mills manufacture products on a short run
basis.
In considering raw waste loads it must be appreciated that except
where initial recovery systems are involved, little can be done to
control the volume and character of the waste waters discharged. It
must also be realized that most mills operate with some degree of
flexibility relative to the products manufactured. This flexibility
is reflected in effluent character, strength and volume. Recovery systems
tend to minimize effluent variations from pulp mills.
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TABLE I
MAJOR MANUFACTURING CATEGORIES OF THE
PULP AND PAPER INDUSTRY
I. WOOD PREPARATION
A. Hydraulic Barking
B. Drum Barking
C. Wood Washing
II. GHOUNDWOOD PULP
A. Stone Grcundwood
B. Refiner Groundwood
C. Cold Soda Pulp
III. NEUTRAL SULFITE SECT-CH3iMICAL PULP
A. No Recovery
B. With Recovery
IV. KRAFT AND SODA PULPING
V. PRE-HYDROLYSIS
VI. KRAFT BLEACHING
A. Semi Bleach
B. High Bleach
C. Dissolving Grades (Soft Wood)
D. Dissolving Grades (Hardwood)
VII. ACID SULFITE PULPING
A. No Recovery
B. MgO Recovery
C. NHo Recovery
VIII. SULPHITE PULP BLEACHING
A. Paper Grade
B. Dissolving Grade
IX. DEINKED PULP
A. Magazine and Ledger
B. News
X. PAPER MAKING
A. Coarse Paper
B. Fine Paper
C. Book Paper
D. Tissue Paper
E. Specialties
XI. WASTE PAPERBOARD
XII. BUILDING PRODUCTS
A. Building Papers
B._ Felts
C. Insulating Board
D. Hard"boaM
E. Exploded
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CATEGORY I
WOOD PREPARATION
Underwater Log Storage
Some mills store their wood supply underwater, others spray log piles
with water to prevent deterioration and maintain a uniform moisture content.
The latter practice has taken precedence over the former because of its
much lower cost. The leaching effects of underwater storage were studied
by (Schaumburg) (12). In his experiments (unbarked and barked) logs
were submerged for 7 days in water containing sufficient mercuric chloride
to prevent biodegradation of the leached substances. Data obtained for
three species of wood is shown in TABLE II»giving the BOD,- values of the
water containing the leachings and the BOD^ leached from each square
foot of log surface exposed. From these data it was computed that a cord
of unbarked wood will add from 0.5 to 7.0 pounds of BOD and 0.8 to 23
pounds of COD to the water in which it is stored.
Log Washing
Logs are frequently washed before debarking by a water shower to
remove silt. This practice applies to both wet and dry barking. In most
installations the shower water discharge is activated by the log on the
conveyer so that a minimum of water is used. The actual quantity dis-
charged per unit of wood handled or pulp produced is most difficult to
ascertain because of the wide variation in stick size relative to weight
and the fact that at all installations all the wood debarked is not pulped,
a portion going to lumber.
It is established that this effluent is very low in volume, color
and BOD and that its suspended solids content is largely silt. Hence,
it is generally disposed of on the land together with grits from the
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pulp mill or ashes from the boiler plants in dry barking establishments
or combined with the general discharge in the case of wet barking installations.
Debarking
Most of the pulpwood used in the United States is small in diameter
and it is debarked dry. However, when large diameter wood is used?wet
debarking is employed. These latter operations are pretty much limited
to the Northeast and Northwest. Wet barking of logs is generally accom-
plished by one of three methods namely, by drums, pocket barkers or
hydraulic barkers as described in Volume I of the Joint Textbook of the
Paper Mills (1). Slabs are generally handled by hydraulic units as is
the larger diameter/round wood. The wet drum barker consists of a slotted
drum equipped with internal staves which knock the bark from the wood
as the drum rotates in a pool of water. The bark falls through the slots
and is removed with the overflow of water. Water is recycled in some units
which debark from 7 to 45 cords daily. Performance of these devices vary
widely with wood size.
Wet pocket barkers are stationary machines which abrade bark from
timber by jostling and gradually rotating a confined "wood stack against
an endless chainbelt equipped with "dogs" which raise the pile allowing
bark to pass between the chains. Water is sprayed through appatures ••
in the side of the pocket at rates of between 330 and 600 gpm for pockets
of 2.8 and 5.7 cords respectively.
Hydraulic barkers employ high pressure water jets to blow the bark
from the timber which is either conveyed past them or indexed under a
moving jet which traverses the log.
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Water discharged from all three types is generally combined with
prewash water from sprays, which give the logs a preparatory cleaning
and coarse screening to remove the large pieces of bark and splinters
which are conveyed away continuously. The flowage then passes to fine
screens of the drum or horizontal vibrating type having mesh or perforated
plates with openings in the range of 0.05 to 0.10 inches. Screenings
are conveyed away and mixed with the coarse materials, the mixture being
dewatered in a press prior to burning in the bark boiler. Press water,
(which is combined with the fine screen effluent is minor in volume).
This waste amounts to about 300 gallon a ton and carries less than one
pound of BOD and three pounds of suspended solids per ton of product.
The combined discharge contains bark fines and silt, the latter
varying greatly in quantity since its presence is due mainly to soil
adhering to these logs. In dry weather the percentage of silt in relation
to bark fines is low as is the case for logs stored in or transported
by water. However, attachment of mud in wet weather can make this material
a substantial percentage of the total suspended matter passing the fine
screens.
Analyses of fine screen effluent following hydraulic barkers has been
given by several investigators (2) (3) (4) (5) and examples are shown
in TABLE III.In the case of this effluent the water originally employed is
all fresh process water since the close clearances of the high pressure
pumping systems supplying water to the jets will not tolerate the presence
of suspended solids in the water. It can be concluded from these data
that these effluents have a total suspended solids content of from
521 to 2350 mg/1 with an ash content ranging from 11 to 27%, usually
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running below 15% for clean logs. BOD5 values range between 56 and 250
mg/1. These low values are due to the fact that the contact of the water
with the bark is short and no grinding action on the wood takes place.
Hence,leaching of wood and bark solubles are minimized. This is not
the case with drum and pocket grinding where attrition in contact with
water over an appreciable period of time takes place. Also, spent pulping
and bleaching process waters already high in BOD are not infrequently
used for barking which raises further the ultimate level of organics
in the screened effluent. While wet drum and pocket barker screens
discharges are not greatly different from that of hydraulic barkers in
suspended solids content, the BOD,- ranged from 480 to 987 mg/I (6) (7 )
in the data shown in TABLE III.
BOD values are also greatly affected by the species of wood debarked
and the season in which the wood was cut since the wood juices and trash
extractables are responsible for it. That contributed by the suspended
matter present is a minor fraction of the total BOD curves (3) indicate
the 15 day values to be about twice that of the five day with little
further demand being exerted after this period. The oxygen demand
rate over five days is similar to that of sanitary sewage.
Settling will remove from 70 to 90 percmt of the total suspended
solids present and is essentially complete in 30 to 60 minutes. Settling
curves were published by Draper and Mercier (2 ) and Blosser G ) and a
typical one is presented in Figure j . Because of the good settling
characteristics of the screened effluent sedimentation is employed for
clarifying it. Also, because of this attribute coagulants are not needed (8)
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Settling is sometimes accomplished in alternating earth embarked basins
from which the settlings, which compact well, are dredged. More modern
practice is the use of circular, heavy duty type clarifiers. These
are designed for a rise rate of 1000 to 1200 gal/ft^ of suface area a
day and have a retention period of about two hours. These are equipped
and piped to handle dense sludge such as that produced when considerable
silt is present in the underplane as well as a skimmer to collect the
floating materials, some of which are always present, The underflow is
removed by means of a diaphram, plunger or screw pumps and delivered
to drying beds or to a vacuum filter for dewatering. The latter can be of
the disc or drum type, and because of the freeness of the solids this can
operate at high submergence producing a thick cake. Drum speed is variable
so that variations in cake freeness can be accomodated and a vacuum of about
15 inches is desireable. Filter media frequently consists of 120 mesh
stainless steel wire cloth. Filter cake produced contains about 30% solids
and loadings range from 10 to 12 pounds of dry solids per square feet
per hour. Such cakes are either disposed of on the land or sold as mulch.
A diagram of the entire process is presented in Figure II
Effluents from clarifiers are not treated furtner separately but combine
with pulp mill and other wastes when biological treatment of them is practiced,
As can be judged from the BOD rate biological treatment of them represent
no problems.
Pennsylvania established raw waste standards for barker effluents
in the early 1950's (9). These allowed 50 to 70 pounds of total suspended
solids and 15 to 20 pounds of BODc per ton of pulp produced. Raw waste
standards for barker effluents are of little significance since no control
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can be exercised over the process discharge except to see that screening
and clarification are adequate. The state of Washington, however, has set
an effluent standards of less than 200 mg/1 of volatile suspended matter,
a value which can be met by clarification installations of good design and
operation. It is impossible because of the many variables involved to set
a fixed number for the volume, pounds of BOD^ and total suspended solids
discharged per ton of pulp produced. However, a single barker of the
usual size operating on common sizes of logs can generally serve a 200
to 300 ton/day pulping operation and employs between 100 and 150
gpm of water.
10
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TABLE II
LEACHATE FROM LOGS OF DIFFERENT SPECIES - (7 DAYS EXPOSURE)
BOD
(WATER TREATED TO PREVENT
BIO-DEGRADATION)
COD „
Douglas Fir
50 years old
Douglas Fir
Douglas Fir
120 years old
Hemlock
Pondorosa
Pine
Bark
No Bark
Bark
No Bark
Bark-
No Bark
Bark
No Bark
Bark
No Bark
54
34
84
120
6
42
15
. 79
42
92
0.9 .
0.9
1.3
1.2
0.1
0.6
0.3
0.9
0.8
1.4
193
287
272
313
53
142
101
174
284
185
3.2
3.2
3.9
3.4
1.0
1.9
0.15
0.45
4.2
2.8
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TABLE III
ANALYSIS OF DEBARKING EFFLUENTS
Mill
I
2
3
4
5
6
7
8
9
10
11
Type
Debarking
Hydraulic
IF
II
(1
1 1
M
fl
ft
Drum
Drum
Drum
SSttSa
— — —
««_
^« M
...
(Avg)
Tot al ,
Suspend
Solids
2362
889
1391
550
521
2017
2000
600
2017
3171
2875
Non-
gSIids
141
101
180
66
53
69
<200
41
69
57
80
p/c Ash
of S.S.
27
14
17
11
13
21
19
10
21
18
BOD
85
101
64
99
121
56
97
250
480
605
987
Color
MM/1
<£50
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FIGURE I
SETTLING RATE OF
BARKER SCREENING EFFLUENT
EH
U
s
O
w
Q
§
^
P?
Pn
W
CQ
100
90
80
70
60
50
imri±a<«CTco]jr^UMMi
80 100
3240
1620
1000
810
648
CLARIFIER SURBACE LOADING- Gal./Ft./Day
13
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FIGURE II
Water
Raw
Logs
[-
Log Wash
•<>
Deck
Drain
West Barker
Drum Packet
or Hydraulic .Type
Logs
Coarse
Screening
...
A
Off
Gas
3yclon«
, ' Press I
r~Fmra;rRe-t"rn-^ VTSTrT ^ j
r Fine I •
Screening Bark
1 ' Boiler
i
Filter I ~~ Bark
Cake Vacuum Underflow Clarifier I Overflow To Mill
poll *»-. Filter P1| [ "*" Treatment Plant
jConditioner
Product
Bark ....
Water > _
Gas __ .
Bark
Ash
Wet Debarking
Flow Diagram
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REFERENCES
WOOD PREPARATION
1. "The Pulping of Wood," Textbook Committee of the Paper Industry,
2nd Edition, Volume I, McGraw Hill Book Company, New York (1969).
2. Draper, R. E., and Mercier, F.S., "Hydraulic Barker Effluent Clarifier
at Wood Products Division," Weyerhaeuser Company, Everett, Washington.
3. Blosser, R.O., "Practice in Handling Barker Effluents in Mills in
the United States", NCASI Technical Bulletin, No. 194 (1966).
k. "Pollutional Effects of Pulp and Paper Mill Pastes in Puget Sound,"
U.S. Dept. of Interior, FWPCA, Portland, Oregon, Washingtci State
Pollution Control Commission, Glympia, Washington (l-larch. 1967).
5. Rudolfs, W. , "Industrial Wastes," Chapter #10, ACS Monograph #118
(1953).
6. New Zealand Forest Products,Ltd., Private Communications.
7. Vickerman, J. L., NCASI Technical Bulletin, Purdue University,
Lafayette, Indiana.
8. Klingner, K., "Clarifying Debarker Waste Waters through Flocculation,'
Zellstoff Papier (German), 13, No. 181 (1964).
9. Pennsylvania State Department of Health, "Raw Waste Standards for the
Pulp and Paper Industry"(1951).
10. Washington State Standards for Barking Effluents.
11. Graham J., and Schaumburg, F.D., "Pollutants Bleached from Selected
Species of Wood in Log Strange Waters," 24th Industrial Wastes Con-
ference, Purdue University, Lafayette, Indiana (1968).
12. Schaumburg,, F.D., "The Influences of Log Handling on Water Quality,"
Department of Civil Engineering, Oregon State University, Project
No. 2, FWPCA Regular Grant, #WP-013220 (1969-1970).
15
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CATEGORY II
GROUNDWOOD PULP MILLS
Groundwood is produced from roundwood by pressing logs against a
large grindstone hydraulically in machines designed for this purpose.
The logs are barked prior to grinding, hence groundwood mills generally
have a wood preparation plant similar to that of chemical pulp mills.
On discharge from the grinder the pulp is screened free of splinters
and other coarse wood debris then thickened on deckers. The decker
filtrate is generally recirculated with some being bled off continuously
to prevent solubles from building up in the system with attending slime
problems. This discharge seldom exceeds 10,000 gal/ton of product and
in some cases is as low as 2000 gal/ton. The BOD5 of these wastes ranges
from about 5 to 20 ppm and is due largely to wood juices. Hence,
the species of wood and the season at which it was cut influences this
number and nothing can be done in the manufacturing process to control it.
Total suspended solids content is quite uniform at mills exercising good
loss control, running from 10 to 20 pounds per ton. In the case of large
mills this is frequently on the lower sides.
A list of mills showing their effluent volume together with their
BOD^ and total suspended solid losses is shown in TABLE IV the U.S.
Forest Products Laboratory, and others, give similar numbers.
The only raw waste standards of record for mills of this type are
those set forth by Pennsylvania. These set forth an effluent flow range
of 5 to 10 thousand gallons per ton of product with a BOD5 loss of 16
to 22 pounds per ton of products and a suspended solids loss of 70 to 35 .
The latter figures were based on older practice in which decker seal pit
water was not recirculated.
16
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Groundwood pulp is also produced from chips by passing through disc
refiners. Two stages of refining are employed followed by a third
generally a part of the papermaking process. These machines consist of
fixed and rotating serrated discs,; between which chips or saw mill residues
are passed. Some machines employ discs turning in opposite directions.
Water is added with the chips and the pulp is discharged as a thick slurry.
In the case of both stone and refiner groundwood, the pulp is diluted,
screened and then deckered to the desired consistency. The discharge
from the process is water lost from the deckering system, the remainder
being returned for stock dilution. Figure III and IV show flow designs.
Groundwood pulping effluents can be clarified by settling of flotation
yielding a clear effluent since about 90% of the total suspended solids
are settleable. However, the sludg'e produced is very hydrous averaging
only about 0.5% consistency and most resistant to dewatering. It can
be dewatered by the addition of other pulp and paper mill solids if a sufficient
percentage of them are available. These are generally supplied by settling
two wastes together.
Groundwood mill effluent is responsive to biological treatment alone
and in combination with other wastes such as kraft pulping and bleaching
effluents. However, when treated alone by the- activated sludge process
a relatively lower oxidation rate has been observed for it than when com-
bined with kraft mill discharges.
Two large mills treat this waste in combination with bleached kraft
effluent by the activated sludge process and two others in aerated
stabilization basins. Another mill employs storage oxidation for like
treatment.
17
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Bleaching of Groundwood Pulp
Groundwood pulp is generally bleached with hydrogen or sodium
peroxide, sodium or zinc hydrosulfite and sodium sulfite. Interest
has developed recently in the use of. peracetic acid, sodium borohydride and
amine borides for this purpose, but their use is not established.
The pH is generally adjusted to between 4.5 and 7.0 depending
upon the bleaching agent and sometimes 'complexing chemicals are added to
tie up heavy metals and other undesirable material which may be present.
Buffers and catalytic agents are also used at times.
Since groundwood can be bleached at high consistency it is frequently
used without washing. Hence, the bleaching operation itself produces no
liquid effluent, the small amount of residues appearing in the paper machine
white water.
18
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TABLE IV
Effluent Characteristics of Ground Wood pulp Mills
Eff. Floxj
Thous . /gal/t on
Mill
1 6.3
2 1.9
3 4.4
4 5.4
5 8.3
6 2.7
7 2.2
U.S Forest Prod. Lab.
Gur nil am,'' Inc.. Was t e
V/at er Contr oi''
Chap. 20 - Genm 4 to 10
Penn. Rav; V.'aste
Standards 5 to 10
BOD^5
ft/ton
11
8
11
9
18
19
4
rrl 0 o
1,0. v.-
#/tor
16
1<
11
1?
1"
-
•,2
3 to 18
15 to 25 40 tO 80
16 to 22 70 tO 85
19
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Product _
Water
Screenings .,
Chemicals
FIGURE III
Groundwood
Pulp
Flow Diagram
Water
Overflow
Peeled
Wood
Storage
•C»4 Grinders
I
Course
Screens f
Screenings
Water
Product
20
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FIGURE IV
Product
Water
Refiner Groundwood
Pulp
Flow Diagram
Return
Fiber
Water
ProducUo
Overflow
to
Sewer
21
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CATEGORY III
NEUTRAL SULFITE
SEMI-CHEMICAL PULPING
Approximately 10,000 tons of NSSC pulp is produced in the United
States daily. This is a two stage process in which the wood chips are
softened by a short cook with a neutral sodium or ammonium sulfite
solution; then defibrinated in a refiner. Pulp yields from the
wood range from 60 to 80 percent on a bone dry basis to produce a variety
of products from corrugated'board to a bleachable pulp. Most, however,
goes to coarser products since the bleaching of this pulp will soon
come to an end in this country.
While some mills buy the -cooking chemicals, most prepare liquor by
burning sulfur and absorbing it in ammonia or soda ash. This part of
the process produces little liquid wastes 'other than fioo drainings
and equipment wash-up waters.
Chips are cooked in both batch and continous digesters and passed
through refiners prior to washing. Digester relief and blow gases are
condensed, and in some mills used for pulp washing. Wash water together
with drainings from the blow tank are delivered to the.recovery or
liquor burning system. Since many of these mills are adjunct to kraft
pulp mills the spent liquor is recovered in the kraft system, supplying
the necessary chemical make-up.
From the washers the pulp is conveyed to an agitated chest where it is
diluted with white water from the paper mill to the desired Consistency
for feed to the secondary refiners serving the paper making operation. Other
than spent liquor,the pulping and washing operations discharge little waste
water since the small amount of residual liquor solids present in pulp
22
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is carried through the machine system passing out with the overflow white
water.
Spent liquor is commonly fed to triple effect evaporators after which
it is burned with bark, in a fluidized bed or in a special furnace if chemical
recovery is practiced. The latter practice is limited to a few large mills.
The final effluent from NSSC pulping is low in volume because of the
high degree of recirculation practiced. For the same season it is usually
high in BOD^ ranging from 1500 to 5000 mg/1 with a suspended solids content
of from 400 to 600 mg/1. The color and COD content are correspondingly
high. Overall process losses without recovery are shown in Figures "
and VI. Figure "VTI shows a flow diagram of the NSSC Pulp Mill.
23
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FIGURE V
700
600
500
I
g
§
CO
o
Pk
400
300
200
100
BOD LOAD OF
EFFLUENTS FROM
NSSC PULPING
BLEACHED
UNBLEACHED
1___L
50
55
60
65
J_
70
75
tn&e-'Brt
80
PERCENT YIELD
24
-------
FIGURE VI
O
ra
en
P
O
CO
P
s
55
w
^
CO
en
P
120
100
80
SO
40
20
SUSPENDED SOLIDS LOSS
FROM
NSSC PULPING
0
60
65
70
75
80
85
PERCENT YIELD
25
-------
Product _
Water
Chemicals
Steam
FIGURE VII
NSSC Pulp Mill
Flow Diagram
Chip
Storage
Cooking
Liquor
Digesters
1
Cooling
Water
Steam
Dilution
Liquor
Blow
Tank
Refiners
I
Washers
Spent Liquor
Evaporators
i
i
vap.
onfl.
Boiler
Plant
1—
White
Water
Tank
t
I
o-—
Overflow
to
Sewer
Saveall
Shredder
Fitter
to
Process
Paper
Machines
Stock
Gas
Liquor
Burning
or Recovery
Product
Water
Recovered Chemical
26
-------
CATEGORY IV
KRAFT AND SODA PULPING
About 85 percent of the chemical pulp produced in the United States
is kraft pulp. In the kraft pulping process wood chips are cooked in
either batch or continuous digesters with solution of caustic soda and
sodium sulfide. Because of the high cost of the chemicals employed and
other reasons,a recovery process is inherent to this pulping method.
This necessitates separating the spent liquor from the pulp to a high
degree and in as high a concentration as possible.
The liquor is then evaporated in multiple effect evaporators followed
by either a contact evaporator or a concentrator. The heavy liquor is then
burned for its heat value in a recovery furnace and the ash,which is
in the form of a smelt, dissolved in water and processed to render it
suitable as fresh cooking liquor.
The waste water streams of greatest importance which are discharged from
the cooking section of the mill are digester relief and blow condensates.
Turpentine is generally separated from these by gravity and the water
sewered. It contains mainly methanol, and accounts for about one-third
of the BOD5 lost from the process.
Spent liquor is separated from the pulp by counter-'-.urrent vacuum
or diffuser washing and the pulp diluted for screening. It is then
deckered back to high consistency for refining and the water removed
is sewered. This accounts for another third of the BOD^ loss and
contains some suspended solids.
The remaing third consists of evaporator condensates, chemical
plant wash waters, flow and miscellaneous drains.
Combined kraft mill effluent generally ranges between 150 and 300 mg/1
27
-------
BOD,- and contains a similar, concentration of suspended solids together with
750 to 1500 mg/1 of color. Total solids run normally from 1200 to 2000
mg/1, the inorganic portion of which consists mainly of sodium and
calcium sulfates. The pH is between 9.0 and 10.0 under normal operating
conditions and the COD between 350 and 500 mg/1.
This waste responds well to common treatment processes such as sedimentation
and biological oxidation when nutrients are added. Methods for removing the
color and refractory organics are under large scale mill investigation
by the industry and Office of Water Quality. Mainly methanol accounts for
about 25 percent of the total BOD load of a mill.
Figure VIII shows a kraft pulping flow diagram.
Figure IX shows a kraft recovery system flow diagram.
28
-------
Product"
Water
Chemicals
Steam
Kraft Pulping
Flow Diagram
FIGURE VIII
Chips
Steam
J" White Liquor
_|" Black Liquor
Condensate
C>JTo Sewer
rurpentine
Recovery
Turpentine
Cooling
Water
Accumulator ._ _ —
lulti Effect
Evaporators'
Weak Liquor
Storage
Blow Tank
Contact
Evaporator
To
Recovery
System
Talloil
Non-condensable
Gases
Fresh Water
i
i
Washers
Knotters
Rejects «^—I
Screening
Decker
Brown
Stock
Storage
29
-------
Product
Water
Chemicals
Steam
Kraft Recovery
System
Flow Diagram
FIGURE IX
Off
Gases
•
Strong Steam <>• •
Black
Liquor -^
-i _ _ _ ^»
Storage
Salt
Cake
t
ff Gases
i r Weal
£ Water Lm
; j— L"vdLt;i ffasj
i
i
Scrubber — - (
T.imp
Grits L- '
J0' ' _ _ ./i
! * *
1 '.._ _i tator
A
T
i
Recovery
Furnace
j
I" ' T j
9 *
Dissolving
Tank
1
< i
i i
^
Green
Liquor
Clarif ier
i
i i
- "7
Caus.ticizing
i
*
White
Liquor
Clarif ier
! !
i i
i
i
i
• • ^.<="-i
— - 1
i
i
i
>
i
i
i
i
i
i Salt
^ Cake
Water
i
^
Dregs
Washer
4
i
i
i
V
Dregs
Whi te
-._ Liquor
Storage
30
-------
CATEGORY V
PRE-EYDROLYSIS
In order to obtain a more easily bleaching pulp from the kraft and
sulfite processes, the chips are sometimes steamed in the digester prior
to addition of the cooking liquor. After steaming the digestor is relieved
and drained. The condensate and drainings contain wood solubles and have
a BOD5 value of from 2,000 to 5,000 mg/1. This practice is followed
particularly in the production of dissolving grades where coupled with a
"soft" cook, "bleaching chemical consumption and bleach plant as well as
overall mill losses are reduced since more organic material goes to the
recover plant. The pre-hydrolysate is frequently added to the weak black
liquor, hence does not enter the sewer system.
31
-------
CATEGORIES VI AND VIII
KRAFT-SULFITE BLEACHING
The most important bleaching operations from the effluent standpoint
are those for sulfite and kraft pulps.. This is because a considerable amount
of organic material is separated from the pulp as compared to bleaching
mechanical pulps and no method for its recovery is available. Hence, no
control of these losses can be exerted other than by external treatment
The inorganic constituents of the waste, mainly chlorides, can also prove
a problem in receiving waters.
While there can be many stages in a bleach plant, the important
ones from an effluent standpoint are the chlorination and alkaline
extraction stages. The finishing steps such as those involving
hypochlorite and chlorine dioxide usually produce a wash water that can
be recycled to the chlorination and extraction stages.
Bleaching effluents are high in color, in particular those from the
caustic extraction stages in which color bodies chlorinated in the first
stage are washed from the pulp. Color values of 6000 mg/1 are not
uncommon in the combined chlorination and extraction wash waters while BOD
values range from 150 to 300 mg/1 depending upon the de'gree of recirculation
practiced. Chloride concentration in the effluent can be accurately com-
pited by adding the chlorides present in the process water to those added
in the forms of chlorine, chlorine dioxide and hypochlorites to the process.
Degrees of bleaching vary and the sewer losses increase with the
brightness to which the pulp is bleached. The bleaching technique is also
. used to produce dissolving grades of pulp which consists almost entirely
of alpha cellulose. Since the shrinkage experienced in producing these
giades is Of the order of 25 percent, as compared to 5 percent for papermakir.g
32
-------
grades, sewer losses are correspondingly high. This is particularly
the case for the oxygen demand values since considerable hydroloysis of
cellulosic material takes place. However, when soft wood is involved more of
the load is in the prehydrolysate and cooking liquor since these woods
can be better prepared for bleaching than the hardwoods.
Figure X shows a four stage bleachery flow diagram.
33
-------
Product
Water
Chemicals
Steam
FIGURE X
FOUR STAGE BLEACHER*
FLOW DIAGRAM
Brown
Stock
Storage
Chlorination
Stage
1
f
— Chlorine
Fresh Water
Caustic
Extraction
[Caustic
""[Soda
Chlorine
Dioxide
Fresh
Water
Sulfur
Dioxide
Hypochloriteo— - -
I Hypochlorite
Bleached
Pulp
Storage
34
-------
CATEGORY VII
ACID SULFITE PULPING
About 10,000 tons of sulfite pulp is produced daily in the United
States. It is produced by, cooking wood chips with a bisulfite solution.
This was originally calcium bisulfite, but modern mills employ more soluble
bases such as magnesium, ammonia or sodium so that the liquor can be
readily burned and the chemicals recovered.
Cooking acid is made by reacting the base with sulfur dioxide, usually
produced by burning sulfur. The finished acid is cooled, filtered and
adjusted to strength and for use. Practically all the water leaving
this step in the process is cooling water which can be reused elsewhere.
The remainder comes from floor drainage, filter backwash and other
equipment cleaning operations and the impurities contained therein are in-
organic in nature.
After cooking the pulp is blown to a tank or blow pit and the "pulp
washed either in the latter or on drum washers. Final wash water is
sewered together with relief and blow condensates when the latter are
collected. The combined wastes amount to about one-third the total
BODc lost from the process.
Spent liquor is then evaporated in multiple effect long tube
evaporators and subsequently in a contact evaporator. Condensates from the
evaporation step are high in acetic acid and account for over 50 percent
of the BODr of the combined mill discharge.
The liquor is burned for its fuel value in special furnaces and in
the case of magnesium and sodium the chemicals are recovered from the ash
or smelt. Sulfur dioxide recovered from the off-gases is employed in
this recovery.
35
-------
Total effluent from sulfite mills employing recovery range from
1000 to 2000 mg/1 BOD5 and from 100 to 200 mg/1 in suspended solids.
COD values range from 1000 to 1500 and the pH is acid running from 2.0
to 3.0.
After neutralization, sulfite pulping effluent responds to biological
treatment for BOD reduction when nutrients are added..
Figure XI shows an acid sulfite pulping flow diagram.
Figure XII shows a tnagnesium base sulfite recovery system flow diagram.
36
-------
FIGURE 11
Product ^ r
Water ACID SULFITE
Chemicals PULPING
Steam FLOW DIAGRAM
Sulfur "1 cj Sulfur
J Burner
Water
Lime I -^ Absorption
Stone S L£^fL__
*
-, . i
Cooking oUcid
J*0 Cooler | S02
Chip To Process
Storage
Cooking Acid
Storage >
i
_A__ ]
e
->. ^^ ^ Relief •
Steam 1 Digester ['Gases'' • i
Red
Liquor
Storage
Blow Pits
or
Washers
To Recovery
or
By-Products
I
Pulp
Blow Gas
wash
i
37
-------
Product
Water
Chemicals
Steam
FIGURE 12
Magnesium Base
Sulfite Recovery System
Flow Diagram
[v
eak Red
^iquor Storagi
Evaporators
Condensates
1
Strong Red
JLiquor Storagi
To
Sewer
Fresh
Water
Off
Gases
*
•
•
•
._ S09
"^r, ^ *& ~
Recovery ^
•
i.
fortification
Tower
f i:_ .
Sulfur
Burner <> —
Direct Contact
Evaporator
1
\
Recovery
Furnace
I
I
Dust
Collector
WgO
r-Mg
|_ Ma
- - s>
_ — Sulfur
1
O
keup ,
»
r
Acid
Filter
i
i
Cooking
Acid
Storage
Bac
Was
:k
3h
-------
CATEGORY VTTT
PEINKING PULP
Waste papers are deinked for recovery of their fiber content mainly
at nine large mills in the United States. Six of these deink magazine,
ledger and other high grade raw stocks and three mills newsprint only.
A large number of small mills deink a variety of waste papers on a small
scale and frequently on an intermittent basis. Some mills also reclaim pulp
from trimmings, brake and other papers which have not been used but are
manufacturing wastes.
The deinking process involves cooking the papers in an alkaline solution,
soda ash, caustic soda, sodium silicate and at times sodium peroxide is
used. Some employ dispersing agents as well. The chemicals saponify these
ink vehicles and solubilize coating adhesives allowing the ink, coatings and
fillers to be subsequently washed from the pulp. In the case of news print,
*
which consists only of fiber and ink, a detergent is used to separate the
ink so that it can be washed out.
Washing is accomplished on Lancaster washers, in beaters, and in the
case of some small operations, on side hill screens. With some magazine
stocks as much as 40% of the bale weight of the paper is lost to the sewer
in the washing operation
After washing, the recovered pulp is generally given a light bleach
with a hypochlorite. The pulp is washed again after bleaching on drum washers
in large mills, but small ones usually wash in the beaters. Loses from this
operation are very small as compared to the others from the process, and
since the effluent from it is generally combined with this total flow, it
is included in the overall sewer loss data.
39
-------
Since the range of losses from the deinking of magazine and ledger
type stocks is so wide and newsprint so constant separate figures are presented
for each. The ash content' of the suspended matter contained in the former
is generally and in the latter low.
The suspended solids concentration deinking wastes from magazine
and ledger stock stocks runs from 1000 to 3100 mg/1 and the BOD in the
order of 300 to 500 mg/1. Combustibles present in the suspended solids
range from 28 to 61 percent and the total solids from 1,900 to as high
as 10,800.
Figure 13 shows a deinking of waste paper flow diagram.
40
-------
Product
Water
Chemicals
Steam
Waste
Paper
Steam
FIGURE 13
I
Rifflers
I
Centrifugal
Cleaners
Washers
Bleaching
Washer
Effluent
to
Sewer
To Process
Deinking of Waste;
Paper
Flow Diagram
jf"*-.
v-»
I_
___
Digester
1
r
Refiner
[cooking
(Chemicals
JFresh
"JWater
Bleaching
Chemicals
-------
REFERENCES
DEINKING PULP
1. TAPPI Monograph #16, "Deinking".
2. "Deinking Report", NCASI Technical Bulletin #5 (1946).
3. Hodge, W.W. and Morgan, P.F., "Characteristic and Methods of Treatment
of Deinking Wastes", Sewer Works Journal, p. 830 (1947).
4. Data supplied by NCASI and mills
5. Pulp and Paper Industries, Joint Textbooks, Vol. Ill, McGraw Hill Publishing
Company (1969).
6. Klebbe, P.J. and Rogers, C.N., "Survey of Water Utilization and Waste
Control Practices in the Southern Pulp and Paper Industry,"Dept. of
Wood and Paper Science, North Carolina State University, Raleigh, N.C.(1970).
7. Nemerow, N., "Theories and Practices of Industrial Waste Treatment",
Addison-Wesley Publishing Company, Reading, Massachusetts (1963).
8. Pulp and Paper Manufacturing, Volume III, McGraw Hill Publishing Company,
New York (1970).
42
-------
CATEGORY X
MANUFACTURE OF FI1IE PAPERS, BOOK PAPm AM) TISSUE
Most fine paper, took paper and tissue is manufactured on Fordrinier
machines. The pulp employed is refined and cleaned with centrifugal
cleaners and the necessary additives applied ahead of the machine. These
consist of sizing materials such as alum and rosins, sodium aluminate and
certain wax emulsions. Synthetics such as acrylics, isocyanates, alkene
ketene dimer, fluocarbons and others are sometimes employed to impart
special characteristics to the paper produced. Fillers such as clays,
calcium carbonate and sulfate, talc "barium sulfate, alumina compounds
and titanium dioxide are examples of these. When fillers are employed,
retention aids, generally synthetic resin type compounds are added to in-
crease retention of the filler in the sheet. Fillers add opacity to the
sheet and improve printatdlity. They are added in quantities up to 15$
•"by dry weights of the materials employed in the process.
Some papers are machine coated with mixtures of pigments and filler
materials and adhesives such as especially prepared starches, dextrines
and gums such as mannoglactans and synthetic resins.
All modern mills recycle most of the machine waters and employ a
save-all to capture materials lost through the Fordrinier wire. These
employ sedimentation, filtration and floation with the separated materials
being returned to the process and a portion of the clarified water re-
turned for stock preparation and other uses in the paper machine system.
White water from paper manufactured without fillers produces a machine
overflow water containing from 150 to 300 ppm of suspended matter
which consists mainly of pulp fines and is about 90% organic in nature.
EOD5 values are in the same range, the demand "being due to the cellulose
43
-------
present as veil as organic additives.
Filled and coated sheets produce effluents of about twice the
suspended solids content of those not containing inorganic additives.
About half of the additional suspended matter consists of these sub-
stances, hence their ash content is high, frequently amounting to kO% to
50$ of the total suspended solids. BOD values are frequently higher
"because of the adhesives used to retain the filler or coating in or on
the paper. The inorganic materials impart a high turbidity to these
effluents which is generally in proportion to the percentage used in the
furnish. The true color of such effluents is low and the pH is in the
neutral range.
These machine waters respond well to treatment "by the usual pro-
cesses with the exception of the fac.t that due to the presence of very
fine, high "brightness inorganics, removal of all opalescence is
difficult.
Tissue and toweling papers are produced on Fordrinier paper machines
from furnishes consisting mainly of bleached sulfite, kraft and ground-
vood pulp. Rosins are sometimes added to give these products special
properties such as high wet strength. Because of the light weights of
these sheets the volume of water employed is high and the effluents weak
ranging in total suspended solids content of from 15 to 250 -mg/1 and
BOD values of from 35 to 100 mg/1. These run higher at a few mills
vhich use some deinked pulp in the finish. The pH value is substan-
tially neutral and natural color is very low.
Figure 14 shows a Fordrinier Paper Machine Flew Diagram.
44
-------
Product
Water
Chemicals
Steam
Fordrinier Paper Machine
Flow Diagram
FIGURE 14
Pulp
Chest
Refiners
Fresh Water
Filtered
White
Water
Tank
Save
All
Rich"
White
Water
Tank
Ui
Overflow
to
Sewer
-------
REFERENCES
MANUFACTURE OF FINE PAPERS AND BOOK PAPER AND TISSUES
1. Wisconsin State Department of Health, Pulp and Paper Advisory
Committee Report (1965).
2. Black, H.H., "Baseline for A Normal Tissue Mill", Division of Pure
Waters, State of New York.
3. State of Pennsylvania, "Raw Waste Standards" (1951).
4. NCASI Data Review.
5. State of Ohio, "Raw Waste Standards" (1953).
6. Gurnham, F., "Industrial Waste Water Control", Chapter 20, #357
Academic Press (1965).
7. Pulp and Paper Industrial Joint Textbook Vol. #ni McGraw Mill
Publishing Company, New York.
8. Private Communications - Scott Paper Company, Westvaco, Inc. and
Mead Corporation.
46
-------
SPECIALTY PAPERS
Specialty paper mills produce over a thousand kinds of paper which
is made and used in small quantities. Some mills produce as little :as
two tons daily. Many single mills produce as many as one hundred different
grades. They employ a wide variety of pulps and use an almost endless
number of additives. Runs of a particular grade are generally short, so
that changeover losses can be higher than those entailed in continuous
operation.
A number of these employ cotton linters or textile fibers such as
flax, jute and some synthetics. Most of the mills once pulping rags now
employ cotton linters. The raw fiber is cooked in boilers and washed in
beaters where the stock is bleached if necessary and the other materials
making up the furnish added. From here it goes to a stock chest from
which it is withdrawn for preparation of the machine furnish.
Because of the great variation of these operations, it is not possible
to give specific numbers of their sewer loses. Howaver, where information
is needed to give some idea of the magnitude of these, reference is made
to the following publications:
(See next page)
47
-------
REFERENCES
SPECIALTY PAPERS
NCASI
Camp, Dresser & McKee Report on Industrial Wastes at Pittsfield, Massachusetts.
Pirnie, Malcolm, Report on Industrial Wastes at Watertown, New York.
Nemerow, N. , "Theories and Practices of Industrial Waste Treatment, Addison
Wesley Publishing Company, Reading, Massachusetts (1963).
NCASI, Technical Bulletin, Rag, Rope and Jute Pulping.
"Pulp and Paper Manufacturing, Volume II, McGraw Hill Publishing Company,
(1970).
-------
CATEGQRy XI
WASTE PAPERBOARD MILLS
Waste paper is the primary furnish for waste paper board mills
although a small percentage of new filler is .-.used to produce products
having a lining or coating. They employ both cylinder and Fordrinier
machines and in some a special stock preparation system is employed to
refine the waste pulp and disperse asphalt which is frequently present.
This is known as the A D or asphalt dispersion system. A few mills employ
a special vertiformer wet end on the paper machines.
Numerous types of board for a multitude of uses are produced in 145
mills in the United States, ranging from crude products such as pad backing
to food boards and patent coated specialities.
Effluent, Volume, BOD5 and total suspended solids data for 34 mills
have been collected. These were compiled from data collected by the
Department of Environmental Services at Rutgers University, the Michigan
Water Resources Commission, the Connecticut Water Resources Commission,
the Pennsylvania State Health Department and the NCASI. The volume
of effluent ranged from 3.3 to 21.6 thousand gallons per ton and it is known
that at three mills the effluent has been virtually eliminated through
clarification and reuse. However, these mills manufacture a small number
of products of a coarse grade which makes this procedure possible.
Extended full-scale trials on complete water resue after diatomite filtration
at several other mills indicated this practice to be unsatisfactory when
a variety of high quality products were made.
The minimum quantity of water required depends on whether or not
food packaging grades of board are produced. If they are not, a reuse to
the extent that 7,000 gallons or less per ton of produce are discharged,
49
-------
can generally be achieved. Reuse is somewhat restricted when food
board is produced since taste and odor producing substances tend to
accumulate in the system
-------
These wastes are generally substantially neutral though leaning
toward the acid side due to alum used as sizing. They do not contain
mineral acidity and can be treated biologically without neutralization.
They seldom contain much true color unless such as is imparted by the
water supply, but can be quite turbid due to the presence of clay or
titanium dioxide used in the process or entering the system with the
waste paper. They are not toxic, but can have a high bacteria count
these being largely aerogenes and frequently some E.Coli. They appear
to have no other undesirable characteristics. Concentrations of suspended
solids, BOD^ - and COD are similar to that of strong -sanitary sewage
and it responds well to treatment applied to sewage. According to
Rudolfs about 25% of the BOD is removed by settling and 30% by
coagulation and settling. This is accompanied by total suspended solids
removals of about 85 and 95 percent respectively.
Close to one-half of the news and wastepaper board mills discharge
to public sewage systems and more can be expected to follow. These
are frequently available since many of these mills are in or close to large
municipalities which serve as their souce of raw materials. Over thirty
mills treat their waste water, most by sedimentation or flotation and
coagulation. Four employ activated sludge, three have aerated stabilization
basins and two practice storage oxidation.
Published results from the two large activated sludge plants reveal
that they are capable of achieving effluent BOD^ values in the order
of 10 to 30 mg/1 and total suspended solids in the order of 5 to 25 mg/1.
COD effluent values at one of these mills ranged from 65 to 101 mg/1.
Th values will vary with the influent concentration. Both have dif-
ficulty in disposing of the waste activated sludge.
51
-------
Data on analyses of Waste Paperboard and Mill Effluents is shown in
Table V. A Waste Paperboard Mill flow diagram is covered by Figure 15.
52
-------
* TABLE V
Production-Tons
Flow-Million Gallons
Pounds of B.O.D. (Net)
Pounds of B.O.D. P
Pounds of Dry Soli
Pounds of Dry Soli
Pounds of Vol. Sol
Pounds of Vol. Sol
Gallons Waste Per
Fibre Loss-Percent
Population Equivalent
ANALYSIS OF WASTE PAPERBOARD AND
MICHIGAN
>ns
(Net)
3er Ton Product
Ids (Net)
.ds Per Ton Product
Lids (Net)
Lids Per Ton Product
Ton Product
Lent
MICHIGAN
>ns
(Net)
'er Ton Product
ds (Net)
ds Per Ton Product
.ids (Net)
ids Per Ton Product
Ton Product
ent
MILL #1
Survey
No.l
29.25
0.735
349
11.9
524
17.9
328
11.2
15,200
0.59
2,090
MILL #2
Survey
No.l
43.19
0.54
1,224
28.3
1,857
43.0
1,496
34.6
12,500
1.82
7,330
MILL EFFLUENTS
Survey
No. 2
35.38
0.729
344
9.7
486
13.7
381
10.8
9,830
0.57
2,060
Survey
No. 2
43.0
0.518
.957
22.3
1,080
25.1
880
20.5
12,050
1.08
5,730
Survey
No. 3
30.89
0.820
279
9.0
932
0.2
632
20.5
15,300
1.08
1,670
Survey
No. 3
43.4
0.593
870
20.1
940
21.7
785
18.1
13,650
0.95
5,210
Production-Tons
Flow-Million Gallons
Pounds of B.O.D. (Net)
Pounds of B.O.D. F
Pounds of Dry Soli
Pounds of Dry Soli
Pounds of Vol. Sol
Pounds of Vol. Sol
Gallons Waste Per
Fibre Loss-Percent
Population Equivalent
Source: Michigan Water Resources Commission
53
-------
Product
Water —
Trash
Chemicals —
Fresh
Water
FIGURE 15
Waste
Paper
Waste Paper Board Mill
Flow Diagram
r
$ \
Hydro
Pulper
LI
Junker
-"•{ Cleaner
Overflow to Sewer
I Trash
Dump
Refiner
'
f
Screen
Fresh
Water
Stock
Liner
Beater
Cylinder Type
Paper Machine
Product
54
-------
REFERENCES,
WASTE PAPERBQARD
1. RidolfSj w. , "White Water Research Report", NCSI, Technical Bulletin
Number 9 (1947).
2. Wisconsin State Department of Health, Pulp and Paper Advisory Committee
Reports.
3. NCASI Technical Bulletin #220, "Biological Waste Treatment Case Histories
in the Pulp and Paper Industry (1968).
4. Michigan Water Resources Commission, "Reports on Kalamazoo River".
5. Pulp and Paper Manufacture, Volume II, McGraw Hill Publishing Company,
New York (1970).
55
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CATEGORY 12
BUILDING PRODUCTS
Building papers are made in generally the same manner as other coarse
papers or waste paperboard, kraft and NSSC or groundwood pulps being used as
finish.
Building felts are produced from single refiner groundwood pulp together
with waste paper and in some instances, other fibrous materials such as
bagasse pulp and extracted licorice roots, etc. They are made on forming
machines of the Fordrinier or cylinder type and since the furnish is generally
hot, a very high degree of recirculation of the white water can be practiced
lowering the discharge to as little as 1000 gallons-per-ton of product.
Effluent characteristics are similar to that of waste paperboard except for
the fact that these products are impregnated with bituminous materials or
contain preservatives which can be toxic to aquatic life. BODc values»can
run as high as 5000 mg/1 when a high degree of recirculation is practiced,
and total suspended solids in the range of from 4000 to 6000 mg/1. They
are highly turbid and while the true color is not very high it can be
appreciable. This waste is difficult to treat by the usual processes except
if mixed with a relatively large quantity of sanitary sewage or other dilute
effluents. Most of the mills producing felts discharge to public sewage
systems.
insulating board is produced from a furnish similar to that of building
felts except for the fact that the quantity of refiner groundwood is usually
much higher. It is also made on a forming machine generally of the mold or
Fordrinier type and is produced in various thicknesses and both with and
without impregnation. Water reuse depends greatly upon the grade produced
56
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and this practice is reflected in the suspended solids content of the machine
effluent. High grade products necessitate high suspended solids losses since
a substantial portion of the refined wood must be rejected from the product.
Hence the total suspended solids content of these effluents can run as high
as 3500 mg/1 and the BOD5 to 3200 mg/1 most of which can be removed by
settling.
Most hardboard is produced by adding binders to a sheet produced in the
same manner as insulating board and consolidating it on a wire surface in a
hot press. This treatment removes all the moisture and sets the natural
binders present in the wood as well as those added which can be linseed, tung
I,
or tall-oil or phenol-formaldehyde resins. A tvPical effluent from this
process amounts to 5.3 thousand gallons-per-ton of product containing 30 Ibs.
of BOD and 39 Ibs. of total suspended solids.
Hardwood is also produced by the Masonite process in which wood chips are
placed in a "gun" under steam pressure of 1000 psig ,then exploded against a
target. The material so produced is disc refined, washed and formed into a
wet lap which is pressed between platens of a hydraulic press having a
screen on one side. Water is removed and the natural binders present in the
wood allow its moulding into a solid sheet. The losses of both BOD5 and
suspended fines from this process can be high since washing of the pulp
produces a molasses-like waste.
Figure XVI shows Insulating Board, Building Board and Hardboard, flow sheet.
57
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Product
Water
Chemicals
Steam
Insulating Board,
Building Board and
Hardboard, Flow Sheet
FIGURE XVI
Steam. ..
fFreSh
[Water
Condensate
Building Felt
or <*
Ins. Board
Drier
Overflow
to
Sewer
Hydrau
Press
E
ilic
Additives
Hardboard
58
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REFERENCES
BUILDING PRODUCTS
New Zealand Forest Products, Ltd., Private Communications.
NCASI
Joint Textbook, Pulp and Paper Industry
Kleppe, P. J. and Rogers, C.N., Report
TAPPI Air and Water Conference, Jacksonville, Florida (1969)
59
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Other Mill Effluents
In addition to process effluents many mills discharge water from
their utilities. These consist of filter backwash and sedimentation tank
underflow or clean out from water treatment, boiler blow down and cooling
water. In some instances the latter is salt or brackish water. In
addition, mills burning bark and/or coal usually sluice ash to a. ponding
area. Frequently the grits and dregs from kraft recovery systems are combined
with this flowage. In addition to these effluents, some mills dispose
of process clarifier underflow in land fill areas. In respect to the
latter good practice dictates the return of overflow water to the
waste treatment system since it can be high in both suspended solids and
BOD. The overflow water from ash sluicing ponds generally carries but
a small pollution load which frequently is discharged- only during periods
of high precipitation. Hence, it is diluted with rain water and th'e
receiving stream at relatively high run-off.
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WATER QUALITY PARAMETERS Iff ESTABUSHI1IG SKWL
FOR PULP, PAPER
tal_smd Volatile Suspended Solids_
Basic considerations related to the raw materials "being processed
and the process requirements results in the presence of organic matter,
dissolved and suspended in the process wastewaters. Therefore, "biochemical
oxygen demand (BOD), total and volatile suspended solids are parameters
recommended for measurement at all mills. These three parameters measure
the most significant components of these vastewaters and provide the basis
for quantitative evaluation of treatment effectiveness.
BOD the principal product of the paper-making process is wood fiber,
the cellulose component of wood. To get the fiber freed from the wood re-
quires a separation of the fiber from its binders usually by a digestion
process which, in turn, may convert up to 50$ of wood solids into soluble
organics such as wood sugars, lignins, and hemicelluloses. These solu-
bilized extracts, along with the chemicals used in digestion, have very
limited commercial use, therefore, constitute the principal waste of the
papermaking process. As soluble organic matter the sugar and cellulosic
components are biodegradable and cause heavy oxygen depletion if discharg-
ed into natural waterways. Thus, the BOD test serves to measure the
biochemical oxygen consuming capability of the wastewater.
Since this test can be quantified in terms of quantity of oxygen
required, it is one of the fundamental measurements of wastewater
characteristics, and is particularly applicable to wastewaters of the
pulp and papermaking process.
The EQD5 or 5 -day test is the agreed standard test by which all
61
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organic putrescible waste-waters are evaluated. It is recommended, there-
fore, that all waste-waters of the pulp and paper-making processes be re-
ported in terms of the BOD5, as described in the latest edition of
"Standard Methods". This procedure, being based on empirical considerations.
and being dependent upon biochemical processes using living organisms,
must be performed with careful attention to all details. Even so, the
results obtained are not universally comparable, particularly when attempt
is made to compare raw and primary effluent with secondary effluent. The
FWPCA Manual "FVZPCA Methods for Chemical Analysis of Water and Wastes"
November 1969, recognizes this in its appraisal of the method, but can
give no practical alternative. Yet, the universal applicability of the
test to all wastes containing putrescible organic matter requires that it
be used until a better test has been demonstrated.
Other BOD intervals, i.e.,BOD 20 have been utilized, and have
applicability for specific purposes. However, these would serve no use-
ful function in terms of wastewater quality assessment since nearly all
available historical data on effluent or process wastewaters has been re-
ported as BOD5- It should be pointed out that BOD is not a requirement
of established stream quality criteria. This is due to the basic
character of the test, which, in reality, is an assessment of oxygen con-
suming potential. Such a criterion has been found to be unrealistic for
^tream quality assessment. The National Technical Advisory Committee on
Water Quality Criteria in its review and recommendation of criteria for
the various water uses to be accommodated did not propose BOD as a
criterion, since the BOD effect, namely the dissolved oxygen level, is
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the primary criterion. However, effluents must "be judged on their
Potential for affecting stream criteria, consequently, the EOD5 is a
much more significant effluent criterion "because of its adverse effect on
steam oxygen resources.
In parallel with the EOD5 effect of mill vastewaters are the
visible solids that result from these processes. There are two basic
types of solids from these mills; those of inorganic substance and those
of organic character. In general, the organic fraction is the more
damaging if allowed to escape to the stream, because of its oxygen demand-
ing sludge forming tendencies when allowed to settle under quiescent
conditions. On the other hand, the loss of organic solids implies loss
of the fiber which is the sought for product. Thus, heavy organic solids
losses can imply inefficient fiber handling and consequently, a heavy
profit drain on the mill.
Inorganic solids result from the primary wood handling steps in the
clean up of the wood before 'digestion, and in the paper making step where
specific materials are added for opacity control or as fillers and in
coatings. The properties of these solids are somewhat different in that
the vood handling process solids reflect the randosized contact of the
raw material, in its excursion to the mill, in the form of mud, clay and
silt washed from the vood. These solids, in general, settle adequately
and are removable in conventional treatment devices. In contrast, the
"fillers" in the paper making process are substances with specified
properties, one of which is the ability to remain in suspension. When
these substances escape to the environment they my cau.3e a relatively
63
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greater visible impact "because they produce a greater turbidity in relation
to the quantity lost. Although the stream quality effects of these in-
organic suspended solids are not as serious as the organic solids,
neverthless they create objectionable aesthetic effects and they do settle
and may interfere with the natural ecology by smothering spawning areas
of fish and affecting insect and other macro vertebrate propagation.
Because these suspended solids have differing properties depending
upon their organic or inorganic nature, it is pertinent to distinguish between
or to characterize the nature of the solids discharged. This is determined by
differentiating between volatile and non-volatile fraction of the solids
that are present in the wastewaters. The method for suspended solids
(non-filterable solids) is specified in the FWPCA manual, previously
cited, and requires filtration through a glass fiber filter of specified
pore size, followed by drying at 103-105°C. The "Standard Methods" pro-
cedure offers alternatives in filtration media such as the "asbestos mat"
and the membrane filter. Historical data based on the "Standard Method"
should be acceptable for this test. However, the "Federal" method
should be specified for future testing.
The method for volatile suspended solids is specified in "Standard
Methods as Volatile and Fixed Suspended Matter". The "Standard" method
uses an electric muffle furnace set at 600°C. The "Federal" (FWPCA manual)
specifies 550°C as the temperature of the electric muffle furnace. Other-
wise both methods are identical. Historical data based on the "Standard"
method should be acceptable for this test. This test, therefore, will
characterize the type of suspended matter in the waste in terms of
"Volatile or Fixed" residue. In general, the volatile fraction represents
64
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the organic component of suspended solids found in an effluent.
.Chemical Oxygen Demand (COD)
The National Council for Stream Improvement, Tech Bulletin 193,
1966 reports on a study of 60D/BOD relationship of raw and biologically
treated Mill Effluents. It concludes;
"Based on the results obtained it does not appear possible
to develop time-automated treatment process and effluent discharge con-
trols for rapid BOD estimation based on the COD test. Examination of
BOD, COD, and lignin content relationships on 352 samples of untreated
and treated pulpmill effluents showed no fixed relationship between
these values. It is probable that materials other than lignin which are
resistant to biological oxidation are present in the waste, as well as
some lignin materials do decompose. Possibly these are functional groups
of the large lignin molecule. There is also wide variation in momentary
relative concentration of the various constituents present in these wastes.
Correcting COD values for oxygen equivalent of the lignin content of both
untreated and treated wastes significantly lowers the COD/BOD ratio.
However, it does not yield a ratio sufficiently constant for reliably
estimating BOD by this technique.
In view of the large* number of representative samples used and
the well-controlled laboratory techniques employed, it appears that final
solution of this problem will depend on the separation and measurement of
those constituents contributing to both chemical and biochemical oxygen
demand".
65
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This is not surprising, nor has there yet teen discovered any
physical chemical procedure that correlates -well with the BOD test. How-
ever, this shortcoming, the lack of correlation, is not sufficient to rule
out a test procedure that can provide meaningful information that may be
translated into stream or effluent quality appraisal. The dichromate
procedure for COD (with chloride correction) has been recognized as a
"Standard" method. This method seems to correlate well with filtured
domestic sewage and with wastewaters having characteriistics similar to
domestic sewage. A less favorable correlation is experienced with treated
effluents, with the COD/BOD ratio increasing with greater bio-
logical stabilization. This serves to indicate that biologically stabi-
lized effluents contain organic components that react very slowly bio-
logically, but retain chemically oxidizable properties„ The COD test is
also more easily repeatable since its conditions are better controlled.
On the other hand, there is no established usage of the COD test in which
it is readily quantified. Treatment plant designs are strictly on BOD/
suspended solids criteria, especially through secondary treatment stages.
As yet, criteria for advanced treatment have not been thoroughly standard-
ized. These criteria would more likely reflect the tertiary process that
was needed to remove a specific residue from secondary«treatment, i.e,
residual ammonia, carbon, phosphorus, etc.
Therefore, the COD test as currently practiced, provides some use-
ful information that may be utilized to provide a general classification
of the oxidizable carbon content of a wastewater or its receiving stream,
but the interpretation of COD values, without other qualifying data,
provides very little of value for classifying effluents or the resultant
effects on stream quality. Currently the usage of COD data is in process
66
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control wherein intimate knowledge of the process can be used to interpret
e COD value of effluents and to make appropriate process adjustments.
It is therefore recommended that the COD test not he required as a deter-
mination of Standard Raw Waste loads from the pulp, paper and paperboard
industries.
Turbidity
This empirical test differentiates the light scattering properties
of fluids. Its unit of measurement in water and wastewater analysis is the
Jackson Turbidity Unit (JTU). Turbidity is a qualitative criterion for
aesthetic uses, which require such waters to be free of substances that
produce objectionable turbidity. Another quantitative (but indirect)
criterion is the Secchi disc test to measure clarity,which is generally
used for recreational waters.
As a criterion for uses for public water supply, the absence,of
turbidity is considered desirable, as is the absence of a frequently
changing turbidity, to the treatment plant operator. Because turbidity
can not define other properties of the suspended particles causing it,
the water supply criterion remains qualitative. The criteria for uses
for the propagation of fish, aquatic life and wildlife are set to a
limit of 50 JTU for warm water streams, 10 JTU for coldwater streams,
25 JTU for warm water lakes and 10 JTU for cold water lakes. These
criteria are based on the probable settling out of the turbidity causing
particles on spawning grounds of fish and habitats of aquatic insects,
resulting in interference in the life cycles of these organisms, and on
light penetration requirements for aquatic life propagation and produc-
tivity of stream bottoms. In marine waters, a qualitative criterion is
67
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recoEmended which states that no effluent should be added which causes
changes in turbidity unless it has been shown that such will not be de-
leterious to aquatic life. For other water uses (Agricultural,Industrial)
turbidity of raw water does not appear to be a serious impediment, and is
not specified as a specific criterion for these uses. Turbidity and
suspended solids parameters are not synoymous. Suspended Solids (S3)
measures nonfilterable particulates in the fluid, turbidity meansures the
light scattering properties of a fluid. Where SS is present, turbidity is
always found. However, sometimes turbidity may be observed under condi-
tions of extremely fine particle size, which pass through the standard
filters used for SS measurement.
In the mill, turbidity is found in all wastewater systems carrying
suspended solids. High turbidity can be due to mud, clay and detritus
carried on logs and removed during washing operations, in fiber losses
during processing, and in white water losses from the paper making process.
In the latter instance, the finely divided materials used for fiber, such
as clay, calcium carbonate, titanium oxides, and the various chemicals
used in special finish coatings may escape detection as Suspended Solids,
but would be readily detected as turbidity. Historical data on turbidity
of mill process steams is non existent, since this has traditionally been
reported as Suspended Solids. However, the quality effect on water uses
that distinguishes turbidity from Suspended Solids requires that effluents
be characterized using both parameters. It is therefore recommended that
turbidity be a standard measurement of plant effluents only, since its
usage in the operating mill process flows has no important significance.
68
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Color-
Basic to the conversion of wood into paper is the extraction of color
rom the raw material or its converted products during the refining pro-
cesses. The origin of most of the color in the wastewaters of these pro-
cesses are the lignins and tannins of the wood. As the fiber is separated,
these hinders are solubilized into the color extracts found in the result-
ing wastewaters. Therefore, all processes in pulping and "bleaching con-
tribute waste-water with more or less significant qualities of color per
unit of product. Along with Suspended Solids and BOD, color is a "basic
parameter that characterizes the wastewaters of -this industry.
A second characteristic of the color extracted from these processes is
its refractory nature when present in the water environment. It persists
indefinitely in solution, having practically no "biological activity,
therefore its reduction must "be through chemical attack or "by absorption.
The need to measure color and to limit its presence in receiving
vaters is spelled out in the quality criteria for aesthetic, water supply,
fish, aquatic and wildlife propagation and some industrial uses. For
aesthetic uses the criteria specify the absence of objectionable color.
For water supply uses, the criteria specify a limit of 75 color units
(cobalt-platinum standard units). This standard permits the treatment
plant to produce a satisfactory water with moderate dosages of coagulants
and chemicals. For fish, aquatic life and wildlife propagation, the
criteria specify the need for at least 10$ of incident light to reach the
bottom of a desired photosynthetic zone in order to maintain adequate
dissolved oxygen levels. The conversion of this requirement into standard
color units is not possible because of associated turbidity, fro^ natural
69
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and -waste-water sources. However, a value above 50 units has "been signi-
ficant in limiting photosynthesis and having a deleterious effect upon
aetuatic life, particularly phytoplankton and the benthos. Some specific
industrial vater users primarily the food and beverage producers specify
raw water color to "be limited to 5 units. However, industry in general
sets no specific limit, since its varied uses usually require a complete
treatment for removal of most substances including color.
The standard method for color measurement is in terms of platimum-
cobalt unit of color, as specified in "Standard Methods" for water.
Since the color of the wastewaters from pulp, paper and paperboard
manufacture have the characteristic brown color very similar to the
platinum-cobalt system, there is little need to modify this procedure
except for those special processes in .which dyes are used to introduce
other colors. Gehm suggests, however, that all mill effluent measurements
be made at pH 7.6 because there may be significant pH effect on the color
of the wastewater being measured.
It is recommended therefore that color measurement should be a
requirement in the quality evaluation of these wastewaters.
pH (Hydrogen Ion Concentration)
Processes used in pulp, paper and paperboard manufacture result in
wastewaters with pH values encompassing both ends of the scale, from
highly acidic level of 1.2 to alkaline levels above 12.0. Water quality
criteria for nearly all uses allow the pH range to remain within the limits of
5.0 to 9.0, with some uses, i.e., marine organisms having much more narrow
limits (6.7-8.5). Adverse effects, such as corrosion of metals and concrete
occur at both ends of the pH scale. Toxicity effects of some substances
70
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re enhanced by changes in pH, such as ammonia toxicity which increases
higher pH values, and Cyanide toxicity which increases at lower pH values.
It: is universally recognized that pH is a significant water quality criterion
and that its acceptable levels lie within narrow limits surrounding the
neutrality level of 7.0. Therefore, all effluent measurements should in-
clude pH as one of the required parameters to be reported.
It should be understood that pH measurement by itself does not indicate
the acidic or alkaline effect of the wastewater discharge. To evaluate this
effect it is necessary to have information on the alkalinity or acidity of
the wastewater and of the receiving stream. However, so long as the pH
level of the effluent is within the water quality criteria set for the
receiving waters, there is very little likelihood that the pH changes
in the stream caused by the wastewater assimilation will exceed those
criteria.
Other Significant Parameters
The parameters that have been reviewed above have applicability to nearly
all the mill wastewaters of the industry. Those to be discussed below may
be applicable to some process wastewaters and effluents, but are not
universally applicable for all mills therefore they are recommended only
for those specific conditions that may be critical to a particular receiving
body of water.
- Medium Tolerance Limit
This is a bio-assay procedure that is used to establish a concentration
level of the substance under test that will result in survival (or non injury)
to fifty percent of a test population during a specified time interval. A
static procedure and a flow-through procedure are used in measuring this
criterion. The static procedure has been standardized in "Standard Methods"
71
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using fish as the test organism for those instances in which the material
"being tested is persistent, non volatile and without significant oxygen
demand.
It is well known that process wastewaters from various pulping processes
exert varying degrees of toxic effect upon the ecology of receiving waters.
It is also well known that "biological treatment reduces these toxic effects
significantly. Since toxicity tests are not yet recognized universally as
standard tests and they are relatively expensive and tedious to perform, .it
would seem logical to suggest that these tests "be required only under those
circumstances that would constitute a sensitive relationship "between the use
of a body of water for -?7astewater disposal and its use for the propagation of
valuable fish and food organisms. In these instances, the test should "be
performed under continuous flow through conditions where feasible. The ultimate
purpose of the test would be its use. as a regulator of the discharge
rate of the final effluents from the affected mill.
Heavy Metals
Low concentrations of chromium, nickel, lead, mercury and zinc have
been found in process wastewaters of the industry, and particularly in the
waters resulting from the pulping and bleaching operations. These metals
have known toxic effects on aquatic life, and their presence in water
for human consumption is limited to very low concentrations. Mercury
and lead may be present in the caustic used in the pulping process,
chromium and nickel are picked up as corrosion products along with iron
from the process equipment. Zinc is used in groundwood bleaching operations.
It would serve no useful purpose to require analysis of these substances
in the various process wastewaters since they are only minor or incidental
components of the basic materials being processed. However, their
absence from wastewater discharges should be a basic requirement and
analysis to prove their absence should be specified.
72
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and Dissolved Solids
in
Digestion and bleaching operations in a pulpmill can result in a
dup of significant levels of acidity, alkalinity and dissolved salts
the wastewaters from these operations. Dissolved salts are also accumulated
in steam boiler blowdown and in cooling tower blowdown. Where recovery
of chemicals is practiced, as in the more modern kraft and sulfite mills,
losses of acid and alkaline components are minimized.
For purposes of determining the resultant pH effect of a plant discharge
on the receiving water body, and for the regulation of such discharges in
order to maintain pH criteria, it is necessary that the acidity or
alkalinity of discharges be known. Therefore, these tests should be
a requirement for all effluents.
Dissolved salts, when added in quantity to cause a significant increase
in the ionic levels of the receiving body of water, may adversely affect
some forms of natural biota common to the water course. For these reasons^
addition to natural waters which are to be protected for fish, aquatic life
and wildlife uses have been limited to a level that will restrict such
increase to • a factor 1/3 greater than the background ionic level. In
addition, the maximum concentration of the ionic components should not
exceed the ionic effect of a 1500 mg/1 solution of sodium chloride;
(50 milliosmoles, in terms of osmotic effect). Where public water supply
is to be protected, the total dissolved solids level of 500 mg/1 is the
limiting criterion for this parameter. Specifications for industrial
wastes at the raw water level are usually less restrictive than the
criteria for public water supply and fish and wildlife uses. This is
due to the .wide range of quality required in industrial processing,
73
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which requires that the raw water be treated to a needed specification.
For these uses, increases in dissolved salt concentration result in an
increased economic burden to the user, especially in those uses that require
deionization.
It is therefore concluded that the total dissolved solids test be
required of all effluents from this industry.
Coliforms
The use of the total coliform test as a quality criterion for natural
waters is rapidly being displaced by the fecal coliform test. This
differentiation is significant to the assessment of natural water quality
for contact recreation purposes and for public water supply because it
is being universally recognized that the protection of the public health
is served better through the elimination of those organisms that are
directly related to human and animal fecal matter.
It has also been amply documented that many of the wastewaters from
this industry have a property of stimulating the multiplication of coliform
organisms because of the presence of various carbohydrates that are extracted
from wood during the pulping process. The resultant high coliform con-
centrations may appear significant, but invariably, these are classified
as non-fecal types, with only a very small fraction testing out as of fecal
origin. Where mill sanitary sewage is combined with process wastes,
there is, of course, a relatively higher fecal coliform content.
Based on these considerations the total coliform test should no longer
be a requirement for effluent bacteriological quality. It-should be
replaced by tests that differentiate the presence of the fecal coliforms.
74
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Excessive concentrations of the nutrient elements phosphorus and
nitrogen, when present in a, natural water body have been implicated as
the causitive agents in overfertilization or eutrophication leading to
overgrowth of undesirable aquatic organisms. Sources of these nutrients
are the wastewaters from municipal wastes and some industrial wastes. The
processes in use by the pulp paper and paperboard industry result in
wastewaters that are usually deficient in one or both of these critical
nutrient elements. Therefore, it has been a general practice to add
calculated quantities of nitrogen and phosphorus to the biological treatment
processes in order to optimize treatment. Where secondary biological
treatment is being practiced, it has been determined that a ratio of
1:5:100 of phosphorus to nitrogen to BOD should be maintained for optimum
treatment. It is therefore concluded that there is very little likelihood
of excessive nutrient concentrations being found in the process wastes or
wastewaters from this industry, therefore, no useful purpose would be
served to require nutrient analyses of these waters.
75
ft U.S. GOVERNMENT PRINTING OFFICE : 1971 O - 420-295
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TABLE VI
STANDARD RAW WASTE LOADS FROM PULP AND PAPER MANUFACTURING PROCESSES
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