and calcium carbonate are also formed and serve as coagulants to assist
in removing the gelatinous calcium hydroxyapatite. In addition, lime is
used when necessary as a sludge conditioner.

The analysis and documentation of environmental alterations which
are assigned to the Ely AWT plant as a result of using lime include only
those associated directly with the processing of limestone. Both the
mining of limestone and the transporting of the limestone to the pro-
cessing plant generate pollutants which are not considered here. All
lime used at the AWT plant is purchased from the Cutler-Magner Company
of Duluth, Minnesota. The calcining data in this paper is based largely
on information supplied by Cutler-Magner Company (LaLiberte 1975). Lime
is produced by calcining limestone at temperatures in excess of 1093°C
(2000°F) in rotary kilns fired 37% of the time by #6 fuel oi1 and 63% of
the time by natural gas. In the analysis which follows, the calculations
are based on the fact that it requires 7,500,000 Btu's of oi1 to produce
one ton of lime and 8,000,000 Btu's of natural gas. The difference
between natural gas and fuel oi] is that the kilns are more efficient
when fired with fuel oil. It takes approximately 2Mg of limestone to
produce 1Mg of lime. In this operation, power is required to drive the
rotary kilns, induced draft fans, water cooling pumps, feeders, com-
pressors, crushers, screens, conveying equipment and to generate high
D.C. voltage in the electrostatic precipitators. Water is required for
cooling kiln bearnings and cleaning the exit gas samples going to the
continuous gas analyzers which record levels of oxygen and combustibles
in the exit gases of the three kilns. The resources utilized and the
pollutants generated as a result of producing lime are presented in
Tables 7 and 8. Other literature (EPA, 1974; Lewis and Crocker, 1969,
Boynton, 1966) all indicate that the Cutler-Magner data are generally
representative of the industry as a whole.

TABLE 7. RESOURCE REQUIREMENT FOR PRODUCTION OF LIME
FOR AWT AT ELY, MINNESOTA*
488 Mg (537 Tons)/year

Per Mg Lime Per Ton Lime Per Year
Limestone, Mg (tons) 2 (2) 976 (1070)
Fuel 011, m° (gal) 0.209 (50) 38 (9935)*
Natural Gas, mn (cu ft) 237 (7619) 73,200 (2.58x10°)*
Electricity, MWh (kWh) 9.055 (50) 27 (26900)
Water, m> (gal) 9.334 (88) 148 (42700)

* Based on fact that 37% of the time kilns are fired with #6 fuel oil
therefore it was assumed 37% of the total lime consumed at Ely was
produced by this fuel and 63% was produced by natural gas.

12


SECTION VI
SI UNITS AND CONVERSION FACTORS USED

UNITS
length metre (m) energy joule (J)
mass kilogram (kg) volume cubic metre (m?)
area square metre (m?)

SI PREFIXES

Multiplication Factors Prefix SI Symbol

104° tera T

106 giga G

103 mega M

105 kilo k

107 hecto h

10_) deka da

10_5 deci d

10_3 centi c

107% milli m

10_9 micro u

10} nano n

1045 pico p

10_13 femto f

10 atto a
CONVERSIONS

To Convert From to Multiply By

BTU joules (J) 1.055 x 10°
foot? metreé (m?) 9.290 x 107°
foot? metre? (m?) 2.832 x 107
gallon (U.S. liquid) metre (m°) 3.785 x 1079
kilowatt-hour (kWh) joules (J) 3.600 x 10°
mile (U.S. statute) kilometer (km) 1.609
pounds (1b avoirdupois) kilogram (kg) 4.536 x 107!
ton (short-2000 Ibm) megagrams (Mg) 0.907
barrel (bb1) gallon (U.S. liquid) 4.2 x 10

29


SECTION III
RESOURCE UTILIZATION AND POLLUTANT GENERATION

As discussed in the Introduction, the operation and maintenance of
the Ely AWT requires resources and the production of these resources
generates pollutants. This section describes and quantifies the major
resources utilized both directly (Table 2) and indirectly by the AWT.

In addition to the resources discussed below, there is the human re-
source which will be discussed in a later paper on socioeconomic fac-
tors. However, it should be noted here that at present there are eleven
people employed directly in the operation of the treatment facility.

The significant pollutants caused by the production of these resources
are also identified and quantified. These data will allow an assessment
of the trade-offs which exist between the benefits accrued to the AWT
through improved effluent quality and the costs incurred by the AWT
through resources employed and pollutants generated.

TABLE 2. RESOURCES USED DIRECTLY AT ELY PER YEAR
SHEEHY AND EVANS (1975), BRICE (1975)

1. Lime Mg (Tons) 488 (538)
2. CO, Mg (Tons) 152 (168)

3. Chlorine Mg (Tons) 4.7 (5.2)
4. Electricity (kwh) 780,000

5. Fuel Oi] mn (gals) 238 (63,000)
6, FeCl; Mg (Tons) 39.9 (44)

7. Sulfuric Acid Mg (Tons) 74.4 (82)

8. Polymer kg (lbs) 304 (670)



In the manufacturing of FeCl, there are no waste products produced
that are either discharged to the’water or emitted to the air (Sharp,
1975). There are, however, a total of approximately 17.7 kg of sludge
produced for every Mg of product ferric chloride (35.4 lbs/ton). This
Means that the amount of solid waste produced each year as a result of
using FeCl, at Ely is approximately 706.5 kg (1558 lbs). There is no
detailed iiformation on the chemical composition of the sludge but it is
expected that it would contain grease, silica, sand, ferric chloride,
and iron oxide and hydioxide (EPA, 1975). No environmental insult has
been assigned to the chemicals contained in the sludge.

CHLORINE

Chlorine is added at a dosage of approximately 3.0 g/m? (mg/1) to
provide a final effluent residual of 0.2 g/m> (mg/l). This serves as a
control for potential pathogenic bacteria and results in the use of 4.7
Mg (5.17 tons) of chlorine per year.

The industrial process and energy requirements for the production
of chlorine has been detailed by Saxton et al (1974) and EPA (1974).
The electrolytic processing of brine by either diaphram or mercury cells
accounts for 96% of the total chlorine production in the United States.
The remaining 4% is presently produced as a by-product of other indus-
trial processes. In this study it has been assumed that the chlorine
used at Ely has been produced by the electrolytic process. The follow-
ing information and assumptions are important in analyzing resource
requirements of the chlorine industry: 1) 75% of the installed elec-
trolytic capacity in chlor-alkali plants consist of diaphram cells and
25% of the capacity consists of mercury cells; 2) 41% of the cells use
graphite anodes, and 59% use metal anodes; 3) for every megagram (Mg) of
chlorine produced, 1.13 Mg of caustic soda (NaoH) are produced (1 ton
chlorine/1.13 ton caustic soda). Since most available raw data that are
for the co-production of chlorine and sodium hydroxide, this last fact
could lead to misinterpretation of data. This study has allocated
resources between chlorine and caustic soda on a weight basis. For
example, if the co-production of 1 Mg of chlorine and 1.13 Mg of caustic
soda requires 3197 kwh of electricity, 1500 kWh are assigned to the
production of 1 Mg of chlorine. In this case, it is legitimate to
allocate energy resources between chlorine and caustic soda because both
products are in high demand and the dollar value of both products is,
high. In other words, caustic is not necessarily just a by-product of
chlorine production, or vice versa. If caustic was simply a by-product
with little or no economic value, it would not be legitimate to allocate
resources between the two products. Further, the total process yields
hydrogen gas as a by-product which is sold. However, this paper does
not allocate any of the resources to the production of hydrogen (i.e.,
it was considered solely as a by-product of producing chlorine and
caustic soda).

The net and gross energy costs of producing chlorine by different

technologies are shown in Table 11. In this analysis, net electrical
use, rather than gross electrical use, has been used in calculating

16


FOREWORD

Effective regulatory and enforcement actions by the Environmental
Protection Agency would be virtually impossible without sound
scientific data on pollutants and their impact on environmental
stability and human health. Responsibility for building this data
base has been assigned to EPA's Office of Research and Development
and its 15 major field installations, one of which is the Corvallis
Environmental Research Laboratory (CERL).

The primary mission of the Corvallis laboratory is research on the
effects of environmental pollutants on terrestrial, freshwater,
and marine ecosystems; the behavior, effects and control of pollu-
tants in lake systems; and the development of predictive models on
the movement of pollutants in the biosphere.

This report describes some of the resources used and pollutants
generated as a result of operating an advanced wastewater treatment
plant which includes phosphorus removal. Other reports are being
prepared which describe the improvement in the Shagawa Lake eco-
system due to the reduction in phosphorus loading, and the social
and economic consequences of operating the advanced wastewater

treatment plant. a -
op Jot
we. 7

A.F. Bartsch
Director, CERL


10.
i.
12.

13.

SECTION V
LITERATURE CITED

Antonucci, D. C. 1973. Environmental Effects of Advanced Waste-
water Treatment at South Lake Tahoe, California. M.S. Thesis,
Oregon State University.

Antonucci, D. C. and F. D. Schaumberg. 1975. Environmental Effects
of Advanced Wastewater Treatment at South Lake Tahoe. J. Water
Pol. Cont. Fed. 47:2694-2701.

Boynton, R. S. 1966. Chemistry and Technology of Lime and Lime-
stone. John Wiley and Sons, NY.

Brice, R. M. 1975. Personal Communication.
LaLiberte, C. 1975. Personal Communication.

Larsen, D. P., K. W. Malueg, D. W. Schults, and R. M. Brice (1975).
Response of Eutrophic Shagawa Lake, Minnesota, U.S.A., to Point-
Source Phosphorus Reduction. Verh. Internat. Verein. Limnol.
19:884-892,

Lewis, C. and B. Crocker, 1969. The Lime Industry's Problem of
Airborne Dust. Air Pollution Cont. Assoc. 19:31-39.

Malueg, K. W., D. P. Larsen, D. W. Schults, and H. T. Mercier (1975).
A Six Year Water Phosphorus and Nitrogen Budget for Shagawa Lake,
Minnesota. Journ. of Envir. Qual. 4:236-242.

Pigford, T. H., M. J. Keaton, B. J. Mann, P. M. Cukor and G. L.
Sessler, 1975. Fuel Cycles for Electric Power Generation in Compre-
hensive Standards: The Power Generation Case. Final Report by
Teknekron to EPA.

Pressman, M. A. 1975. Personal Communication.

Rutka, R. R. 1975. Personal Communication.

Saxton, J. C., M. P. Kramer, D. L. Robertson, M. A. Fortune, N. E.
Laggett, and R. G. Capell. 1974. Industrial Energy Study of the
Industrial Chemicals Group. Final Report to the Department of
Commerce and the Federal Energy Office. Contract #14-01-0001-1654.
ASTM Metric Practice Guide, E 380-74.

Sharp, J. 1975. Personal Communication.

27


€L

TABLE 8. ATMOSPHERIC POLLUTANT DISCHARGE DUE TO PRODUCTION OF LIME FOR AWT AT ELY, MINNESOTA
488 Mg (537 Tons)/year

Per Per Per
Mg Lime Ton Lime Year
To Air

S0,kg (Ibs) 2.04 (4.1) 996 (2196)
Particulates, kg
(1bs) 0.16 (0.32) 78 (172)
Heat, GJ (BTU) 5.20 (4.5x10°) 2500 (24.0x10°)
*NO,> kg (bs) 0.61 (1.23) 299 (661)
*CO, kg (Ibs) 0.05 (0.16) 24.6 (54)
*HC, kg (Ibs) 0.035 (0.07) 17.1 (37.8)

* NO., CO, and HC are calculated from "Compilation of Air Pollution Emission Factors" (EPA 1972)
and are based on the fact that approximately 209 dm-(liter) of fuel oi] are burned to
produce 1 Mg of lime (50 gallons/tori). Sulphur content of fuel oi] was assumed to be 1.6%.
Kilns are fired 37% of the time by fuel oi] and 63% of the time by natural gas.


Table 13 shows the atmospheric and aquatic emissions that result
from the manufacture of chlorine. To calculate these numbers, addi-
tional assumptions were made: ash content of coal = 12%; ash content of
fuel oi] = 0.5%; sulfur content of coal and fuel oi] = 1%; and emission
controls = 98% particulate removal.

TABLE 13. POLLUTANT DISCHARGE DUE TO PRODUCTION OF CHLORINE
FOR AWT AT ELY, MINNESOTA
4.72 Mg (5.20 Tons)/year

gm per Ibs per Per Year
Mg Chlorine Ton Chlorine gm Ibs
To Air
Particulates 45 9 210 47
S05 590 118 2780 614
co 45 9 210 47
HC 20 4 94 207
NO, 540 108 2550 561
C15 9070 1800 42800 9360
C05 15900 3180 75000 16500
To Water!
Suspended
Solids 320 64 1510 330
Lead 2.5 0.5 10 2.60
Hg Negligible Negligible Negligible Negligible

Based upon effluent guidelines for best practical control technology.

Allowable discharge of Hg from chlorine plants using mercury cells
is 0.14 g/kg of chlorine produced. Since this analysis is based
upon the assumption that only 25% of Ely's chlorine comes from
mercury cells, the discharge of mercury is 0.0315 g/kg of chlorine
produced.

SULFURIC ACID

As the wastewater leaves the second stage lige clarifier, sulfuric
acid is added at a dosage of approximately 37 g/m> (mg/1) which is
sufficient to maintain a final effluent pH of 7.0-7.5. This results in
the use of 74.5 Mg (82 tons) per year. Sulfuric acid is produced pri-
marily by burning sulfur to produce $0., followed by oxidation to yield
$035 which is reacted with water to préduce H5S0q- This process consumes

19


FERRIC CHLORIDE

Ferric chloride is added to the processes at two points. First it
is added to the second stage lime clarifier at the rate of approximately
6 g/m” (mg/1) of iron. This serves to form complex insoluble phosphorous
salts which are precipitated or filtered out.

Second, after the effluent leaves the second stage lime clarifier,
chlorine, ferric chloride agd sulfuric acid are added. Ferric chloride,
at a level of 1.0 - 2.0 g/m (mg/1) of iron, provides a floc blanket
which improves filter efficiency and extends filter runs. There is an
annual usage of 39.8 Mg (43.8 tons) of ferric chloride.

There are several different techniques and processes for producing
ferric chloride. The analysis which follows is based upon information
supplied by Dow Chemical Company (Sharp, 1975) and information contained
in the Development Document for Effluent Limitation Guidelines and
Proposed New Source Performance Standards for the Significant Inorganic
Products (EPA, 1975). The manufacturing of ferric chloride utilizes
mostly waste products from the steel industry - scrap steel and/or waste
pickle liquor (WPL) (Table 10). Chlorine is added to the iron solution
in a reactor and ferric chloride is formed. In some processing plants,
additional hydrochloric acid is added to the reactor. However, since
the facility at Shagawa has been using Dow or DuPont ferric chloride,
neither of which use HC1, it has not been included in this analysis.
While the reaction 2 FeCl, + Cl, > 2 FeCl, is basically exothermic,
external heat is used at times to concentrate the final product. The
quantity of energy utilized for this step is insignificant (Sharp, 1975)
and is not counted in this analysis.

TABLE 10. RESOURCE REQUIREMENTS FOR PRODUCTION OF FERRIC CHLORIDE
USED AT AWT AT ELY, MINNESOTA
40 Mg (44 Tons)/year

Mg Per Mg Ton Per Ton Total Per Year
Ferric Chloride Ferric Chloride Mg Tons

Waste Pickle
Liquor (as Fe) 0.34 0.34 13.7 15.1
Chlorine 0.66 0.66 26.2 28.9

15


14,

15.

16.

17.

18.

19.

Sheehy, J. W. and Evans, F. L. 1975. Tertiary Treatment for
Phosphorous Removal at Ely, Minnesota AWT Plant April, 1973 thru

March, 1974, EPA 660/2-76-082.
Shreve, R. 1967. Chemical Process Industries, McGraw-Hill, NY.

U.S. Environmental Protection Agency. 1972. Compilation of Air
Pollutant Emission Factors - 164 p. EPA Report No. AP-42.

U.S. Environmental Protection Agency. 1974. Development Document
for Effluent Limitations Guidelines and New Source Performance
Standards for the Major Inorganic Products Segment of Inorganic
Chemicals Manufacturing. EPA 440/1-74-007a.

U.S. Environmental Protection Agency. 1975. Development Document
for Interim Final and Proposed Effluent Limitations Guidelines and
Proposed New Source Performance Standards for the Significant
Inorganic Products Segment of the Inorganic Chemicals Manufacturing
Point Source Category. EPA 440/1-75-045.

Vorel, C. J. 1975. Personal Communication.

28


OL

TABLE 5.
9.273 m

RESOYR

CE REQUIREMENTS FOR PRODUCTION
(2450 gal) Gasoline and 238.5 m

3

F PETROLEUM PRODUCTS FOR AWT AT ELY, MINNESOTA
(63,000 gal) Fuel Oi] per Year

3

Per me

Per m Per 1000 gal Per 1000 gal Per year
Gasoline Gasoline Fuel 0i1 Fuel 071 Total

Mater, m° (gal) 6.19x10" (6.19x10') 3.01x10” —(3.01x10!°) 7. 76x10° (2.05x10!4)
Natural Gas, nm

(cu ft) 0.748 (100) 0.364 (48.6) 93.5 (3304)
Progere and Butane

(gal) 1.028 (1020) 0.538 (538) 138. (36400)

Crude O71, m (gal) 6.29x1073 (6.29) 3.05x1079 (3.05) 0.786 (208. )



as a result of the operation and maintenance of the Ely AWT plant. The
following assumptions and limitations imposed on the study were due to
both data restrictions and manpower constraints: 1) Only the operation
and maintenance of the AWT plant has been considered. Resources utili-
zed and pollutants generated during the construction of the plant have
not been considered. 2) Consideration has been given only to the uti-
lization of resources and pollutants generated at the AWT plant and in
first order industries. A first order industry is any industry that
supplies products directly to the AWT plant at Ely. Resources utilized
or pollutants generated by second order industries (i.e. those indus-
tries supplying products to first order industries) have not been
considered. As an example, pollutants generated as a result of pro-
viding electricity to the AWT plant are considered; pollutants generated
as a result of supplying electricity for the manufacturing of lime are
not considered. 3) The city of Ely was operating a secondary treatment
plant. The phosphorus removal facility was added to the existing plant.
Consequently, an environmental assessment of advanced wastewater treat-
ment might cover only the tertiary phase, or that portion of treatment
beyond secondary treatment. This study, however, examined the entire
treatment process - primary, secondary and tertiary. The reasons for
studying the entire plant, instead of just the tertiary phase are: a)
the tertiary phase of the facility cannot operate without primary and
secondary treatment, and b) water quality improvements in Shagawa Lake
result from the treatment provided by the entire plant, not just the
tertiary plant.

To put the present study into proper perspective, a brief history
of the initiation of the AWT plant and a description of the plant itself
is necessary. Prior to the operation of the AWT, phosphorus entering
the lake was discharged from the secondary facility operated by the City
of Ely. The U.S. Environmental Protection Agency (EPA), in cooperation
with the City of Ely, funded construction of an advanced wastewater
treatment facility to demonstrate that a reduction in phosphorus from a
point source could reduce the trophic status of Shagawa Lake (Malueg et

, 1975). The tertiary plant which began operation in the spring of
i373, was designed to limit the phosphorus content of the effluent to 50
Mg/m? (0.05 mg/1') or less. Operating data since that time indicate
that the effluent from the plant does indeed meet design criteria. Both
the improvement in water quality and the limnological characteristics of
Shagawa Lake have been reported in the literature by Malueg et al (1975)
and by Larsen et al (1975) and will not be discussed here.


TA

TABLE 17. COMPARISON OF RESOURCE REQUIREMENTS FOR AWT AT ELY, MINNESOTA
AND LAKE TAHOE, CALIFORNIA

ELY TAHOE
Per 3 Per Per 3 Per
1000 m Million Gallons 1000 m Million Gallons
Chlorine, kg (1bs) 19 (160) 12.7 (106)
Salt, kg (lbs) 3.26 (27.2) 33.6 (280)
Sodium Carbonate, kg (lbs) 0.02 (0.19) 0.31 (2.6)
Lime, kg (1bs) 302.0 (2520) 192.0 (1600)
Limestone, kg (1bs) 600.5 (5011) 383.5 (3200)

Energy, GJ (BTU) 16.19 (58.1x10°) 29.5 (106x10°)



2

TABLE 14. TOTAL ENERGY’ REQUIREMENTS PER YEAR FOR ANT AT ELY, MINNESOTA

Converted to
Indirect Direct Total Td Bru
Electricity, Mih (kwh) 60.2 (60200) 780. (780,000) 840.2 (840,200) 3.03 (287x107)
Fuel O11, m° (gat) 38 ( 9,935) 238.5 (63,000) 276.5 (72,935) 11.7 (1109x107)
Gasoline, m? (gal) -- - 9.27 (2450) 9.27 (2450) 0.330 (31.3x107)
Natural Gas, m> (cu ft) 73,200 (2.88x10°) -0-  -0- 73,200 (2.58x10°) 3.10 (271x107)
7
Propane & Butane, m? (981) 138 (36,400) -0- -0- 138 (36,400) 3.67 (348x10")
Crude 011, m? (ga1) 0.79 (208) -0-  -0- 0.79 (208) 0.03 (2.87x10")
Misc. GJ (BTU's) 35.8 (33.9x10°) -0- 0+ 35.8 (33.9x10°) 0.04 _(3.39x10")
Sub Total 21.6  (205.3x108)
Gross Net
Ty BTU 1 BTU
2Fuel O11, m> (gal) 115.2 (4069) 0.65 6.18x10® 0.43 4.08x10® 0.43 (4.08x108)
2c0a1, Mg (Tons) 326.4 (359) 6.43 6.10x109 4.24 4. 02x10? 4.24 {40.2x10")
Grand Total 26.34 (249.6x108)

1 Energy Factors Used:

Electricity 3413 BTU/kWh
Fuel 01 19,000 BTU/1b (8 1b/gal)
Gasoline 20,750 BTU/1b (6.152 1b/gal)

1050 BTU/cu ft
95,590 BTU/gal
138,100 BTU/gal
8,500 BTU/1b

Natural Gas
Propane & Butane
Crude 0i1

Coal

eunenee

Fuel required to produce direct electricity shown on Ist line of table. In these lines, gross refers to energy content of
fuel, and net refers to energy after the energy content of electricity has been subtracted - assuming 33% thermal efficiency.


II
III

Iv

VI

CONTENTS

Introduction

Wastewater Treatment Plant
Resource Utilization and Pollutant Generation
Energy

Lime

Polymer

Carbon Dioxide

Ferric Chloride

Chlorine

Sulfuric Acid

Discussion and Summary
Literature Cited

SI Units and Conversion Factors Used


ABSTRACT

The results presented in this report give an indication of the
pollutants that would be generated and the resources consumed in opera-
ting a treatment facility similar to the one at Ely, Minnesota. The
study analyzes not only the facility itself, but also those industries
that supply products to the treatment plant. It was found that the
total energy requirement of the advanced wastewater treatment plant was
50x10° Btu/million gallons of water treated.

iv


Ut

TABLE 6. POLLUTANT DISCHARGE Que TO PRODUCTION OF PETROLEUM PRQDUCTS FOR AWT AT ELY, MINNESOTA
9.273 m> (2450 gal) Gasoline and 238.5 m> (63,000 gal) Fuel Oil/year

kg per lbs per 3K9 per Tbs per Per Year
m Gasoline 1000 gal Gasoline m Fuel 0117 1000 gal Fuel 0i7 kg Tbs
To Air
Particulates 15.9 (133) 7.8 (64.7) 1993 (4394)
Organic 127.6 (7966 61.8 13583 15930 (35,000
NO, 99.4 (830 48.3 403) 12440 27,000
SO, 118.0 (985) 57.3 (478) 14760 (33,000)
co’ 24.1 (201) 1.7 (97.6) 3014 (6650)
To Water
Chlorides 134.9 (716) 65.4 {548} 16850 (37157)
Grease 0.34 2.8) 0.17 1.4) 43.1 (95.1)
NH, - N 9.34 (2.8) 0.17 (1,4) 43.1 (95.1)
Phsphate 0.02 (0.14) 0.01 (0.07) 2.2 (4.8)
BOD 9.56 (4.7) 0.28 (2.3) 70.9 {136:4)
cob 36.40 (304) 17.70 (148) 4567 10,100)
Suspended Solids 1.13 (9.4) 0.55 1aee 142 (333)
Dissolved Solids 618.0 (5160) 300.10 2505) 77320 (170,000)



SECTION I
INTRODUCTION

The environmental effects of wastewater treatment include more than
the improvements in water quality that result from operating the treat-
ment facility. To understand the total environmental effects of a
facility, it is necessary to know the environmental tradeoffs that have
occurred as a result of construction and operation. For example: What
are the social and economic costs and benefits associated with treating
wastewater? What pollutants are generated in the manufacture of pro-
ducts used at the treatment facility? How much energy is consumed both
directly and indirectly in the construction and operation of the plant?
What changes have occurred in receiving water quality as a result of
reduced pollutant loadings to the system? What effect has the disposal
of sludge had on nearby terrestrial ecosystems?

These are but a few of the questions to be answered by an environ-
mental assessment being conducted by the Corvallis Environmental Research
Laboratory of the Shagawa Lake Demonstration Project. It is hoped that
this environmental assessment will aid in understanding the types of
significant environmental effects that may occur if similar technology
were transferred elsewhere. The reader must be congizant that the
Shagawa Project was a research effort, not simply a state-of-the-art
application. Consequently, the costs and benefits of the project cannot
be developed into a traditional C/B ratio. For example, a primary
benefit has been an increase in both limnological and technological
knowledge. This increase in knowledge is unquantifiable in any tradi-
tional sense and no attempt is made to place a numerical value on this
commodity.

The purpose of this part of the overall environmental assessment is
to examine only one aspect of the environmental impact of the Advanced
Wastewater Treatment (AWT) facility at Ely, Minnesota, namely resource
utilization and pollutant generation resulting from the operation and
maintenance of the AWT plant. These results give an indication of the
pollutants that would be generated and the resources consumed if the
technologies developed at Ely were transferred to another location.
Further, the results may be compared to those of a similiar AWT study at
South Lake Tahoe (Antonucci and Schaumberg, 1975).

Boundaries for the area of consideration need to be carefully
defined in order to assess the resources used and pollutants generated


a

TABLE 11. ENERGY REQUIREMENT FOR THE PRODUCTION
(Modified from Saxton et al, 1974)

OF CHLORINE

Net Electrical! Gross Electricalé Total net?
Energy Energy Process Steam Energy
69/Mg aTU/Ton Gd/Mg ATU/Ton Gd /Mg BTU/Ton —«GY/Mg_—«BTU/Ton
Mercury Cell
Graphite Anode 6.1 52.6x10° 19 164x10° 13 11.2x10° 7.4 -63.8x10°
(1700 kith)
Meta? Anode 5.2 44.8x10° 16 138x10° 1.3 2x0? 6.5 56x10
(1445 kivh)
Diaphragm Cell
Graphite Anode 5.5 47.4x10° V7 147x10° 5.6 48.3x10° 11.1. 95.7x10°
(1527 kith)
Metal Anode 47 40.5x10° 15 129x10° 5.6 48.3x10° 10.3. —-88.8x10°

(1300 kWh)

1 Power consumed directly in the electrolytic cell and elsewhere in the chlorine plant.

2 Fuel required to generate the net electricity (in some instances electric power is generated on-site).

3 Total of Net Electrical Energy and Process Steam.


Ecological Research Series



CHLORINE FEED
SYSTEM

CARBON DIOXIDE FES]

Service
FEED SYSTEM water

Gravity filter
oir blower

Exhoust
LIME FEED
system

po-- eH
1 [eter
1 | Metering. =

Ejector water 4} frome |

pumps FERRIC CHLORIDE

seryrargeaggreo FEES eta
fe 4 ------~-~- ~~~ ------~--

pump

oe c
1 SULFURIC ACID

1

1

0 f
1 1
- ~ == = --A-A meororing
\ '
Apa
it i

FEED SYSTEM

POLYMER.
i FEED SYSTEM

Flow
splitter box

EE

Grit
chambers Tricklin« Secondar
Plont fiter > clarifier”
influent ap
Comminater
Lift
station
‘Storm flow. Scum,
ond septic res
droinage ,
from swamp Recirculation
pump station ray
‘Sludge pump station

Gravity

og r
oe filter

Tertiary influent
pump station

Leffiuent
sampler

he Effluent to
‘Shagawa Lake

r

Lift

Sludge
thickener

Vacuum filter

station Scum : Effluent pump
storm flow ond SEE] Air blower ; Sludge conveyor _— station
Soptic dramage sludge pum Ly Fiarate ISludge hoppers
from Stinky Gr udge pump ain station haa ige hopp
‘ 3 9 Truck to landfill

ELY, MINNESOTA
WASTEWATER TREATMENT PLANT
NORMAL FLOW SCHEMATIC

MODIFIED FROM
TOLTZ, KING, DUVALL, AN@ERSON AND ASSOCIATES SCHEMATIC

tanks
Thickened sludge

Thickened st Sludge to holding pond

Process piping
——-— Chemical feed piping


SECTION II
WASTEWATER TREATMENT PLANT

Prior to construction of the tertiary treatment plant, the Ely,
Minnesota, waste treatment facility consisted of a conventional second-
ary treatment operation. Wastewater entered the facility, passed
through two parallel grit chambers and then through a bar screen and
comminuter. The waste proceeded through a primary clarifier, trickling
filter and secondary clarifier. After the effluent left the secondary
sous) it was chlorinated and discharged into Shagawa Lake (Brice

Historically, sludge from the secondary clarifier was returned to
the influent line of the primary clarifier and sludge from the primary
clarifier was digested and discharged to sludge drying beds. The plant
was designed to use digester gas in the plant boiler burner. However,
it 5° necessary to use supplemental gas to heat the digester (Brice
1975).

The tertiary treatment system was constructed as a research faci-
lity with a maximum of operational flexibility. Because of this, it is
possible to pump almost any part of the waste “from anywhere to any-
where". Chemicals can also be introduced at many points in the system.
However, much of this capability is not used and a standard procedure
which is working quite satisfactorily, was developed. It is this normal
operating procedure which will be described. A plant flow schematic is
shown in Figure 1.

The effluent from the secondary treatment facility is pumped to a
solids-contact clarifier at a rate of 4164 m°/day (1.1 mgd), Sheehy and
Evans (1976). Flow from this clarifier goes to a second, similar clari-
fier and then to a flow splitter box which feeds by gravity to four dual
media filters.

The filters polish the effluent by removal of suspended solids
containing phosphorous. Use of dual media (anthracite and sand) permits
longer filter runs while still retaining excellent solids retention
capability. Backwash water is returned to the secondary plant influent
line. The filter effluent is chlorinated and discharged to Shagawa Lake
or pumped back to the plant for use as process water.

It should be noted that an activated carbon feed capability is
available for the removal of soluble organic phosphorous, or other uses
as indicated. However, due to normal plant efficiency activated carbon

3


v2

TABLE 16.

RESOURCE REQUIREMENTS PER YEAR FOR OPERATION OF AWT AT ELY, MINNESOTA

Chlorine
Lime
FeCl,
HoS0q

Polymer

Salt

Sodium Carbonate

Limestone

Indirect Direct Total
Na Tons Mg Tons Mg Tons
26.2 28.9 4,7 5.2 30.9 34.1
-- -- 488.1 538.1 488.1 538.
-- -- 39.9 44.0 39.9 44,
0.03 0.03 74.4 82.0 74.4 82.0
-- -- 0.15 0.17 0.15 0.17
5.30 5.80 -- -- 5.3 5.8
0.04 0.04 -- -- 0.04 0.04
971 x 10° 1070. -- -- 971. 1070.0



TABLE 15. SUMMARY OF MAJOR POLLUTANT DISCHARGES PER YEAR DUE TO OPERATION OF AWT
AT ELY, MINNESOTA

Indirect Direct Total
Mg Tons Mg Tons Mg Tons
To Air
Particulates 3.88 5.23 0.43 0.4* 4.3] 5.71
SO, 20.6 22.74 4.08 4.50 24.7 27.2
co 3.20 3.59 1.84 2.03 5.10 5.62
HC 0.15 0.16 0.27 0.29 0.42 0.45
NO, 15.88 17.5 1.29 1.43 17.15 18.9
Clo 4.28 4.70 -- -- 4.28 4.70
n
# To Water
Suspended
Solids 0.33 0.37 -- -- 0.33 0.37
H,SO 0.007 0.07 -- -- 0.007 0.01
Phosphates 0.007 0.01 -- -- 0.007 0.01
BOD and COD 4.6 5.1 -- -- 4.6 5.1
To Land
Sludge 0.78 0.78 893.0 984. 894. 985.
Fly Ash 2.12 2.34 -- -- 2.12 2.34



ACKNOWLEDGEMENTS

The authors wish to thank R. M. Brice at Ely for his enormous
amount of help in supplying data on the operation of the treatment
facility. Without his help, this paper would not have been possible.
In addition, we would like to thank Mr. C. LaLiberte, Cutler-Magner
Corporation; Mr. M. Pressman, Betz Laboratories; Mr. C. Vorel, Cardox
Products; and Mr. J. Sharp, Dow Chemical, for supplying us with in-
formation on their respective industries, and for reviewing the draft

manuscript. Additionally, Dr. John Sheehy provided useful comments on
the manuscript.

vi


POLYMER

In addition to the lime, a cationic polymer (Betz 1150) is used as
a coagulant aid and added at a dosage of 0.1-0.2 (mg/1). This results
in 299 kg (659 lbs) of polymer being used each year. Betz polymer 1150
is "actually a co-polymer of acrymlamide with a portion of quaternary
ethyl acrylate included in the structure" (Pressman, 1975). However,
since this polymer is only one of several products being manufactured
simultaneously, Betz Laboratories could not furnish detailed information
on resource utilization such as energy consumption. The company claims
no waste products are given off during the manufacturing process. All
constituents which are not used are recycled and used in other produc-
tion (Pressman, 1975). The resources utilized and energy costs of
transporting 299 kg (659 lbs) of polymer from Trevose, Pennsylvania to
Ely, Minnesota, are insignificant compared to other energy and resource
requirements of the AWT plant. As a result of these findings, even
though the cost of the product, $8367 per Mg ($7606/ton) would indicate
that the process of producing Betz 1150 may be highly energy consuming,
no environmental impacts are assigned to the utilization of the polymer
at Ely.

CARBON DIOXIDE

Commercial grade carbon dioxide is added to the second clarifier at
a level of 100 g/m” (mg/1). This reduces the excess calcium by forming
calcium carbonate resulting in an annual usage of 152.4 Mg (167.6 tons)
of CO,. Carbon dioxide is generally obtained as a by-product of some
other’ reaction and is either emitted to the atmosphere or diverted to a
purification and liquefaction plant. There are only two resources
required to produce liquefied C0, - electrical energy and cooling water
(Vorel, 1975). The information bn electrical consumption and pollutants
generated, as supplied by Cardox products (Vorel, 1975) is shown in
Table 9. This information is valid only for gas produced as a byproduct
of another reaction, and not appropriate if gas were produced in an
inert gas generator.

TABLE 9. RESOURCE REQUIREMENT FOR AND POLLUTANT
DISCHARGE DUE TO PRODUCTION OF CO, FOR AWT AT
ELY, MINNESOTA
152 Mg (168 Tons)/year

Per Per Total
Mg CO, Ton CO, Per Year
Electricity, kWH 176 160. 26800
Waste Heat to Cooling 5
Water, GJ (BTU) 0.32 (3.0x10°) 53.1 (503 x 10°)

4


insignificant quantities of energy, 174.4 kJ/kg (75 BTU/1b) (Saxton et.
al, 1974), and, in many cases, much of the excess steam is utilized
either internally or in a nearby plant. For these reasons, this paper
does not include a detailed analysis of the fuels required to produce
the 174.4 kJ/kg (75 BTU/1b) of H,SO,. The total energy requirement,
13.0 GJ (1.23 x 10° BTU's), is counted in the energy consumption of the
facility at Shagawa. The processes produce an emission of 20 g of SO
per kg of H S04 (0.02 1b/1b) (EPA, 1972). Acid mist is produced and
emitted to the air. If the HyS0 facility has acid mist eliminators,
then from 0.01 to 0.1 g/kg of 560, is emitted. If there are no eli-
minators then from 0.15 to 3.75°g/kg are emitted. The following as-
sumption was made: acid mist elimigators are present at the facility
supplying Ely and 0.1 g/kg (1 x 10°" 1b/1b) are emitted. This results
in the assignment of 7.45 kg (16.4 lbs) per year of acid mist emissions
due to the production of HoS0, used at the Ely AWT.

20


DISCLAIMER

This report has been reviewed by the Office of Research and Development,
U.S. Environmental Protection Agency, and approved for publication.

Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.

ii


ENERGY

Electricity

On an average annual basis approximately 65 MWh (65,000 kWh) are
used monthly at the wastewater treatment facility at Ely, Minnesota.
This electricity is purchased from the City of Ely, who in turn buys
electricity from Minnesota Power and Light (MP&L). The environmental
analysis which follows is based on the fuel mix for the base load of
MP&L, which is approximately 80% low sulfur western coal, 12% hydro-
electric, and 8% residual fuel oi] (Rutka, 1975). The following assump-
tions were made with regard to the fuels: 1) coal = 0.65% sulfur, 19.77
Md/kg (8500 BTU's/1b), ash content = 7%; 2) Fuel oi] = 1% sulfur and
0.5% ash; and 3) hydroelectric - no environmental insults are assigned
to production of electricity by hydroelectric generation.

It is recognized that production of electricity by hydroelectric
generation creates environmental alteration such as changing a free
flowing stream to a standing water reservoir. This in turn alters
recreational opportunities and species composition of the aquatic
ecosystem. Further, dams can and do create other potential environ-
mental effects, such as gas bubble disease. However, with present
assessment techniques it is not possible to allocate a percentage of
these types of effects to the AWT at Ely. It must simply be recognized
that the AWT at Ely contributed to the demand for electricity and that
demand is being partially satisfied by hydroelectric power.

The resources consumed and pollutants generated, as shown in Tables
3 and 4 respectively, were calculated from Pigford et al (1975). While
Pigford et al have included pollutants generated throughout the entire
fuel cycle of both fuel oi] and coal, this analysis includes only pol-
lutants generated at the power plant. This paper has not included an
analysis of potential environmental effects associated with the extrac-
tion, transportation, or processing of fuels prior to burning in the
power plant.

TABLE 3. RESOURCE REQUIREMENTS FOR PRODUCTION OF ELECTRICITY
FOR AWT AT ELY, MINNESOTA

Per MWh Per year (780 MWh)
Fuel of] (8%) m> (gals) 0.020 (5.2) 15.4 (4070)
Coal (80%), Mg (ton) 0.420 (0.46) 328 (359)

Hydro-electric (12%) _ a



Fuel Oi] and Gasoline

; Significant quantities of pollutants are generated by burning fuel
oi and gasoline at the AWT facility. Further, the oil refineries
required to produce these products are the most significant indirect
source of pollution that can be assigned to the operation of the AWT at

y.

The direct pollutants generated and energy consumed as a result of
burning these fuels may be accounted for as follows. The trucks which
haul sludge from the AWT to a sanitary landfill consume 9.273 m> (2450
gallons) gf gasoline pew year. This is a direct energy consumption of
3.30 x 10°MJ (31.3 x 10° BTU's). In addition, based on air pollution
emission factors (EPA, 1972) this study assumes the following air
pollutants are emitted from these trucks: 1) carbon monoxide, 1838 kg;
2) hydrocarbons, 183 kg; 3) Nitrous Oxide (NO,), 1503kg. Based on
assumptions shown in Table 2, the burning of 338.5 m° (63,000 gallons)
of fuel oi] at Ely may be expected to emit the following air pollutants:
1) SO,» 4113 kg; 2) CO, 6 kg; 3) HC, 83 kg; 4) NO, 1145 kg; 5) parti-
culatés, 429 kg; and an undetermined amount of flV ash, (EPA, 1972). 7
This yosults in a direct energy consumption of 1.01x10° MJ (957 x 10
BTU's).

As noted above, the refining of the fuel oi] and gasoline con-
stitutes the largest indirect source of pollutants and energy consump-
tion required for the operation of the AWT. To allocate pollutants
generated and resources consumed at an oil refinery it is necessary to
know the percentage of gasoline and fuel oi] produced by the total
refinery process. For this analysis, it is assumed that gasoline
represents 44.7% of the crude input and fuel oi] represents 21.7%
(Pigford et al, 1975). Tables 5 and 6 show the resources consumed and
pollutants emitted in refining the fuel oil and gasoline consumed at
Ely. This information has been taken from Pigford et al, (1975), and it
should be noted that it represents industry-wide data for 1969. Thus it
does not represent the most modern technology; rather is indicative of
existing operations in the United States. It is interesting to note
that of the total amount of energy consumed as a result of operating the
AWT at Ely 65% can be assigned to the direct use of fuel oil and gaso-
line, and/or the refining of these products. In a wastewater treatment
plant that uses digester gas in the boilers, significant savings in
energy and pollutant discharges, both directly and indirectly, would be

realized.
LIME

The Ely AWT facility uses 488 Mg (537 tons) of lime per year. Lime
is fed into the clarifier at an average dosage of 275 g/m (mg/1) as
CaO to maintain a pH of 11.8 - 12.2 and to react with the ortho-phos-
phate to form calcium hydroxyapatite. This is the primary mechanism by
which phosphorus is removed from the wastewater. Magnesium hydroxide

9


EPA-600/3-76-092
August 1976

ENVIRONMENTAL IMPACTS OF ADVANCED WASTEWATER
TREATMENT AT ELY, MINNESOTA

by

Harold Kibby and Donald J. Hernandez
Criteria and Assessment Branch
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330

CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330


TECHNICAL REPORT DATA

(Please read Instructions on the reverse before completing)

7. REPORT NO. 2.

EPA-600/3-76-092

3. RECIPIENT'S ACCESSION NO.

4. TITLE AND SUBTITLE

Environmental Impacts of Advanced Wastewater
Treatment At Ely, Minnesota

5. REPORT DATE
August 1976

6. PERFORMING ORGANIZATION CODE

7. AUTHOR(S)

Harold Kibby and Donald J. Hernandez

8. PERFORMING ORGANIZATION REPORT NO.

I9. PERFORMING ORGANIZATION NAME AND ADDRESS

Corvallis Environmental Research Laboratory
U.S. Environmental Protection Agency

200 SW 35th Street

Corvallis, OR 97330

70, PROGRAM ELEMENT NO,

71, CONTRACT/GRANT NO.

12, SPONSORING AGENCY NAME AND ADDRESS

same

13. TYPE OF REPORT AND PERIOD COVERED

714, SPONSORING AGENCY CODE

EPA/ORD

75. SUPPLEMENTARY NOTES

16. ABSTRACT

similar to the one at Ely, Minnesota.

ment plant was 50x10

The results presented in this report give an indication of the pollutants that

would be generated and the resources consumed in operating a treatment facility

The study analyzes not only the facility

itself, but also those industries that supply products to the treatment plant.

It was found that the total energy requirement of the advanced wastewater treat-
Btu/million gallons of water treated.

n7. KEY WORDS AND DOCUMENT ANALYSIS

a DESCRIPTORS

b. IDENTIFIERS/OPEN ENDED TERMS [c.

COsATI Field/Group

Environmental Assessment

Resource Consumption Treatment.

Advanced Wastewater

13. DISTRIBUTION STATEMENT

19, SECURITY CLASS (This Report)

21. NO. OF PAGES

unclassified 36
Release to public 20. SECURITY CLASS (This page) 22. PRICE
unclassified
EPA Form 2220-1 (9-73)

30

# US. GOVERNMENT PRINTING OFFICE 1976~697.991 1124 REGION 10


pollutant emissions and energy consumption. This is done because the
entire analysis is limited to first order industries. The gross energy
figures represent the energy required to produce the electricity.
However, nearly 50% of the electrical consumption by the chlor-alkali
industry is generated on site, therefore, gross energy values are given
in Table 11 so that (if desired) the reader may recalculate energy
values for the production of chlorine.

In addition to electrical energy, the production of chlorine
requires large amounts of process steam in the evaporators. Natural gas
is the primary fuel used in the boilers to produce steam. However,
there are no data on the specific fuel mix used in the boilers. There-
fore, the emissions generated from producing chlorine have been calcu-
lated using the same fossil fuel mix as utilized by the alkalies and
chlorine industry (SIC 2812) as a whole (5% fuel oi1, 18% coal, 77%
natural gas). It has been assumed that these,fuels have the following
heat content: 3fuel oil, 39.8 GJ/m> (143 x 10 BTU/9q1)s coal, 30.34
Md/kg (13 x 10> BTU/1b); and natural gas 39.12 Md/m” (1056 BTU ft”)
Based on these assumptions, Table 12 shows the resources consumed in
producing 1 Mg (and 1 ton) of chlorine, as well as the resources uti-
lized in producing the 4.72 Mg (5.20 ton) of chlorine that is used
yearly at the AWT plant in Ely.

TABLE 12. RESOURCE REQUIREMENTS FOR PRODUCTION OF CHLORINE
FOR AWT AT ELY, MINNESOTA
4.72 Mg (5.20 tons)/year

Per Per Per
Mg_Cl Ton Cl Year
Electrical, MWh (kwh) 1.4 (1250) 6.5 (6.45x10°)
Steam!, J (BTU) 4.8 (41.6x10°) 22.8 ~~ (21.6x108)
Fuel O11, dm> (gal) 6.3 (1.51) 29.7. (7.7)
Coal, kg (1bs) 28.9 (38.0 136. (300.)
Natural Gas, m (cu ft) 95.0 3050 448 (15%8x10>)
Rock Salt, Mg (tons) 1.1 (1.25) 5.3 (6.5)
Sulfuric Acid, kg (1bs) 6.1 (12.2) 28.8 (63.5)
Sodium Carbonate, kg (1bs) 8.2 (16.4) 38.7 (85.3)

J Steam includes fuel 071, coal and natural gas.

2
Rock Salt was allocated on a molecular weight basis between chlorine
and caustic soda.

18


RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped ‘into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:

1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research

4. Environmental Monitoring

5. Socioeconomic Environmental Studies

This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal
species, and materials. Problems are assessed for their long- and short-term
influences. Investigations include formation, transport, and pathway studies to
determine the fate of pollutants and their effects. This work provides the technical
basis for setting standards to minimize undesirable changes in living organisms
in the aquatic, terrestrial, and atmospheric environments.

This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.


Ely. Secondly, the AWT at Ely does not incinerate its organic solids,
but mixes them with the lime sludge and hauls them to a landfill. At
Tahog the incineration of these solids results in an energy cost of 6.64
kd/m” (23,800 BTU's per million gallons). The only energy value that
was calculated differently in the two studies was the amount of energy
required to produce chlorine. In this study the energy consumed in
producing chlorine and caustic soda was allocated between the two end
products, whereas Antonucci and Schaumberg (1975) assigned all of the
energy in the production of chlorine and caustic soda to chlorine. This
difference is insignificant when compared to other energy requirements
of the AWT plants.

In order to put the resource consumption due to the operation of
Ely's AWT in perspective, one can compare this consumption with a common
"baseline", for example, home consumption of energy. On the average an
all-electric home, 111.5 m° (1200 sq ft), in Ely, Minnesota, consumes
approximately 3240 kWh/mo which is equivalent to 11,065,000 BTU's. The
AWT plant at Ely uses 65,000 kWh per month (221,980,000 BTU's) plus
another 798 million BTU's in fuel oi1. Thus the direct energy consump-
tion at the AWT facility is equal to the direct energy consumed in 74
all-electric homes. Using another comparison, the 2450 gals of gasoline
used in the trucks for hauling sludge would drive an automobile (getting
20 mpg) approximately 49,000 miles, about what four average families
would drive in one year.

Based on 1975 emission standards, which are more stringent than the
emissions from an average auto, it is possible to compute the number of
miles of auto travel that would create the equivalant grams of certain
pollutants as does the operation of the AWT at Ely: i CO, 337,200
miles; 2) HC, 224,000 miles; and 3) NOs 57,950,000 miles.

Other comparisons can be made. However, the purpose of this paper
is not to evaluate operation of the Ely AWT facility by comparing its
operation to other activities of man. The purpose of this study is to
assess what pollutants have been emitted and what resources have been
consumed as a result of operating the AWT at Ely. Ideally, it would be
desirable to carry this analysis a step further and discuss the effect
these pollutants have on human health and natural ecosystems. This is
not possible using techniques available today.

Consequently, we are faced with the situation where it is possible
to quantify, to some extent, the unquestionable improvement of the
Shagawa Lake ecosystem, and compare this improvement to unquantifiable
environmental effects that are being borne, not by the users of Shagawa
Lake and the residents of Ely, Minnesota, but by others who live in the
area of the oi] refineries, chlorine plants and other support industries.
While we cannot quantify these tradeoffs it is important to understand
that they do exist and because of this technology fixes may not neces-
sarily be the solution to all environmental pollution problems.

26


SECTION IV
DISCUSSION AND SUMMARY

The.total pollutants generated and resources consumed for treating
1.616 hm’ (427 million gallons) per year of wastewater at the AWT faci-
lity in Ely are summarized in Tables 14, 1g, and 16. Of the total
energy requgrement of 26.34 TJ (24.96 x 10° BTU's) (Table 14), 10.1 TJ
(9.57. x 10° BTU's) are contained in the fuel oi] burned at the AWT
plant. The major indirect energy sources are for refining gasoline and
fuel oil and in the energy content of the fuel required to produce the
electricity used for the AWT. The operation of the oil refinery was the
single largest contributor of pollutants generated as a result of oper-
ating the Ely AWT.

When the values for the AWT at Ely are compared to those of the AWT
at Lake Tahoe (Antonucci and Shaumberg, 1975) there are some apparent
differences (Table 17):

1) At Ely, chlorine is consumed both directly and indirectly in
the manufacturing of FeCl,. At Tahoe, since alum is used instead of
FeC1,, chlorine is only cénsumed directly. Because of this difference
in operational procedure, chlorine consumed at Ely is 1.5 times that
used at Tahoe. However, when direct consumption of chlorine is con-
sidered then the chlorine consumed at Ely is only 0.25 times that used
at Tahoe. Likewise, salt and sodium carbonate, used in chlorine manu-
facturing, values are much higher at Tahoe. The difference jn these
values is,due to: 1) the chlorine dosage at Tahoe is 12 g/m” (mg/1),
and 3 g/m” (mg/1) at Ely; and 2) in this study, the resources used in
chlorine production were allocated between chlorine and its co-product,
caustic soda.

2) Lime is used in greater quantities at the Ely facility pri-
marily because there is a lime recovery system at Tahoe, whereas at Ely
the lime sludge is trucked to a sanitary,landfill. This must be balanced
against energy cost at Tahoe of 3.8 x10 kJ (35.7 x 10° Btu's) to recover
lime.

3) Finally, it is apparent from Table 17 that it takes twice as
much total energy, per million gallons of effluent to operate the Tahoe
facility. Of the 111.8 SJ (106 million BTU's) used at Tahoe over 36.9
GJ (35 million BTU's) are used in recalcining lime, which is not done at

21


is seldom used, consequently the analyses which follow do not include an
assessment of the activated carbon system.

Chemical sludge is withdrawn from the tertiary system at both
clarifiers and pumped to a gravity sludge thickener. Organic sludge
from the primary and secondary clarifiers goes to the sludge thickener
where it is mixed with the chemical sludge from the tertiary plant.
From the sludge thickener, the sludge is pumped to a rotary belt vacuum
filter and trucked to an approved sanitary landfill. In the event of
equipment failure, the sludge can bypass any given treatment facility
and be discharged to a sludge holding pond. Filtrate from the vacuum
filter and slurry from the vacuum are discharged to the equilization
tank and returned to the head of the plant.

The tertiary treatment plant was designed to treat 5,678 m/day
iy 5 mgd) and from April 1, 1973 - March 31, 1974 was treating 4,164
/day (1. 1 mgd). Overall plant performance relative to certain para-
meters ts presented in Table 1 (Sheehy and Evans, 1976).

TABLE 1. ELY AWT PLANT PERFORMANCE

Influent Effluent Removal
g/m? afm? % g/m? kg/d Mg/yr
Total P 7.1 0.05 99.4 7.02 29.2 10.7
Suspended Solids 202.0 1.30 99.4 201.0 837.0 306.0
Alkalinity (as 181.0 41.90 76.9 139.0 579.0 211.0
CaCO)
BOD 90.0 12.30 86.3 78.0 325.0 119.0



TABLE 4. POLLUTANT DISCHARGE DUE TO PRODUCTION OF ELECTRICITY FOR AWT
AT ELY, MINNESOTA 780 MWh/year

kg (Ibs) of pollutant

kg (lbs) of pollutant

per MWh per year
3 3
S05 5.56 (12.3) 4.34 x 10 (9.6 x 10”)
NO 4.04 (8.91) 3.15 x 10° (6.95 x 10°)
. x
To Air
co 0.25 (0.55) 193 (426.0)
HC 0.045 (0.10) 34.9 (77.0)
Particulates 2.31 (5.09) 1.80 x 10° (3.97 x 103)
Suspended
Solids 9.053 (0.116) 41.2 (90.8)
HyS0q 0.009 (0.020) 7.02 (15.5)
Clo 0.003 (0.006) 2.3 (5.1)
To Water
Phosphates 0.005 (0.010) 3.6 (7.9)
Boron 0.036 (0.080) 28.3 (62.4)
BOD Negligible Negligible
To Land Fly Ash 2.72 (6.00) 21.2 x 10° (46.7 x 10°)

! Assumes fuel mix of 80% coal, 12% hydro and 8% fuel oil.

It is emphasized that the data in Table 3 indicate the pollutants
generated as a consequence of electric energy use by the Ely AWT.
However, it must be recognized that these pollutants are discharged to
the environment at the generating location, not at Ely. Consequently,
as with all indirect pollutants generated as a result of operating the
AWT, the environmental costs are being borne not by the users of Shagawa
Lake or the residents of Ely, but by the residents living near, and the

people using the environment at another location.

8