EPA
Office of
Research and
Development
Energy,
Minerals and
Industry
Cleaning Up Mixed
Waste Streams-
The Tank Truck
Washing Example
EP 600/9
77-007
LIBP A BY
tt, S- Ei,vL. . . -iAL
EDISON, N. J. 08817
&TECTION AGENCY
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THE INDUSTRY/ENVIRONMENT
R&D DECISION SERIES
This volume is part of the Industry/Environment R&D Decision Series. The series presents the
findings of EPA's Office of Research and Development (ORD) on a number of key issues in the
Industry/Environment R&D Program in a format conducive to effective information transfer. The
volumes are of three types: summaries—short synopses of larger research reports; issue papers-
concise discussions of major industry/environment technical issues; and executive reports-
in-depth discussions of an entire programmatic or technical area.
The Division of Industrial and Extractive Processes within ORD's Office of Energy, Minerals,
and Industry is charged with planning and coordination of the Industry/Environmental R&D Pro-
gram. Areas of research include the entire materials processing and production cycle from extrac-
tion through production, with emphasis on the assessment of pollution from industrial processes
and the development of effective control technologies.
The Decision Series is produced for both industry/environment decision-makers and the inter-
ested public. If you have any suggestions or questions, please write to Series Editor Richard Laska,
Office of Energy, Minerals, and Industry, RD-681, U.S. EPA, Washington, D.C. 20460 or call
(202) 755-4857. Extra copies are available on request.
Mention of trade names or commercial products does not constitute endorsement or recom-
mendation for use by EPA. This document is available to the public from the National Tech-
nical Information Service, Springfield, Virginia 22161.
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Cleaning Up Mixed
Waste Streams -
The Tank Truck
Washing Example
April 1977
STATEMENT OF PROBLEM
Pollution threats posed by chemicals manufacturing and transportation involve toxic and highly
variable discharges requiring nontraditional clean-up technologies. As in chemical manufacturing
where discharges vary greatly with different production operations, transportation of the chemi-
cals results in a highly variable waste discharge. Chemical tankers carry wide varieties of products
and must be drained and cleaned between trips. Wastewaters from tanker cleaning, exceeding 50-
million gallons per year, now go to municipal waste streams. Chemically burdened wastewaters
from tanker cleaning operations profile comparable but higher volume conditions that prevail
throughout the chemical manufacturing industry. Demonstration of new and effective technol-
ogies for tanker wastes and wastewater treatment as described in this report portend widespread
application in a broad range of chemicals manufacturing industries.
LIBRARY
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OVERVIEW
One of the most difficult environmental problems the
transportation industry faces is the treatment of waste-
waters from tank truck interior washing operations.
The root of the problem is lack of proven treatment
technologies which embody economic feasibility. Be-
cause hauled materials vary widely in character, washing
operation wastes reflecting these cargoes are also variable
and difficult to treat. The wastestreams primarily con-
tain oil and organic materials, many of which, because of
high concentrations or toxicity, may upset municipal
waste treatment plants or physical/chemical treatment
methods.
In 1974 EPA prepared a Development Document for
proposed effluent guidelines and standards for these
wastewaters. EPA based some of the proposed standards
on treatment techniques which were available but not
demonstrated specifically for the tank truck industry.
The tank truck carriers requested demonstration of a
technically and economically viable process for treating
the wastewaters before promulgation of the effluent
guidelines and standards.
Matlack Corp., one of the nations largest tank truck
operators, has long recognized the need for treatment
alternatives and has investigated a number of techniques
since 1966. Last year Matlack approached EPA's Office
of Energy, Minerals and Industry, resulting in a joint
venture into construction and demonstration of a full-
scale plant to determine technical and economic viability
of a treatment system.
TANK TRUCK TERMINAL
The system under demonstration involves an integra-
tion of new and state-of-the-art physical, chemical and
biological waste treatment unit operations into a unique
and promising hybrid system. Matlack's Swedesboro,
N.J. terminal cleaning facilities, which produce some
15,000 gal/day of interior tank wash wastewater, was
chosen as the test site.
This report presents a perspective on the problem
posed by the tank wash waters and presents preliminary
data on the treatment system under demonstration.
THE POLLUTION THREAT
Tank truck carriers operate more than 90,000 tank
trucks in the U.S. About one-third of these are part of
the private fleets such as those operated by major petro-
leum and chemical companies. These fleets haul prod-
ucts of the parent company, and are generally dedicated
to haul specific products. The interiors of these dedi-
cated tankers seldom require washing.
The remaining 60,000 or so tankers constitute the
industry common carrier fleet and are "for public hire".
Some of these tankers are also "dedicated" to carry
specific products, and don't require frequent washing.
But most of the 60,000 tankers are not dedicated and
their cargoes can vary from highly toxic materials to
innocuous materials such as fish oil.
THE VARIABILITY PROBLEM
The cargoes can be chemicals, petroleum, or other
products. Table I shows, through cargoes hauled, the
variability of experience in one month. In another
month 550 tank interiors containing 47 different chemi-
cals were cleaned at the same facility.
Roy F. Weston, Inc., has studied the variability of
wastes for the National Tank Truck Carriers Association.
The high degree of variability in "pollutional content"
of these wastewaters is indicated by the ratio of prob-
able occurrence of high to low values for the parameters
listed in Table II.
Variability of volume and characteristics of waste-
water from the cleaning of tankers can be attributed to:
• the product hauled,
• the amount of undelivered product (heel),
• the cleaning procedure used, and
• the number of tank trucks cleaned daily.
These wastes contain materials which range from high
biodegradable materials, such as sugars, to phenols, plas-
ticizers, oil and acids.
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TABLE I
COMMON CARRIER TANKER CARGO VARIABILITY
NUMBER OF POTENTIAL IMPACT ON
CARGO UNITS CLEANED BIOLOGICAL SYSTEM
Cutting Oil
Lube Oil
Toluene
Unidentified Product
Fuel Oil Additives
Carbon Black Oil
Acetic Anhydride
Ammonium Thiosulfate
Naphthalene
Wax
Tall Oil
Phenol
Fish Oil
Sodium Nitrite
Latex
Resin
Plasticizer
Caustic Soda (Liquid)
Lard
Hydrochloric Acid
Fatty Acid
Liquid Sugar
1
366
71
8
2
9
1
22
18
62
1
18
1
44
66
76
348
19
13
1
5
32
1,184
Low
Low
High
—
High
Low
Medium
Medium
Medium
Low
Medium
High
Low
High
High
Medium
High
High
Low
High
Low
—
TABLE II
TANK TRUCK RAW WASTEWATER
POLLUTIONAL CHARACTERISTICS
MEAN ^VARIABILITY RATIO
Flow, Gals/tanker washed 1390 5
BOD5,Mg/l 2800 5
COD, Mg/l 12000 3
SS. Mg/l 4035 19
Phenols, Mg/l 29 12
"Ratio is generated using monthly average values at 5 terminals. Each value is an average of
3-6 daily composite values taken that month. Values at 90 percent level of occurrence are di-
vided by those at 10 percent level of occurrence to produce the variability ratio.
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WHY WASTEWATERS VARY
WASTEWATER VOLUME AND FATE
Heels are the portions of the product not delivered,
but returned to the terminal for disposal. Whenever fea-
sible, heels are segregated from the wash water stream
and sent to approved disposal sites or, if feasible, return-
ed to the sender. However, heels may be inadvertently
flushed to the treatment system or sewer when a wash-
ing operation is initiated. Heel volumes range from
10-500 gallons, and if discharges reach downstream
physical/biological treatment systems they can exert
significant shock load or toxic impact, thus reducing or
completely eliminating the system's functional capa-
bility.
Waste treatment procedures vary with size of trucking
operations, type of cargo hauled and cleaning agent. The
interior tank washes are usually performed at terminals
equipped with wash racks and lightweight, high-velocity,
omnidirectional spray nozzles. Matlack, for example,
operates 2800 tankers and 52 terminals, 22 of which are
equipped for interior tank wash operations. (External
truck washes are performed at all 52 terminals.) Several
other large tank carriers operate in this mode, but more
than 5000 carriers operate fleets of 5 trucks or less.
EXTERIOR WASH STATIONS
These smaller companies cannot operate such clean-
ing terminals and some of them discharge their wastes to
sewers. Also, the tank cleaning methods vary with the
type of cargo hauled. The principal cleaning agents are
water, steam, detergents, caustics, and other specific sol-
vents. Use of these agents, sprayed into the tanks under
high nozzle pressure and subsequent physical mixing re-
sults in highly emulsified waste streams, rich in organics,
suspended solids and oils.
The wastewater discharged from interior tank wash-
ing ranges between 600-900 gal/tanker, but can reach
much higher volumes. EPA estimated that less than 10
percent of the terminals surveyed generate more than
15,000 gal/day of wastewater. These wastewaters are
relatively limited in quantity but their environmental
impact can be both highly visible and very significant.
Table III shows some typical flow rates and pollutional
characteristics that could impose significant environ-
mental impacts.
EPA estimates that two-thirds of the tank truck in-
dustry discharges wastes to municipal systems, with little
or no pret.reatment. Where it has been provided, treat-
TABLE III
TYPICAL FLOW RATES AND
POLLUTIONAL CHARACTERISTICS
WASHWATER
EFFLUENT
CHARACTERISTICS
ESTIMATED
RAW
WASTELOAD
Typical 'low
900 gal/unit washed
High pH
lalkaline)
10-12
High in Organic Chemicals,
•oxic to biological
' ystems
High BOD
1465 mg/l
11 Ib/unit washed
High COD
14,920 mg/l
112 Ib/unit washed
High in Solids Content
Isuspenced solids)
1,000 mg/l
7.5 Ib/unit washed
High in oils and grease
content
1,000 mg/l
7.5 Ib/unit washed
High in specific toxic
material content
Phenols
Chromium
Cyanide
67 mg/l
0.05 Ib/unit washed
5.3 mg/l
0.04 Ib/unit washed
0.93 mg/l
0.007 Ib/unit washed
4
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ment has generally been limited to: sedimentation,
neutralization, evaporation ponds and lagoons and other
relatively unsophisticated techniques. The prevailing
treatment practices observed in the EPA survey for their
development document are summarized in Table IV.
HOPE FOR FUTURE WASTE TREATMENT
Industry practices and problems in treatment of tank
interior wastewater can be summarized as follows:
• The tank interior wash operation has been identi-
fied as a major source, and as one of the industry's
waste streams that is most difficult to treat.
• While wastewater volumes are relatively small, the
potential impact of the materials in the waste
stream is significant—both to the environment and
to conventional treatment systems.
• State regulatory agencies such as those in Cali-
fornia, New Jersey, Connecticut, Louisiana, Ken-
tucky, Texas and other states, requiring compli-
IIMTERIOR WASH STATIONS
ance with effluent limits issued with their own
discharge permits, are creating impetus for new
treatment technology.
TABLE IV
ERA'S 1974 SURVEY OF PREVAILING TREATMENTS
TREATMENT AFFORDED THIS WASTE STREAM
Terminal
Sur-
veyed
by EPA
A
B
C
D
E
F
G
H
1
J
K
Principal
Type of
Materials
Handled1
C, D
C
Asphalt
C
C
C
C, D
D
D.P
B (3)
F (4)
^
CQ £ >-
Gravity Chemi- Filtra- ™ °" c o = £
Oil cal Air tion g> | o s ™ »
Sedimen- Equili- Separa- Neutral- Coagu- Flota- Media Extrac- Clan- B 5 o> £ o » >
Sump tation zation tion ization lation tion Screen tion tier m c/> -J < Z 3 Q
X XX X X 30
X X X (spray) 10-25
in pond
X (spray) N D
X 18
X N D
XXX 35
XX XX X holding 30
X X 80-90
X X 30-40
X 50-60
XX X 80-90
a 15
l°L
o|
1 1-
1200+
500-
800
N D
N D
N D
570
N D
N D
100-
300
N D
200+
C=Chemicals (2) N D = no data
P=Petroteum (3) B-beef/animal carcasses
D=Dry bulk (4) F=foodstuffs (dairy-vegetables)
CG=Compressed Gases
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The EPA program to define effluent limitations
for the tank interior wash wastes was delayed by
lack of data on the industry and the applicable
control technologies. The variable nature of the
waste stream and the absence of a demonstrated
control technique were the main hurdles.
Several attempts are being made to develop tech-
nically and economically feasible methods to treat
tank interior wash wastewaters. Table IV lists the
prevailing treatment techniques used in this indus-
try. They include:
(a) A sequential air flotation and biological
system in Downington, Pa. (Chemical Lea-
man Corp.)
(b) A sequential physical/chemical system in
Louisville, Ky. (Liquid Transporter Corp.)
(c) A modified (bleed in) biological system in
Deer Park, Texas. (Robertson Tank Lines)
(d) The joint EPA/Matlack hybrid system in-
volving physical, chemical and biological
methods in Swedesboro, N.J.
THE EPA/MATLACK SYSTEM
The hybrid system under test by Matlack involves a
combination of these seven specific unit operations:
1. Oil separation: to remove oil/grease
2. Air flotation: break emusion and remove oil/
grease/suspended solids
3. Chemical coagulation and pH adjustment: to aid in
removal of suspended solids
4. Equilibration/sedimentation: allow separation of
solids and prepare waste for further treatment
5. Mixed media filtration (MMF): to further remove
solids/color
6. Carbon adsorption: remove organics which may be
toxic to biological systems
7. Rotating filter-biofiltration system: to remove de-
gradable organics
The treatment system is operated on a 5-day week. It
consists of the above unit operations as shown in Figure
1. Gravity oil separation, pH adjustment, cationic and
TANK TRUCK
WASHING
OPERATIONS
WASTEWATERS
DISSOLVED
AIR FLOTATION UNIT
API GRAVITY
OIL SEPARATOR
COLLECTION
TANKS
CATIONIC
POLYMER
BATCH
EQUALIZING
TANKS!2'
SULFURIC
ACID
NEUTRALI-
ZATION
VESSEL
ANIONIC
POLYMER
AIR
SLUDGE
STORAGE
VESSELS
CARBON
C _2| SURGE ADSORPTION TOWERS
r*( ' TANK
SLUDGE TO
DISPOSAL SERVICE
CLARIFIER
FIGURE 1
EPA/MATLACK TANK TRUCK WASTEWATER TREATMENT SYSTEM
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anionic flocculant addition and air flotation operations
constitute the "basic" or primary portion of the system.
In addition to these operations, multi-media filtration,
carbon adsorption and rotating biofiltration units are
used for final wastewater treatment. The system oper-
ates eight hours/day. The biofiltration unit operates con-
tinuously.
The test system configuration affords maximum flex-
ibility with respect to the sequence of unit operations
used, flow capability and evaluation of alternative
methods. The Swedesboro facility has been in operation
since January 1976. Thus, the results presented here are
"preliminary" and will be reaffirmed and elaborated as
the project proceeds.
THE TERMINAL OPERATIONS
The Swedesboro Terminal is approximately two miles
east of the Delaware River in Gloucester County, New
Jersey. Effluents from the plant are regulated under a
New Jersey discharge permit issued for the duration of
the demonstration project. The tankers using this ter-
minal primarily haul organic chemicals and products,
such as those listed in Table I. Heavy metals are rarely a
part of the cargoes at this terminal and consequently are
seldom a problem in the wastewater to be treated by the
test system, but they are an industry problem.
WASH FACILITIES AND SYSTEM
Roofed and exposed wash facilities are provided at
this terminal. The wash area is paved and sloped to maxi-
mize wash water collection but minimize rain fall collec-
tion. Lightweight, omnidirectional, high intensity nozzles
are used to direct steam or hot caustic solution and fresh
water rinses into the tanks while valves are in the open
position. Any solvents used for cleaning and product
heels are segregated whenever possible. A central drain
carries the wastewater from interior and exterior washes
to two collection tanks.
The wastewater produced in the wash operation is an
emulsion of oils, organic and some inorganic chemicals.
It varies in color from white to various shades of tan and
brown reflecting its variable content and potential im-
pacts. Two collection tanks receive the alkaline and
emulsified wastewater, which occasionally contains heels
despite efforts to segregate them. No sanitary wastes are
discharged to the treatment system. Total wastewater to
the system is estimated at 12-18,000 gal/day for a 6-day
collection week.
SLOPED WASH AREA
OIL REMOVAL
A diaphragm pump moves the wastewater from the
sump to a 1,640 gal API separator at an average rate of
16 gal/min. In the API separator, baffled flow patterns
and a detention time of about 1-2 hr allow free oils to
float to the surface where they are skimmed and col-
lected. About 500-700 gal/week of oil are recovered and
stored in underground tanks. The recovered oil is sold
for re-refining at a current rate of $0.03/gal. This unit
operation also produces approximately 4,000 gal/week
of sludge. The 15 gal/min of effluent from this unit,
contains large quantities of colloidal and dissolved oils
and has a pH of 11. Other characteristics of effluents
from this unit operation are shown in Table V.
API SEPARATOR
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TABLE V
PRELIMINARY EFFLUENT DATA FOR EACH OF THE UNIT OPERATIONS
CARBON ADSORPTION
pH
Color
Turb [a]
COD
BOD5
O&G [b]
Phenols
SS[c]
OIL
SEPARATION
10.5-12.5
Over 500
Over 500
1 ,800-1 1 ,000
600-2,000
110-350
1-250
300-1 ,300
MIXED MEDIA
FILTRATION
6.5-8.0
50-100
5-30
1,100-5,500
-
5-15
1-200
10-20
LEAD
CARBON
6.5-8.5
1-10
5-10
900-1 ,900
800-1 ,500
—
—
—
POLISH
CARBON
6.5-8.5
1-5
1-5
650-1 ,800
550-1 ,300
<1
0.1
0.1
BIOFILTRATION
6.5-8.5
10-50
—
1 25-300
20-100
<1
0.1
_
[al Turbidity (mg/l)
[b] Oil and Grease (mg/l)
[c] Suspended Solids (mg/l)
EQUALIZATION
Effluent from this process is pumped to one of two
20,000 gal batch tanks and allowed to "equalize" for
16-24 hrs. This equalization is essential to the air flota-
tion process downstream. Sedimentation in this tank is
limited due to the emulsified nature of the wastewater.
Approximately 30 gal/min of "equalized" wastewater
plus 70 gal/min of recycle from the flotation unit goes
to a mix tank.
BATCH TANK
CHEMICAL TREATMENT/PHYSICAL
SEPARATION
In this tank wastewater pH is adjusted with sulfuric
acid to 6.5-7.5, and cationic polymer is added at the rate
of 1-20 gal/hr. The polymer is added to promote devel-
opment of floe (agglomerated particles) which can be
more easily removed in the flotation unit.
An air eductor introduces 40 psi air into the waste-
water. Anionic polymer is added at the rate of approxi-
mately 7 gal/hr to further promote coagulation and the
pressurized waste stream is then released to atmospheric
pressure in a 2,200 gal dissolved air flotation unit. As the
small bubbles of air form and rise, the colloidally sus-
pended materials become attached to the bubbles and
rise with it to the tank surface where it is skimmed and
stored for collection by a disposal service. Heavier floe,
formed by polymer addition, settles to the bottom of
the tank.
The sludge produced in this process approximates 5
percent of the wastewater volume, or approximately 700
to 1,000 gal/day. Sludge collected from this unit opera-
tion is typically 10 percent solids.
The dissolved air flotation unit operation breaks the
emulsion of wastewater with oils and solids, and removes
these materials which could interfere with subsequent
treatment processes. Operation of dissolved air flotation
is still being optimized. It depends heavily on the segre-
gation and removal of heels and solids settled in the API
unit. Detergents which tend to sustain emulsions, are
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counterproductive in this unit and their presence is mini-
mized when possible.
Treated wastewater from the dissolved air flotation
unit is fed to a 2,250 gal storage feed tank for distribu-
tion to the next operation.
DISSOLVED AIR FLOTATION UNIT
MIXED MEDIA FILTRATION/
DISSOLVED AIR FLOTATION
Effluent from the flotation unit feeds the filtration
unit at the rate of 30 gal/min. This unit is filled with a
bottom layer of 40 mm mesh sand and 0.5mm mesh,
Anthrafilt (coal derivative). The effective bed depth is 18
inches for each media. The pressure drop across the filter
under operating condition is 8-15 psi. The filter and dis-
solved air flotation units reduce the solids level in its
effluent to the 10-20 mg/1 range. Other effluent charac-
teristics are shown in Table V.
The filter is backwashed when pressure drop across
the filters reaches 12-15 psi. Backwash is returned to the
batch tanks. The filter is oackwashed on the average of
once per week under the current operation schedule.
CARBON ADSORPTION UNITS
Effluent from the mixed media filter flows to two
activated carbon towers operated in series. These units
remove organic chemicals which might be toxic or other-
wise deleterious to the biological process that follows.
Theoretically, complex organic molecules (typical of
"toxic" cargoes), are preferentially adsorbed on the car-
bon. This allows the less complex "non-toxic" molecules
to pass through to the biofilter unit operation which
follows.
When breakthrough occurs in the first or lead tower,
wastewater flow is directed to the second tower and the
exhausted carbon is replaced. The new adsorbent is
placed on line in the second or polish tower position.
The adsorption carbon and regeneration services are
rented from Calgon Corp. The carbon used is a mixture
of Filtrasorb 300 and 400. The system currently uses
about 2,000 Ib. of carbon per month. The carbon units
have been performing well.
A mild caustic soda treatment can inhibit inordinate
biological degradation activity on the carbon which
could interfere with the adsorption process.
The characteristics of effluent from the carbon unit
shown in Table V indicate the applicability of this tech-
nique for removal of soluble organics, some of which
may be toxic to the biological process.
BIOLOGICAL DEGRADATION
Effluent from the carbon adsorption unit flows to a
holding tank and then to the biofilter operation. Waste-
water is fed at the rate of 30 gpm. A 40 percent biofilter
effluent recycle during wastewater feed and 100 percent
recycle at other times maintains the flow into the unit at
50 gpm and allows its continuous operation. Because
biotreatment influent is biodegradable, air is introduced
by an air eductor to the influent to maintain dissolved
oxygen levels.
This unit combines the principle of rotating disc
systems and trickle bed biofiltration. A 7.5 ft. long x 6
ft. dia. drum-shaped container formed from perforated
steel is mounted horizontally aand filled with 1-1/2 x 2
inch polyethylene raschig rings. This packing provides 35
sq. ft. of surface per cubic foot of packing. As shown in
Figure 2, the basket rotates in an open tank partially
filled with wastewater.
Preliminary data shown in Table V clearly demon-
strates that this unit can reduce influent BOD by as
much as 50-90 percent based on current loads.
OVERVIEW OF TREATMENT SYSTEM
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PROCESS ECONOMICS
The system at Swedesboro will treat wastewater from
tank interior wash at a cost of approximately $50/1000
gal or $7 50/day. It should be noted that about
$30/1000 gal (the largest single cost) is due to equip-
ment rental. This cost could be substantially reduced by
equipment purchase and amortization. At Swedesboro
some 15,000 gal/day of wastewater are produced from
washing 15-20 tank interiors and exteriors per day.
The present costs of rented equipment and laboratory
support to optimize operating conditions for the system
do not necessarily approximate typical full-scale operat-
ing system economics. The analysis of costs to date
shown in Table VI is based on 15,000 gal/day six-day
work week, with five days for treatment operations.
Similarly this cost is expected to be reduced by
equipment purchase and more efficient water use.
TABLE VI
OPERATIONAL ECONOMICS
(In Dollars)
Cost/Day
Cost/1000 Gal.1
OPERATING COSTS-TOTAL
Labor2
Chemicals
Sludge Disposal
Power
$181.62
$ 73.93
57.69
38.46
11.54
4.93
3.85
2.56
.77
$12.11
RENTAL COSTS-TOTAL 496.16
Activated Carbon5 461.54
Biofilter6 34.62
CAPITAL COSTS-TOTAL 72.12
Depreciation7 72.12
TOTALS $749.90
30.77
2.31
4.81
33.08
4.81
$50.00
Notes:
Per 1000 gallons of treated wastewater
2One full time hourly worker, 5-day 9-hour day
Sulfuric acid, cationic, and anionic polymers
6.25i/gallon of sludge removed
Rental includes regeneration
6RBF rental at $900/month
7Over 8Vi years, building cost is $42,000+
10
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