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                    Waste Water From Fume scrubbing


Control Costs


The three processes in present use for the control of water effluent are
the Derham Process, the  Alcoa  Process,  and  the  use  of  A1F3  as  a
demagging agent.

The equipment cost of the Derham Process was obtained from the licensing
company  (Andrews,  1973) as between $5,000 and $10,000 for a production
rate of 5,450 tons of aluminum/year.  Addition of other capital items of
installation, piping, etc., at an average cost of $7,500  results  in  a
total  capital  requirement  of  $3.U/annual ton.  The capital equipment
includes the molten aluminum pumps, an additional holding  furnace,  and
other  items  necessary for conversion of a standard demagging operation
to the Derham Process.

The licensing company claims that several cost savings to the  secondary
smelter would result when the Derham Process is used.  The major savings
claimed are:

(1)  The reported chlorine usage is 3 kg/kg of magnesium removed,
     in lieu of the value of 3.5 kg/kg found in conventional
     demagging operations.

(2)  An increase in melt rate of 20%.

The  operating  cost  of  $2.5/ton  calculated  for  the  Derham Process
includes the savings expected as a  result  of  the  two  claims  above.
However,  because  of  the  present uncertainty as to whether the Derham
process may meet all air pollution control standards, the costs for this
alternative have also been calculated for two possible cases of scrubber
use.  If the Derham process were applied in a small treatment unit   (the
recommended  method) a relatively small volume of gases would need to be
scrubbed.  This case was calculated on the basis of a  caustic  scrubber
treating  500 actual cubic feet per minute of gases at 150°C (300°F)  and
gave additional increments of costs amounting to $0.55/annual metric ton
capital cost  and  $0.13/metric  ton  operating  cost.   If  the  backup
scrubber  for the Derham process treated all the gases (i.e., combustion
gases and demagging fume combined), the  cost  of  the  larger  scrubber
would  be  higher.  This case is calculated on the assumption that there
are some operational factors such as lack of space or very stringent air
pollution control conditions that would lead to the use of the  scrubber
on  the  combined  gases.   The  conditions assumed for this case were a
caustic scrubber with capacity to treat 11,000  actual  cubic  feet  per
minute  at  650°C   (1200°F) giving a capital cost of $2.23/annual metric
ton and an operating cost of $0.54/metric ton (i.e., over and above  the
costs of the Derham process itself).
                                 89

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The  equipment  cost  of  the  Alcoa  503  process was obtained from the
licensee  (Demmler,  1972).    The  equipment  cost  includes  the  basic
reactor,  the  salt-tapping   vessel,  and the metal-tapping vessel.  The
calculated capital investment for a 17,000-ton capacity installation was
$5.9/annual ton.

The operating costs were calculated based on information provided by the
licensee.  These represent a difference between the cost  of  the  Alcoa
503  process  and those of the usual fume scrubber operation.  The total
operating cost was calculated to be $2.9/ton.  The Alcoa 503 process  is
an entirely a dry process.   No water is used for fume control.

The  third  method  of  water  control  is by the use of a wet scrubbing
system in conjunction with A1F3  as  the  demagging  agent.   The  major
advantage  of  this  scrubbing  system over a conventional chloride fume
scrubber is the ability to recirculate the  water  used  for  scrubbing.
The  fluoride  is  precipitated with caustic in the recycle loop.  It is
claimed that total recycle can be effected, which would result  in  zero
discharge of water.  However, as the process is relatively new, rhere is
not  enough  operating  experience  to  determine  whether a small bleed
stream would be required.  For the  purposes  of  this  report,  it  was
assumed that total recycle is being accomplished.

The  capital  cost of equipment was obtained from the equipment supplier
(Waki, 1973) and includes  the  cost  of  the  scrubber,  packed  tower,
neutralization  facilities,  thickening tanks, and associated pumps.  The
total  capital  required  is  about  $14/annual  ton  of  aluminum.   An
operating  cost  of  $5.t/ton  has been calculated for the A1F3 process.
This cost includes the additional expense of  using  A1F3,  rather  than
chlorine, as the demagging agent.

Costs associated with another control technique for fume control process
(the  "Tesisorb")  have  been  calculated  based on data from a fluoride
control  installation in a glass plant  (Teller, 1972).  These costs  were
$27.7/annual  metric ton capital and $7.3/metric ton operating.  Because
of the proprietary nature of the process, the elements involved in  this
cost  estimate  have  not been given.  The technical feasibility of this
process  applied to fume control in a demagging operation  has  not  been
sufficiently  established,  although  it  does  have  the  advantage  of
resulting in a zero water effluent discharge from demagging fume control
operations.


Treatment Cost§


The method  of treatment of scrubber water in use at the present time  is
neutralization  and settling.  Costs for this operation are  estimated at
$2.8/annual metric ton capital and  $1.50/ton operating.    The  equipment
cost  includes the neutralization facility, settling pond,  and associated

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pumps,  piping, controls, etc.  The costs of caustic and polyelectrolyte
accounts for about 1/3 of the total operating  cost  to  neutralize  and
settle scrubber water.


Cost Benefit


A  summary  of  the  effluent  loadings  and costs for the treatment and
control models is given in Table 31.  It is readily seen that the Derham
Process gives the best cost benefit.  Of the other  two  dry  processes,
the Alcoa 503 is only slightly more expensive; however, the installation
of the Tesisorb system would result in higher costs.

                      Waste Water From Residue Milling

Control_Costs


At the present time, the only technically feasible means of removing the
soluble  constituents  from  the  waste is evaporation.  The alternative
control measure is to perform the residue milling dry.

The costs for evaporation are dependent on the amount of  soluble  salts
in  the  residue  being milled.  The capital cost to evaporate the water
from a low salt-content residue (dross) is $16/annual  metric  ton  with
operating costs of $24/ton.  The major equipment included in the capital
cost  of  evaporation  is  an  evaporator  and  crystallizer.   Tne heat
required for the evaporation amounts to about 70 percent  of  the  total
operating  cost  in this cost, assuming a cost of $0.50/million Btu.  In
the case of a residue with high salt  content  (slag),  operating  costs
would  be  very  high  (greater than $300/ton) due to the large amount of
heat necessary for evaporation.  For economic feasibility in the case of
water discharged from slag wet milling,  some  means  must  be  used  to
increase  the  salt  concentration  in the water and lower the water use
before evaporation can be considered.


Treatment Costs


Settling treatment in practice  has  been  found  to  be  99.9+  percent
effective  in removing the suspended solids.  Dissolved solids, however,
are not removed at all.  Costs reported from one plant were  $8.7/annual
ton  capital, and $3.3/ton operating,  corresponding costs reported from
a second plant were $15.3/annual ton and $10.9/ton.  The reason for  the
substantial difference in costs between the two plants is related to the
amount  of  water  use.   In  the  first plant, the residue is primarily
dross, with a low salt content, and consequently, a water  use  of  only
29,000  liters/ton  (7,000  gal/ton).  However, in the second, the water
used for  the  wet  milling  operation  is  217,000  liters/ton   (52,000
                                 91

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                 TABLE 31.   COST BENEFIT OF CONTROL AND TREATMENT
                            FOR WASTEWATER FROM FUME SCRUBBING
                              Waste Loads,
                          grams/kg MR Removed
Process
Suspended    Dissolved
 Solids        Solids     Al    Mg    pH
                                                       Costs
                     Capital        Operating
                   $/Annual ton*      $/ton*
Once-Through      175
  Scrubbing

Neutralize        ^50
  and Settle      "*

A1F  Process        0

Derham              0
  Process

Derham
  Process
with small
  scrubber**

Derham
  Process
with large
                800


                500


                  0

                  0
50    5


40    1.0


 0    0

 0    0
1.5


9.1
*  Ton = metric ton = 2200 Ib.
**  Insufficient data available to characterize effluents.
 0


 2.8


14.0

 3.4
                                                 3.9
0


1.5


5.4

2.6
                                        2.7
scrubber**
Alcoa 0
Process
Tesisorb 0
(Teller)
5.6
0 0 0 5.9
0 0 0 - 27.7
3.1
2.9
7.3
                                       92

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gal/ton)   because of the higher salt content of the residue (slag)  which
is milled in this plant.


Cost Benefit


The data on cost benefit are presented in Table 32.  It is evident  from
this  data  that  control costs to reach a zero discharge are very high.
The only economically feasible method of  attaining  zero  discharge  of
water  is  for new sources to install a dry milling operation in lieu of
wet milling.  At this point, however, evaporation cannot  be  ruled  out
completely  because  of  the potential to reduce costs by countercurrent
milling and selective crystallization of saleable salts.  On  the  other
hand,  the  cost  to  remove  the  suspended  solids  is  moderate,  and
represents less than half the economic burden of evaporation.
                                 93

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                 TABLE 32.  COST BENEFIT OF CONTROL AND TREATMENT
                            FOR WASTEWATER FROM RESIDUE MILLING
Waste Loads, kg/ton
Process
No Treatment
Settle
Suspended
Solids
720
1.0
Dissolved
Solids
present
present
Costs
Capital
NH,. $/annual ton*
35 0
35 8.7-15.3

Operating,
$/ton*
0
3.3-10.9
Settle and Evaporate,
  Low Flow           0           0          0          16                24

Dry Milling          0           0          0         130
* Metric ton of aluminum produced.
                                        94

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                               SECTION IX
             BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
                 AVAILABLE—GUIDELINES AND LIMITATIONS


                              Introduction


The effluent limitations which must be achieved by July 1, 1977, are  to
specify   the  degree  of  effluent  reduction  attainable  through  the
application  of  the  best  practicable  control  technology   currently
available.   Such control technology is based on the average of the best
existing  performance  by  plants  of  various  sizes,  ages,  and  unit
processes  within  the  industrial  category.  Because of the absence of
data on the characterization  of  waste  water  by  this  industry,  the
recommended   treatment   technology   and  the  corresponding  effluent
limitations are  based  on  a  sampling  survey  of  waste  waters  from
exemplary plant operations in this subcategory.  Consideration must also
be given to:

    (a)   The total cost of application of technology in
         relation to the effluent reduction benefits to
         be achieved from such application

    (b)   The size and age of equipment and facilities
         involved

    (c)   The processes employed

    (d)   The engineering aspects of the application of
         various types of control techniques

    (e)   Process changes

    (f)   Nonwater quality environmental impact (including
         energy requirements)

The  best  practicable control technology currently available emphasizes
treatment facilities at the end of a  manufacturing  process.   It  also
emphasizes  the control technologies within the process itself when they
are considered  to  be  normal  practice  within  the  industry.   Other
technology currently available was considered for its degree of economic
and engineering reliability.
                                 95

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               I ndustry Category and Waste Water Streams


The  secondary  aluminum smelting subcategory is defined as that segment
of the aluminum industry which recovers, processes, and remelts  various
types of aluminum scrap to produce metallic aluminum alloy as a product.
Although primary aluminum producers recover captive scrap generated from
their  own  operations,  they are not included in this subcategory.  The
secondary smelters buy scrap in various forms  on  the  open  market  as
their raw material.

A   more   useful  approach  for  the  purpose  of  developing  effluent
limitations  guidelines  is  to  deal  with  the  waste  water   streams
themselves.   The  principal  streams  are   (1)  waste  water from metal
cooling,  (2)  waste water from fume scrubbing, and  (3)  waste  water  from
residue  milling.   Each  stream has an associated loading of pollutants
per pound of product or scrap processed.  For example,  the  recommended
guidelines require a smelter generating only cooling waste water to meet
the  effluent  limitations established for that waste stream.  A smelter
generating cooling, scrubber, and residue milling waste waters would  be
required   to   meet  the  effluent  limitations  established  for  each
respective waste water stream.


                     Waste Water From Metal Cooling

S££lugQt_Limitations Based gn^the Application of the
Best Practicable Control Technology Currently Available

The recommended effluent limitations based on  the  application  of  the
best  practicable control technology currently available is no discharge
of process waste water pollutants.

The achievement of this limitation by use of the control  and  treatment
technologies  identified in this document leads to the complete recycle,
re-use, or  consumption  of  all  water  within  the  process,  with  an
associated result of no discharge of water.

Identification_gf_Best^Practicable Control
Technology__Currently Available

The  best  practicable  control technology currently available for metal
cooling in the secondary aluminum industry is the  elimination  of  water
discharge through the use of the following approaches:

     (1)  Air cooling of ingots

     (2)  Total consumption of cooling water  for ingot cooling

     (3)   Recycle or re-use of cooling water  for deoxidizer-
                                   96

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         shot cooling or ingot, cooling

With  re-use  or  recycle  of water, the need for sludge removal and oil
removal will be dictated by plant operational procedures  and  the  care
used in controlling contaminants caused by poor housekeeping.  Dissolved
salt  contamination  may  be  reduced  with  improved  housekeeping  and
improved manufacturing procedures.  Such precautions would  provide  for
an  extended  period  of  water  reuse  which  approaches  that  of zero
discharge.

To implement the air cooling method or  the  total  evaporation  cooling
method  (the  air cooling method with water mist added to assist the air
cooling)  requires:

    (a)  The addition of ingot molds to the lengthened
         conveyor line

    (b)  The installation of blowers

    (c)  In the case of total evaporation cooling, the
         addition of special nozzles, flow meters, and
         controls to existing water lines.

To implement a recycle system for ingot cooling requires:

    (a)  The addition of a cooling tower, holding tanks,
         and pumps to the existing water cooling facility

    (b)  Provisions for oil and grease removal

    (c)  Provisions for sludge removal, dewatering, and
         disposal.


Rationale for Selecting the Best Practicable
Control Technology Currently Available

Thirty-one of the 58 plants canvassed  (or 54 percent) are cooling ingots
by one of the methods given above.  Existing cooling lines  using  once-
through  water  cooling  could  be converted to one of three alternative
methods to eliminate the discharge of water.  Shot cooling will continue
to require direct water cooling and only the last option above, (c),  is
available to these plants.

Age	and Size of Eguipment_and Facilities.  As set forth in this report,
general   improvements   in   production   concepts   have    encouraged
modernization  of  plant  facilities  throughout  the  industry.   This,
coupled with similarities of  waste  water  characteristics  from  metal
cooling  for  plants of varying size, substantiate the identification of
total recycle of cooling and/or consumptive cooling as practicable.
                                  97

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Total Cost of Application^in Relation to Pollutant Reduction.   Based  on
the information contained in Section VIII of this report, a capital cost
of  about $O.H3/annual metric ton of aluminum alloy would be required to
convert an existing once- through cooling  systems  to  a  recirculation
system.   An  operating cost of $0.15 per ton would be required but does
not  include  savings  resulting  from  the  lowered  fresh  water  use.
Conversion  to  an  air-cooled  ingot  line  from a water-cooled line is
estimated to require an investment of $9.2  per  ton.   Operating  costs
would be $1.09 per ton with no credit being claimed for water savings.

Engineering Aspects of Control Technique Application.

This  level  of technology is practicable because over 54 percent of the
plants in the industry are now achieving effluent  reductions  by  these
methods.  The concepts are proven, available for implementation, and may
be  readily adopted by adaptation or modification of existing production
units.
               .  This technology is an integral part of the whole  cost
saving  and  waste  management  program now being implemented within the
industry.  While the application of  such  technology  requires  process
changes, they are practiced by existing plants in the industry.
                     Environmental  lID£§£ii   There  are  four  possible
associated impacts upon major nonwater elements of the environment:

     (1)  An incremental addition to the thermal load of
         the plant by thermal radiation from air cooling
         of ingots.

     (2)  Added electrical energy requirements of about 11
         kwhr per ton would be needed for air cooling oper-
         ations.

     (3)  Negligible impact on air quality is anticipated
         from water evaporation either from consumptive
         water-mist cooling or from sludge drying.

     (4)  Solid waste disposal of dried sludge would be a
         minor impact because of very small amounts accumu-
         lated, and its nontoxic character  (A12O3) .  Oil
         and grease collected during recycled water cooling
         operations may be disposed of through responsible waste oil
         disposal contractors.

                    Waste Water From Fume Scrubbing


Ef fluent Limitations^Based^on the Application_of^the
Best Practicable Control Technology Currently Available
                                  98

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The recommended effluent limitations based on  the  application  of  the
best  practicable  control  technology  currently available are given in
Table  1  for  waste  water  generated  during  magnesium  removal  with
chlorine.   The recommended effluent limitation based on the application
of the best practicable control technology  currently  available  is  no
discharge  of  process  waste water pollutants for waste water generated
during magnesium removal with aluminum fluoride.

JRationale^fgr Effluent Limitations Based on the Application
of the Best Practicable Control Technology Currently Available

The values given in Table 1 were derived as follows:

    (1)   The 30-day-average value for  total  suspended  solids  is  the
         average  of  the values given in Table 29  (namely 284 gm/kg and
         66 gm/kg)  for Cases I and II of Plant C-7.   These  two  values
         are  considered  the  most representative available.  It may be
         noted that both these "after treatment" values are higher  than
         the  suspended  solids  values  in  the  untreated  waste.  The
         increase in values during treatment is due  to  the  fact  that
         neutralization  produces  fine  particles  of reaction products
         which add to the suspended solids values.

    (2)   Similarly, the 30-day-average value for Oil and Grease  is  the
         average  of the two values (O.U and 3.5 grams/kg)  from the same
         effluent values (Plant C-7, Cases I and II) given in Table 29.

    (3)   The 30-day-average value for  Chemical  Oxygen  Demand  is  the
         average  of  the  two values (6.1 and 6.8 grams/kg for the same
         effluents (Plant C-7, Cases I and II, Table 29).

    (4)   The 30-day-average ranges of pH given in  the  limitations  are
         those   estimated   to   provide  the  optimum  conditions  for
         acceptable pH and co precipitation of both heavy metals, such as
         copper, and amphoteric elements such as zinc and aluminum.

                           Practicable Control
                 _
Technology Currently Available

The best practicable control technology currently available for  control
of the discharge of pollutants contained in fume scrubber waste water is
the following:

    (1)   When chlorination is used for magnesium removal,
         adjustment of the scrubber effluent pH to between
         7.5 and 8.5 followed by settling for solids removal.
         Prior adjustment of the pH of the scrubber liquor
         so that the resultant effluent from the scrubber
         is at a pH of 7.5 to 8.5 followed by settling for
         solids removal is equally practicable.
                                  99

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    (2)   When aluminum fluoride is used for magnesium re-
         moval,  adjustment of the scrubber effluent pH to
         between 7.5 and 8.5 followed by settling for solids
         removal.   (In practice this treatment is an integral
         part of the control technology discussed in Section
         X.)   After neutralization and settling, the super-
         natant  is recycled continuously.  Solid fluorides
         are removed continuously.

The  fume-scrubber  water  from  the chlorine magnesium removal process,
upon pH adjustment, cannot be recycled  continuously  due  to  excessive
buildup  of  sodium  chloride.  Partial recycle of the clarified treated
effluent will reduce water consumption.

The use of neutralization and settling treatment  to  remove  pollutants
from  chloride  scrubber  waste  water  requires  reaction  tanks for pH
adjustment, mixing tanks for polyelectrolyte addition  (if  settling  is
not  rapid),  a   settling tank for solids removal, and associated pumps,
controls, and plumbing.

The implementation of continuous  recycle  of  fluoride  scrubber  waste
water   will  require  the  additions  of  liquid  storage  and  pumping
capabilities.  A chain conveyor for continuous solids removal also would
be required.


Rationale for Selecting the Best Practicable
Control Technology Currently Available

Of the 29 plants using wet scrubbing to control air emissions 20  (or  69
percent) are practicing some form of pH adjustment.  Of these 20, 15  (or
51 percent) are removing solids by settling.

The  adjustment  of  pH  to  7.5  to   8.5  and settling are effective in
removing aluminum and magnesium ions as hydroxides  from  chloride  fume
scrubber  waste  water.  Some removal  of heavy metals as hydroxides also
occurs with the removal of the aluminum and magnesium hydroxides.  At  a
pH  of  9.0  or  greater  aluminum  hydroxide and other amphoteric metal
pollutants are dissolved.  Therefore,  to  maximize  the  overall  metal
removal,  the  pH  generally  should   not  exceed 8.5.   (See Discussion,
section VI and Table 29, section VII.)

An adjustment of  pH  to  7.5  to  8.5  is  effective  in  reducing  the
solubility  of  fluorides  by  neutralizing the hydrogen fluoride in the
effluent.  Acid  fluoride  salts  are  more  soluble  than  the  neutral
fluoride  salts of the common pollutants in fluoride fume scrubber waste
water.  The limited solubility of the  neutral fluoride  salts  in  water
provides  a  supernatant  solution  suitable  for  recycle  in   scrubber
operation.
                                 100

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        §iS.e  of  Eguipjnent  and  Facilities^   Those  segments  of  the
industry  that  are  refining  aluminum  alloys must remove magnesium to
attain the specifications of their customers.  Therefore, regardless  of
the  size  or  age  of  the  facility,  chemical removal of magnesium is
practiced.  Control of air emissions from demagging operations with  wet
scrubbers  also  is  practiced  by  a majority of the secondary aluminum
smelters.  Control of the pH and solids content of the effluent from the
scrubber is also practiced.  In such cases, investments would have to be
made for  sludge  disposal.   In  a  large  tonnage  secondary  smelter,
scrubber  equipment  is  used continuously and requires larger treatment
facilities than a smaller tonnage plant.   A  small  plant  may  require
treatment  capacity for operations lasting only four hours per day.  The
capital investment for treatment  equipment  per  annual  ton  would  be
greater  for  the  smaller plant.  However, the similarities in the fume
scrubber waste water generated in each type of magnesium removal process
(chlorine or aluminum fluoride), regardless of the size or  age  of  the
facility,  substantiate  the  level of pollutants that can be removed by
the pH adjustment-settling treatment.

Those plants using aluminum fluoride for magnesium removal can, by using
the same technology, eliminate the discharge of pollutants  by  adapting
the system to completely recycle the supernatant after settling.

Total	Cost of Applicatign^in Relation^to Pollution__Reduction.  Based on
the information contained in Section VIII of this part of the report,  a
capital  cost  of  about  $2.75  per annual metric ton of aluminum alloy
produced would be required to install a pH adjustment-settling treatment
capability to  control  pollutant  levels  from  the  chloride  scrubber
systems.  An operating cost of $1.5 per metric ton is estimated for such
an  installation.  Lesser capital expenditure would be required by those
already neutralizing the scrubber effluent.

For  those  plants  using  aluminum  fluoride  for  magnesium   removal,
treatment   of  the  scrubber  waste  water  requires,  in  addition  to
neutralization and settling, a means to recirculate the  scrubber  water
continuously  and  continuous  solids  removal.   This  would require an
estimated capital investment of  $9.9  per  annual  metric  ton  and  an
operating cost of $2.US/metric ton.

Engineering	Aspects of Control_Technigue Applications.  This technology
is practiced by over 51 percent of the plants in the industry to  reduce
the  discharge  of  pollutants  from  fume  scrubbing  operations.   The
concepts are proven and are available for implementation.  They  can  be
adopted  to fume scrubbing effluent streams by those presently not using
them as an end-of-pipe treatment facility.


E£2£§§§_2h§LS3§§•  Tne technology of pH adjustment and settling to remove
solids is an integral part of the whole waste management program already
implemented by part of the industry.  All plants in the industry use the
                                 101

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same or similar demagging processes which  produce  similar  discharges.
There is no evidence that operation of any current manufacturing process
will  affect  the  capability  of a plant to implement these end-of-pipe
waste treatment technologies.


Nonwater Quality Environmental Impact.   There  is  only  one  essential
impact  upon  major  non water  elements  of  the environment.  It is the
potential effect on soil systems due to the reliance upon the  land  for
ultimate disposition of final solid waste from the treatment.  The solid
wastes  are  primarily inorganic and nonleachable.  The solid waste from
fluoride recovery potentially can affect  ground  waters  adversely  and
should  be  disposed  of  in  an  acceptable  landfill  to  prevent  the
contamination of surface or subsurface waters.


Ef fluent mLimitations_Based_Qn_rthe Application of the
gest Practicable Control Technology Current ly^Ayailable

The recommended effluent limitations based on  the  application  of  the
best practicable control technology currently available are:

    (1)  When chlorine is used for magnesium removal,
         those presented in Table I in Section II.

    (2)  When aluminum fluoride is used
         for magnesium removal, no discharge
         of process waste water pollutants.


Guidelines for_the Application of Ef fluent^Limitatigns
Selection   of  Production  Units^   Effluent  limitations  specify  the
quantity of pollutants which may be discharged from a point source after
the application of the best  practicable  control  technology  currently
available.   This  quantity  must  be related to a unit of production so
that the effluent limitations can be broadly applied to  various  plants
in the same subcategory.

The  amount  of  pollutant  generated  during  the  chemical  removal of
magnesium from a given heat is dependent upon the  amount  of  magnesium
originally  present in the charged scrap and the final magnesium content
desired in the metal produced.  Judicious selection  of  scrap  entering
the  melt  will  reduce this difference, the length of time required for
chemical treatment, and the amount of chemical required for reducing the
magnesium content to the desired level.  These variables in turn  estab-
lish  the  amount  of  material  entering the scrubber water.  There are
variabilities in the amount of magnesium removed for a  unit  weight  of
chemical agent.  Frequently these are dependent on the furnace operators
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techniques  and/or  plant  practice  and  therefore are not suited for a
production  unit.    An   invariant   production   unit   suitable   for
determinations  of pollutant loadings is the amount of magnesium removed
relative to the amount of metal produced.  This can be  determined  from
the  percent  magnesium contained in the charge before magnesium removal
and the resultant magnesium content.

The application of this guideline requires the reporting of  the  number
of  pounds  of  magnesium  removed based on the magnesium content of the
melt before magnesium removal, the  magnesium  content  of  the  product
metal,  and  the  net weight of the metal treated for magnesium removal.
These data are currently a part of company records.  Also  required  are
the  flow  rate  of the discharge water stream from the scrubber system,
and the analyses of the pollutants in that stream.


                    Waste Water from Residue Milling

Effluent Limitations Based on the Application^nof the
Best Practicable Control Technology Currently Available

The recommended effluent limitations based on  the  application  of  the
best practicable control technology currently available is that given in
Table 2 in Section II.

Ratignale_for Effluent Limitations Based on^the^Application
of the Best Practicable^Control Technology Currently Available

The values given in Table 2 were derived as follows:

    (1)  The 30-day-average value for Total  Suspended  Solids  is  that
         reported for Plant D-4 in Table 21.  This value is used because
         it  was  based  on  verified,  seven-to-nine- month averages of
         sampling, and is otherwise considered  a  valid  value  on  the
         basis of plant operations and raw material variation.

    (2)  The value for fluoride is derived from data for  Plant  D-8  in
         Table  21  and is based on 9 composite samples over a three day
         period.

    (3)  The  value  for  ammonia  was  derived  by  using  the   actual
         concentration  of  ammonia  in  the effluent from a plant using
         exemplary milling practice (0.3 mg/1. Plant D-8, Table 21)  and
         calculating  the  loading  on  the associated flow (200 gpm, or
         1,090,080 liters/day) and  production  (37.8  metric  tons  per
         day).   This use of concentration reflects the chemistry of the
         reaction during  alkaline  wet  milling.    The  calculated  net
         loading  of  ammonia  for  Plant  D-8 in Table 18 is a negative
         value, that is, the  discharge  water  from  the  alkaline  wet
         milling operation contained less ammonia than the intake water.
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         The limitation value for  aluminum  was  derived  in  the  same
         manner  as  the ammonia value,  i.e., using  the  concentration of
         28  mg/1 for  Plant  D-8  in  Table  21.  The   same  flow,   and
         production as in (3)  were used,  giving a value  of 1.0 kg/metric
         ton of metal recovered.

    (5)   The  values  of  ammonia,  aluminum,   copper,    and   pH   are
         interrelated.  The pH specified is to be achieved with reagents
         other  than  ammonia.   However, if an ammonia  loading were not
         specified, the specified pH value could be   present  due  to  a
         high  ammonia content.   Further, ammonia and copper interact to
         form chemical complexes whose presence would not necessarily be
         reflected in the measurement of pH.  Aluminum  is  specified  to
         prevent under or over-alkalization.

    (6)   The value of Chemical Oxygen Demand specified   is  that  listed
         for  Plant  D-3  in Table 21 (0.97 rounded  to  1 kg/metric ton).
         The  source  of  COD  in  the  effluent  has  not  been   fully
         documented.


Identification of the Best Practicable
Control^TechnologY^QlJ£renfely-^y§ilgfal?

The  best practicable control technology currently available for control
of the discharge of pollutants contained in  waste  water  from  residue
milling is the following:

    A settling treatment of three to four stages with
    partial  recycle of the sludge and the clear super-
    natant from the fourth stage to the mill.  Adjust-
    ment of  the intake water pH is necessary to reduce
    ammonia  levels in the waste water during milling.

When  milling is done without pH adjustment of the intake water, ammonia
remains in solution as a pollutant.  To aid the settling of the  milling
wastes,  a  polyelectrolyte  is  frequently added to reduce the level of
suspended solids.  Recirculation of the sludge  in the last settling pond
to the mill will reduce the overall sludge content of the final pond.
      alg_fQ£_Selecting the Best Practicable
         __
Control Technology Currently Available

Only 6 of the 23 plants (or 26 percent) processing  residues  use  water
for  milling.   Of these, only three are discharging to navigable waters
after  treatment  in  such  ponds.   The  remaining  three   use   total
impoundment.

settling  is capable of reducing settleable and suspended solids to very
low levels.  Dissolved salts are not removed, however.
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Evaporation and crystallization, although a viable alternative for  salt
removal, is not currently practiced in the United States.  The principal
reason  is  that  the cost of salt recovery (for flux cover use) exceeds
the price of the salt, even if more  concentrated  salt  solutions  were
attainable  through  process  changes.   The alternative to discharge is
total impoundment.

Age and _Size._of Equipment and Plant.  Regardless of the size and age  of
the facility, the waste water generated from residue milling is similar.
All  plants  are practicing the same type of waste management.  Loadings
do vary with techniques employed and the  amount  of  molten  metal  re-
covered  from  the  operation.   Modernization  of  this  segment of the
secondary aluminum industry has already reduced the number  of  smelters
processing  residues for metal value recovery to 23 plants.  Since 17 of
the 23 plants process the  residues  dry,  this  trend  is  expected  to
continue.   The  life  of  the equipment in the wet mill is 2 to 3 times
longer  than  equipment  in  dry  mills  because  of  the  lower  energy
requirements needed for comminution.

Total Cost^in^Rela tion_to^ Pol lution_ Reduction

Based  on  the  information  contained in Section VIII of this report, a
capital cost of about $8.7 to $15.3  per  annual  metric  ton  of  alloy
recovered  as  molten  metal  and an operating cost of $3.3 to $10.9 per
annual metric ton to treat residue waste water by settling is estimated.
Variations in the cost are dependent upon  (1)  the amount of  water  used
for milling and (2)  the solids content of the residue.

Engineering  Aspects  of  Control  Technique Application^  This level of
technology is practiced by three of six plants which process residues by
wet  methods.   The  concepts  are   proven   and   are   reliable   for
implementation.

E£2.C-§.§.§._CJ2§.!12§.§ •  Only minor process changes are foreseen.  The practice
of  partial  recirculation  of the treated effluent is currently used by
two plants in the industry.

NQELwater 2Uaii£Y. Environmental Impact^  There is no  added  impact  upon
major nonwater elements of the environment by the adaptation of settling
for  removal  of  suspended solids.  An impact on soil systems currently
exists due to the reliance upon land for the ultimate disposition of the
final solid waste from a wet residue milling operation.

Guidelines for thA^Q  Effluent Limitations
Effluent limitations specify the quantity  of  pollutant  which  may  be
discharged  from  a  point  source  after  the  application  of the best
practicable control technology currently available.  This quantity  must
be  related to a unit of production so that the effluent limitations can
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be broadly applied to various plants in the same category, regardless of
their production capacity.

The amount of pollutants  in  the  waste  waters  from  residue  milling
largely  depends  upon the source of the residue.  Residues from primary
smelters, foundries, etc. (dross, skimmings)  contain  little,  if  any,
soluble  salts  and  up  to 40 percent recoverable metal.  Residues from
secondary smelters  (slags) contain high levels of  soluble  salts   (KCl,
NaCl) and as little as 5 to 10 percent metal.

The  production  unit  used  for  effluent  limitations is the amount of
molten metal recovered from the residue.  The information  required  for
the  application of this guideline includes the weight of metal produced
(currently a matter of routine record), the rate of flow of the effluent
from the residue  milling  operation,  and  the  concentrations  of  the
pollutants in that  flow.
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                               SECTION X
                 BEST AVAILABLE TECHNOLOGY ECONOMICALLY
                     "ACHIEVABLEf GUIDELINES AND LIMITATIONS


                              Introduction


The  effluent limitations which must be achieved by July 1, 1983, are to
specify  the  degree  of  effluent  reduction  attainable  through   the
application  of  the  best available technology economically achievable.
This technology can be based on the  very  best  control  and  treatment
technology  employed  by  a  specific  point  source within the industry
category or subcategory or technology that is readily transferable  from
one  industry process to another.  A specific finding must be made as to
the availability of control measures  and  practices  to  eliminate  the
discharge   of   pollutants,  taking  into  account  the  cost  of  such
elimination.

Consideration must also be given to:

(a)  the age of the equipment and facilities involved;

(b)  the process employed;

(c)  the engineering aspects of the application
     of various types of control technologies;

(d)  process changes;

(e)  cost of achieving the effluent reduction
     resulting from the technology;

(f)  nonwater quality environmental impact (including energy
     requirements) .

The best available technology economically achievable also assesses  the
availability  in all cases of in-process controls as well as the control
or additional treatment techniques employed at the end of  a  production
process.

A  further  consideration  is  the availability of processes and control
technology at the pilot plant, semi-works, or other levels,  which  have
demonstrated both technological performances and economic viability at a
level  sufficient  to  reasonably  justify investing in such facilities.
Best available technology economically achievable is the highest  degree
of control technology that has been achieved or has been demonstrated to
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be  capable  of  being  designed  for  plant-scale  operation  up to and
including no discharge of pollutants.   Although  economic  factors  are
considered,  the costs for this level of control are intended to be top-
of-the-line of current technology  subject  to  limitations  imposed  by
economic   and   engineering   feasibility.     However,  best  available
technology  economically  achievable  may  be  characterized   by   some
technical risk with respect to performance and with respect to certainty
of   costs   and   thus   may  necessitate  some  industrially-sponsored
development work prior to its application.
                     Waste Water frgm_Metal_Cooling


The effluent limitations attainable  by  the  application  of  the  best
available technology economically achievable for cooling waste waters is
no  discharge  of  process waste water pollutants to navigable waters as
developed in Section IX.  The  best  available  technology  economically
achievable  is  identical  to  the  best  practicable control technology
currently available.


                    Waste Water from Fume Scrubbing


Identification^of^Best^Available Technology Economically Achievable


The best available technology economically achievable is the use of  in-
process   and  end-of-process  controls  and  treatment. to  achieve  no
discharge of waste water pollutants into navigable waters.  This can  be
done using one of the following approaches:

 (1)  The use of currently available processes for fumeless
     chlorine magnesium removal

 (2)  Using a combination of AlF3^ for demagging and continuous
     recycling of scrubbing water from emission and effluent
     control systems

 (3)  Using a combination of A1F3 for demagging and a coated
     baghouse system for air pollution control.


Fumelgss Chlorine Demagqing Processes..  The process developed by Derham
and the process developed by Alcoa are techniques for removing magnesium
from molten aluminum scrap with a rrinimum of fume generation through the
efficient  use  of  chlorine.   No  water is used for fume control but  a
back-up scrubber may be required with the Derham system.
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In the Derham Process a thick cover of  fluxing  salt  over  the  molten
metal  almost  completely arrests fume emissions and the subsequent need
for wet scrubbing for their control.  Details of this process are  given
in Section VII.

The  Alcoa  process  operates  on  a  similar principle, using efficient
chlorination of magnesium to minimize emissions.  The unit  is  inserted
between  the  casting  line  and the furnace and demagging with chlorine
takes place as the metal is being cast.


AlF^Magnesium_RejrtO^aJL_with_Cont^uous_Recirculation_of Scrubber __ Water.
The  use  of  A1F3  for removing magnesium from molten aluminum scrap is
advantageous in that  it  permits  fume  scrubbing  waste  water  to  be
continuously   recycled.    This  is  because  the  fluoride  salts  are
relatively insoluble and can be settled out.  The same approach for  wet
scrubbing  fumes  from  chlorine  demagging  for emission control is not
possible because of the dissolved solids build-up.

A1F3 Magnesium Removal Fume Control With the  Coated  Baghouse  (Teller^
Process^   In  this  process  fumes  from  A1F3  magnesium  removal  are
controlled by passing them  through  chemically-treated  filters  (bags)
which remove the pollutants from the exhaust.  The system eliminates the
use of water for fume control.

Ra t iona le _f or _S e 1 e ct in g_ Be_s t_ Available Technology
Economically Achievable
       Available   for  Achieving  Effluent  Limitation.   The  effluent
limitation of no discharge of process waste water pollutants  from  fume
scrubbing  is required before July lr 1983.  This allows sufficient time
for the planning,  purchasing,  installation,  and  trial  operation  of
equipment needed for the three control alternatives identified.


Cost  2f_  Achieving  the  Effluent  Limitations^  The  estimated cost of
achieving the effluent  limitations  from  fume  emission  control  will
depend on which of the three techniques given above is used.  The use of
the  Derham  Process for magnesium removal involves an estimated capital
expenditure of $3.4 per annual metric ton of capacity and  an  estimated
operating  cost  of  $2.5  per  metric  ton.  The Alcoa Process has been
estimated to require a capital cost of $5.9/annual  metric  ton  and  an
operating  cost  of  $2.9/metric  ton  (with  no  credit being taken for
selling the magnesium chloride) .  The use of A1F3 for magnesium  removal
combined  with  continuous  recirculation of scrubber water for emission
control involves an estimated capital expenditure of  $14.0  per  annual
metric  ton and $5.4 per metric ton operating costs,  use of chemically-
treated baghouse systems (Teller System)  for  removal  of  air  emission
during  magnesium removal with A1F3 was similarly estimated to require a
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capital expenditure of about $27.7 per annual metric ton of capacity and
an operating cost of $7.3 per metric ton.
            Aspects of_ Control Technique  Application.  The  engineering
practicability  of the Derham Process is demonstrated by its present use
in the industry.  Currently, the process is under license  or  operating
at four plants within the U. S. and in four plants outside the U. S.  In
a  telephone  canvass of the secondary industry several plants indicated
that they were considering using this  process.   Both  the  Derham  and
Alcoa  processes will require extensive research and development efforts
to meet their limited capacity  (Alcoa) and to reduce their  reliance  on
back-up scrubbers  (Derham)  to meet air quality standards.

The  use of A1F3 for demagging with continuous recirculation of scrubber
water is considered achievable because two large plants in the secondary
industry are using this technique for emissions and effluent control.

The use of chemically-treated baghouses   (Teller  System)  for  dry  air
pollution  control  during  A1F_3  demagging  is yet unproven from an air
quality standpoint.  One major  plant  in  the  secondary  industry  has
installed the system and is presently evaluating its effectiveness.


Process __ Changes.   The  application  of the Derham Process or the Alcoa
Process for magnesium removal would require those plants using  A1F3_  to
change  to  chlorine  and  adopt  the  appropriate procedures and safety
measures for its application.  No major process changes are  anticipated
for those already using chlorine.

The  use  of  A1F3_  with  continuous  recycling  of scrubber water would
require those plants presently using chlorine  to  change  to  A1F3_  for
demagging.   This  would  not  involve  a  major  process change, as the
application of AlF^ for demagging is simpler than chlorination demagging
but twice as expensive for the removal of the  same amount of  magnesium.
Those  plants  with  low-energy  wet-scrubbing systems used tor chlorine
demagging would need  to  change  over  to  higher  energy  systems  for
effective  scrubbing  of  the  fumes  generated  with  the  use of AlF3_.
Although not a principal process change, the change  to  AlF3_  demagging
would  require  extensive  modification of present air pollution control
equipment now used for collecting fumes from chlorine demagging in   some
of the larger plants.

The  chemically-treated  baghouse  system   (Teller  System)  for dry air
pollution  control  would  require  those  plants  using  chlorine   for
demagging  to  change  to  AlF_3.  Those already using A1F3 would have no
process change.

Nonwater Quality, Environmental impact^  The use of  the  Derham  Process
results  in  no  known  nonwater  quality  environmental  problems.  The
residues resulting from its application may be too high  in soluble  salts
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for economic processing by residue milling techniques for metal recovery
and  could  present  a  solid  waste  disposal  problem.    Insufficient
information exists on the process to assess this impact.

Application  of  A1F3  with continuous scrubber -water recirculation will
result in a solid waste disposal problem.  Fluoride  salts  precipitated
and  settled  from  the  scrubbing  water are slightly soluble and could
possibly be leached in a landfill disposal.

Application of chemically-treated baghouse systems for dry air pollution
control also results in a  solid  waste  as  the  bag  coating  and  the
collected  dust  and  fumes may contain fluoride salts that are slightly
soluble and leachable to ground water.  Disposal of solid wastes  in  an
acceptable  landfill  is required to prevent contamination of surface or
subsurface waters.


Waste Water^from Residue Milling


Identification of Best Available^ Technology Economically Achievable


The best available technology economically achievable  for  waste  water
from   residue   milling  is  the  replacement  of  present  wet-milling
operations by totally dry milling methods.  In dry milling, the  residue
is crushed and the contained salts, fracturing into small particles, are
screened  out  as  undersized  waste  material.   The  dry  operation is
extremely dusty and requires extensive air pollution controls.

Recovery of dissolved salts contained in waste streams from wet  milling
by  evaporation  and  crystallization  is  a  potential  approach to the
control or elimination of the discharge of pollutants.  The salts can be
reused for flux and the condensed water can  be  recycled  back  to  the
milling  process.  Salt recovery has not been demonstrated in the United
States but is used in Europe.

Rat ionale^for^Selecting[_the_Best Available Technology
Economical! Y_ Ac hi evable .


Time  Available  for  Achieving  Effluent  Limitations.   The   effluent
limitation  of  no  discharge  of  process  waste water pollutants to be
achieved July 1, 1983, allows time for the retirement of  existing  wet-
milling operations by those plants using this practice.
      2f  Achieving  the  Effluent Limitations. The cost of achieving no
discharge of process waste water pollutants from the milling of residues
is estimated to be about $130.00 per annual ton of  aluminum  production
capacity.   This is the cost of building a new plant, for the changeover
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from wet to dry milling involves a complete process  change.    Data  are
not  available  for  operating  costs,  but estimates from the secondary
industry indicate such costs to be higher than for wet processing.

The cost of recovery of salts from waste water from residue  milling  is
dependent on the type of residue being processed.  The estimated capital
cost to evaporate the water from low-salt content residues is $16/annual
metric  ton of aluminum, while operating costs are $24/metric ton.  When
high salt-content residues are processed, the  estimated  capital  costs
are $200/annual metric ton and the operating costs are $124/metric ton.
             Aspects  of  Control  Application.   That dry processing of
residues  for  aluminum  recovery  is  practical  from  an   engineering
standpoint is demonstrated by the fact that, out of 23 plants processing
residues, 15 use a totally dry mill operation and generate no associated
waste  water  stream.   Thus,  the  technology  is well proven by actual
practice.
             §.§ •  Plants presently wet-milling  residues  will  need  to
completely  alter  their  presmelter processing facilities to adopt dry-
milling practices.  Crushing, screening, conveying, and dust  collection
equipment will be required for the conversion.

Non water Quality Environmental Impact.  Both dry milling and wet milling
of residues generates large quantities of solid wastes, ranging from 2.3
to  9  tons per ton of aluminum recovered, depending on the grade of the
residue.  Generally this solid  waste  from  dry  milling  contains  the
highly  soluble  chloride salts that were washed out during wet milling.
Solids should be disposed  of  in  an  acceptable  landfill  to  prevent
contamination of surface or subsurface waters.

Dry   milling   also   generates  large  quantities  of  airborne  dust.
Appropriate dry collection systems are  normally  able  to  control  the
atmospheric emissions of the dust.

Recovery  of  salts  by  evaporation  from  wet  milling  waste water is
estimated to require additional consumption of thermal energy of  8.6   x
106  kg  cal/ton  for  the low-salt residue waste water and 176 x 106 kg
cal/metric ton for the high-salt residue waste water  (on  the  basis  of
metric tons of aluminum recovered) .
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                               SECTION XI
                    NEW SOURCE PERFORMANCE STANDARDS


                              Introduction


The  standards  of performance which must be achieved by new sources are
to specify the degree  of  effluent  reduction  attainable  through  the
application  of  the  best  available  demonstrated  control technology,
processes, operating methods, or other  alternatives.   The  added  con-
sideration   for  new  sources  is  the  degree  of  effluent  reduction
attainable through the  use  of  improved  production  processes  and/or
treatment  techniques.   The  term "new source" is defined by the Act to
mean  "any  source,  the  construction  of  which  is  commenced   after
publication   of   proposed   regulations   prescribing  a  standard  of
performance".

New Source Performance Standards are based on the best in-plant and end-
of-process technology identified with additional consideration given  to
techniques  for  reducing  the  discharge  of pollutants by changing the
production process itself or adopting alternative  processes,  operating
methods,  or  other alternatives.  The effluent standards of performance
reflect levels  of  control  achievable  through  the  use  of  improved
production  processes  (as  well  as  control  technology) ,  rather than
prescribe a particular type of  process  or  technology  which  must  be
employed.  A further determination must be made as to whether a standard
permitting no discharge of pollutants is practicable.

Consideration must also be given to:

(a)  the type of process employed and process changes
(b)  operating methods
(c)  batch as opposed to continuous operations
(d)  use of alternative raw materials and mixes of raw materials
(e)  use of dry rather than wet processes  (including substitution
     of recoverable solvents for water)
(f)  recovery of pollutants as by-products

                     Waste Water from Metal Cooling

Standards^of Performance based on the Application of
the_Best_Available^Demonstrated. Control Technology

The  recommended  standards of performance to be achieved by new sources
is no discharge of process waste water pollutants into navigable  waters
as developed in Section IX of this document.
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Identification of the Bestr Available Demons-bra ted Control
Tg-ChnQlQgy.1 -Processes A-QEggating Me thodgj or Other ^Alternatives
The  Best  Available  Demonstrated  control Technology for metal cooling
waste water is identical to  the  Best  Practicable  control  Technology
Currently  Available described in Section IX.  The control and treatment
technologies identified in Section IX are:

         (1)  Air cooling of ingots
         (2)  Total consumption of cooling water for ingot cooling
         (3)  Recycle or reuse of cooling water for deoxidizer shot
              cooling or ingot cooling.

Rationale for the_Select ion of the Best Avai lab le^Demonstrated
Con t r o 1 _ Tec hno 1 22y_

Thirty-one of the existing plants or 54 percent of the plants  canvassed
during  development  of  these  guidelines  were  using  the  technology
identified above and described in Sections VII and XI of this  document.
Thus, the technology is judged to be both available and demonstrated.

A  new  source  has  the  freedom  to design a technology, initially, to
achieve the standard of  performance  without  any  change  in  existing
equipment.   The  current  practice  of  these control technologies by a
large  fraction  of  the  industry  demonstrates  that  there   are   no
significant   technical  or  economic  barriers  to  the  selection  and
implementation of such technology.

The cost of application of the technologies, identified in Section VIII,
is estimated to be the same or less for new sources  than  for  existing
plants.

                    Waste Water from Fume Scrubbing

Standards of Performance based on the j Application of
the Best^Available^Demonstrated Control Technology

The  recommended  standards of performance to be achieved by new sources
discharging to navigable waters are:

    1)   Identical to the effluent limitations  presented  in  Table  1,
         Section  II,  for  those  plants  using  chlorine for magnesium
         removal

    2)   No discharge of process waste water pollutants for those plants
         using aluminum fluoride for magnesium removal.

I^gptif ication of the Best_Available Demonstrated Control
                 ^s^gx Operating Methods^ or Other Alternatives
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The technology previously identified in Section X as the best  available
technology  economically  achievable  for control of fumes from chlorine
demagging does not meet the criterion of "demonstrated" and may  not  be
capable  of  handling the anticipated capacities of new plants and still
permit the control of air contaminants by dry methods.   Therefore,  the
technology  previously  identified  in  Section  IX  as Best Practicable
Control Technology Currently Available is considered  identical  to  the
Best  Available  Demonstrated  Control  Technology for waste waters from
magnesium removal processes.

Rationale fpreselectign_of_the Best Available Demonstrated^Control
Technology

The rationale  for  concluding  that  the  Best  Available  Demonstrated
Control   Technology  is  identical  to  the  Best  Practicable  control
Technology Currently Available for waste waters from  magnesium  removal
processes using chlorine is as follows:

    (1)  Although the  technology  described  in  Section  X,  the  Best
         Available  Technology  Economically  Achievable, indicates that
         the Derham  and  Alcoa  processes  are  able  to  control  fume
         emissions  from  chlorine  demagging  without the use of water,
         there are some technical limitations to their adoption  by  new
         sources.  The Alcoa prototypes have been limited to inhouse use
         for  primary  aluminum processing and have not been used by the
         secondary aluminum industry in the United States.  In addition,
         the  design  may  require  modification  to  meet  the  casting
         poundage  rates  presently  used  by  most of the industry.  In
         effect, the system may not be applicable to new sources without
         further development work.

    (2)  The Derham process is used by two secondary  aluminum  smelters
         in  the  United  States  to  control fumes generated during the
         process of magnesium  removal  with  chlorine.   One  of  these
         plants  was not studied and the other was found to be not fully
         operational.  Therefore, it  was  concluded  that  insufficient
         data  are available to prove that the system is effective under
         typical operating conditions.  A supplemental wet scrubber  may
         be  required  with  the  Derham  process to meet air emmissions
         standards.  This is the case for at  least  one  plant  in  the
         subcategory.   The  Derham process is considered insufficiently
         demonstrated to be  applied  to  new  sources  without  further
         technical evaluation.

                    Waste Water^from Pesidue Milling

Standards of Performance based on the Application of the Best
Ayailable Demonstrated Contro1 Technology
                                 115

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The recommended standard of performance to be achieved by new sources is
no discharge of process waste water pollutants into navigable waters.

Identif ication_of ^the i Best Available Demonstr at ed Control Technology^
PrQcessesJ_^OBerating^MethQdsx_Qr Other Alternatives

The Best Available Demonstrated Control Technology, processes, operating
methods, or other alternatives for residue milling waste water are:

    (1)  Dry milling, currently in practice in existing  plants  in  the
         U.S.

    (2)  The evaporation of waste waters from wet  milling  of  residues
         with the associated reclamation and reuse of fluxing materials.
         This  technology  is not currently demonstrated in any existing
         plant in the U.S., but is demonstrated in Europe.

The details and costs of these technologies are presented in Section VTI
and VIII of this document.
Technology

The rationale for the  selection  of  the  best  available  demonstrated
control technology is as follows:

    (1)  A new source has the freedom to choose  the  most  advantageous
         residue-processing techniques for maximum recovery of metal and
         by-products with the minimum use or discharge of water.

    (2)  In contrast to an  existing  source  which  may  have  a  large
         capital  investment  in  waste  treatment  facilities  to  meet
         effluent limitations by July 1, 1977, a new source has complete
         freedom in the selection and  design  of  new  waste  treatment
         facilities.

    (3)  In contrast to an existing source, a new source has freedom  of
         choice  with  regard  to  geographic  location  in  seeking any
         economic advantage relative to power cost or land cost.

Since  the technology for achieving no discharge of residue milling waste
water  has been demonstrated for a facility currently being  constructed,
it  is considered the best available demonstrated control technology for
new sources.  The possibility of a slightly higher cost in  relation  to
several  orders  of  magnitude  reduction  in pollution and the possible
elimination of monitoring expense for no discharge of effluent  warrants
the  selection  of  this  technology  as the best available demonstrated
control technology for the secondary aluminum smelting subcategory.
                                  116

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Time  Available  for  Achieving  Effluent  Limitations.,   The   effluent
limitation  of  no  discharge of process waste water pollutants for best
available technology economically achievable, to be implemented July  1,
1983,  allows time for the retirement of existing wet-milling operations
by those plants using this practice.

Cost of Achieving No Discharge of Process Waste  Water  Pollutants^  The
cost  of  achieving  no discharge of process waste water pollutants from
the milling of residues is estimated to be about $130.00 per annual  ton
of  aluminum  production  capacity.   This  is  essentially  the cost of
building a new plant,  for  the  changeover  from  wet  to  dry  milling
involves  a  complete  process  change.   Data  are  not  available  for
operating costs, but estimates from the secondary industry indicate such
costs to be higher than for wet processing.

The cost of recovery of salts from waste water from residue  milling  is
dependent of the type of residue being processed.  The estimated capital
cost  to  evaporate  the water from low-salt content residues is $16 per
annual ton of aluminum, while operating costs are  $24/ton.   When  high
salt-content  residues  are  processed,  the estimated capital costs are
$200/annual ton and the operating costs are $124/annual ton.

Engineering Aspectg of _Control __ Application.   That  dry  processing  of
residues   for  aluminum  recovery  is  practical  from  an  engineering
standpoint is demonstrated by the fact that out of 23 plants  processing
residuse, 15 use a totally dry mill operation and generate no associated
waste  water  stream.   Thus,  the  technology  is well proven by actual
practice.
                  Plants presently wet-milling  residues  will  need  to
completely  alter  their  presmelter processing facilities to adopt dry-
milling practices.  Crushing, screening, conveying, and dust  collection
equipment will be required for the conversion.
                                 117

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                              SECTION XII
                            ACKNOWLEDGEMENTS


Appreciation is expressed to the following organizations associated with
the secondary aluminum industry that provided information:

    Apex Smelting Co., Des Plaines, Illinois
    Diversified Materials, Inc., St. Louis, Missouri
    Newark Processing Co., Newark, Ohio
    Rochester Smelting and Refining Co., Rochester, N.Y.
    U.S. Reduction Co., East Chicago, Indiana
    Vulcan Materials Co., Metals Division, Sandusky, Ohio
    Wabash Smelting and Refining Co., Wabash, Indiana

Acknowledgement  is  made  of  the  cooperation of the personnel in many
plants in the secondary aluminum industry that were  canvassed  and  who
voluntarily  provided  background  information and wastewater management
practices.  Special acknowledgement is made to those plant personnel and
company officers that cooperated in providing plant operating  data  and
cost  data  and  provided  facilities  for  sampling  of  their in-plant
streams.  The assistance provided by the Aluminum Recycling  Association
during this study is appreciated.

Special  acknowledgment  is  made to Mr. Marshall Dick for his technical
evaluation and comments and to Ms. Chris Miller and Ms.  Kay  Starr  for
the timely preparation of this report.
                                   118

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                              SECTION XIII
                               REFERENCES
(1)   Aluminum Association,  "Aluminum Scrap Consumption and
     Recovery",  Aluminum Statistical Review,  New York (July,
     1969) .

(2)   Andrews, C.,  Vice President,  Aluminum Processes, Inc.,

(3)   Danielson,  J.  A., "Air Pollution Engineering Manual",
     U.S.  Dept.  of Health,  Education, and Welfare, Cincinnati,
     Ohio  (1967) .

(4)   Demmler, J. A.,  Staff  Member, Technical  Marketing Division,
     Aluminum Corporation of America, private communication,
     June  22, 1973.

(5)   Francis, F. J.,  "Secondary Aluminum Smelter Air Pollution
     Control  Using a  Chromatographic Coated Baghouse — A
     Technically New  and Economic  Solution",  Proceedings, 65th
     Annual Meeting of the  Air Pollution Control Association
     (June 22,  1972) .

(6)   Ginsburg,  T.  H. ,  "Scrap Utilization by Secondary Aluminum
     Smelters",  Proceedings of the Third Mineral Waste Utiliza-
     tion  Symposium,  Chicago, Illinois (March 16, 1972) .

(7)   Patterson,  J.  W. , and  Minear, R. A., Waste Wgter Treatment
     Technology* Report t IIEQ71-4, from Illinois Institute  of
     Technology to state of Illinois, Institute for Environmental
     Quality, August,  1971.
(8)   Peters,  M.  S. ,  and Timmerhaus, K.  D., PI an tmDe s ign
     Economics  for  Chemical Engineers,  2nd Ed. , McGraw Hill
     Book Co. 7  New  York, 1968.

(9)   Shirley, W.  C. , "Secondary Aluminum Industry Emission
     Control",  Rept. prepared for the Aluminum Smelting Research
     Institute  (1971) .

(10)  Siebert, D.  L., "Impact of Technology on the Commercial
     Secondary  Aluminum Industry",  U.S. Bureau of Mines Informa-
     tion Circular  8445 (1971) .
                                 119

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(11)   Spendlove,  M.  J.,  "A Profile of the Nonferrous Secondary
      Metals  Industry",  Proceedings of the Second Mineral
      Waste Utilization  Symposium, M. A. Schwartz, Chm.  (March
      19,  1970) .

(12)   Staff,  Bureau  of Mines,  "Mineral Facts and Problems—
      Aluminum",  U.  S. Bureau  of Mines Bulletin 650 (1970) .

(13)   Staff,  "Metal  Statistics—Aluminum Profile", American
      Metals  Market  (1972) .

(1U)   Staff,  "Aluminum—Profile of an Industry—Part II", Metals
      Week,  (August  12,  1968) .

(15)   Staff,  "Process Effluent Water Data Development",
      Aluminum Recycling Industry Survey  (November 28, 1972).

(16)   Stamper, J. W., "Aluminum", U. S. Bureau of Mines Mineral
      Yearbook (1971).

(17)   Teller, A.  J., "Air Pollution Control", Chemical Engin-
      eering—Deskbook Issue (May 8, 1972).

(18)   Teller, A.  J., "Control  of Emissions from Glass Manu-
      facture", Ceramic  Bulletin, Vol. 51, No. 8  (1972) .

(19)   Wahi, B., Environmental Research Corp., St. Paul, Minn.,
      private communication, June 19, 1973.

(20)   Weston, Roy F., Inc., Draft, "Pretreatment Guidelines for
      Discharge of Industrial Wastes to Municipal Treatment
      Works", Contract No. 68-01-0346, for the Environmental
      Protection Agency  (November 17, 1972) .
                                 120

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                              SECTION XIV



                                GLOSSARY


Act

The Federal Water Pollution Control Act Amendments of 1972.


Alloying

The  process altering the ratio of components in a metal by the addition
or removal of such components.


Borings and Turnings

Scrap aluminum from machining of castings, rods, bars, and forgings.


Captive Scrap JRunaround Scrap)

Aluminum scrap metal retained by fabricator and remelted.


COD

Chemical oxygen demand parameter used to assess water quality.


Compatible Pollutants

Those pollutants which can  be  adequately  treated  in  publicly  owned
sewage treatment works without harm to such works.


Demagging

Removal of magnesium from aluminum alloys by chemical reaction.
Residues  generated during the processing of molten aluminum or aluminum
alloys by oxidation in air.
                                 121

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Effluent

The waste water discharged from a point source to navigable waters.


Ef fluent_Limitation

A maximum amount per unit of production (or other unit)  of each specific
constituent of the effluent  that  is  subject  to  limitations  in  the
discharge from a point source.


Fluxing gaits jor Covering Flux^

Sodium  chloride  or  a  mixture  of equal parts of sodium and potassium
chlorides containing varying amounts of cryolite.  Used  to  remove  and
gather contaminants at the surface of molten scrap.


Heat

A  fully  charged  reverberatory  furnace  containing  aluminum alloy of
desired composition.


Heel

That part of the molten aluminum  alloy  remaining  in  the  furnace  to
facilitate  melting  of  scrap  being  charged  for  the  preparation of
following heat.


Incompatible Pollutants

Those pollutants  which  would  cause  harm  to,  adversely  affect  the
performance  of,  or  be  inadequately  treated in publicly owned  sewage
treatment works.


Ingots

A mass of aluminum or aluminum alloy shaped for convenience  in  storage
and  handling.   Sizes  according  to  weight  are  15, 30, 50, and 1000
pounds.
                                122.

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Irony Aluminum

High iron content aluminum alloy recovered  from  old  scrap  containing
iron.    Prepared   in   sweating   furnace  operating  at  temperatures
sufficiently high to melt only the aluminum.


    Q 1 i pjDi nc[S _a nd_ Fo r gings
Scrap from industrial manufacturing plants such as  aircraft  and  metal
fabricators.
Ingots of aluminum alloy weighing 15 to 50 pounds.


Point., Source

A single source of water discharge such as an individual plant.


Pretreatment

Treatment   performed   on   waste  waters  from  any  source  prior  to
introduction for joint treatment  in  publicly  owned  sewage  treatment
works.


Residues

Include  dross,  skimmings  and  slag  recovered from alloy and aluminum
melting operations—both from primary and secondary  smelters  and  from
foundries.


Reyerberatory Furnace	(Reverb^

An  open-hearth  furnace  used for the production of aluminum alloy from
aluminum scrap.


Skimmings

Wastes from melting operations removed from the surface  of  the  molten
metal.   Consists  primarily  of  oxidized metal but may contain fluxing
salts.
                                 123

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Fluxing salts removed from the surface of molten aluminum after charging
and mixing.   Contains 5 to 10 percent solid aluminum alloy.


Solids

Aluminum scrap metal.


Sows

Ingots weighing 500 to 1000 pounds.


Standard of Performance

A maximum weight discharged per unit of production for each  constituent
that  is subject to limitations and applicable to new sources as opposed
to existing sources which are subject to effluent limitations.


Sweated Pigs

Ingots prepared from high iron aluminum alloy.
Aluminum recovered from bauxite
                                124

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