United States
                   Environmental Protection
                   Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
                   Research and Development
EPA/600/S2-87/076  Dec. 1987
&ER&          Project Summary

                    Removal  of Uranium  from
                    Drinking  Water by Ion
                    Exchange and  Chemical
                    Clarification
                   Steven W. Hanson, Donald B. Wilson, Naren N. Gunaji, and
                   Steven W. Hathaway
                     A pilot demonstration  was con-
                   ducted of ion exchange and chemical
                   clarification  equipment for removing
                   uranium from drinking  water. Four
                   commercial-type ion  exchange col-
                   umns and a  prefiltering and regenera-
                   tion solution system were constructed
                   along with  a pilot-scale chemical
                   clarification  unit.  These units were
                   assembled and installed in a van trailer
                   for location  at a well  site containing
                   uranium-contaminated water. Uranium
                   concentrations in the well varied during
                   the study period from 190 to 400 fjg/L.
                     The four ion exchange columns each
                   contained 2 ft3 of resin. Three different
                   ion exchange resins were used. The 1 -
                   gal/min chemical clarification unit
                   consisted of a rapid-mix tank and
                   precoat rotary vacuum filter. The unit
                   was  operated  continuously for 3
                   months at pH values of  6 to 10 and
                   ferric chloride concentrations of 15 to
                   40 mg/L. Greater than 99% removal
                   of uranium was achieved when oper-
                   ating at 30  mg/L ferric  chloride and
                   pH 10. The diatomaceous earth precoat
                   filter achieved complete solid-liquid
                   separation.
                     In addition to the pilot study, the
                   report analyzes several currently oper-
                   ating water treatment  systems whose
                   feed supplies contain  uranium. Cost
                   analysis data for capital equipment is
                   also included in the report along with
                   a  discussion of ultimate disposal
                   methods for uranium-containing water
                   treatment wastes.
                     This Project Summary was  devel-
                   oped by EPA's Water Engineering
Research Laboratory, Cincinnati. OH,
to announce  key findings of  the
research project that is fully docu-
mented in a sepatate report of the same
title (see Project Report ordering
information at back).


Introduction

Background
  Most drinking water supplies come
from groundwater. The quality of these
supplies depends on the mineral and
biological content,  which vary widely
from source to source. Nearly all supplies
contain some small quantity of uranium.
In most drinking water supplies,  the
average uranium concentration is 3 /t/g/L
(equivalent to 2.0 pCi/L Uranium), but a
large number of  community supplies
have uranium concentrations in the 10-
to 50-//g/L uranium range. Though no
federal regulations currently exist setting
a maximum contaminant level (MCL) for
uranium  in drinking water, the  U.S.
Environmental Protection Agency (EPA)
is evaluating a limit of 15 ug/L (approx-
imately 10 pCi/L). That evaluation
involves the  assessment of available
control (removal) technology for uranium
and the economic impact of such an MCL.
  Aqueous solutions of uranium salts
have an acid reaction  as a result  of
hydrolysis, which increases in the order
U3+ < U0l+ < U4+. The uranyl, U02+, and
U4+ solutions are well studied. The main
hydrolyzed species of U0|+ at 25°C are
U02OH+, (UOz)a(OH)i+, and (UCMafOHJs;
but the system is a complex one, and the

-------
species present depend on the medium.
In addition to these hydrolytic products,
uranium ions  can undergo complexing
reactions with all ions other than C10i.
  Figure 1  shows the pH dependency of
the uranyl ion in aqueous solution in the
presence of carbonate, a constituent in
most drinking  water supplies.  '
  Previous  work  at EPA's Oak  Ridge
National Laboratory  at Los Alamos
National Laboratory had shown that ion
exchange  and chemical  clarification
were effective treatment  methods of
removing uranium species from aqueous
solutions.

Scope of Work
  This report presents the results  of a
demonstration  of  pilot-plant  ion
exchange  and chemical  clarification
equipment for the removal of uranium
from drinking water. The test units were
housed in  a 40-ft van trailer  (Figure 2}
and located at a uranium-contaminated
groundwater welt on the  New Mexico
State University campus. The well had
not been used for a long period and was
returned to service for this project. The
uranium concentration in the  water
varied over the project, begining with 190
fjg/L, rising to 350 to 400 pg/L during
the project, and falling back to 200/ug/L
at the end. These levels greatly exceeded
the tentative study level of  15 0g/L(~10
pCi/L).
   Four  ion exchange columns were
constructed, each containing 2  ft3 of
resin. Three  different ion  exchange
resins  were   used:  DOWEX  SBRP,
DOWEX 21 K, and IONAC A641.* Three
columns were  operated in the conven-
tional down-flow mode, and the fourth
column was operated with upward  flow
of  the  feed water. Pretreatment  con-
sisted of paniculate filtering only. Regen-
eration was by chloride ion (10% NACL).
Four bed-volumes of chloride solution
were used at one-third the normal  flow
rate  followed  by  two bed-volumes of
rinse (product water). Resin capacity was
represented by 12,000 to 20,000 bed
volumes. Four cycles of operation were
completed for each column, processing
a total of approximately 4  million gal of
feed containing  an average  uranium
concentration  of 300 //g/L.
   The chemical clarification  unit  con-
sisted of a  Joy Manufacturing Co. Model
0-12 Laboratory Sub-A Flotation Cell as
a rapid-mix  vessel and a continuous

 •Mention of  trade names or commercial  products
 does not constitute endorsement or recommendation
 for use.
     100
   in

   *
   I
Figure 1.   Uranium species in aqueous solution at various pH levels.
      t.  Water Supply

      2.  Feed Pump

      3.  Pro-Filter

      4.  Chemical Clarification System

      5.  Four  Unit Ion  Exchange
         Columns
      6.  Ion exchange Control System
 7.  Product Pump

 8.  Product Tank

 9.  Product Discharge
1O.  Regenreation Solution

11.  Regeneration
12.  Waste Discharge
13.  PHot-Scale Up Flow Unit
Figure 2.    Organization of van system.
precoat rotary vacuum filter, The system
flow rate was 1 gal/min. This system was
operated  continuously over a period of
3 months using pH values of 6 to 10.0
and ferric chloride concentrations of 15
to 40 mg/L. Greater than 99% removal
of uranium was achieved when operating
  at 30 mg/L ferric chloride and pH 10.0.
  The  diatomaceous earth precoat filter
  achieved   complete    solid-liquid
  separation.
    The full report also analyzes  several
  currently operating water  treatment
  systems  whose  feed  supplies  contain

-------
uranium. In addition, cost analysis data
for capital equipment is included along
with a discussion of ultimate  disposal
methods for uranium-containing water
treatment wastes.


Demonstration Test Program
  Table 1 outlines the quality of the well
water  used  in this project.  The major
constituent of interest was the uranium.
At the start of the project, the  uranium
concentration was 190A»g/L. During the
project, the uranium concentration rose
to 450/jg/L but returned to around  200
jjg/L at the end of the project period. Both
the ion exchange units and the chemical
clarification  units were operated on a
continuous basis. Initially, sampling for
uranium was performed daily.  Later, it
was done weekly until breakthrough was
anticipated, and then daily samples were
taken. The chemical clarification effluent
was sampled on a daily basis until steady
state was reached  (after a change  in
operating  conditions); then  it was
sampled every other day.

Ion Exchange
  Water treatment  using ion exchange
technology is a well established opera-
tion. Table 2 summarizes the operation
of the four ion exchange units. Though
the  feed to  each  unit was adjusted
individually and a uniform flow through
all columns was attempted, it  was not
achieved. Each  column effluent  was
sampled individually,  but when  one
column reached breakthrough,  all  four
were regenerated. Thus throughout the
four cycles, some units had not been
processed to exhaustion.
  All four systems operated well once the
problems of mechanical equipment had
been corrected.
  Several physical and chemical charac-
teristics of the resins  need to be con-
sidered in the selection of ion exchange
as a water treatment technology. Phys-
ical  bead breakage  may occur  in some
applications. For downflow systems, this
breakage results in increased  pressure
drop and reduced efficiency. The three
downflow units exhibited no resin break-
age. In an  upflow unit, breakage could
result in entrainment of broken resin in
the  effluent and  subsequent  down-
stream problems in addition to the loss
of exchange capacity  through  loss  of
resin. The upflow unit exhibited no resin
breakage. These  determinations were
based  on operating pressure drop and
visual inspection of the resin at the end
of the project.
  Thermal  stability  of  the  resins is a
second  consideration in selecting ion
exchange. Weak-base resins are usable
up to 212 °F, followed  by Type I strong
bases to 122°F (the  resins of this
demonstration). Temperatures in the van
housing the units ranged from a winter
low of 35°F to a summer high of 115°F.
The average inlet (well temperature) was
65°F. No noticeable change in operation
occurred as a result of thermal effects.
  Although chemical degradation is not
normally a problem  in most water
treatment applications, strong oxidizing
agents can rapidly degrade the polymer
matrix and should be avoided.  Slower
degradation with  oxygen may be cata-
lytically induced, so ionic iron, manga-
nese, and copper  should be minimized.
In the present operations, the raw water
had high iron and manganese contents
(4 mg/L and  1.1  mg/L, respectively).
Resin degradation was not observed.
  The capacity of the ion exchange resin
is the  measure of ionic attraction per
volume, and it is expressed in a number
of ways. Total capacity is the theoretical
measure of the total number of exchange
 Table 1.    Chemical Composition of Well Water* Used in Demonstration (mg/L, except as
           otherwise noted)
Component
U
/Va+
/r
Ca2*
M/+
cr
COa2"
HCOi
sof
TDS
AS*
BA*


Concentration
(mg/L)
0.30±O.10*
17.9
18.4
375.2
69.0
555.2
0
96,4
400.0
2152
0.005
0.12


Component
Cd*
Cr3*
Pb"
Hg*
SE*-
Ag-
NOi
F'
Fe"
MN*
Hardness
(as CaCOJ
Alkalinity
pH
Electrical
conductivity
mmhos/cm
Concentration
(mg/L)
<0.005
<0.01
<0.005
0.0004
0.005
<0.05
0.01
0.54
1.69
0.95
1220
79
7.62
2.36
Notes:
"Uranium concentration in the well water varied and ranged from 200 to 450 ftg/L; pH of
 well water was 7.62: electrical conductivity of well water was 2.36 mmhos/cm.


Table 2.    Operation Summary for the Demonstration Ion Exchange Units*
Resin
Type
DOWEX21K
DOWEXSBR-P
ION AC A -641
IONACA-641
Flow
Condition
Down
Down
Down
Up
Total
Gallons
Processed
797,540
890,600
853,870
903,450
Number
of
Cycles
4
4
4
4
Average
Bed- Volumes
Treated/Cycle
12920
14925
16040
15370
Maximum
Removal
Efficiency
(%)
99
99
99
99
'Inlet water concentration ranged between 200 and 400 ug/L uranyl complex (as uranium).

-------
sites available and is normally calculated
in three different  ways: Dry  weight
capacity (meq/dry g), wet volume capac-
ity (meq/wet g) and wet volume capacity
(meq/mL).  Table  3 gives the average
capacities for  the resins  used in  this
operation.
  Regardless of how it  is expressed,
operating capacity is the  most realistic
performance measure for ion  exchange
resins, and in water treatment,  it  is
usually  expressed as kilograins/ft3  of
resin. Here the resin  is measured  in a
column for actual operation under pres-
cribed conditions.
  A final consideration in the selection
of an ion exchange resin is the cost  of
regeneration. Small differences in  effi-
ciency will be  magnified over  the life  of
the system. Perhaps of equal importance
are the potential environmental prob-
lems encountered in disposing of waste
regenerant.
  This demonstration showed that chlo-
ride ion (NaCI) successfully regenerated
all resins used.

Chemical Clarification
 . The flotation cell was used as the rapid
mixer and  adsorption vessel.  Entrained
air only was used—that is, no forced-air
mixing was used,  and  no surfactants
were used to enhance bubble stability of
flocculation. This vessel   had a 1-min
residence time at a 1 -gpm feed rate. The
effluent was channeled by gravity  flow
to the filter vessel,  where a continuous
rotary vacuum filter separated the ferric
hydroxide precipitate.
   The filter membrane was 0.45-micron
polymer mesh, which allowed precipitate
to bleed through into the filtrate when
operated without precoating.  A 0.25-in.
precoat of diatomaceous earth was  used
and gave a complete solid-liquid sepa-
ration as  measured  by  our  analytical
procedures.  Additional  diatomaceous
 Table 3.    Ion Exchange Resin Capacity
earth (12% by weight) was added to the
filter feed and mixed by a mechanical
agitator with the feed slurry. A stationary
knife removed the cake  buildup. Visual
inspection of residual precoat showed no
binding by the ferric hydroxide precipi-
tate. Sampling of the precoat material
after a run for uranium showed that all
uranium  removed was adsorbed on the
ferric hydroxide  and not on the diato-
maceous earth.
  Table 4 summarizes the effect of  pH
on  removal of uranium from the well
water  at a constant ferric chloride
addition of 30 mg/L
  Table 5 shows how varying the ferric
chloride  concentration affects uranium
removal efficiencies at pH 6 and 10.
  Experimental data for the effect of the
ferric chloride dosage and the equilibra-
tion pH of the solution show that pH is
a major controlling factor in the removal
of uranium from drinking water by means
of the coagulation/filtration  process.
 Proper choice of pH is a  requirement for
effective  chemical coagulant treatment.
The results of the pH dependence  for
uranium  removal with iron salt can be
interpreted by the stability and charge
characteristics of uranyl  species and
metal  hydroxide  precipitates at  the
adjusted  pH of the solution. No data are
shown for similar experiments examin-
ing the  pH dependencies for other
dosages  of ferric chloride.  However,
similar results can be expected from the
physiochemical properties of the metal
hydroxide formed during  the coagulation
process at a given pH and the dominant
uranyl  species in the solution. The role
of ferric hydroxide as a coagulant formed
from ferric chloride in aqueous solution
is well known. The stability, solubility,
and reactivity (adsorption) of the hydrox-
ide are pH-dependent. The pH depend-
ence of the distribution of uranyl species
in natural water is also known. Dominant



Resin
DOWEX21K
DOWEXSBRP
IONACA641
IONACA641
(up flow)

Uranium
Capacity"
(kilograins/ft3)
2.95
3.15
3.67
3.54

Uranium
Wet Volume
Capacity +
(meq/mL)
0.03
0.032
0.038
0.037

Total
Wet Volume
Capacity?
(meq/L)
1.20
1.20
1.16
1.16

 "As UO2(CO3)l'.
 •*Average over three cycles of operation (i.e.. cycles 1,2, and4).
 ^Manufacturer's value: 1.2 meq/mL is 26 kilograins/ft3 as CaCOa.
uranyl species and charge characteris-
tics of iron hydroxide floe at pH 4, 6, 8,
and 10 are shown in Figure 1. At a low
pH (say pH < 5), ferric hydroxide had a
positive charge. Fe(OH)3-wandthe uranyl
carbonate complex also dissociated to a
positively charged  uranyl ion  (UO|+,
UOzOH*). Thus at pH 4, less adsorption
can occur because of the strong repul-
sion between ferric hydroxide and uranyl
ion or  ion-complex.  As the  pH  was
increased to 6,  the  dominant  uranyl
complex would be U02CO3, with a small
positive charge of uranyl ions, and the
mixed charge  of  negative and neutral
hydrolyzed ferric  iron would be overall
negative.  Statistically, the  possibility
exists for adsorption, since at least there
is no repulsion between the two charged
particles, UO2CO3 and Fe(OH)i. At pH 8,
the same phenomenon was observed as
at pH 4,  except  that  both  interacting
species would  have negative charges.
Thus  a lower removal efficiency  was
obtained in both conditions (pH 4 and 8).
When the pH exceeds 9.5, the U02(CO3)4~
species are known  to  be stable;  but
(U02)3(OH)5 would  be the  dominant
species in carbonate-depleted water. The
carbonate in water could be depleted by
CaCO3 precipitation during the coagulant
treatment process. The reaction is shown
as follows:

       3 UO2(C03>r + 15 Ca2+ +
    2  FeCI3 + 15 OH' - (U02)3(OH)J +
  12  CaCO3(s) + 2 Fe(OH)f (s) + CaCI2

  Since the charge of the ferric hydroxide
is pH-dependent,  it should adsorb on its
active surface sites  the  stable  uranyl
complex through electrostatic attraction.
Minimum  uranium removal was there-
fore observed  when  the  charge of the
uranyl species was  the  same as the
charge of the  floes, and  maximum
removal occurred when  the charges
were  opposite or neutral.

Monitoring  Program
  As  part  of this study, an analysis was
conducted of several currently operating
conventional water treatment facilities
with  uranium  in  their feed supplies. A
detailed search was conducted to locate
such  facilities. For this search, a  min-
imum uranium  level  of  15 fjg/L  was
arbitrarily  selected,  and  conventional
water treatment facilities were defined
as  any type of treatment facility more
complex  than sand separation  and
chlorination.
  The wide variety  of state and  U.S.
Goverment agencies responsible for the

-------
 Table 4.    Summary of Uranium Removal Using 30 mg/L of Ferric Chloride Solution on
           Samples with Various pH levels
Adjusted
pH
4.0
4.9
5.3
5.8
8.2
9.4
10.0
Uranium Remaining in
the Tested Water (ug/L)
309
251
180
86
369
6
<2
Uranium
Removed
(%)
31.3
44.2
60.0
80.9
18.0
98.7
99.0
 Table 5.    E ffect of Ferric Chloride Concentration on Uranium Removal Efficiency in Solutions
           of pH6 and 10
FECI3
pH6
pHIO
Dosage (mg/L)
30
60
90
30
60
90
Uranium Remaining in
the Tested Water (ug/L)
86
60
59
<2
<2
<2
Uranium
Removed
(%)
80.9
86.6
86.9
98+
98+
98+
radiological monitoring of water supplies
made the search very time-consuming.
A total of 34 municipal systems and an
additional 21  municipal wells were
located  in a 6-state area. Of these 55
possible  study  sites, only four  provide
treatment above and beyond sand sep-
aration and chlorination. Three of these
cities are located in Colorado—Arvada,
Denver, and North Table Mountain—and
they  all draw  their water from  the
uranium-contaminated  Ralston Reser-
voir. The  fourth city is a small city in
South Dakota (Harrisburg).
  The City of Arvada treats their water
using a microfloc system. The system
employs alum and Separan (a polyelec-
trolyte) to create the microfloc. The water
is  then passed through mixed-media
filters. A  125-cc  water sample is  col-
lected daily from the  raw water  and
treated water to form monthly composite
samples. For the  past couple of years,
these monthly samples have been tested
for uranium. The raw water from Ralston
Reservoir  contains a range of less than
1 fjg/L to 36 ug/L, with an average of
14.7  ± 9.6 (South  Dakota) ug/L of
uranium.  The Arvada facility removed
18% to  90% of this incoming uranium
with a mean efficiency of 60% ± 15%.
The meticulous  nature of these records
and  the  time span  of the monitoring
clearly indicate  that conventional water
treatment facilities  can greatly reduce
the uranium content of natural waters.
  The Moffat Treatment Facility (Denver)
also draws water from Ralston Reservoir
and has been keeping  uranium records
for about  2  years.  Unfortunately,
Denver's  monthly  samples  are  grab
samples, and correlation between raw
and treated waters are less meaningful.
Using their  records, uranium removal
efficiency  varies widely: 78% ± 190%.
North  Table  Mountain  declined to
participate.
  Harrisburg, South Dakota, treats about
100,000 gal/day using aeration, KMnCu
greensand  filters,  chlorination,  and
f luoridation.  No previous data exist on the
uranium  removal  efficiency of  this
facility.  Duplicate  sampling  over  two
different periods of operation showed no
uranium removal by the current treat-
ment system.

Ultimate Waste  Disposal
  As  previously described,  uranium-
contaminated drinking  water  is a  com-
mon problem, particularly in the western
United States. If regulations are accepted
and enforced, many communities will be
required to  remove the uranium  from
their drinking water supplies. Removal
of this radioactive element produces a
new problem of radioactive waste dis-
posal. The physical form of this waste
and  the longevity  of  uranium  cause
difficulties in formulating a waste dispo-
sal plan.
  Three disposal alternatives were con-
sidered  in  this study:  Dilution and
release, reuse or resale, and burial. The
choice of method  must be based  on
environmental acceptability. Each partic-
ipating  community will have  unique
drinking water and waste characteristics,
so it is impossible to prescribe a single
solution to the problem. Each community
must consider its situation and choose
the optimum plan.  The full report ana-
lyzes two cases: (1) a community using
150,000 gal  water/day with 30 ug/L
uranium,  and (2)  a community using
150,000 gal water/day  with 200 ug/L
uranium. Table 6 summarizes the quan-
tity and form of uranium to be disposed
of for each case. The first alternative of
dilution and release is by far the most
economical; however, there are usually
restrictions on the  quantity of uranium
that  can be returned to  surface waters
(e.g., in New Mexico,  such flows must
be less than 5 mg/L). Table 6 shows that
for both Cases 1 and 2, the ion exchange
regeneration solutions  could be dis-
charged to surface  flows. However, the
value given for Case  2 is an average
value,  and  during operation of this
project, we observed solutions exceeding
25 mg/L at the start of regeneration. This
discharge would be the usual disposal
solution for ion exchange systems.
  Total  environmental  consideration
suggests that there be alternative means
of disposing of the uranium, and the filter
cake resulting from chemical clarification
is the first step in such disposal. In Case
1, the cake would contain 0.057 nano-
curies of uranium/g, and in Case 2,0.38
nanocuriesof uranium/g. Both cases are
well  below the 100-nanocurie/g defini-
tion of waste requiring special packaging
and disposal in a permanent repository.
The filter cake could be drummed and
sent  to an  approved  site for shallow
surface burial. The alternative is to send
it to a uranium mill for processing as part
of the mill feed.

Design Analaysis
  Though complete cost analysis  has
been covered by several recent publica-
tions, two specific designs are summar-
ized in Tables 7 an 8. They include capital
costs for equipment only, since operating
costs are site dependent.

-------
Table 6.    Ultimate Disposal Values for Uranium in a Community Using 150,000 gal water/
           day
Uranium Source
         Amount and  Form  of
                 Uranium
             to be Disposed of
Case } (30-iug/L uranium content):

  Ion exchange treatment regenerant solution
  Chemical clarification filter cake
  Total uranium

Case 2 (200-ug/L uranium content):

  Ion exchange treatment regenerant solution
  Chemical clarification filter cake
  Total uranium
         0.3mg/L, 1500 gal/day
          17.03 kg/day
          1.7 g/day
          2.0 mg/L. 1500 gal/day
          17.04 kg/day
          11.35 g/day
 Table 7.    Ion Exchange System Design*

                      Item
           Design Data
Average influent concentration ofUO

Feed needed (1 -day basis)
  based on average capacity of 3.3 kilograins/ft3
 Resin needed for 1 day of operation


 Size of tank based on fOgpm/ft* flow rate


  Diameter of tank 9 ft

  Bed depth 3 ft


 Use 10O% freeboard for B/W and/or expansion

  tank size

 Approximate running time between regeneration

  Time of operation


  Salt needed for regeneration

 Estimated capital equipment cost"
84 fjg/L or si 50 fjg/L as uranium

600  gal  x .084 ppm x .0547
     min
grains/gal , M ltr,mmins
  ppm               hr

3960 grains
3.96 kilograins   = j 20 ft3
3.3 kilograins/ft3
600 gpm  ,
10 gpm/ft2

Area = 63.6 ft1

Resin quantity = 63.6 ff
x 3 ft =191 ft3



9 ft dia. xSft side shell
191 ft3
            = 160 days
1.20 ft3/day

15 Ib/ft3 x 191 ft3 = 2.86 fb

$125,000
"Cost analysis for chemical composition is given in Table 1.
  The  cost curves  for  the two unit
operations considered were updated to
1985 costs using the Civil Engineering
plant cost  index data  published in
Chemical Engineering. The index used
was 375.2 (July 1985) based on  1957-
59 as 100. These cost curves were scaled
for the specific processing of uranium.

Conclusions
  Four commercial-type  ion exchange
columns and prefiltering  and regenera-
tion solution systems were tested to
remove  uranium concentrations in the
water supply well in which concentra-
tions varied from 190 to 400//g/L during
the study period.
  Greater than 99% removal of uranium
was achieved when operating at 30 mg/
L ferric  chloride and pH  10. The  diato-
maceous  earth  precoat filter achieved
complete solid-liquid separation. No
thermal  degradation  of  resins  were
observed  in the temperature range of
35°F to  115°F. Chemical degradation
also was not experienced in this  study.
Minimum  uranium  removal   was
observed when the charge of the uranyl
species was the same as  the charge of
the floes, and maximum  removal was
experienced  when the charges  were
opposite or neutral.
  Review and  analysis  of records of
currently operating water treatment
systems  whose  feed supplies contain
uranium  indicated that  conventional
water treatment facilities can greatly
reduce the uranium contents of natural
waters.
  Ultimate waste disposal  plans for
radioactive waste from drinking  water
supplies are difficult  to formulate
because of the longevity of uranium and
the physical form of the waste. Methods
considered in this study are dilution and
release, reuse or resale, and burial. If the
uranium content of the waste is  below
that required by the permanent repos-
itory guidelines to have special packaging
and disposal, then the waste can be
drummed and sent to an  approved site
for shallow surface burial or to a uranium
mill for processing as part of the mill feed.
  The  full report was  submitted in
fulfillment of Cooperative Agreement CR
810453 by New Mexico State University,
under the  sponsorship of the U.S.
Environmental Protection Agency.

-------
Table 8.    Chemical Clarification System Design

	Item	Design Data	
Average influent concentration                   0.5 mg/L as U

Feed rate                                     60 gpm

Joy Manufacturing flotation cell                  16 ft3

Residence time                                2 min

Ferric chloride addition                          25 mg/L, 35.7 Ib/day

pH adjustment (assuming feed at pH 7 to 10)        2L cone. (37%) HCI/day*

Continuous rotary vacuum (precoat) filter           6 ft2 total surface area

Filter-aid addition 2x weight of ferric chloride
  (diatomaceous earth)                          70 Ib/day

Total filter production/day (dry weight and wet
  weight. 8% moisture)                         106 to/dry weight, 115 Ib/wet weight

Total estimated capital equipment costs            $44,000


*NaOH could also be used if pH needs to be increased.
   Steven W. Hanson, Donald B. Wilson, and N. N. Gunaji are with New Mexico
     State University, Las Cruces, NM 88003.
   Richard P. Laucfi is the EPA Project Officer (see below).
   The complete report, entitled "Removal of Uranium from Drinking Water by
     Ion Exchange and Chemical Clarification," (Order No. PB 88-102 90O/AS;
     Cost: $13.95, subject to change) will be available only from:
           National Technical Information Service
           5285 Port Royal Road
           Springfield, VA 22161
           Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
           Water Engineering Research Laboratory
           U.S. Environmental Protection Agency
           Cincinnati. OH 45268

-------
United States                    Center for Environmental Research                                     BULK RATE
Environmental Protection            Information                                                 POSTAGE & FEES PA
Agency                        Cincinnati OH 45268                                                EP^
                                                                                        PERMIT No. G-35


Official Business
Penalty for Private Use $300

EPA/600/S2-87/076
       0000329   PS
       U  $ EMVIf? PROTECTION  AGENCY
       RSGI0N 5  LIBRARY
       230 S  DEARBORN  STREET
       CHICAGO             IL   6Q6Q4
                                                                                                  /„
                                                                                              1 C_
                                                                                           'o
                                                                                           r   "   z.
                                                                                           ^   '-   ^i

-------