Technical Report WRD82030
EXPERIMENTS WITH POL YELECTROL YTES AS FLOCCULANT AIDS
TO LIME WATER TREATMENT FOR RUM JUNGLE - MAY, 1982
.
,
PREPARED BY
EAST POINT LABORATORY
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Page 1 of 17.
Technical Report WRD82030
NOT1?S ON POLYELECTROLYTE EXPERIMENT
'II so 1 U~10ns
~.
were d ose d
1~
. Lh
W1G
...
<")
,.~
"r] 1mB.
.
mg/w
The method uses for both the C-atoleum and the Cyanamid
flocculants involved mixing the lime and stirring for
one minute followed by addition of the required dose of
flocculant.
After further gentle stirring for one
mirlute settljng rate recording was commenced.
Cato1eum Products
CatolcLun 620, 625 and 630 liquid polyelectrolytes were
t.ested at
l~O,
3.0 and 5.0 mg/L cO:1centrations.
The heJght of the clear solution versus time grnphs are
ShO\·iD.
A blank without polyelectt'olyte is included for
compnrison,
All graphs are preceeded by data where
XCI) is the time
Y(l) is the height of the clear solution
The graphs show:
C620 has negligible effect at 1.0, 3.0 and 5.0 mg/L
C625 has some effect at 3.0 and 5.0 mg/L
C630 is the most effective.
There is little
difference between 3.0 mg/L and 5.0 mg/L
In
Graphs of turbidity versus time are shown for CG30,
the case of CG20 and C625 solution above the interface w~s
ess'entially clear (i. e. less 5 NTG).
Cyanamid Products
Cyanamid solid products A2100, A2115 and A2137 vlere Lest.ed,
Dissolution in water was effected after 24 hours s"tirrirlg.
Purchase of the flocculant in concentrated solution is
recommended.
.it')
• I "'"
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Technical Report WRD82030
-2-
The flocculant A2100 produced quicker. settling and pulp
compression.
Dosage of 3.0 and 5.0 mg/L of A2100.were
equally successful.
Graphs of clear solution height
versus time are shown.
On} y one dose rate. 1.0 mg/L "as tested for A2137
flocculant as this was less effective than comparable
A2100 dosage.
The best of the cYi'lnamid A2100 and the best of the
catoleum C630 are gri'lphed together illustrating the
superiority of the A2100.
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Technical Report WRD82030
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-"';
...
NAPES AA85769
MAPES AA44114
ATTN:
HORST i\AMBECK
C.C.
B08 WILDE, LAURIE MARSLAND
I
DATE:
5.5.82
TLX NO:
1874
RE'
.I
SETTLING TESTS
PRELIMINARY SIZING'OF THICKENER FOR RUM JUNGLE INDICATES THAT IN
ORDER TO REDUCE SIZE OF PLANT THERE MAY BE ADVANTAGES IN USING
POLYELECTROLYTE FLOCCULANTS.
WOULD LIKE HUGH WILSON TO PERFORM SOME SETTLING
ACCORDINGLY, I
TESTS USING SUCH REAGENTS TO ACCELERATE SETTLING RATES.
PROCEDURE TO BE FOLLOWED IS AS BELOW
IoU
(1)
PREPARE TEST USING STANDARD LIME ADDITION RATE (2.22 GMSI
LITRE PULP) AND FLOCCULANT AT RATES OF 1 3 5 MG/LITRE
(ADD FLOCCULANT AS it. SOLUTION)
~
(2)
RECORD SETTLING RESULTS USING COMPRESSED TIME SCALE IN
FIRST 3 MINUTES, AS PER PROCEDURE OUTLINED PREVIOUSLY.
(3)
A SUITABLE .FLOCCULANT MAY NOT BE AVAILABLE IN WATER
DIVISION LABORATORIES.
I AM ARRANGING WITH CYANIMID
FOR A TEST KIT TO BE AIR FREIGHTED TODAY.
HOXX
HOWEVER, CALGON WT - 3100 OR EQUIVALENT IS A GOOD FLOCCULANT
TO START WITH.
(!)
<t
en
U')
I
.
w
II ..
i
NOTE - MY FIRST SIZING OF THICKENER INDICATES DIAMETER SHOULD BE
APPROXIMATELY 55M.
THIS IS CONSISTENT WITH HALLIDAYS ESTIMATE
OF 70M AS THEY USE A MORE CONSERVATIVE FUDGE FACTOR.
IF
SETTLING RATE CAN 8E ACCELERATED BY USE OF FLOCCULANTS
(I EXPECT THAT IT WILL BE) I SEE NO PROBLEM GETTING SIZE DOWN
TO 25 TO 30 M DIAMETER.
:e
><
J.U
AT TRsSE SIZES FLOCCULANT USE WILL
PAID FOR BY REDUCED CAPITAL COST.
1
,I
, I
PROBABLY BE MORE THAN
REGARDS
...I
MARTIN ACKLAND
1&1
10.05 A.M. EST
l-
i
•
I
,
..
HAPES 'AA85769
MAPES AA44114
I
W
t!>.
.
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Technical Report WRD82030
SUPERFLOC* FLOCCULANTS
for Water Treatment
~Tradematk
of AmerIcan CyanamJd Company
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Technical Report WRD82030
imizes b'l!esswork and costly plant experimentation. For this evaluation, the following
products should be included.
SUPER FLOC Flocculant
C. 4. _,t)
~·
C435
C 110
C 100
iI
N 100 S
increasing
cationic
chanrc
c
no charge
increasing
N 100
A 95
A 100
A 105
A 110.
A 115
A 120
A 125
A 130
A 137
A 150
A ]85
II
I
viscosity
increasing
I
1
I
I
I
I
anionic
i
For lest procedures and dissolving, please refer to the Cyanamid lntemational bulletin
SUPERFLOC Flocculants for Water Treatment IND 146-2,4/77.
USE CONCENTRATIONS
Usually, laboratory testing will indicate the dosage of SUPERFLOC Floccubnt thai will
perform most effectively and economically. The following dosage ranges are recommended
as guidelines for evaluation:
mg/liter
End use
• Flocculants
Flocculating aids
Filtra tion aids
Sludge-conditioning agents
Fdction reducers in turbulent flow applications
0.2 ·2.0
0.05 - 1.0
0.01-0.1
10 - 200
25 - 250
As with any type of flocculant, the effect, of polymer concentration, point of application,
timing of addition, and other variables lmique to each syskm ShOllld be determined and
then adjusted to giv" best overall perfoTInance.
2
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Technical Report WRD82030
-,•
"
Figure 3.
6
pH
Viscosity·pH curve of SUPERFLOC A 130 Flo«ulant (0.25% solution).
STORAGE STABILITY OF POLYACRYLAMIDE SUPERFLOC
FLOCCULANT SOLUTiOr\lS
Polyacrylamide solutions are not stable indetlnitely. In solution, some alteration in polymer
charge density can take place O\'er a period of time resulting in a change in mobility (see
figure 4) which can affect perfonnance. This change is particularly assodated with cationic
polymenl and depends on the solution concentration and pH.
In general, the more dilute the solution and the higher the pH, the faster the polymer is
aiTected. Therefore, 0.1 % solutions of cationic polymer should not be slored for more than
one day, particularly when the solutions are alkaline. In I % solutions cationic polymers are
more sJable; however, they should not be ~torcd longer than 10 days at normal pH.
Nonionic polymers in 0.1 % ,;olutions sh ould be used within 10 days of preparation. The 1%
nonionic polymer solutions are more stahle and can be sJored for up to 30 days at normal
pH. At pH 10, the storage stability is reduced to only one day.
5
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Technical Report WRD82030
t
l~
l!Jb pH 7
~--------------~------------------~O~.~1%~'-P~H~7------====================
SUPERFlOC
C 100
Increo'Sing ,
pmlt.ive
Flocculent
charge
0.10/0 pH 10
I
SUPER flOC
N 100
Flocculont
lnc:reoslng
negative
djQrg(..~
I,
0.1% and 1% pH 7
O.I%pHl0
1
d
11
A110
Flocculont
20
10
0
} SUPERFlOC
30
Days
Figure 4. Relative mobility of SUPERFLOC Flocculants as a function of storage time.
6
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Technical Report WRD82030
5. Remove the vacuum and measure the c'lke thickness.
f,. Remove the cake from the leaf and weigh.
7. Dry the cake in an oven and wei"h to determine moisture lost.
B Measure the volume of the fil trate and note clarity.
Turbidity of the overllow, calculated in mg!l and measured by means of a device such as a
Hellige turbidimeter, can also be determined from the settling tests. Ovcrnow clarity is not
necessarily proportional to the settling rate and, at times, is more important than settling
rate.
PLANT APPLICATION TECHNIQUES
C-areful attention should be given to preparation and concentration of 110ccnlant feed
solutions, dosage levels, and points of addilion. As a general rule, highly diluted (eed
solutions will give the best results, but many times practical considerations will necessitate a
conlpromise,
The l10cculant solution should be added to the sludge just prior to the settling or filtratioll
operation, While the flocculant action is extremdy rapid and requires only minimum
agitation, sufficient contact time should be allowed to ensure complete distri1,ution
throughout the entire suspension. Dilution water added at this time can aid mixing and thus
increase the efficiency of the polymer. Vigorous mixing by prolonged agitation with a
propeller-type mixer or by passage through a pump should he avoided, as this can prevent or
break up 110c fonmation.
STOCK SOLUTION TANKS
In order to have a continuous supply of l10cculant solution, a makeup tank and a holding
tank are recommended. TIle size of the m~kcup tank will depend on the amount of polymer
to be used, the desired feed concentration, and the number of preparations per ,by that arc
convenient. The choice of makeup tank mol' vary from a 200 liter dwm to a 1000 liln
tank. The larger holding tank need not be equipped with an agitator.
Mechanical mixers or, preferably, air spargers can be used for agit~-ltion during solution
makeup. High-speed mcchanical mixe!> and those having a shearing action should be avoided
because they can cause degradation of the higher molecular weight polymers and decrease or
even nullilY their 110cculating properties. Use of positive displacement pumps rather than
centrifugal pumps will help reduce degradation of the polymers.
PREPARING STOCK SOLUTIONS
Flocculants must be properly dispersed and dissolved with care to avoid the formation of
gummy particles or masses which dissolve slowly and may lead to pumpmg problems.
Efficient dispersion is of the utmost importance. Two methods are described helow.
Preferred Method
for best results, the use of a disperser as shown in figure 1 is recommended. The disperser
operates on inlet watcr pressure whkh creates a vaCuum in the flexible tubing, thus drawing
up the polymer. TIlis results in polymer which is completely wctted and dispersed prior to
6
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Technical Report WRD82030
delivery to the makeup tank. The inlet pipe or hose to the disperser should have a 1.9 cm
diameter. The outlet pipe should be maintained well above the makeup solution surface.
Disperser units are available for trial purposes or can be purchased from Cyanamid International. Contact your nearest Cyanamid International representative.
FLEXIBL:E
.,
'..,...-----------------PLASTIC "-......./
......- VACUUM - POLYMER
TUBING
I
--------------
I
("'
#':.-~~
'(D
1:' ~
1
,
~t ---!NLE~~;--=-
1
.~----------
.
'"l
~
t.
~;
L,j
OUTLET PIPE WELL ABOVE
SOLUTION SURFACE
i
1111[1[1
\[11 J-. WETTED AND
I DISPERSED POLYMER.
----
[[ I[II
__ -
Figure 1. Disperser for SUPERFlOC Flocculants.
Alternate Method
Add the SlJPERFLOC Flocculant slowly from a mechanical or electrically vibrated feeding
device to a tank equipped with a stirrer. The stirring action should create a vortex. Direct
the dry powder to the edge of the vortex, as shown in figure 2; otherwise, it will collect on
the surface in gummy masses which will be very difficult to dissolve.
Figure 2. To prepare stock solutions of SUPERFlOC Flocculants, slowly
feed dry flocculant into the edge of the vortex.
7
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Technical Report WRD82030
RECIRCULATION OF STOCK SOLUTION
Experience has shown that continuous recirculation of stock solution through small pipelines and high shear pumps at high velocities can result in degradation of the higher
molecular weight polymers. When using the highest molecular weight flocculants, stirring
above 400 rpm should be avoided.
DOSAGE RATES
In many applications the amount of SUPERFLOC FloceuUmt required is only a few grams
per tonne of dry solids in suspension. In very dilute suspensions, floceulant levels from 0.1
to 5 mg/l are usually effective. Centrifuging operations may require dosages as high as 50 to
250 gil. As a filter conditioning aid, concentrations as low as 0.01-0.05 mg/I are effective.
Again, it is stressed that, for maximum efficiency and economy, the flocculants should be
added as very dilute solutions, in staged amounts, to locations where the suspended solids
will be thoroughly mixed with the flocculant. Intense agitation must be avoided.
Excessive additions of flocculants can produce lower settling rates, poorer flocculation,
poorer clarity, and lower efficiency. Dosage rates should be estimated from laboratory tests
and usually will be lower than those determined in the laboratory.
METERING FLOCCULANT TO SYSTEM
Any liquid-feeding device. can be used for meiering flocculant solutions. Positive displacement pumps will give accurate flow rates and small centrifugal pumps are suitable for larger
feed rates. A flowmeter or automatic flow control valve may be inserted in the line to give
more accurate feeding. Highly accurate control can be achieved with cup-and-disc feeders.
Also, a siphon feeder can be improvised to maintain a constant flow rate as the level in the
stock solution tank changes.
.
Plants using flocculants for improving filtration rates sometimes use automatic feed controls. As the turbidity level falls, flocculant dosage is cut back and, as it rises, dosage is
increased slightly. We recommend the use of devices such as a controlling turbidimeter for
tillS purpose.
POINTS OF ADDITION
In thickening or fIltration operations, the solution can be gravity fed into the thickener feed
well or injected into the pipe transporting the slurry to the thickener or filter.
In centrifuging, the flocculant usually should be added at a carefully determined point
inside the centrifuge, close to the point where the solid-liquid separation occurs, but not so
close that efficient floc forming is prevented.
8
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Technical Report WRD82030
STORAGE Ar1l0 HANDLING
Solid SUPERFLOC Flocculants are supplied in 25 kg bags. Liqt:id flocculanb are supplied
in 225 kg net steel drums. Storage in low humidity areas is recommended. Unopened packages show good stability, but storage in excess of a year shoule be avoided. Solutions are
noncorrosive to most common construction materials, but galvanized or aluminum equipment should be avoided.
Corrosion tests run with 1% SUPERFLOC Flocculant solutions at room temperature
indicate that the nopionic and anionic t10cculants have a corrosion rate on carbon steel
about equal to that of water, but a somewhat higher rate on aluminum. The cationic
110ccuJanb have a"higher corrosion rate than tap water on both materials.
Liquid, cationic StJPERFLOC Flocculants should not be stored i:J unlined mild steel or iron
containers or tanks.
.
TOXiCITY
American Cyanamid Company has conducted a wide range of experimental investigations on
animals and patch testing on humans in order to establish safety of use of the SUPERFLOC
FI occulan ts.IiUEE~e1!l!i!!tP.Ji;i5it$:;lIpJ[~])w11i~,[a:fi!li!~;()J.:Qg1CilllY$.\jr£J!I~)::rwafinaJ1;,
~~l.l!;~~jQ(,!"Q1[~tb'JFi~''!R!&:m:~!Qil~~:;WA11Wy':posse,:s£rrg";!i)gm.!icifufa1lilitY
\!o/'ittitl!Jll:QE~.ngrt~~lln.:;[klnf
Ordinary measures of personal hygiene and standards of plant housekeeping should be
adequate to assure safety. Spills of solid t1occulant, should be swept up and placed in a
waste disposal container. Flush area with water. Spills of liquid 110cculants or solutions of
solid flocculants arc very slippery. Cover with some inert absorbent material, sweep up,
place in a waste disposal container, and flush area with water.
TECHNiCAL SERVICE
Technical service and information for making the best use of SUPERFLOC Flocculants are
available through your Cyanamid International representative.
9
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Page 12 of 17.
Technical Report WRD82030
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Page 13 of 17.
Technical Report WRD82030
I.ll".: ,jun:'C!O.--:;rilUh ('<jrf1.;'iJr':~ drv
PU~',,11'(':1 !:;dt'l \~':li; in..:.\~::-I<E."Flid, .
lll}!P<.::l' di .:):')kh 1,;;,,1 In-3':',hmQ In';
in':""t(~r (\lif~''-\.>I'i;:S irl \);;,"dh..lc ~.x>
j">
,
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.:mn
:;"r~0.ru
.,'
~,
';--
'1
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;.'
",.-
j
,
627
625
62\J
PEODUCT NUMBER
NON
iONIC
1
J
'5
!\N\~~i.<:____ - - , - -
---
----
GENEBi\L
DESCElFflON
- .--"._--"-,-- "-'-- ---,-.~-CHi'\HGE
INCRb'\5iNG Cl-IAR<JE DENSiTY - - - - - - "..~
~ _..... ..- ...... ,.~,- - ,._' ......• ~,.- - - - " - ' _ . - , - . -.-- -.' .•...
OPNJU[
w}·nTE UQUID
...____.._. __ ,v\lLKY
_____ -r.-----.-.-.~-------- ----- -~-------.---,
--
--~--
{)DOUH.
-
.,.,'
,._- "-'---
..
..
....,.-1"
---,-- .,..
....__ .--- ---_._-
..
SUCHT NOT UNPLEASANT
- ..
_-
-_..
_---
1.0S ___, ______________
,..
-.-~- --_._'--'--- --------- --..-.--'- ---'---
SFSC1F1C GH/>;ViT\"
1.1~1
-_._---- -----_.
-
.~.--j
I
.._-'-' -------
VISCOSITY I Nfj\r1 ---------\W3COSl1'{O,1%
.'--- -
.-----...-
..
.----
__ \2.~T~C.:"::~O(~~\(;~~~lU c_'l)_5_._~__ _
-- ,_.
VI5~(=)S~! i ):,,:~',".... , - - -
..
------ .----
-
.
5 _______________________
uO
- ..-- .-_._---.. _,- .-_...--_ .
.----- .-'.-
j
---
-,
\-.. \.2.'~-. -----..----.'-.---.-.-.-_-.-.-.-.-.-..-.-.-.-.-,-,--.. . 12(Jfl
I
H;,SH P01NT
O,E,\TER TH\N 7U"C WM.cC.)
.._ .. _ ,_' ""_j'" . . , - -__ ' ---r'--'.r '"--Y' - ... ,- r--" .. ,
POTN3LE EQUlVi"LENTS
! 5020 \ 8022 \ 8023
8025 i 8027 \ 8030
" .'"'_ ."...
I
\--_-. ___ .......__ ,__..__ ..__ -.. __ ..__ -'--- ..- ,__ .._..1--.---'.-- ._L-- .._' ., __ 4
_ _ _.)1.. L'c
P rJ']"\?'
tN.H. and tvtH,C. 2lIll_)rDV~d-l vcrslon.s of thes~
nqu1d pnh'i...~\(.!ctrdY'1>2.s .:.ln~ ,}'.)('.ila.b\-e lor
Q\/al-l1;;tl(H'L
(;1",d.:
{,:.\]fkK BOOf) S,::rlt1.S pot~b\e
"}1,U,""~C" i{..' the
l-;le5c l'"wducts 3re
dose k!l.rels: -~
....~~~~~~Ii.'.'.9.t~.'.ri?'MlIi....iI
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Technical Report WRD82030
i
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,
ALFLOC LIgUID
FLOCCUIJ~ITS
,
Method of preparation of solutions for laboratory testwork.
General
It is best to prepare prirr~ry solutions of 0.5% strength, and to further
dilute these to 0.05% strength before testing. O.5\. solution will keep
for 1 week in a cool building.
O.05~ solutions shoulq not be kept for
more than 1 day.
,
Equioment required
Clean, dry syringes (1 ml or 2 mIl
Beaker
Bigh-spee5 laboratory stirrer
Bottles for storing prepared solutions
Method for preparing primary solutions
1.
2.
Sbake sample or liquid ilocculant until it is homogenous~
Measure out required amount of liquid flocculant with a
syringe~
Hake sure there are no air bubbles in the syringe,
(e.g. Use 1 ml of liquid floccu1ant in 200 mIs of water,
1
f
11
U
n
400 II
II
n
1•
or, 2 !n_S
0
3.
}~easure out reqllired- amount of water into the beaker.
4",
Place stirrer in water and switch on.
creates a strong vortex in the water.
5.
Add contents of syringe to the vortex.
6.
continue stirring for 5 minutes.
7.
Allow primary solution to age for 30 minutes before dilution
to secondary solution~
Hake sure stirrer
t-1ethoD. for preparing secondary solution.
1..
t'leaSUIe required amount of primary soJution into a hottle ..
(e.g .. use 50 mls primary solution in a 500 ml bottle) '"
2.
Add required 2.I.'1lount of ....'ater (eg .. 450 mls) ..
3.
Stopper bottle and shake gently for 1 minute.
then ready for use ..
Solution is
CATOLEUM PTY.LTD.
15/9/81
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Page 15 of 17.
Technical Report WRD82030
Cyanamid Austri1lii1 Ply, Limited
88 Christie Street, St, Leonards,
New South Wales, Australia, 2065
Telephone 430395
Telex AA20772
WATER TREATMENT CHEMICALS DEPARTMENT
SUPERFLOC DISPERSERS
INSTRUCTIONS FOR n,STALLATION'
To obtain the most desired results with the enclosed polymer disperser,
it should be connected to a 3/4", or larger, water line using
a gate type shut-off valve. The connection should be made at the'
threaded 3/4" opening in the side of the body of the disperser
with the long end pointing down into the solution tank to be used.
The length of plastic hose supplied should be inserted into the
top, or short end, of the disperser. lInen the water valve
is turned on full with a minimum water pressure of 40 psi, the polymer
or pmlder to be dispersed can be sucked up through the plastic hose
and disnersed throuf'h the disperser into the solution tank. The
disperser should be installed high enough that it will also be-atoll;:'
the highest liquid level in the solution tank.
TI,e disperser is never to be disassembled as it would disturb the
venturi setting inside the unit. If cleaning is ever necessary
the lilli t should be rinsed and the contamination should be al101'icd
to dry on the unit, than it may be very easily removed with the
head of a large nail or other instrwnent that would not scratch
the h\side surfaces of the unit.
NOTE:
DO NOT USE WATER PRESSURE OVER 80 POUNDS
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Technical Report WRD82030
·L..~
__ ,, _ _ _
FLOVl/ CHART
,;-;:==::;;'1
~1
It,>-:v.:::
~
EDUCTOR
J WAT:':RSUPPLY
..
/
SLOW MIXER
1),:/
"
~~7/
WATER
,- I
It should be remembered that the molecular weight
of an the Qjanular flocculants exceeds approximately
ten mi!lion, The dlSSo!ution of a:l1ong cham fjocculants
therefore _requires care, bccalso of the tendency to
form rigId insQluble gelled clumps if improperly mixed.
It is most desirable to prepare 1!occulant solutions in
su-ch a way that the granules are wet with \,>va1er evenly
avoiding clumps. A convenient me1hod is to use our
€ductor shown in Figure 3.
..
DlLUT!ON
//r;==\\ f/ATER
'<if
...............
......
..
••••"/ •:•.
/
"-
DILUTION
MIXING BOX
WITH BAFFLES
deAtlULAR
FLOCCUlANT , -_ _JJ.......,
I
I
r'-""j r-':"~
FLOCCUL~~---n-.J
;~6~!~E~
01
=
. % -
-<:)
~
O·~ ....
=t,
;:tJ
~
l~~ -;
'.';~:~:J
T
DlsTRlBulroR SYSTEM
LOCATED TO G!VE
GOOD MIXING IN FLOW
TO FlOCCULATOR
POSITIVE
OISPLACEMENT
DOSING PUMP
FIG. 4.
FIG. 3.
The maximum practical concentration of f!occulant
feed solution is around 0,1"/0. Solutions at this concentration are quite viscous .and should be fed INith
care to ensure adequate mixing jn the stream to be
treated.
EDUCTOR KIT
4 '<:; e fl.,:,'!' -:-i-)'?rt rd ? t:'P!-C2' fl-'JC'S~_d2rt feec
preparation system. The dissolving tank is partly tilted
\vith '.vater and the mixer started. The water supply to
the cdector is thon turnod on and the fiocculant induction tube lowered gently into the previously measured
polymer. When the charge of flocculant has been added
to the dissolvino tank, water is .added to the tank to
bring it to the required level. To avoid damage to the
polymer molecules -use low speed electric stirrers (400
rpm) or alternatively air agitation to dissolve the
floccu!ant. Most long cham flocculants reqUire approximately 1 - t 1,.<2 hours for complete solution, and when
solution is complete the agitation should be slopped.
Fi~;jf"'"
,
In general, the best system
IS
to feed f10ccuJant in the
most allute SOJUHOn POSS!Dle at a pomt OJ moderah3
turbulence through some kind of feed distributor. as
shown In Figure 4. After initial mixing the turbulence
in the treatment stream should be progressively reduced to promote maximum floc building.
Once floes have been buiit it is important that excessive turbulence be avoided, otherwise the floes may be
destroyed. For example, sharp changes in fiow dir2c~
tion. increases in velocity of flow, attempts to pump
the stream. etc, may result in floG damage. Once floes
have formed and been destroyed it is usually very
difficult to reform them properly.
Cyanamid Australia Ply. Limited
88 Christie Street, SI. Leonards,
New South Wales, Australia, 2065
Telephone 430395
Telex AA20772
•
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