Note: Descriptions are shown in the official language in which they were submitted.
14(~79
The present invention relates to the clarification of
water suspensions of finely divided solids. More particularly, it relates
to an improved process for the 10oculation and separation of suspended
particles, both organic and inorganic, in aqueous dispersions including
raw water, raw sewage and various industrial process and waste waters.
The term "clarification" as used herein includes conventional means of
separating the flocculated suspended matter from the aqueous phase, such
as filtration, settling, centrifugation, flotation, etc., or ccmbinations
thereof.
The separation of suspended solids in aqueous systems has
kecome a problem of considerable importanoe . For example, present anti-
pollution laws require that the solids content of waste water be reduced ;
to a fixed maximum value befoi-~ discharge into a river or stream. In
many cases, due to the stability of the suspensions and the small size of
the suspended particles, sedimentation and filtration procedures are
relatively ineffective insofar as meeting the imposed anti-pollution
standards without prior flocculation of the suspended matter. musl it
has naw hecome the practioe in the art to treat the suspensions with
chemical flocculating agents which cause the fine particles to agglomerate
thus converting them into larger particles having an increased tendency
to settle and which at the same time have less tendency to plug the filter
medium.
r~nicipal sewage treatment, for example, requires the separation
and disposal of large quantities of water frcm sewage sludge. Flocculating
agents have heen used to good advantage in the settling and filtration of
such sludges in sewage treating plants.
Another difficult industrial pro~lem is the clarification of
industrial wastes which would otherwise cause pollu-
~ .
lA~7~9
tlon Of l~nds ~nd 8tre~m~. ThU~, W~8tes~ re8ultlng from indu~-
trial operations, such a8 coal mlnlng, ore processing, chemical
manuracturlng and the llke, comprlse suspenslons of ~lnely
dlvided sollds in water. These suspensions remaln fitable for
days 80 that if the sollds are not removed the water cannot be
reused and a dlsposal problem 18 presented. In coal plant
operations, for example, the coal wash water contains finely
divided coal and clay particles whlch must be separated out
prlor to reu~e or dl8po8al of the water ln a river or stream.
Also, the proce6sing Or ores results in the productlon Or large
guantities of fines (or slimes), through attritlon grinding.
After removal ~r the mineral values, the slimes must, in many
lnstanCe8, be dewatered ~or further processing or disposal.
Bettling or ~lltration, or a combination thereof, have been used
to ~eparate such rine suspensions and the efficiency Or the
8eparation8 ha8 been greatly improved by the use o~ flocculat-
lng agent8.
Another problem whlch has developed i~ that Or supply-
lng the increasingly large amounts Or clean water required for
~drinking and various industrial uses. Thus, the natural sources
Or ~water supply, i.e., lakes, rivers and streams, are constantly
becomlng less available due to pollution which has been built
up in these sources by discharge of industrial wastes therein
over the~year8. The clarification of such raw waters, whlch
25~ ~ Contain flnely 8u8pended pollutants, has been ef~ected by settl-
ing and/or ~iltratlon processes and flocculants have been used
to improve the~e processes. However, the clarities achieved by
the heretoPore employed flocculants or flocculant comblnatlons
àre ~requently lnadequate for these use6.
30;~ It~ls the obJect Or this inventlon to provide an
lmproved method ~or clarifylng aqueous suspenslons Or finely
dlvided solids. It 18 a rurther ob~ect to provide a method for
the ~locculation and 5ettllng Or the flne partlcles ln such
- 2 -
4 0~9
suspens10ns whereby the ~upernatent water thus provlded 18 of
markedly hlgher clarlty than obtalnable by flocculatlon and
settllng methods known heretofore.
As has been brought out herelnabove, flocculatlng
agents have been used ln the clarlflcation of aqueou3 suspen-
slons. Of the various flocculatlng agents which have been
used, those whlch have proved most effectlve are moderate to
high molecular welght polymers, i.e., polymers havlng molecular
welghts ranglng from about lO,000 up to about 30 mlllion or
hlgher. Polymers whlch have been used, for example, are (a)
acrylamide polymers, including polyacrylamides and copolymers
of acrylamide with up to about 70 mole percent acrylic acid or
lts aIkall or ammonium salts and partlally hydrolyzed polyacryl-
amldes contalning up to about 70 mole percent sodlum acrylate
groups; (b) hydrolyzed polyacrylonitriles contalning up to about
70 mole percent sodium acrylate groups; (c) cationlc vlnyl addl-
tion polymers such as (l) copolymers of acrylamide with from 1
bo about 30 mole percent of a monomer such as dlallyldimethyl-
~mmonium chloride, the methyl chloride or dimethyl sulfate
~quaternary of dimethylamlnoethyl methacrylate, vinyl pyrldine
or its substituted derlvatlves or other copolymerlzable amine
or quaternary amlne, (2) polydlallyldimethylammonlum chlorlde,
~3) polyvlnylpyrldlne, (4) polyvlnyllmidazollne; (d) amino-
alkylated polyacrylamldes; and (e) condensatlon polymers of (1)
aIkylene dihalides and polyalkylene polyamines? (2) amines and
halohydrlns and (3) halohydrins and polyalkylene polyamlnes.
Whlle, as a~ore-lndicated, the varlous polymer floccu-
lants have proved useful in the clarlficatlon of the variou~
aqueous suspeAslons, ~till, the clarlties requlred ~or many
30 -; ~munlclpal ~nd lndustrlal uses have elther not been attalned or
h~ve requlred the use of relatlvely large amounts of the polymer
~flocculants. Thus, ln the case of coal wash waters, for example,
the use of polymer flocculants alone have not provided the
~:
.. . . . .
11~4(~79 :--
clarities desired.
According to the present invention, there is provided a method
for clarifyin~ an aqueous suspension of finely divided solids, said suspen-
sion beingselected from the group consisting of
(1) ooal wash water
(2) coal oe ntrate
(3) iron ore slime
(4) raw water and
(5) raw sewage,
CQmprising treating said suspension with a polymeric flocculating agent
and an aqueous said colloidal sollution of a meLamine/formaldehyde resin
containing fram 2 to about 12 moles of formaldehyde per mole of melamine
provided that:
(I) in treating said suspension (1), the polymeric flocculating
agent is selected fmm the group consisting of an anionic partially hydrolyz-
ed polyacrylamide, an anionic partially hydrolyzed polyacrylonitrile and
an anionic copolymer of acrylamide and acrylic acid or its salts; and the
aqueous acid colloidal solution of melamine/formaldehyde resin contain
from 4 to about 12 moles of formaldehyde per mole of melamine;
(II) in treating said suspension (2), the polymeric flocculating
agent is selected from the group consisting of an anionic partially
hydrolyzed polyacrylonitrile, an anionic partially hydrolyzed polyacrylamide.,
an anionic copolymer of acrylamide and acrylic acid or its salts and a
non-ionic polyacrylamide containing less than 1% carboxyl groups; and the
aqueous acid colloidal solution of melamine/formaldehyde resin contains
from 4 to about 12 moles of formaldehyde per mole of melamine;
(III) in treating said suspension (3), the polymeric flocculating
agent is selected fram the group consisting of a cationic polydiallyldi- : . :
methylamm~nium chloride, a cationic amine/epichlorohydrin polymer, cationic
polyacrylamides, cationic aIkylene polyamines and a non-iQnic polyacrylamide
c~ntaining less than 1~ carboxyl groups; and the a~ueous acid colloidal
solution of melamine/formaldehyde resin contains from 4 to about 12 moles
4079
of formaldehyde per mole of melamine;
(rV~ in treating said suspension (4~, the polymeric flocculating
agent is selected fram the group consisting of a cationic amine/epichloro-
hydrin polymer, a cationic aminoaIkylated polyacrylamide, an alkylene
polyamine polymer and a cationic acrylamide/vinylamine copolymer; and the
aqueous acid collodial solution of melamine/formaldehyde resin contains
from 2 to about 12 moles of formaldehyde per mole of melamine;
(V) in treating said suspension (5), the polymeric flocculating
~ agent is a cationic aminoaIkylated polyacrylamide, a cationic amine/epi-
chlorohydrin polymer, a cationic acrylamide/vinylamine copolymer or a
cationic aLkylene polyamine; and the aqueous acid colloidal solution of
melamine/formaldehyde resin contains from 2 to about 12 moles of formalde-
hyde per mole of melamine.
In accordan oe with the present invention, it has now been found
that the clarification of aqueous suspensions by the uæ of polymer floc-
culating agents is greatly improved if, in conjunction with the polymer
flocculant, the suspension is also treated with either a melamine/formalde-
hyde acid colloid or a formaldehyde-fortified, melamine/formaldehyde acid
colloid as defined hereinafter. Thus, it has been found that the use of
such an acid colloid in conjunction with the polymer flocculant in so~e
instanoe s provides suFernatant clarities not obtainable by the use of the
polymers alone, even at high dosages; and generally, permits the use of
substantially reduced amounts of the polymer flocculant without sacrifi oe
of the clarity obtained using the polymer flocculant alone. Accordingly,
it will be appreciated that the use of the acid colloid in cambination
with the polymer flocculant in accordan oe with the invention provides not
only improved water clarities over those attainable by the use of the
polymer flocculants alone but can also provide considerable savings in
polymer usage. That the use of the acid colloid in conjunction with the
polymer flocculant would provide such ~arkedly superior results as ccmpared
to the use of the polymer flocculant alone was surprising sin oe the acid
colloid itself would not ke e~pected to exhibit flocculating activity due
- 4a -
'
- . . .
- 1~140~9
to its lcw molecular weight. Applicant does not kncw for certain why the
acid colloid provides the improved results. Without limiting the invention
to any theory, however, it is considered that the acid colloid, which is
highly cationic, effectively neutralizes the negative charges usually
associated with the suspended particles thereby making them more readily
flocculated by the polymer flocculant.
The Melamine/Formaldehyde Acid Colloids
Ihe melamine/formaldehyde acid colloid and the
- 4b -
.~ .
.. . . , . - .
.
7~9
form21dehyde-fortified, mela~ine/formaldehyde acid colloid
employed in the invention are well-known materials. The mela-
mine/formaldehyde acid colloid is shown in United States No. 2,345,543.
Thus, as shcwn in the patent, the colloid is prepared by reacting the
melamine with formaldehyde in the presence of a defined amount of -
acid and sufficient water to provide an aqueous solution of a melamine/
formaldehyde condensation product (resin) having a pH of from about
0.5 to about 3.5 when measured at 15% solids and then aging the acid
solution until the resin is converted to colloidal form as evidenced
by the appearance of a blue colloidal haze in the solution. The
colloidal resin solution thus provided contains about 2 - 3 moles of
formaldehyde per m~le of melamine.
Alternatively, the colloid resin solution may be pre-
pared by first forming the melamine/formaldehyde (trimethylol
melamine) resin in the absen oe of the acid and then converting
the resin to the colloid by dissolving it in an aqueous acid
of the required pH and aging the acid solution until colloid
formation is effected.
m e formaldehyde-fortified, melamine/formaldehyde
acid colloid used in the invention is disclosed in United Stated Patent
No. 2,986,489. Thus, as shown in the patent, this colloid
is formed by reacting the melamine/formaldehyde resin acid
cDlloid solutions described in Uhited States No~ 2,345,543 with addi-
tional formaldehyde and aging the solution until the resulting
formaldehyde-reacted resin is converted to colloidal form.
Alte m atively, a melamine/formaldehyde (trimethylol
melamine) resin prepared in the absenoe of aqueous acid (i.e.,
in non-colloid fonm) may be reacted with the additional formal-
dehyde and then converted to colloidal form by dissolving in
acid solution and aging to form the formaldehyde-fortified colloid.
-- 5 --
~ .
111407~
For the purpose Or the present lnventlon, the amount
Or formaldehyde reacted with the melamlne/formaldehyde resln
1~ ~rom about 2 to about 10 moles per mole of comblned mel~mlne
ln the resln and preferably from 3 to 8 mole~ since these
amounts provide formaldehyde-fortifled products which are the
most effectlve for use ln the present lnventlon. Thus, as
opposed to the unfortiPled mel~mlne/formaldehyde colloid, whlch
contalns 2-3 moles of formaldehyde per mole Or melamlne, the
~ormaldehyde-fortifled collold contalns a total of from about
4 to about 12 moles, preferably from about 5 to about 10 moles,
Or formaldehyde per mole of mel~mine.
A typlcal formaldehyde-fortified, acid colloid prod-
uct ~or use in the present lnventlon was prepared as follows:
To 114 p~rts Or commerclal spray-drled trlmethylol melamine in
69B parts of hydrochlorlc acid of such strength as to provide
0.5 mol o~ HCl per mol o~ comblned melamlne present there was
added 188 part~ o~ 37% aqueous ~ormaldehyde solution (5 mols
per mol of combined melamlne in the acid solution). After
gentle stlrring for a few mlnutes, the regulting solution was
aged for 16 hours at room temperature, during which time the
solutlon had developed a blue haze characteristic of the acid
collold. The resultlng formaldehyde-fortified, melamine/form-
~ aldehyde acid colloid solution (pH = 1.3) 18 identifled here-
; ~ lnarter as "Colloid Solutlon A".
A typlcal, non-formaldehyde-fortified catlonic mela-
mlne/formaldehyde acld colloid used in the invention was pre-
pared as follows: A solution Or 114 parts of commercial spray-
drled trlmethylol melamine in 886 parts of hydrochloric acid
of such strength as to provide o.65 mols of HCl per mol of com-
`:
30~ bined mel~mine present was prepared and permitted to age for 16
hours at room temperature during whlch time it had developed
the blue haze characteristic o~ the acld collold. Thl 8 collold
solution 18 identlfied herelnafter as "Collold Solution B".
- 6
:
~ 11 4 ~7 ~
The marked lmprovement in the flocculatlon and clari-
flcatlon of varlous types of solld suspenslons when the afore-
descrlbed acid collolds are used ln conJunction wlth particular
type~ Or hi~h molecular welght polymer flocculants, a8 found
by the present lnventlon, i8 lllustrated by the ~ollowing exam-
ples. It will be appreciated ~rom the examples that the ~orm-
aldehyde-fortl~led collold, ln conJunctlon with the specl~ied
polymer ~locculants, provldes superlor clarltles to tho~e pro-
vlded by the unfortl~ied colloid in the treatment of high solids
sUspenslon~ i.e., su8penslons contalnlng more than about 0.5%
by welght o~ suspended sollds, such as coal wash water, coal
centrate and iron ore sllmes (Examples 1-6).
It wlll be further appreclated ~rom the examples that
elther one of the collolds of the lnventlon, when used in con-
~unctlon wlth the speclfled polymer ~locculants, provldes
8uperlor clarltles to those provlded by the employment of the
polymer8 alone ln the treatment o~ low solld8 su8penslons, l.e.,
tho8e contalnlng less than about 0.5~ by welght Or suspended
8011ds, such a~ raw water and raw sewage (Examples 7-11).
Accordingly, for the treatment o~ these suspenslons, melamlne/-
formaldehyde acld collolds having from 2 to about 12 moles of
ormaldehyde per mole of melamlne may be used.
EXAMPLE 1
Clarl~lcatlon tests were conducted on spent coal wash
~;~;25 water, from a West Vlrglnia coal preparation plant, containing
3-4% sollds comprised o~ about 90~ clay and about 10% ~ine coal
part~cles, by treatlng the wa~h water with typical commercial
polymer flocculants alone and In combination wlth a typical
forxaldehyde-fortifled~melamine/~ormaldehyde cationic acid col-
30~ 101d of~bhis inventlon, vlz., Colloid Solution A (CS-A). The
polymer flocculants used were as ~ollows.
Polymer C: An anlonlc, hydrolyzed polyacrylonitrlle
havlng ~ molecular welght o~ approximately 200,000 and contaln-
ing about 70% carboxyl and about 30~ acryl~mide groups.
- 7
4079
Polymer D: An anlonic hydrolyzed polyacrylamide hav-
lng a molecular welght of 12-15 mllllon containlng about 35
carboxyl groups,
The te~t procedure was as follows: A given amount
of the polymer ~locculant ln the rorm of a dilute aqueous solu-
tlon thereof and/or the collold of the inventlon (as Collold
Solutlon A, i.e,, CS-A) 18 added to a l-llter sample of the
coal wQsh water in a l-llter graduate cyllnder. The treated
sample 18 then stroked up and down slx tlmes wlth a perforated
metal plunger to ~orm a substantlally homogeneous mlxture. It
i8 then permitted to stand until the compacted solids are at
the 200 cc. level at whlch polnt the turbldlty o~ the supernate
18 measured uslng a Helllge Turbidlmeter.
The test results are glven in Table I. (In Table I
8nd all o~ the followlng Tables, the concentration of CS-A or
CS-B 18 gIven ~8 ppm. calculated as trlmethylol melamlne.)
TABLE I
Amount Added ~P~m.) ( )
Test No. Polymer CPolymer D CS-ATurbidity(2)
l --- --- 4 1500
2 2 -__ __ 365
3 l --- 2 90
~, ~. . ,
4 1.2 2.6 -- 175
~5 1.2 1.3 4 50
. : 6 o. 6 1.3 4 117
)Ba~ed on total volume (1 llter) of suspension; l ppm.
e~uals 1 milligram per liter.
(2)Parts per mllllon o~ suspended solld~.
As can be 6een from Table I, while the formaldehyde-
.
a~ for;tlrled colloid itsel~ 18 relatively lne~ective, it markedly
lmprove~s~the~erfectlvenes~ of the polymer flocculants. Thus,
r` the u8e of the relatively inexpenslve colioid agent affords a
conslderable economlc advantage from the ~tandpoint of reduced
u~uage Or the relatively expenslve polymer flocculants.
-- 8 --
.
4 ~7
EXAMPLE 2
-
A serles o~ rlocculatlon tests were conducted on a
centrlruge centrate ~rom the Mohave generatlng statlon ln
Nevada, whlch resulted rrom the dewatering o~ a 70~ slurry of
coal rlnes in water. The centrate contalned 4% sollds (about
95% coal and 5% clay) and had a pH ad~usted to 6.8 wlth H2S0~.
The te~t procedure was the same as ln Example 1. In thls
series one of the polymer flocculants used was a polyacrylamlde
containlng less than 1% carboxyl groups and having a molecular
weight of 12-15 million (Polymer E). The test result~ are
8hown ln Table lI.
TABLE II
_ Amount Added (~pm.)
Test No.Polymer C Polymer E CS-ATurbidity
1 30 15 __ 460
2 10 10 10 90
10 lo ?0 45
Here again, as in Example 1, it i8 seen that the
~ormaldehyde-~orti~ied acid colloid markedly lmproves the
~ef~ectiveness of the polymer rlocculants, provlding superlor
reaults at reduced flocculant d~sages.
EXAMPLE
: .
As has been stated hereinabove, the formaldehyde-
~ortlf1ed melamine/formaldehyde acid collold employed ln the
~` present lnventlon ls markedly superior to the unfortified
melamlne/formaldehyde acid colloid a8 a ~locculant aid for use
ln con~unction with polymer flocculants for thé treatment of
high sollds suspensions. This superiority is shown by the fol-
lowlng tests in which the fortifled colloid, Collold Solution A
30~ (CS-A3 and the un~ortified colloid, Colloid Solution B (CS-B)
wer~ used in con~unctlon with two typical commercial polymer
locculants, ~iz., Polymer C (supra) and Polymer L, a copolymer
of 70~ acrylamlde and 30% ~cryllc acld having a molecular welght
: _ g _
111407~9 1
^
o~ about 5 million. The testa were made on the s~me type of
coal refuse slurry tested in Example 1 usine the test procedure
of Example 1. The results are shown in Table III.
TABLE III
Amount Added (Ppm~)
Test No. Polymer C Polymer L CS-A CS-B Turbidit~
1 3.o ______ ___ 1200
2 2.0 --- 2.0 --- 65
3 , 2.0 -__ ___ 2.0 115
4 ___ 2.0 --_ ___ 1500
--- 1.0'3.0 --~ 175
6 ___ 1.0 --- 3.0 45
As shown in Table III, Colloid A improves the e~fi-
clency o~ the polymers to a much greater extent than does
Collold B. ',
EXAMPLE 4
The super10r1ty of the ~ormaldehyde-~ortl~ied colloid
: Or the inventlon over conventional, non-colloldal, catlonic
' r-slns as ~locculant aids 18 evldent ~rom tests conducted on the
,~ 20 ~same type of coal refuse slurry used in Example 1. m e resins
tested were (a) ~ urea-~ormaldehyde-diethylenetrlamine cationic
'oondensation resln (Resin I) and (b) an adiplc acid-diethylene-
'trlamine-epichIorohydrln catlonic condensatlon resin (Resin II).
~"'~ The;~locculant polymer used was Polymer C (supra). The tests
25 ~ were~conducted as in Example 1. The results are ~hown ln
T~ble ~V.
~ ,
ABLE IV
Amount Added (ppm.)
Test~No.~ Polymer~C;~ CS-A ;Resln I Resln II Turbidity
2 ~ }.0 2.0 ~ - go
,,
3 ~ l. o: ; --- 3. o ___ 610
4~ .o --- --- 2.0 630
. . . . . . .. .
`79
-
Whlle, aB shown in Table IV, the other reslns glve
improved clarlty, the lmprovements are not nearly as good as
that obtalned wlth the collold.
EXAMPLE 5
A serles of tests were conducted on a taconlte (lron
ore) ~lime from Mlnnesota contalnlng 3-4~ sollds by the same
procedure used ln Example 1. In thl~ serles the polymer ~loc-
culants used were (a) polydlsllyldlmethylammonlum chlorlde
(p-DA~M), a catlonlc polymer, (b) a nonion$c polyacrylamlde
havlng a molecular weight of 3-5 mlllion (Polymer F) and (c) a
cationic amlne/epichlorohydrln condensatlon polymer (A/E~I).
TABLE V
Amount Added l~m.)
15 Test No. ~ymer F ~-DADM A/EPI CS-A Turbidity
1 0.15 ---- ---- 530
2 0.10 ---- ____ 0.25 115
3 ---- 0.50 ---- ---- 390
4 ____ 0.25 ~ 0.25 175
___ ____ o,50 __ _ 325
~6 ---- _-__ 0.25 0.25 145
As shown ln Table V, a marked improvement in super-
natant;clarlty is obtained by uslng the formaldehyde-fortified
acid~collold ln con~unotion with the polymer flocculants.
~ ~ EXAMPLE ~
It 18 also observed that the formaldehyde-~ortified
. ~ .
melamlne/~ormaldehyde acid collold provldes superlor clarlty,
ove-r the un~ortlfled collold ln conJunction with polymer floc-
culànts, ~or;treatment of iron ore 611mes. The superiority is
shown~b~the~following~test re8ults in whlch the fortifled
;collold,;~Collold~Solution A (CS-A) and the un~ortified colloid,
Collold Solution B (CS-B) were used in con~unctlon with two
typ~cai commerclal polymer ~locculant~, vlz., Polymer F and a
.. , , . . . _
. .
.
4 ~7 ~
catlonlc amlne/eplchlorohydrln polymer (Polymer G) The te~ts
were made on the s~me iron ore sllme as Exnmple 5 by the same
procedure u~ed in ~xample 1. The results are glven ln Table VI.
TABLE VI
Amount Added, (ppm.)
Test No. Polymer F Polymer G CS-A CS-~ Turbidity
1 0 2 ~ - 325
2 0.1 ---- 0.3 ~ 90
3 0.1 ---- ---- 0.~ 175
4 --- 0.50 ---- ---- ~25
--- 0.25 0.25 ---- 145
6 ___ 0.25 ____ 0.25 230
EXAMPLE 7
When polymer~ alone are used to clarify low solid~
~u6pension8, a llght haze is usually left in the treated water,
even at optimum polymer dosage. In the followlng te~ts, Colloid
Solutlon A (CS-A) was used in con~unction wlth a commercial
catlonic amlne-epichlorohydrin condensation polymer (Polymer G,
sUpra) to clarify samples of water ~rom Lake Houston, Texas,
having an initlal turbidity of 100 Jackson Turbidlty Units
(JTU) as measured on a Hach, Model 2100A turbidimeter calibrated
with Formazin 601ution. In each case, the polymer was added
prior to the colloid. The test procedure was as follows. One-
lit~r samples o~ water were stirred wlth an electrlc paddle
8tirrer at 100 rpm for one minute after each reagent was added,
then at 30 rpm for 15 minutes. The su~penslon was allowed to
settle ~or 30 minutes~a~d turbldities of the supernate measured.
The re~ults are sh~Wn in T~ble VII.
, ':
.
- 12 -
.
.. . . - . . . : . . . ::
`` lil4079
ABLE VII
Amount Added (ppm.)
Test No. Polymer G CS-A Turbldity fJTU)
1 3 0 5.5
` 2 2 1 3.0
3 4 0 4.6
4 3 1 2.
6 0 2.8
6 4 1 1.8
7 10 0 2.6
8 6 1 1.0
9 4 5 0.59
0 2.7
11 10 1 0.74
12 10 5 o.45
As shown in Table VqI, the formaldehyde-fortified acid
collold markedly improves the effectivenesæ oi the polymer, pro-
vldlng superior results at reduced polymer dosages; and, ln
some lnstances, at lower total reagent dosages.
~ EXAMPLE 8
;~ 25 Similsr tests to those oi Example 7 were run on
: another highly colloidal sample of Lake Houston water which had
. an lnitial turbldlty o~ 56 JTU and the results are shown ln
Table VIII.
~: :30 ~
.
.
40q9
TABLE VIII
Amount Added (ppm.)
Test No. Polymer G CS-A CS-B Turbldlty (JTU)
1 . 20 2 0 7.7
2 20 0 2 8.2
3 20 4 o 3,5
4 20 o 4 3,~
8 o 1.7
6 20 0 8 1.7
. It i8 e~ident from the data ln Table VIII that the
regular acld colloid and the ~ormaldehyde-~ortified acld colloid
are equally effectlve ln clarifying thls raw water.
EXAMPLE 9
Followlng the procedure of Examples 7 and 8, tests
were carrled out on samples of Ml~sisslppi rlver water whlch
had an inltlal turbldlty of 18 ~TU. In these tests, the floccu-
lant polymer u~ed was a commerclal catlonic amine-epichloro-
hydrln conden~ation polymer (Polymer G, supra). The test
results ~re shown ln Table IX.
~ TABLE IX
: Amount Added (~pm.~
Test No. Pol.vmer G CS-B Turblditv (JTU)
1 0 0 14
2 0.5 0 7~3
3 0.5 1.0 ~.6
4 1.0 0 7.0
1.0 1~0 2.8
6 2.0 0 8.5
Agaln, the co-use of the regular acid colloid produces
tr~ated water wlth better clarltle~ than can be obtalned no
m~tter how much of the catlonlc polymer is u~ed.
- 14 -
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: . .
~ ` 111407~
EXAMPLE 10
Low turbldity water~ are extremely dl~ficult to
clarlfy with polymerlc flocculants. Te~ts ~ollowlng the same
procedure as ln Examples 7-9 were conducted on samples o~
Rlppowam River (Conn.) water (lnltlal turbldity 1.5 JTU~ uslng
Polymer K ln comblnatlon wtth Collold Solution A and ln comblna-
tlon wlth Collold Solution B. No improvement in turbidlty at
all was observed at any dosage when Polymer K, a catlonlc amlno-
alkylated~;polyacrylamlde, was used alone. The results with the
co-use o~ the acid collold are glven ln Table X.
TABLE X
Amount Added (~m.)
Tost No. Polymer K CS-A CS-B Turbldlty (JTU)
1 0.5 1 0 0.7
2 0.5 0 1 0.74
3 0.5 4 0 0,40
4 ; 0.5 0 4 0.45
. !
Remarkably clearer water resulted by use of the
catlonic collolds along wlth Polymer K and no difference in
, ,
porrormance could be observed between the use of CS-A or CS-B.
EXAMPLE 11
~ . .
The polymer flocculants alone are of limlted effec-
tlvenesa for the re~oval of the very flne particles from raw
~25~ sewage, even at la~rge dosages. However, by using the formalde-
hyde-rortirIed acld collold in comblnatlon with the polymer,
~;~ the e~rcctivenes~ o~ the polymer i8 greatly increaaed as shown
by t-sts~made~on raw~ewage from a municipal sewage treatlng
p ~ ~havlng~an~lnltlal turbidity of 38 JTU. Two commercial
0~ polymer~locculants~were used in these;tests, viz., a hlgh
molecul~r~welght cationlc amlnoalkylated polyacrylamide tPolymer
K) and an~anlonic hlgh molecular weight polyacrylamlde
(Polymer~D~supra). The test procedure was the same as in
~ ~.
. .
lllA07~ .
Example 7. The results arc given ln Table XI.
TABLE XI
Amount Added (P~m.)
Test No. Polymer K Polymer D CS-A Turbidlty_(JTU)
l- l.O --- 0.0 18
2 0.1 --- 2.0 15
3 0.1 --- 5. 5-~
4 o.l --- 8.o 1.7
--- 0.5 0.0 17
6 --- 0.1 5.0 6.6
As evidenced ~rom the foregoing Examples, the catlonic
melamine-formaldehyde acid colloids markedly improve the floccu-
latlng effectlveness o~ specific types of polymer rlocculat1ng
agents, when empioyed in conJunction with the polymers, in the
~ieatment of specific types of aqueous solids suspension. In
the case of cationic and nonionic polymers, the improved floccu-
latlng effect is achleved whether the colloid 18 added to the
~u~pension to be clarl~ied before, after or simultaneously with
the polymer flocculant; however, in the c~se of anionic floccu-
l~ants, tho colloid must be added separately (either before or
after the polymer addition) in order to avold electrostatic
lnteraction of the oppositely charged materials. The amount of
the polymer used will, of course, vary depending on the particu-
-
lar polymer and the suspension being treated. Generally, only
very small amounts are required, i.e., from about 0.1 to about
50~parts per mi}llon, and usually from about 0.10 to about lO
parts per million. In practice, the optimum amount ln any
g1ven case can be readily determined by test. The amount o~ the
-oolloid to be used ln conJunctlon with the polymer flocc~lant
will also vary wlth the polymer u~ed and the suspenslon belng
treated. Oenerally~ effective (enhancing) amounts wlll range
. ," , . .
- 16
.. j .. ... . .. . ..... . . .
----` lllAC~79
~rom about one-tenth the amount of the polymer used up to 200
tlmes the ~mount of polymer used, and the optlmum amount can,
of course, be determined by test.
.,
,. .
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~ ~ .
~ ~ .
~25~ `
, ,
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